Woodcrete

University College Cork
Coláiste na hOllscoile Corcaigh
Dept. of Civil & Environmental Engineering
Woodcrete – “Creating a homogeneous composite that integrates
wood with concrete at molecular level”
Authors: Brendan O’Connell & Mark Enright
Supervisor: Dr Y. S. Fan
Submitted as part of BE (Civil) degree
Module CE4002
March 2012

Woodcrete – “The creation of a homogenous composite integrating wood with concrete at molecular level”
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Acknowledgements
The completion of this project is due to the help and guidance of a number of people. Firstly we
would like to express our gratitude to our supervisor Dr Yong Song Fan for his knowledge and
direction throughout the course of the year. Dr Fan’s expertise with concrete and novel insight
into homogenous composites has proven invaluable to this project.
We would also like to take this opportunity to thank the following people for their help with the
project:
- Mr Anthony Flaherty and Mr Michael McLoughlin for their time and assistance in sourcing,
ordering and procuring the various, materials, chemicals and apparatus required for the
experimental program.
- Mr Jim Holland and Ms Theresa Dennehy of the Food & Nutritional Sciences Department,
UCC, for instructing us in the use of and supplying the cold finger chiller apparatus and the
sonication unit.
- Dr Denis Kelliher for his assistance in testing the sample strips.
- Goulding Ltd. for providing the chemical Urea.
- Rainbow Glass Ltd. for providing glass plates.

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Table of Contents
1.0 Executive Summary................................................................................................................ 6
2.0 Introduction............................................................................................................................. 8
3.0 Literary Review .................................................................................................................... 13
4.0 Experimental Preamble......................................................................................................... 47
5.0 Laboratory Testing................................................................................................................ 58
5.1 – Dissolving of Cellulose.......................................................................................... 58
5.2 – Integration of OPC with dissolved Cellulose Solution.......................................... 69
5.3 – Integration of GGBS with dissolved Cellulose Solution ....................................... 74
5.4 – Strength testing of OPC/MCC based Woodcrete Composite ................................ 78
5.5 – Strength testing of GGBS/MCC based Woodcrete Composite ........................... 100
5.6 – Integrating AAC with a Dissolved Cellulose Solution........................................ 117
6.0 Conclusion .......................................................................................................................... 127
7.0 General Appendages........................................................................................................... 130
7.1 Acronyms / Abbreviations...................................................................................... 130
7.2 Bibliography ........................................................................................................... 132

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1.0 Executive Summary
This projects primary objective is to illustrate that the integration of Nano-cellulose fibres,
derived from wood pulp, with concrete creates a homogenous composite that is a viable modern
construction material. Cellulose is the most abundant natural polymer on the earth with
approximately 33% of all plant matter being cellulose (Sjostrom). The molecular structure of
cellulose consists of a series of Hydrogen bonds, which are very strong, thus the idea of using
this natural polymer as a sustainable alternative for use as reinforcement in a composite material
is extremely lucrative.
A series of processes must be undertaken in order to successfully create this environmentally
green bio-material. The most important phase is the initial part of the project, whereby the
Nano-cellulose fibres are dissolved in an aqueous solution using various temperature settings and
the chemical procedures. This process is of paramount importance as the cellulose fibres must be
totally dissolved in solution in order to successfully integrate the cellulose matrix within
concrete. This cellulose solution is then integrated with the concrete agents Ordinary Portland
Cement (OPC) and Ground Granulated Blast furnace Slag (GGBS) to form a composite material
containing both wood fibres and concrete, hence the composites name “Woodcrete”. As only
novel research has been done on this integration process, it is still very much at its early stages.
Thus the laboratory work involved a large amount of trial and error. Finally these composites
were then analysed and their properties compared to existing composite materials.

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2.0 Introduction
2.1 Project Background
In the modern construction world, building practices rely enormously on reinforced concrete
as its primary material, it is the world’s second most used material and over 7.5 million cubic
kilometres of it are manufactured every year. Roughly 10-15% of global CO2 emissions originate
from the concrete production process, with over 90% of these emissions coming from the
manufacture of cement. For every tonne of cement produced, approximately a tonne of CO2 is
released into the atmosphere (Proost, 2002). These figures are predicted to dramatically increase
in the following decade with the rapid development of Asia and South America and the tendency
for new construction to focus on high density development. Thus, the need for a more
environmentally friendly form of concrete is enormous and is drawing a significant amount of
research and investment. There is a universally accepted need to reduce the asymmetrical global
energy demand of both developed and developing countries, therefore there is a massive market
for environmentally green bio based materials such as Woodcrete. It is evident in modern times
that there is a societal shift towards generating more eco-friendly products to ensure that the
annual level of CO2 emissions is lowered significantly.
At the moment the carbon dioxide level in the earth’s atmosphere is 380 parts per million
(ppm), if changes are not made rapidly the carbon dioxide level could increase to over 800ppm
(Eatmon, 2009) which is an extremely environmentally harmful level. Thus, for the sake of
future generations this is a field of great interest and importance.
The ready-mixed industry makes up nearly 75% consumption of cement and this represents a
significant market opportunity for the possible use of wood pulp fibre in ready-mixed concrete
applications. The integration of cellulose fibre into the mainstream ready mix can potentially
have an abundance of benefits such as:
 Fibre and cement matrix bond
 Alkaline stability
 Freeze-thaw durability
 Plastic shrinkage cracking resistance
 Combustibility

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 Fire resistance
 Impact resistance.
This project comprises of an investigation on creating a homogeneous composite that
integrates wood with concrete at molecular level. It is envisaged that this composite material
could eventually be utilised as a sustainable alternative to the concrete that is currently used on
construction sites worldwide. The project itself incorporates a broad literature review into
Nano/micro wood based reinforcement materials, the procedures involved in successfully
dissolving them in an aqueous solution and an extensive laboratory programme, whereby the
discoveries of this literature review are assessed and evaluated.

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2.2 Project Aims & Objectives
Throughout the course of this project there was a series of aims and objectives that were set out
to be achieved, they are listed below in order of importance:
1. The Primary objective of this project was to create an environmentally green
homogenous composite that effectively integrates wood with concrete at molecular level.
2. This firstly involved the task of attempting to successfully dissolve cellulose into an
aqueous solution. Additionally the projects ambition was to examine the most efficient
method of dissolving the cellulose, with numerous procedures studied.
3. The next aim was to integrate this cellulose solution with a cement mix (Ordinary
Portland Cement, Sand & Sodium Silicate) and investigate whether this composite
material possesses the physical properties and attributes required of a modern
construction material. This will be done by testing the composite mixtures for various
properties and then comparing this to materials used in modern construction.
4. In addition the project investigated whether this cellulose solution could be effectively
integrated with other materials such as GGBS, Slag and Electric-arc Furnace Slag.
5. The sociological properties of large scale production and manufacturing coupled with
their environmental impacts are also studied.
6. Finally, the overall objective of this project was to produce a homogenous composite
successfully integrating cellulose and concrete at molecular level that is an economical
and environmentally green alternative to standard concrete.

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2.3 Project Methodology
Due to the fact that this is a relatively novel research field a chronological review of past
research would not be very effective. Therefore it was decided to focus on the different
experimental procedures that were proposed, comparing and contrasting them to find the most
suitable and effective methods that could be replicated.
Therefore a broad study of the following general topics was undertaken:
 Wood Structure and Wood related products
 Sustainable Alternatives
 Bio-materials as reinforcement agents
 Cellulose as a reinforcement agent
 Environmental Effects
 Composite materials
 Dissolving cellulose in an aqueous solution
 Integration of cellulose and concrete
Research papers from multiple sources and various disciplines were gathered and studied. Once a
basic understanding of the concepts and materials was garnered, the focus was shifted to the
specific use of Nano-fibrils as a reinforcement agent in different media. From the research it was
deduced that the experiments involving the use of Microcrystalline cellulose (MCC) and
Carboxymethyl cellulose (CMC) would be the most effective to carry out in the laboratory.
Once satisfied that the experiments could be successfully performed, the required equipment and
chemicals were obtained from different suppliers. With the aid of Mr. Michael McLaughlin and
Mr. Anthony Flaherty the necessary equipment and apparatus was supplied from various
university departments.
Having the necessary chemicals, equipment and armed with the required procedures determined
from the literary review the experimental portion of the project was ready to commence.

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3.0 Literary Review
3.1 Wood Structure & Wood Related Products
Wood is one of nature’s unique, natural composites. Along with rock, wood was one of
humanities first materials. It was used as a ready weapon or as a fuel for fire. Since those early
beginning’s, wood has been the target of much technology and is still being researched not only
for improving the yield of forests but also for ways of better using the tree and the many by-
products of wood. Wood must be considered a valuable engineering material and should be
exploited to its fullest extent because it is environmentally friendly.
3.1.1 Wood Structure
Wood develops through photosynthesis, the chlorophyll in the tree converts carbon,
hydrogen and oxygen to sugar, starch and cellulose. The dry wood used an as engineering
material is composed of the following approximate percentages by weight: cellulose (50%),
lignin (16-33%), extractives (5-30%) and ash-forming mineral (0.1-3%) (Werkstoff).
Cellulose (C6H10O5): Is a high-molecular-weight linear polymer, it forms fibres that make up the
cell walls of the vessels and ducts. The cellulose forms cellular networks of ducts, vessels, fibre
rays and pits, which transport and store the extractives and minerals throughout the living tree.
Lignin: Is an amorphous polymer, it forms a matrix around the cellulose, much like the plastic
matrix in fiberglass. Through the removal of lignin, wood can be broken down into the fibres that
are used to make paper and other synthetics.

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Hemicelluloses: This is another polymer closely akin to cellulose. Like cellulose it breaks down
into sugars when chemically treated.
Ash-Forming Minerals: Include calcium, potassium, phosphate and silica.
Extractives: Have significant commercial value. They are removed by heating the wood in
water, alcohol or other chemicals.
It is important to note that most common engineering materials, such as steel, are isotropic,
which means that generally their strength is the same in all directions because they are
homogenous. Wood is anisotropic, meaning that it has greater strength in some directions, it is
not homogenous. This anisotropy develops as a result of the way a tree grows, with various
factors influencing the wood structure: cellular structure, branches and bending by prevailing
winds. The tensile strength and stiffness of wood are greater in the radial direction than in the
tangential direction. Rays that radiate from the pith outward on the tree tend to tie together the
layers of cells (tracheid’s) growing longitudinally. This directional strength results partly from
the complex structure of cell walls, which have long polymer chains of cellulose that form layers
running in varying patterns to reinforce each other. Primary covalent bonding holds together
these micro-fibrils, which are almost parallel to the cell axis. Weaker, secondary bonds operate
on the perpendicular axis.
Wood has a long history of use in construction dating back many centuries if not into
prehistory. Its applications have virtually covered the range of structural utilization except for
buildings beyond a few stories height. A number of favourable characteristics enhance the
suitability of wood for structural use:
 Durability
 Rate of Load application; Duration of Load
 Anisotropy
 Exposure to extremes of Temperature
 Dimensional Stability
 Resistance to Chemicals
 Strength & structural Design

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3.1.2 Wood Related Products
In the modern construction world, wood is considered a vital material and it has countless uses,
some of these are listed below:
 Commercial Lumber: Is a vital material for construction and manufacturing and is
graded as construction and remanufactured lumber based on the American Lumber
Standard.
 Composite Wood: To gain maximum use of trees and to achieve properties not possible
from solid wood, composite woods have been developed for use in construction and
manufacture. Examples of composite woods include:
o Laminated Timber: Is a product of adhesive-joining-technology. Through
adhesive bonding of pieces of lumber so that the grain of all pieces is parallel to
the length of the timber, it is possible to produce straight to curved structural-
wood members of large size and outstanding strength.
o Impreg-wood: Is a very stable lumber achieved by the bonding of phenolic resins
to the cell wall microstructure. Applications include sculptured models of huge
metal dies used to stamp automobile sheet metal parts.
o Wood & Recycled Plastics: Plastic lumber made of recycled plastics offers many
benefits including, it resists biological attacks and has no need of protective
finishes. Composite woods made from recycled milk jugs and recycled or
reclaimed woods take many shapes and come in a variety of colours. They serve
as replacement for wood decking, stairs and rails. These composite woods aid in
“greening” the materials cycle by keeping plastic out of municipal landfills.

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The pie chart below highlights the use of Wood Plastic Composites (WPC’s) worldwide (Wood,
2008).
Figure 3.1.2.1: Wood Plastic Composites worldwide
 Plywood: Is another form of laminate common in building construction. It is
produced by stacking layers of veneer with the grain direction in each layer at right
angles to the next, beginning with the grain running the length of the panel.
Numerous grades of Plywood are available and it is divided into interior and exterior
Plywood.
 Wood-Based Fibre & Particle Panel Materials: Particleboard panels, also known as
reconstituted panels, are produced through the use of thermosetting resins, such as
urea-formaldehyde and phenol formaldehyde, which serve as a matrix to bind
together wood residues or shavings in the form of small wood flakes, wood flour and
additives. Water resistance is improved through the addition of wax. Medium-density,
high-density or special-density hardboard offers high strength, wear resistance,
moisture resistance, and resistance to cracking and splinting and has good working
qualities.
 Sandwiched Materials: Doors and panels employ these materials. Fibreboards made
of wood fibres bonded with rosin, asphalt, alum, paraffin, oils, fire-resistant
chemicals, and plastic resins are used as insulation panels on walls and roofing to
which other materials is added.

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3.2 Wood Fibres
Wood fibres are the most abundant biomass resource on earth. They are hollow tubes made
up of cellulose embedded in a matrix of hemicellulose and lignin. The most important attribute
of wood is its mechanical properties, in particular its unusual ability to provide high mechanical
strength and a high strength-to-weight ratio while allowing for flexibility to counter large
dimensional changes due to swelling and shrinking.
Related challenges associated with wood fibres are:
o The selection of optimal sources for natural wood fibres
o Optimising fibre length and length distribution for enhanced reinforcing effects
o Special processing of wood fibres for enhanced fibre-matrix interactions
o Chemical/physical fibre treatment, functionalization
o Fibre dosing
The diagram below illustrates the process associated with wood fibre production (Ziegler, 2007).

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3.3 Composite Material
Composite materials, often shortened to composites or called composition materials, are
engineered or naturally occurring materials made from two or more constituent materials with
significantly different physical or chemical properties which remain separate and distinct at the
macroscopic or microscopic scale within the finished structure.
Wood is a natural composite of Cellulose fibres in a matrix of lignin (Lucia, 2007). The earliest
man-made composite materials were straw and mud combined to form bricks for building
construction. The ancient brick-making process can still be seen on Egyptian tomb paintings in
the Metropolitan Museum of Art.
Composites are made up of individual materials referred to as constituent materials. There are
two categories of constituent materials: matrix and reinforcement. At least one portion of each
type is required. The matrix material surrounds and supports the reinforcement materials by
maintaining their relative positions. The reinforcements impart their special mechanical and
physical properties to enhance the matrix properties.

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3.4 The need for Sustainable Alternatives
Sustainable energy is the sustainable provision of energy that meets the needs of the present
without compromising the ability of future generations to meet their needs. Technologies that
promote sustainable energy include renewable energy sources, such as hydroelectricity, solar
energy, wind energy, wave power etc. and also technologies designed to improve energy
efficiency. Moving towards energy sustainability will require changes not only in the way energy
is supplied, but in the way it is used and reducing the amount of energy required to deliver
various goods or services is essential. Recent concerns surrounding energy security and supply
have illustrated the volatile nature of oil prices. This price increase can be seen in Figure 3.4.1.
The increase in price and fears about the finite nature of stocks are further compounded by the
increased development of countries such as China and India. Their massive populations currently
have only minimal oil demand, but considering their aspirations to live more ‘Western
lifestyles’, with greater transport development, ownership and usage, and improved construction
practises, another continent with large petroleum consumption is likely to develop. This will
dramatically increase oil consumption, leading to in the very least an exponential increase in
price.
Figure 3.4.1: Oil Prices 1970 - 2012 (Mb50 World Press, 2012)

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Apart from the obvious cost and security benefits which would accrue from more
sustainable products and materials, another major incentive is the environmentally positive
attributes associated with sustainable products. Sustainable building is an essential aspect of
widening efforts to conceive an ecologically responsible world. Over the past decade anyone
involved in construction has had reason to question how their work product impacts the
environment and the resources future generations will rely upon. Whether compelled to do so by
regulators enforcing environmental responsibility, design professionals insisting on “sustainable”
construction products, or owners mandating more energy efficient buildings, demand for
sustainable construction has increased in an economy that has seen a sharp decline in more
traditional building practices.
A sustainable building must be constructed using locally sustainable materials: i.e. materials
that can be used without any adverse effect on the surrounding environment and which are
produced locally, therefore, reducing the need to travel. Building owners should exercise caution
when embracing sustainable construction. Although the need to protect our environment is
acknowledged and that sustainable construction should be integrated into the construction
industry, no building owner can truly benefit from a sustainable building if the building cannot
reach its expected service life without the need for unanticipated repairs. To that end, adopting
policies that encourage durability is a necessary step towards achieving sustainability.
Bio-fibres certainly suit this requirement. Cellulose fibres, the subject of this project, in their
micro and Nano-scales generated from biomass, are a relatively new concept as a reinforcing
material. They have shown potential due to being lightweight and having a high strength. The
fact that they are produced from a renewable source (mainly wood pulp and cotton) and are
biodegradable is an important element. The production of cellulose has been proven to be carbon
neutral and it possibly may be carbon negative product due to the carbon consumed during
assimilation. Studies have shown that when natural reinforced plastics were subjected, at the end
of their lifecycle, to a combustion process or landfill, the released amount of CO2 of the fibres is
neutral with respect to carbon consumed during their growth (Fink HP, 1994).

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Figure 3.4.2 shows oil consumption with respect to population.
Figure 3.4.2: Energy consumption per capita (Rosenberg, 2011)
In the last few years many investigations have been focusing on alternative reinforcing
elements. In the field of natural fibres, the properties of cellulose are excellent. They have a
modulus of elasticity similar to steel, they do not corrode, they have a very high tensile strength
and they are chemically inert. Due to the latter property, they are not influenced by aggressive
alkaline environment of the surrounding concrete and environmental boundary conditions (e.g.
chlorides) (Basche HD, 2000).

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3.4 Bio materials as Reinforcement Agents
Bio-based materials have attracted much attention as there is a rise in demand for renewable,
biodegradable and biocompatible materials. While Europe and North America are more focused
on petroleum based products, India and China continues to employ natural fibres as
reinforcement for composites. The long term disadvantage of dependence on synthetic materials
has been investigated and this has caused recent interest in natural bio products. These problems
with synthetic materials are primarily the adverse effects production has on the environment.
Synthetic material production requires significantly more energy than bio composites and
historically has been responsible for significant pollution. In addition to the environmental
problems relating to production, recycling synthetics has also proved problematic (Bledzki AK,
1995).
The possible uses of natural fibres in construction and material engineering in general are
extensive. Globally the construction industry consumes 50% of all natural resources, which is a
destructive and unsustainable trend. Environmentally, when the full life cycle is considered,
natural fibres are significantly better for the environment (S., Building with Hemp, 2005). For
example, cellulose is one of the most abundant and renewable natural polymers with low cost,
good compatibility with biological systems and remarkable hydrophilic properties. Utilising
cellulose as a raw material reduces the consumption of the limited petroleum and protects the
environment. Cellulose ((C6H10O5)n), the structural component of the primary cell wall of green
plants (and many forms of algae and the oomycetes), is the most common organic compound on
Earth. About 33% of all plant matter is cellulose (the cellulose content of cotton is 90% and 50%
for wood).
Glass fibres which have been shown to have a high value of strength can be compared to
glass fibre composites. Research shows that while the initial expenditure for flax fibre is about
30% more expensive, its end of life cost and its effect on the environment is reduced. Price is
dependant largely on the extent of fibre preparation and pre-treatment, e.g. finishing including a
coupling agent and other surfactant, which are well established for glass fibres. For such
applications, natural fibres have to be pre-treated in a similar way.

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In most cases the substitution of glass fibres is precluded first of all by economic reasons.
But natural fibres offer several advantages over glass fibres:
 The abrasive nature of natural fibres is much lower compared to that of glass-fibres,
which leads to advantages with regard to technical, material recycling or process of
composite materials in general.
 Natural fibre-reinforced plastics, by using biodegradable polymers as matrix are the
most environmentally friendly materials, they can be composted at the end of their
life cycle. Unfortunately, the overall physical properties of these composites are far
away from glass-fibre reinforced thermoplastics. A balance between life performance
and bio-degradation has to be developed (Fink HP, 1994).
 Plant fibres are a renewable raw material and their availability is more or less
unlimited.
 When natural reinforced plastics were subjected, at the end of their life cycle, to a
combustion process or landfill, the released amount of CO2 of the fibres is neutral
with respect to the assimilated amount during their growth.
While the hydrophilic characteristics of natural fibres do not tend to lead to composites with
weak interface, there exists many pre-treatments that are aimed at improving the adhesion
between fibres and the matrix. In pre-treatments, either hydroxyl groups get activated or new
elements are added that can effectively interlock with the matrix (Valadez-Gonzalez C. J.-F.,
1999).

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3.5 Use of Cellulose as Reinforcement Agent
Cellulose is the most abundant natural polymer found in nature. It is an organic compound
consisting of a linear chain of between several hundred and several thousand linked glucose
units. Its molecular structure is (C6H10O5) as seen below in Figure 3.5.1. It was first discovered
in 1838 by French scientist Anselme Payen when he noticed that the cell walls of a large number
of plants consist of the same substance, to which he gave the name cellulose.
Figure 3.5.1: Cellulose Molecular Structure
Natural plant fibres are constitutes of cellulose fibres, consisting of helically wound
cellulose micro fibrils bound together by an amorphous lignin matrix (Kalia S., 2009). Lignin
keeps the water in fibres. Lignin acts as a protection against biological attack and as a stiffener to
give a plant stem resistance against gravity forces and winds.

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The use of cellulose as a textile has been known and well documented over the last century.
It is the base product for biodegradable packaging cellophane and the material rayon is derived
from cellulose. Considerable interest has been recently focused on finding new material
applications for this biopolymer (A.K. Bledzki, 1999). One of these applications has been the
development of cellulose Nano-crystals. It is well known that native cellulose, when subjected to
strong acid hydrolysis, can be readily hydrolysed to micro or Nano crystalline cellulose (Goetz
L).
Figure 3.5.2: Location and arrangement of cellulose micro-fibrils in the plant cell wall
Because of their wide abundance, their renewable and environmentally benign nature and
their outstanding mechanical properties, a great deal of attention has been paid recently to
cellulosic Nano-fibrillar structures as components in Nano-composites. A first major challenge
has been to find efficient ways to liberate cellulosic fibrils from different source materials,
including wood, agricultural residues or bacterial cellulose. A second major challenge has
involved the lack of compatibility of cellulosic surfaces with a variety of plastic materials
(Hubbe A, 2008).
The mechanical properties of natural fibres are affected by many factors such as variety,
climate, harvest, maturity but also on its cellulose type. Each type of cellulose has its own

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geometry (length of polymer chains, orientation, degree of polymerization etc.). These
geometrical conditions have a large bearing on the properties. The tensile strength of natural
fibres depends on the test length of specimen which is of great importance with respect to
reinforcing efficiency. The tensile strength of flax fibre is significantly dependant on the length
of the fibre, according to the following references: (Kohler R., 1995), (Mieck K.P., 1994) and
(Mukherjee P.S., 1986). In comparison to this however, the tensile strength of pineapple fibre is
reported by (Kalia S., 2009) to be less dependent on the length, but the scatter of the measured
values is mainly in the range of standard deviation.
Cellulose has long been established as a possible polymer in composite materials, as
mentioned earlier, the household product cellophane was one of the first commercially
successful cellulose based composites. Studies have shown that there is huge potential for
utilising microfibrillated cellulose (MFC) as a Nano-composite with polylactic acid (PLA) to
achieve a material with properties which would allow it to compete with mainstream petroleum-
based plastics such as polyethylene (PE), polypropylene (PP), polystyrene (PS) and polyvinyl
chloride (PVC) (Simonsen J, 2009).
This report will focus on the possibility of using a cellulose-cement composite product in the
construction/engineering industry. While limited research exists in this area, all available
information and material supports the view that it is an area with huge potential. There are two
types of cellulose used in this experiment: Microcrystalline cellulose (MCC) and Carboxymethyl
cellulose (CMC).
In order to utilise cellulose as a reinforcement agent, the strong hydrogen bonds between
cellulose crystals must be separated and the cellulose crystals must be well dispersed in the
polymer matrices. MCC and CMC have attracted attention as a potential starting material for the
cellulose reinforced Nano-composites (Mathew AP, 2005). MCC is widely used as a universal
filler and binder in the pharmaceutical industry. The origin of the raw materials and the
production method can decisively influence the characteristics of MCC and CMC.

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3.5.1 Physical structure of cellulose fibres
All natural fibres consist of several cells. These cells are formed out of crystalline micro
fibrils based on cellulose, which are connected in layers by amorphous lignin and hemicellulose.
Multiple layers stick together to form the cell. These cell walls can differ in their composition
and in the orientation of the cellulose microfibrils.
The characteristic values of these structural parameters vary from one natural fibre to
another. The spiral angle of the fibrils and the content of cellulose, determines generally the
mechanical properties of the cellulose based natural fibres.
3.5.2 Engineered Cellulose Fibres
There have been a number of papers published over the years dealing with the structure and
properties of the cellulose based natural fibres.
Summarising experimental results from literature (Valadez-Gonzalez C. J., 1999) it becomes
clear that the mechanical properties of the man-made cellulosic materials depend on their
structure on different levels, depending on factors including:
 Degree of polymerisation (DP),
 Crystal-structure (type of cellulose and defects),
 Upramolecular structure (e.g. degree of crystalline regions),
 Void-structure (content of voids, specific interface, void-size), and
 Fibre diameter.
Generally, the tensile strength of these fibres is strongly influenced by the length of molecules as
shown for viscose and acetate type fibres. A linear correlation with a negative slope between
strength and inverse of degree of polymerization may be modified by orientation effects, by
variations of crystallite dimensions and crystallinity, by impurities and probably by pores and
non-uniform cross-section of the fibres (Valadez-Gonzalez C. J., 1999).

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The degree of polymerisation (DP) of wood is around 10,000 to 15,000 (Fengel D, 1989).
Each unit of cellulose contains three hydroxyl (-OH) groups. These hydroxyl groups and their
innate ability to form hydrogen bonds play a major role in crystal formation and also in
governing the physical properties of cellulose. In raw plant fibres, cellulose is present in an
amorphous state, but also associates to crystalline domains through both inter-molecular and
intra-molecular hydrogen bonding (Fengel D, 1989), (Klemm D, 2005). The fact that cellulose
has good mechanical properties, low density, its ability to biodegrade and availability from
renewable resources have become increasingly important and have contributed to a rising interest
in this material (Zimmerman T, 2005).
Recently, a considerable amount of research has been done on the isolation of Nano-fibres
from plants to use them as fillers in bio-composites (Azizi-Samir AS, Macromolecules, 2004),
(Takagi, 2008). Chemical and mechanical treatments of the cellulose fibrils result in chemical
and mechanical changes on the fibre cells and surface, which affect the properties of the fibre
composites (Zimmerman T, 2005). Acid hydrolytic processes are also used to degrade
amorphous cellulose in forming cellulose Nano-fibres. Traditionally, cellulose crystallites from
cellulostic materials were prepared using hydrochloric acid (HCL) and sulphuric acid (H2SO4)
hydrolysis and cellulose whisker were also obtained from microfibrils by acid hydrolysis
(Nickerson RF, Ind. Eng. Chem., 39, 1507, 1947), (BG, 1952).

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3.6 Dissolving of cellulose
Various methods were researched in relation to the dissolution of cellulose.
As the affluent biopolymer resource in the world, cellulose has attracted much attention for
preparing novel polymers and materials. However, a bottleneck question to cumber the
application of it is the dissolving of cellulose in a simple solvent system. The existence of the
crystalline in cellulose makes it difficult to dissolve. Some solvent systems have been found in
the last century such as ammonium thiocyanate, LiCl/DMAC etc. these may result in serious
environmental problems. A little green solvent has been developed such as NMMO, ionic liquid
and water-based solvent systems. Since the discovery that cellulose can be dissolved in a NaOH
aqueous solution, by freezing the suspension into an ice-state following a thawing process at
room temperature, it opens a new opportunity to dissolve cellulose in other aqueous solution.
Recently, efforts have been made on understanding why the dissolving of cellulose in alkali
aqueous needs a precooling process. Studies revealed that the NaOH-cellulose complex and the
hydration of alkali ions formation are the key factors to the dissolving mechanism. Solubilisation
of cellulose is limited into a narrow region of 8-9 wt. % NaOH and at temperatures of -4o
C and
below. The solubility of cellulose in NaOH aqueous solution is low, typically only 5-6% for
wood pulp, which limits the application of the solution. The stability of the solution is another
problem and it usually results in the formation of a gel in a short period of storage at room
temperature.
It has been found that cellulose can be easily and quickly dissolved in any of the pre-cooled
aqueous solution of LiOH/urea, NaOH/urea or NaOH/thiourea and produce stable cellulose
solution. The role of urea and thiourea is the acceptor of hydrogen-bonding, which connect the
hydroxyl groups in cellulose and prevent the regeneration of cellulose through the inter- and
intra- chains associated.
Some important investigations about the dissolution of cellulose in NaOH-based aqueous
systems are summarized in Table 3.6.1 on the next page. They are all successful dissolution
methods and conditions for cellulose. Table 3.6.1 reveals that NaOH/H2O solution can only
dissolve treated cellulose or cellulose with low DP such as MCC, whereas the NaOH/urea/H2O
and NaOH/ thiourea/H2O solution can dissolve cellulose with relatively high DP. Normally, it

Page 30
can be concluded that the dissolution of cellulose in NaOH-based aqueous systems is mainly
determined by:
 Cellulose materials and DP, such as cotton linters pulp, wood pulp, and MCC.
 Additives, such as urea, thiourea, and PEG
 Dissolution conditions, such as temperature, concentration, and time.
The amount of cellulose dissolved varies according to the process used. As known to us, there
are mainly three processes to dissolve cellulose in NaOH-based aqueous system:
 Freeze–thaw
 Direct dissolution in solvents
 Two-step dissolution process. (Haisong Qi, 2010).
Table 3.6.1: Dissolution methods and conditions for cellulose in NaOH-based aqueous systems (Haisong Qi, 2010)

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3.6.1 Freeze-Thaw Method - Dissolving of cellulose in PEG / NaOH aqueous solution
A new solvent system for cellulose was reported. The solvent is a mixed aqueous solution of 1.0
wt. % poly (ethylene glycol) (PEG) and 9.0 wt. % of NaOH. Cellulose powder was added at
room temperature and froze at -15o
C for 12 hours. This resulted in a clean solution of cellulose
and a homogeneous solution of cellulose formed in the new solvent system.
Figure 3.6.1.1 shows the photo of the dissolved cellulose in PEG/NaOH aqueous solution (a) and
the regeneration of cellulose (b) by adding dilute HCl aqueous solution into it. Clearly, the
cellulose solution is transparent at the beginning and some white cellulose aggregates appear
after adding acid, indicating the regeneration of cellulose.
Figure 3.6.1.1: Photos of cellulose aqueous solutions
.

Page 32
Figure 3.6.1.2: Polarized Optical Microscopy (POM) images of cellulose before dissolving (Yan L G. Z., 2008).
The dissolving process of cellulose in the new solvent system can be detected by polarized
optical microscopy (POM). As shown in Figure 3.6.1.2, the cellulose exists in aggregative state
before dissolving, the size of the aggregates is about several micrometers in diameter and tens
micrometers in length. However, the big aggregates disappear (Figure 3.6.1.2b) after a cooling-
thaw treatment of the cellulose in the 1.0 wt.% PEG/9.0 wt.% NaOH aqueous solution, and at the
end there forms a clean solution with some air bubbles induced under the strong stirring (Figure
3.6.1.2c), this indicates the complete dissolution of the cellulose. If the solution was dried in air,
cellulose should be regenerated and there forms many small aggregates as shown in Figure
3.6.1.2d. The size of the new formed aggregates is much smaller than the original ones, and the
fractal aggregates also indicate the dissolving of cellulose in the solution before drying. (Yan L
G. Z., 2008)

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3.6.2 Direct Dissolution – Dissolving Cellulose in NaOH / Urea aqueous solution
All cellulose composite films should be prepared from a cellulose matrix regenerated from
aqueous NaOH-urea solvent system on the basis of their temperature- dependant solubility. The
composite films will be isotropic and transparent to the visible light and should show good
mechanical properties. By varying the ratio of cellulose to the NaOH/urea aqueous solution, the
tensile strength and elastic modulus of the Nano-composites films could be tuned to reach 124
MPa and 5 GPa, respectively.
A series of novel transparent and photoluminescent regenerated cellulose films having
homogeneous structure, excellent transparency and high tensile strength were successfully
prepared from the cellulose solution through a “green” process (Qi, Chang, & Zhang, 2009).
This new pathway is a relatively low-cost, simple and essentially a non-polluting process, in
contrast to the viscose method with hazardous byproducts. Further, such cellulose films exhibit
good biodegradabilities and are safe, suggesting wide applications in the biomaterial and food
industrial fields.
A new cellulose solvent, 7 wt % NaOH / 12 wt % urea aqueous solution pre-cooled to -12o
C, has
been developed. To commence the method, 200 g mixture of NaOH, urea and distilled water
(7:12:81 by weight) should be precooled to -12.6o
C and 8 g of cellulose (C10) should be added
immediately with vigorous stirring for 5 minutes to obtain a transparent solution. Then the
suspension should be centrifuged at 6000 rpm for 5 minutes at 10o
C for removing air bubbles.
Then the resulting nearly transparent suspension should be spread on a glass plate to give a 0.25
mm thick layer and then it should be immersed into a coagulation bath of 5 wt % H2SO4 for 5
minutes at 25 o
C. (Qi H C. J., 2009)
Figure 3.6.2: Stress-Strain curves of cellulose composite films & pure regenerated cellulose films. (Qi H C. J.)

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3.6.3 Two Step Method – Dissolving Cellulose in NaOH / Urea aqueous solution
The two-step process is a new method for dissolvig cellulose in NaOH/urea aqueous system. The
two steps were as follows: (1) formation and swelling of a cellulose–NaOH complex and (2)
dissolution of the cellulose–NaOH complex in aqueous urea solution.
Figure 3.6.3.1: Photos of the Two-Step dissolution process of cellulose
The dissolution mechanism could be described as strong interaction between cellulose and
NaOH occurring in the aqueous system to disrupt the chain packing of original cellulose through
the formation of new hydrogen bonds between cellulose and NaOH hydrates and surrounding the
cellulose–NaOH complex with urea hydrates to reduce the aggregation of the cellulose
molecules. This leads to the improvement in solubility of the polymer and stability of the
cellulose solutions. By using this two-step process, cellulose can be dissolved at 0–5 o
C in
contrast to the known process that requires -12 o
C. Regenerated cellulose (RC) films with good
mechanical properties and excellent optical transmittance were prepared successfully from the
cellulose solution.
In the previous direct dissolution method, cellulose can be dissolved in NaOH/urea aqueous
solution at -10 to -12 o
C. To reduce the power consumption required to achieve the low
temperature needed in the direct dissolution method, a two-step process was investigated. An
attempt to dissolve the cellulose in NaOH/urea aqueous solution at relatively high temperature
(such as at 0 o
C) was made, resulting in slurry-type mixtures (Figure 3.6.3.1d). As shown in
Figure 3.6.3.1 a-c, the cellulose was swollen in 14 wt% aqueous NaOH solution pre-cooled to 0
o
C and then was dispersed and dissolved when 24 wt% aqueous urea solution pre-cooled to 0 o
C
was added. Finally, a transparent cellulose solution was obtained through this process (Figure
3.6.3.1c), with about 7 wt% NaOH and 12 wt% urea in the solution. This experimental
phenomenon further supported the previous conclusion that NaOH ‘‘hydrates’’ can be more

Page 35
easily attracted to cellulose chains through the formation of new hydrogen-bonded networks,
while urea hydrates can possibly be self-assembled at the surface of the NaOH hydrogen-bonded
cellulose to form a transparent cellulose solution.
Figure 3.6.3.2: Schematic diagram of the solubility of NaOH-cellulose complex.
Figure 3.6.3.2 shows the schematic diagram of the solubility of NaOH–cellulose complex, which
was prepared from aqueous NaOH solution with different temperatures and concentrations, in 24
wt% aqueous urea solution pre-cooled to 0 o
C. The diagram reveals that the NaOH–cellulose
complex prepared from 12 to 18 wt% NaOH aqueous solution at –2 to 6 o
C could be dissolved
completely to obtain a cellulose solution, as shown in Figure 3.6.3.2 area I. Otherwise, the
cellulose could only be dissolved partially (Figure 3.6.3.2, area II) or even could not be
dissolved (Figure 3.6.3.2, area III).
Figure 3.6.3.3: Schematic diagram of the solubility of NaOH-cellulose complex.
The dissolution of the cellulose–NaOH complex, which was formed from 14 wt% aqueous
NaOH solution pre-cooled to 0 o
C and in an aqueous urea solution with different urea (curea) and
temperature was also investigated (Figure 3.6.3.3). For aqueous urea with too low or too high
concentration, the cellulose could only be dissolved partially (Figure 3.6.3.3, area II), or even
could not be dissolved (Figure 3.6.3.3, area III). The current cellulose–NaOH complex could
only be dissolved completely in 14–28 wt% urea aqueous solution at -7 to 5 o
C to obtain a
cellulose solution, as shown in area I of Figure 3.6.3.3. (Haisong Qi, 2010).

Page 36
3.7 Effects of temperature and molecular weight on dissolution of cellulose in
NaOH/urea solution
The dissolution of cellulose having different viscosity-average molecular weight (Mƞ ) in 7 wt%
NaOH/12 wt% urea aqueous solution at temperature from 60 to -12.6 o
C was investigated with
optical microscope, viscosity measurements and wide X-ray diffraction (WXRD). The solubility
(Sa) of cellulose in NaOH/urea aqueous solution is strongly dependant on the temperature, and
molecular weight. Their Sa values increased with a decrease in temperature and cellulose having
Mƞ below 10.0 x 104
could be dissolved completely in NaOH/urea aqueous solution pre-cooled
to -12.6 o
C. The activation energy of dissolution (Ea,s) of the cellulose dissolution was a negative
value, suggesting that the cellulose solution state had lower enthalpy than the solid cellulose. The
cellulose concentration in this system increased with a decrease of Mƞ to achieve about 8 wt%
for Mƞ of 3.1 x 104
. Moreover, cellulose having 12.7 x 104
could be dissolved completely in the
solvent precooled to -12.6 o
C as its crystallinity (Ӽ c) decreased from 0.62 to 0.53. The solubility
of cellulose could be improved in NaOH/urea aqueous system by changing Mƞ , Ӽ c and
temperature. In addition, the zero-shear viscosity (ƞ 0) at 0 o
C for the 4 wt% cellulose solution
increased rapidly with an increase of Mƞ , as a result of the enhancement of the aggregation and
entanglement for the relatively long chains.
Cellulose forms unique microcrystal structures through strong hydrogen bonding networks (Zhao
H, 2007), leading to the difficulty of its dissolution in common solvent. In traditional viscose
route for production regenerated cellulose fibres, CS2 (toxic gas) leads to the serious
environmental pollution and the poor health of the human body. Therefore, several new solvent
systems have been developed to dissolve cellulose at high temperatures. The dissolution of
cellulose in the N-methyl-morpholine-N-oxide (NMMO) occurs at 85–130 o
C (Heinze T L. T.,
2001), (Michael M, 2000). By heating or refluxing cellulose in N, Ndimethylacetamide (DMAc),
or in DMAc containing LiCl at about 150 o
C, transparent cellulose solution can be obtained
(Tosh B, 2000), (Potthast A, 2002). Recently, various ionic liquids (ILs) have been found to
dissolve cellulose (Zhu S, 2006), such as cellulose can be dissolved in the 1-N-butyl-3-
methylimidazolium chloride at about 85–100 o
C (Heinze T S. K., 2005), (Kosan B, 2008). At

Page 37
high temperature, ion pairs in 1-allyl-3-methylimidazolium chloride (AMIMCl) can be
dissociated to individual Cl-
and AMIM+
ions, and then free Cl-
ions associated with the cellulose
hydroxyl proton and the free cations disrupte the hydrogen bonding in cellulose, leading to its
dissolution (Zhang H, 2005). In addition, a solution of cellulose in heavy metal–amine complex
solutions system (such as Cuoxam, Ni-tren, Cd-tren, and so on) is usually prepared at room
temperature.
Microcrystalline cellulose (MCC), having a low degree of polymerization (DP<250), can be
dissolved in 8–10%NaOH aqueous system via a subsequent freeze and thaw thermal cycling.
New solvents, such as aqueous NaOH/urea, NaOH/thiourea and LiOH/urea aqueous solutions
have been used to dissolve cellulose at low temperature. These solvents are attractable because
cellulose can be easily and quickly dissolved in them and produce stable cellulose solutions (Yan
L C. J., 2007). It is worth noting that NaOH/urea aqueous solution is an economical and
environmentally friendly solvent of cellulose. Cellulose could be rapidly dissolved in 7 wt%
NaOH/12 wt% urea aqueous solution pre-cooled to -12 o
C (Cai J, 2005). Native cellulose
(cellulose I) having high viscosity molecular weight (Mƞ ) (Mƞ >14 x 104
) could not be dissolved
completely in 7 wt% NaOH/12 wt% urea aqueous solution pre-cooled to -12 o
C. Namely, the
dissolution of cellulose is related to its molecular weight and conditions. A basic understanding
of the effects of temperature and the molecular weight of cellulose on its dissolution is essential
for the successful development and application of cellulose. In this work, the cellulose samples
having different Mƞ were dissolved in 7 wt% NaOH/12 wt% urea aqueous solution at
temperature from 60 to -12.6 o
C and their solubility and viscosity of the cellulose in the solution
were investigated and discussed.
The dissolution state of the cellulose in 7 wt% NaOH/12 wt% urea aqueous solution at different
temperature has been investigated. Figure 3.7.1 on the next page shows the pictures of the
cellulose solution dissolved at different temperature for 2 min. The results reveal that, at high
temperatures from 0 o
C to 25 o
C, the cellulose hardly changes and at 60 o
C it only swells in the
solvent, showing fibre with diameter of 20–30 µm. By decreasing temperature from 0 o
C to -10
o
C, the swelling degree of the cellulose fibre increased. Transparent cellulose solution has
occurred at -12.6 o
C, indicating that the cellulose has been dissolved completely.

Page 38
Figure 3.7.1: Optical microscope images of the C9 cellulose (4 wt%) dissolved in 7%NaOH/12urea aqueous
solution at different temperature for 2 min
To clarify the change of solubility, the dependence of the Sa value on temperature for C9 in
solvent is shown in Figure 3.7.2. At temperatures from 60 o
C to 10 o
C, the Sa value maintains in a
constant (about 7.6–8.3%), indicating that the few fractions with the low molecular weight
cellulose could be dissolved.
Figure 3.7.2: Dependence of Sa value of cellulose (4 wt%, C9) on temperature from -12.6 o
C to 60 o
C
Clearly, the cellulose could not be dissolved at temperature above 10 o
C in NaOH/urea aqueous
solution. However, with a decrease of the temperature from 10 o
C to -12 o
C, the Sa value of
cellulose increased rapidly, and it could be dissolved in the range from -10 to -12.6 o
C. Ice will
form in the solvent below -12.6 o
C (freezing point), which is a critical temperature (Tc) of this
mixture solution. (Qi H C. C., 2008).

Page 39
3.8 Surface Properties of Cellulose Fibres
To gain the most from new adhesive systems the surface properties of cellulose materials needs
to be understood. The surface of plant materials is a complex heterogeneous polymer composed
of cellulose, hemicellulose and lignin. The surface is influenced by polymer morphology,
extraction procedures as well as physical and processing conditions.
The bonding system utilised in the formation of composites is integral to the successful
combination of materials and to achieve the desired increases in strength. The fact that MCC is
hydrophilic in nature has a major impact on surface interactions. Because of the known
hydrophilic character of cellulose-based materials, suitable methods, which allow the
characterisation of the ‘wet-state’ of these materials, are used to study their surface properties.
The study of the water uptake behaviour (e.g. the swelling) of the investigated natural fibres,
which have been used as reinforcements for polymers, is necessary for the construction of
composite materials, since the adhesive strength is influenced by absorption layers (in particular
of water) at the common interface between the adhesive and the adherent component (Hill CAS,
2000)
A major restriction in the successful use of natural fibres in durable composite applications is
their high moisture absorption and poor dimensional stability (swelling), as well as their
susceptibility to rotting (Hill CAS, 2000). Swelling of fibres can lead to micro-cracking of the
composite and, therefore, to deteriorated mechanical properties.
A deeper understanding of the complex nature of natural fibres and their surface properties is
still needed in order to optimize natural fibre surface modification processes, which might help
to increase the usefulness of those fibres as reinforcing material for polymers and to gain insights
about the interaction between these materials (Felix M, 1993), (Von Hazendonk JM, 1993).

Page 40
3.9 Environmental Effects
Most polymeric materials are synthesized from small organic molecules, which originate from
the limited petrochemical resources. Due to the lack of availability of the source materials, recent
researches have focused on the development of new materials which can be produced from
naturally occurring polymers, such as polysaccharides, proteins, lipids and so on. The benefits of
using naturally occurring polymers include their natural abundance and environmental
compatibility, whereas one of the limitations to their use is the difficulty involved in their
processing and fabrication, because of the polar moieties included in their backbones. One of the
most attractive candidates is cellulose, which is actively used in a variety of different products.
Cellulose is generally regarded as being the most abundant and useful renewable material, due to
its excellent physical properties, such as its gloss, specific gravity and pleasant touch.
Globally the construction industry consumes 50% of all natural resources, a destructive and
unsustainable trend (S., Building with Hemp, 2005). In recognition of this stark reality, the Earth
Summits of Rio (1992) and Johannesburg (2002) identified a way forward for the global
community – sustainable development – based on thirteen key principles where:
 Resources are used efficiently and waste is minimised by closing cycles
 Pollution is limited to levels which natural systems can process without damage
 Natural diversity is valued and protected
 Local needs are met locally where possible
 Good food, water, shelter and fuel are available to all at a reasonable cost
 Good health of the community is protected
 Environment is not damaged by access to facilities, services, goods and other people
 Personal safety of the community from crime and violence
 Skills, knowledge and information are accessible to all
 Participation in decision making is extended to the whole community
 Culture, leisure and recreation opportunities are available to all
 Local distinctiveness and character are valued and protected
Locally sourced, sustainable alternatives, with as little effect as possible on the environment need
to be developed. The market for construction materials in this category is quite a large one and is

Page 41
likely to expand with further regulation and increased public awareness of their environmental
responsibility.
As discussed is previous chapters cellulose has a wide variety of potential uses within the
construction industry. Cellulose is an abundant raw material and available from a wide variety of
renewable and recyclable sources, and also its growth in nature could be classed as
environmentally positive if not in the least environmentally benign.
However certain processes for isolating cellulose into microcrystalline cellulose (MCC) can
prove to have adverse effects on the environment. Established methods of isolating
pharmaceutical grade microcrystalline cellulose include;
Hydrothermal processing of dissolving and paper pulp at 172-185°C
Radiation degradation with deposited electron energy of 60-200 kGy (Cheng Q, 2009).
Enzymatic hydrolysis with the use of enzyme preparations.
Two-step method: radiation and enzymatic treatment (Stupinska H I. E., 2006).
Research has shown the two-step approach to be the most effective way of ecologically
preparing MCC to a grade acceptable even for pharmaceutical standards (Stupinska H W. D.,
2006). Stupinska Et Al. used a method of dissolving pulp and employing the two-step radiation-
enzymatic depolymerisation of the pulp which involves the irradiation of cellulose pulp with an
electron beam and depositing a 50 kGy dose in the pulp which was next subjected to enzymatic
hydrolysis by means of econase CE cellulolytic enzymes. The hydrolysis preceded for 30
minutes at 50 °C with the enzyme, to substrate (E/S) module amounting to 46 UCMC/g. The
unsorted microcrystalline cellulose prepared in laboratory scale from such depolymerised
cellulose pulp was characterized by:
average degree of polymerisation of 150
crystalline content of about 64%
specific volume 38 g/100 cm3
grain coarseness similar to the pharmaceutical requirement for MCC type 12
When comparing the environmental effects of the use of cellulose as a reinforcement agent
compared to other petrochemical based products we must consider their entire life cycle. If a
given product uses a lot of energy in its production, this energy comes to be known as 'embodied

Page 42
energy' and represents part of the true cost of the product. Current economic practices dictate that
this cost is rarely built into to the sale price of conventional products because environmental
impacts and resource use are not to be viewed as an unlimited resource.
In order to create an environmentally-conscious building, the environmental impacts of the entire
service life must be known. Life-cycle assessment (LCA), which evaluates the impacts from all
life-cycle phases, from "cradle to grave," is the best method to achieve this goal. LCA can be
used to quantify the energy use and the environmental emissions during the construction phase.
Steel-frame construction creates volatile organic compound (VOC) and heavy metal (Cr, Ni, Mn)
emissions due to the painting, torch cutting, and welding of the steel members.
To evaluate the environmental effect which a cellulose reinforced material would have, all
aspects of it production, transportation, consumption and final disposal need to be evaluated.
Production of cellulose is the most environmentally impacting element of its use. Depending on
its method of manufacture/isolation such as acid hydroloysis, production may cause significant
CO2 emmissions both directly and also indirectly due to material inputs. However it is well
established that steelmaking from an environmental perspective is of substantial concern. In the
United States iron and steel making accounts for 14% of industrial energy consumption and a
heavy contributor to greenhouse gas directly during production (Stupinska H I. E., 2007). While
advances have been made in recent times to reduce the amount of energy and materials
consumed during production, studies have shown that casting accounts for over 99% of energy
use in ferrous material manufacture (Stupinska H I. E., 2007).
The transportation aspect of using cellulose as a reinforcement agent offers distinct advantages
compared to that of traditional reinforcement products. Cellulose being abundantly available
from a wide variety of sources requires little transportation compared to petrochemical based
products which often require extensive transportation. Cellulose can be produced locally using
resources which are native and available in the community, a trait which is exceptionally
beneficial to developing counting with burgeoning populations and anticipated explosion in
housing and construction requirement.
The disposal and recycling of construction and demolition waste every year causes huge damage.
Cellulose as a standalone product is biodegradable. However when considering the use of

Page 43
cellulose as a reinforcement agent we must also consider the primary product in which it is used
to reinforce. With this in mind however there is certainly scope to use cellulose in an easily
recyclable/biodegradable product.
While there may be little in the way of a difference between the environmental impact of
consuming either cellulose or traditional reinforcement products, it is worth noting that
concreting and cement manufacture in particular, are generally the primary binder in using steel,
e.g. reinforced concrete. Approximately 8-12% of global CO2 emissions originate from the
manufacturing of cement, the third largest source of carbon emission in the United States. In
addition to the generation of CO2, the cement manufacturing process produces millions of tons of
the waste product cement kiln dust (CKD) each year contributing to respiratory and pollution
health risks.

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3.10 Autoclaved Aerated Concrete
Autoclaved Aerated Concrete (AAC), also known as autoclaved cellular concrete (ACC) or
autoclaved lightweight concrete (ALC) (Yong)has been around for decades. The material was
perfected in the mid-1920s by Dr. Johan Axel Eriksson, an architect working with Professor
Henrik Kreüger at the Royal Institute of Technology (Hebel, 2010).
It is a lightweight, precast building material that simultaneously provides structure,
insulation, and fire and mold resistance. AAC products include blocks, wall panels, floor and
roof panels, and lintels.
It has been refined into a highly thermally insulating concrete-based material used for both
internal and external construction. Besides AAC's insulating capability, one of its advantages in
construction is its quick and easy installation, for the material can be routed, sanded, and cut to
size on site using standard carbon steel bandsaws, hand saws, and drills.
Even though regular cement mortar can be used, 98% of the buildings erected with AAC
materials use thin bed mortar, which comes to deployment in a thickness of ⅛ inch. This varies
according to national building codes and creates solid and compact building members. AAC
material can be coated with a stucco compound or plaster against the elements. Siding materials
such as brick or vinyl siding can also be used to cover the outside of AAC materials.
AAC has been produced for more than 70 years, and it offers advantages over other
cementitious construction materials, one of the most important being its lower environmental
impact.
 AAC’s improved thermal efficiency reduces the heating and cooling load in buildings.
 AAC’s workability allows accurate cutting, which minimizes the generation of solid
waste during use.
 AAC’s resource efficiency gives it lower environmental impact in all phases of its life
cycle, from processing of raw materials to the disposal of AAC waste.
 AAC’s light weight also saves cost & energy in transportation.
 AAC's light weight saves labour.

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3.10.1 Raw materials
Unlike most other concrete applications, AAC is produced without using aggregates larger
than sand. Quartz sand, lime, and/or cement and water are used as a binding agent. Aluminum
powder is used at a rate of 0.05%–0.08% by volume (depending on the pre-specified density).
When AAC is mixed and cast in forms, several chemical reactions take place that give AAC its
light weight (20% of the weight of concrete) and thermal properties. Aluminum powder reacts
with calcium hydroxide and water to form hydrogen. The hydrogen gas foams and doubles the
volume of the raw mix (creating gas bubbles up to 3mm (⅛ inch) in diameter). At the end of the
foaming process, the hydrogen escapes into the atmosphere and is replaced by air.
When the forms are removed from the material, it is solid but still soft. It is then cut into
either blocks or panels, and placed in an autoclave chamber for 12 hours. During this steam
pressure hardening process, when the temperature reaches 190° Celsius (374° Fahrenheit) and
the pressure reaches 8 to 12 bars, quartz sand reacts with calcium hydroxide to form calcium
silica hydrate, which accounts for AAC's high strength and other unique properties. After the
autoclaving process, the material is ready for immediate use on the construction site. Depending
on its density, up to 80% of the volume of an AAC block is air. AAC's low density also accounts
for its low structural compression strength. It can carry loads of up to 8 Mpa, approximately 50%
of the compressive strength of regular concrete (www.buildinggreen.com, 2008).
3.10.2 Environmental benefits of Autoclaved Aerated Concrete
The use of autoclaved aerated concrete has a range of environmental benefits:
 Insulation: most obviously, the insulation properties will reduce the heating costs of
buildings constructed with autoclaved aerated concrete, with consequent fuel savings
over the lifetime of the building.
 Carbonation: less obviously, the cellular structure of AAC gives it a very high surface
area. Over time, much of the material is likely to carbonate, largely offsetting the carbon
dioxide produced in the manufacture of the lime and cement due to the calcining of
limestone (Klingner, 2008).

Page 46

Page 47
4.0 Experimental Preamble
4.1 Introduction
This section of the project entails the experimental program which was undertaken to investigate
the viability of the proposed new eco-friendly bio-material. The following topics will be
discussed:
 Laboratory Conditions
 Experimental Constants
 Apparatus Preparation
4.2 Laboratory Conditions
To ensure standard laboratory conditions were maintained, the lab in which the specimens were
prepared was maintained at a temperature of 15 ± 5 °C and a relative humidity of not less than
65%.
The laboratory conditions were kept within these specifications throughout each experiment.
4.3 Experimental Constants
4.3.1 Cellulose
It is a hydrophilic material, meaning it has the physical property of a molecule that can be
transiently bonded with water (H2O) through hydrogen bonding. It is often insoluble in water and
most organic solvents, however this property of cellulose is dependent on its chain length or
degree of polymerisation (the number of glucose units that make up one polymer molecule). The
fact that cellulose from wood pulp has typical chain lengths between 300 and 1700 units is
important to note. Molecules with very small chain length resulting from the breakdown of
cellulose are known as cellodextrins and are typically soluble in water and organic solvents.

Page 48
Cellulose is a straight chain polymer and the multiple hydroxyl groups on the glucose from one
chain from hydrogen bonds with oxygen molecules on the same or on a neighbour chain, holding
the chains firmly together side-by-side and forming “microfibrils” with high tensile strength.
These hydroxyl groups available on the surface of the cellulose are the prime means by which
fibres and cement bond together in fibre cements using cellulose. This tensile strength is what
gives a lot of plants their rigidity, through the presence of cellulose in their cell walls. (Pinkert A,
2010)
Throughout this project two different types of cellulose were used:
 Microcrystalline Cellulose (MCC): This is a purified, partially depolymerised cellulose
prepared by treating alpha-cellulose, obtained as a pulp from fibrous plant material, with
mineral acids. It is slightly soluble in alkaline solutions and is a fine, almost white,
odourless, free flowing crystalline powder. It has a degree of polymerisation of 350.
 Carboxymethyl Cellulose (CMC): also known cellulose gum. CMC is a cellulose
derivative with carboxymethyl groups (-CH2-COOH) bound to some of the hydroxyl
groups of the glucopyranose monomers that make up the cellulose backbone. It is often
used as its sodium salt, sodium carboxymethyl cellulose. It has a degree of
polymerisation of 450 (Sodium Carboxymethyl Cellulose, 2009).
4.3.2 Sodium Silicate Solution
Sodium Silicate (Na2SiO3) is a compound mixture of Sodium Oxide (Na2O) and Silica Sand
(SiO2) with water. The sodium silicate solution used in this experiment has a 50% dilution
factor. Sodium silicate is also known as water glass and acts as a binding agent and purifier. In
the purpose of the experimental program and for ease of reference.
4.3.3 Sodium Hydroxide
Sodium hydroxide (NaOH), also known as lye and caustic soda, is a caustic metallic base. It is
used in many industries, mostly as a strong chemical base in the manufacture of pulp and paper,
textiles, drinking water, soaps and detergents and as a drain cleaner.

Page 49
Pure sodium hydroxide is a white solid available in pellets, flakes, granules, and as a 50%
saturated solution. It is hygroscopic, readily absorbs carbon dioxide from the air and should be
stored in an airtight container. It is very soluble in water and is highly exothermic when
dissolved in water. It also dissolves in ethanol and methanol, though it exhibits lower solubility
in these solvents than does potassium hydroxide.
This chemical is necessary for this project in the break-up of the hydrogen bonds in the
molecular structure of cellulose. These hydrogen bonds prevent the cellulose from dissolving in
solution, thus they must be broken up.
4.3.4 Urea
Urea or carbamide is an organic compound with the chemical formula CO(NH2)2. The molecule
has two —NH2 groups joined by a carbonyl (C=O) functional group.
Urea serves an important role in the metabolism of nitrogen-containing compounds by animals
and is the main nitrogen-containing substance in the urine of mammals. It is solid, colourless,
and odorless. It is highly soluble in water and practically non-toxic (LD50 is 15 g/kg for rat).
Dissolved in water, it is neither acidic nor alkaline. The body uses it in many processes, the most
notable one being nitrogen excretion. Urea is widely used in fertilizers as a convenient source of
nitrogen. Urea is also an important raw material for the chemical industry.
In this project, the purpose of the Urea chemical is to prevent the re-bonding of hydrogen bonds
within the cellulose molecules once they have been dissolved in water using the sodium
hydroxide.
4.3.5 Sulphuric Acid
Sulphuric acid is a highly corrosive strong mineral acid with the molecular formula H2SO4. The
historical name of this acid is oil of vitriol. It is a colorless to slightly yellow viscous liquid and
is soluble in water at all concentrations. It is a diprotic acid. The corrosiveness of it is mainly due
to its strong acidic nature, strong dehydrating property and if concentrated strong oxidizing
property. It has many applications and is a central substance in the chemical industry. Principal

Page 50
uses include lead-acid batteries for cars and other vehicles, mineral processing, fertilizer
manufacturing, oil refining, wastewater processing, and chemical synthesis.
Sulphuric acid is used throughout this project in the coagulation process of the dissolved
cellulose film. Its purpose is to regenerate this cellulose film.
4.3.6 Ordinary Portland Cement (OPC)
Ordinary Portland cement (OPC) is the most common type of cement in general use around the
world because it is a basic ingredient of concrete, mortar, stucco and most non-specialty grout. It
is a fine powder produced by grinding Portland cement clinker (more than 90%), a limited
amount of calcium sulfate (which controls the set time) and up to 5% minor constituents as
allowed by various standards such as the European Standard EN197-1:
The low cost and widespread availability of the limestone, shales, and other naturally occurring
materials make portland cement one of the lowest-cost materials widely used over the last
century throughout the world. Nowadays concrete has become one of the most versatile
construction materials available in the world.
4.3.7 Ground Granulated Blast furnace Slag (GGBS)
Ground Granulated Blast furnace Slag (GGBS) is manufactured from blast furnace slag which is
a by-product from the making of iron. The blast furnaces take in iron ore, limestone and coke,
where they are heated to approximately 1500o
C. After these materials have melted in the blast
furnace, the products molten iron and molten slag are created.
GGBS is regarded as an alternative to Ordinary Portland cement. It can be used as both a partial
additive to Portland cement and also as the sole binder in the form of alkali-activated slag (AAS)
to form concrete (Al-Otaibi, 2007). GGBS was first used as an activator in Portland cement in
1880 (Ecocem, 2009). Due to its low production costs and its improved performance
characteristics in aggressive environments, GGBS has been very successful in the concrete
industry. Furthermore, the use of pozzolans in concrete production is now commonplace. GGBS
is an example of such a pozzolanic material (Ganesh Babu, 2000)

Page 51
4.3.8 Materials Pictures
MCC CMC
NaOH Urea
OPC GGBS

Page 52
H2SO4 Na2SiO3
4.3.9 Main Apparatus used
Kenwood Mixer – Chef and Major KM010 – KM020 series
Electronic Balance – capable of weighing to the nearest 1 g
Cube Moulds
Beakers and Buckets of different sizes to measure quantities of materials and water and to
mix ratios
Milling Pot
Sieve - (600 µm)
Hydraulic Compressor
Cold Finger Apparatus
Sonication Unit
Coagulation Bath
Oven
Stopwatch
Cube Testing Machine

Page 53
4.3.10 Calibration of Balance
In order to ensure the Electronic Balance was giving an accurate reading we calibrated the
balance using a number of standard weights. We placed a standard 50 grams, 100 grams and 200
grams and noted the individual reading for each weight. It was found that the balance was giving
a very accurate reading and no error was obtained. (i.e. The 50 gram weight read 50 grams on
the balance and so on for each weight). Therefore we were satisfied that this balance would give
us sufficiently accurate recordings for all quantities that require weighing during our
experimental program.
4.3.11 Apparatus Pictures
Kenwood Mixer Electronic Balance
Selection of Beakers Cube Mould

Page 54
Milling Pot and Sieve - (600 µm)
Hydraulic Compressor
Curing Ovens

Page 55
Cube Testing Machine
Sonication Unit

Page 56
4.3.12 Cube Moulds
The cube mould sizes used was kept constant throughout the experiment. The mould dimensions
are as follows Width 100mm: Breath 100 mm: Height 100 mm.
Preparation of Cube Mould:
The cube mould consists of four side plates and a base plate. These are connected by a number
of bolts. Before the mixture was placed in the cube moulds the mould was sprayed thoroughly
with a silicone spray. The purpose of this was to allow for ease of dismantling and to prevent
material sticking to the sides of the mould which may cause deformation of the cube.
Cube Forming:
After the mixture was completely mixed, it was then placed into the moulds. It was crucial to
remove all the air products so the cubes were first compacted with a bar and secondly with the
hydraulic compressor, this resulted in the complete removal of the air pockets.
Air - Cured:
The compacted cubes were cured in laboratory conditions. The setting time for each cube was
an overnight period followed by air-curing in the lab for a 7-day period.
Test Cube Striking & Cleaning
Once the samples had been sufficiently cured, they were stroke form the test cube moulds using
spanners. These test cube moulds were then thoroughly cleaned and reassembled.

Page 57

Page 58
5.0 Laboratory Testing
5.1 – Dissolving of Cellulose
5.1.1 The Dissolution of Cellulose in Na OH/Urea aqueous Solution.
Description
In this experiment, a number of different cellulose moulds were produced, each with varying
compositions of Cellulose. The mould was then cured at a constant temperature overnight.
Experimental Principles
A procedure for the complete dissolution of cellulose in water was determined. The cellulose is
to be dissolved in a NaOH/Urea aqueous solution. As mentioned above, the composition of the
cellulose was varied with a constant amount of NaOH, urea and water. The moulds were cured
at room temperature.
Sample Ratios
The ratio of the composition of each sample is given below:
NaOH Urea Water Cellulose
0.09 0.15 1 0.05
Quantity of Materials
The beaker had a capacity to mix enough material for several moulds at the time. Therefore we
had to determine the quantity of each material in the mix. The total solution mass was 208 g,
which would provide enough material for several moulds.
Experiment No. NaOH Urea Water MCC (DP350) MCC(DP450)
1 14 g 24 g 162 g 8 g -
2 14 g 24 g 162 g 7 g -
3 14 g 24 g 162 g - 8 g
4 14 g 24 g 162 g - 7 g

Page 59
Apparatus
Magnetic Stirrer
Balance – capable of weighing to the nearest 1 g.
Beakers & Buckets - Different sizes to measure quantities of materials and to mix ratios.
Cold Finger Apparatus – Anti-Freeze Coolant used to reduce the temperature of samples.
Coagulation Bath
Sonication Unit
Glass Plate – Base of the mould.
Double Sided Sticky Foam – To make the mould.
Sellotape – To fix the dried solution to the mould
Materials
- Sodium Hydroxide (NaOH) - Urea
- Microcrystalline Cellulose (MCC) - Sulphuric Acid (H2 SO4)
- Carboxymethyl Cellulose (CMC) - Water (H2O)
Procedure
Measure 162 g of water using beaker and balance.
The urea is then added and dissolved fully in the water.
Proceeding this the NaOH is added and stirred vigorously for 3 minutes. The resulting
NaOH/urea aqueous solution should be fully transparent.
This solution is then pre-cooled to -12.6o
C.
At this temperature, the cellulose was added slowly while being stirred vigorously until
fully dissolved. Full dissolution of cellulose in NaOH/urea aqueous solution is indicated
by full transparency.
Air bubbles in the solution are removed using a Sonication Unit for 5 minutes at 10o
C.
The resulting near transparent solution is poured into the mould of size 200 x 35 x 2 mm.

Page 60
The glass plate is immersed into the coagulation bath of 5% wt H2 SO4 for 5 minutes at
25o
C.
The resulting film is washed with running water and then deionised water.
The film is fixed onto the glass plate to prevent shrinkage and air dried at ambient
temperature.
Results and Observations
In the laboratory work, a cellulose solvent, 7 wt % NaOH / 12 wt % urea solution pre-cooled to -
12.6o
C, has been developed. It can dissolve cellulose with molecular weight below 1 x 105
. A
series of novel transparent and photoluminescent regenerated cellulose films with homogeneous
structure and excellent transparency were successfully prepared from the cellulose solution.
The solubility of cellulose in NaOH / urea system is strongly dependent on temperature,
molecular weight and the degree of polymerization (DP) of the cellulose. By utilizing cellulose
with different DP’s and the dissolution method at low temperature, regenerated cellulose films
were prepared.
Dissolved Cellulose Slurry
Cellulose
NaOH
Urea
-12.6 o
C

Page 61
The dissolving process of the cellulose took a long time. The NaOH / urea aqueous solution had
to be pre-cooled to -12.6o
C and this process was rather slow. Initially, a steel tank filled with
50% coolant and 50% water was used, but the steel tank was absorbing too much heat from the
atmosphere. A plastic tank was tried and while this was better than the steel tank, the cooling
process was still very slow. Finally, it was decided to insulate the plastic tank using an aeroboard
box and insulation foam. This proved to be the most efficient method for pre-cooling.
The cellulose had to be added very slowly to the pre-cooled NaOH / urea aqueous solution to
ensure that clumping of the cellulose was avoided. While the cellulose was being added, the
solution was being stirred vigorously. If the cellulose was added quickly lumps would form and
the cellulose wouldn’t dissolve effectively.
With the addition of urea to the water, the temperature of the solution is reduced. NaOH is very
soluble and highly exothermic in water, which increases the temperature of the solution.
Transparency is the indication of the full dissolution of cellulose in NAOH/urea aqueous
solution. This is evident in the two pictures below;
Pouring of dissolved cellulose into the mould Fully dissolved cellulose
A regenerated cellulose film was created once the cellulose mould was coagulated in the bath of
sulphuric acid. The MCC solution coagulated better than the CMC solution. This is evident in
the pictures on the next page, where the MCC film is more uniform.

Page 62
Regenerated MCC film Regenerated CMC film
Once the coagulation process was completed, the films were rinsed with running water, as seen
in the photograph below.
Washing the resulting film with running water

Page 63
When the films were allowed to dry at ambient temperature, a frozen crystal like structure was
produced. These films appeared strong and they remain transparent indicating that the cellulose
was fully dissolved in the structure. The MCC film was is more transparent than the CMC film,
as seen the photographs below;
Dried MCC film Dried CMC film
Conclusion
Overall, the experiment was successful in dissolving cellulose in a NaOH/urea aqueous solution.
It must be noted, that the MCC dissolved better in the NaOH/urea aqueous solution than CMC.
This result was predicted as MCC has a DP of 350, which is lower than CMC’s DP of 450. Thus,
indicating that MCC would be easier to dissolve. Also it is recommended that further
investigations should be undertaken to discover a quicker method to dissolve the cellulose.

Page 64
5.1.2 The Dissolution of Cellulose in NAOH-based aqueous system by two-step
process.
Description
The two-step dissolution method of cellulose in NaOH/urea aqueous system was investigated.
The two steps were as follows: (1) formation and swelling of a cellulose NaOH complex and (2)
dissolution of the cellulose NaOH complex in aqueous urea solution. In this experiment, two
different cellulose moulds were produced, each with varying compositions of cellulose. The
moulds were then cured at a constant temperature overnight.
Another procedure for the complete dissolving of cellulose was determined. As mentioned
above, the composition of the cellulose was varied with a constant amount of NaOH, Urea and
water.
Sample Ratios
The ratio of the composition of each sample is set at;
NaOH Urea Water Cellulose
0.09 0.15 1 0.05
The beaker had a capacity to mix enough material for several moulds at the time. Therefore we
had to determine the quantity of each material in the mix. A total solution mass of 100 g would
provide enough material for several moulds. The following ratio of 14 wt% NaOH aqueous
solution : 24 wt% urea aqueous solution : 4 g MCC was used.
Experiment No. NaOH Urea Water MCC (DP350) CMC (DP450)
1 6.72 g 11.52 g 77.8 g 4 g -
2 6.72 g 11.52 g 77.8 g - 4 g

Page 65
Apparatus
Magnetic Stirrer
Coagulation Bath
Sonication Unit
Materials
Sodium Hydroxide (NaOH) Urea Water (H2O)
MCC (DP 350) CMC (DP 450) Sulphuric Acid (H2 SO4)
Procedure
Step 1:
Measure 41.3 g of water using beaker and balance.
Add 6.72 g of NaOH and stir until dissolved fully in the 41.3 g of water.
Precool the NaOH aqueous solution to 0 o
C.
Addition of 4 g of cellulose to the NaOH solution, while stirring continuously for 1
minute.

Page 66
Step 2:
Measure 36.5 g of water using beaker and balance.
Add 11.52 g of urea and stir until dissolved fully in the 36.5 g of water.
Precool the urea aqueous solution to 0 o
C and immediately add to the cellulose NaOH
aqueous solution.
Vigorous stirring for 2 minutes to achieve a near transparent solution indicating that the
cellulose is fully dissolved.
Continued Procedure:
Air bubbles in the solution are removed using a Sonication Unit for 5 minutes at 10o
C.
The resulting near transparent solution is poured into a glass based mould of size 200 x
35 x 2 mm.
Immerse the glass plate into the coagulation bath of 5% wt H2 SO4 for 5 minutes at 25o
C.
Wash the resulting film with running water and then deionised water.
Fix the film onto the glass plate to prevent shrinkage and air dry at ambient temperature.
Results and Observations
In the previous experiment, cellulose was dissolved in NaOH/urea aqueous solution at -12.6 o
C.
To reduce the power and time consumption to achieve the low temperatures required, a two-step
process was investigated. An attempt to dissolve the cellulose in NaOH / urea aqueous solution
at relatively high temperature (such as 0 o
C) was made, resulting in slurry-type mixtures. The
cellulose was swollen in 14 wt% aqueous NaOH solution pre-cooled to 0 o
C and then was
dispersed and dissolved when 24 wt% aqueous urea solution pre-cooled to 0 o
C was added.
Finally, a transparent cellulose solution was obtained through this process, with about 7 wt%
NaOH and 14 wt% urea in the solution.

Page 67
The cellulose had to be added very slowly to the pre-cooled NaOH / urea aqueous solution to
ensure that clumping of the cellulose was avoided. While the cellulose was being added, the
solution was being stirred vigorously. If the cellulose was added quickly lumps would form and
the cellulose wouldn’t dissolve effectively.
When the NaOH was dissolved in the water in stage one, the temperature of the solution increase
considerably due to the exothermic properties of the NaOH. Once it fully dissolved, the pre-
cooling process using the cold finger apparatus, immediately began. Then the second stage
should begin, where the dissolution of the urea in water reduces the temperature of the solution.
Then this solution is pre-cooled. Once both stages reach 0o
C, they are mixed together and the
same procedure outlined in the One-Step method is followed, where the samples are sonicated,
poured, coagulated and rinsed.
Although the same materials used in this experiment are the same, the procedure differs. The
time taken to conduct this experiment was a lot shorter than the previous One-Step method. This
is due to the fact that the temperature had only to be reduced to 0o
C rather than the -12.6o
C.
Dissolved Cellulose
Solution
Vigerous Mixing
Cellulose/NaOH/Water
Pre-Cooled @ 0oC
Urea/Water
Pre-Cooled @ 0oC

Page 68
Similar to last experiment, once the regenerated films were allowed to dry at ambient
temperature, a frozen crystal like structure was produced. These films appeared strong and they
remain transparent indicating that the cellulose was fully dissolved in the structure. The MCC
film was is more transparent than the CMC film. This indicates that the MCC dissolved better in
NaOH/urea aqueous solution than the CMC did. This can be seen in the pictures below:
CMC Mould
MCC Mould
Conclusion
The Two-Step process successfully dissolved cellulose in a NaOH/urea aqueous solution. Time
was saved dissolving the cellulose in comparison to the previous One-Step method which
required reducing the temperature a significant degree lower. This in turn led to much less
energy being consumed. Thus, due to this time reduction and energy saving process, all further
experiments involving the dissolution of cellulose in water would follow the Two-Step process.

Page 69
5.2 – Integration of OPC with dissolved Cellulose Solution
Description
This experiment investigates the addition of OPC to the previously dissolved cellulose solution.
Having successfully dissolved cellulose in NaOH/urea aqueous solution, the next aim was to
integrate this dissolved cellulose with OPC, producing a homogenous composite. Only novel
research has been done in this area, thus this type of composite has never being tried before. The
cellulose was dissolved using the Two-Step method. Where, cellulose was dissolved using a
NaOH/urea aqueous system. The OPC was then introduced to the solution once the cellulose was
fully dissolved. Strip composite moulds were then formed and cured at an ambient temperature
overnight.
The creation of a homogeneous composite integrating wood and concrete at molecular level was
successfully determined by the addition of OPC to a dissolved cellulose solution.
Sample Ratios
The ratio of the composition of each sample is set at:
NaOH Urea Water Cellulose Cement
0.09 0.15 1 0.05 0.05
A total solution mass of 216 g provided enough material for several moulds.
Experiment No. NaOH Urea Water MCC (DP350) MCC (DP450) OPC
1 14 g 24 g 162 g 8 g - 8 g
2 14 g 24 g 162 g - 8 g 8 g

Page 70
Apparatus
Magnetic Stirrer
Coagulation Bath
Sonication Unit
Materials
- Sodium Hydroxide (NaOH)
- Water (H2O) - Urea
- MCC (DP 350)
- Ordinary Portland Cement (OPC)
- CMC (DP 450)
- Sulphuric Acid (H2 SO4)
Procedure
Example 1
Step 1:
Measure 81 g of water using beaker and balance.
Add 14 g of NaOH and stir until dissolved fully in the 81 g of water.
Precool the NaOH aqueous solution to 0 o
C.
Add 8 g of cellulose, with stirring for 1 minute.
`
Step 2:

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