The document discusses crystallinity in polymers. It defines crystalline and amorphous regions in polymers, and explains that polymers exist as a mixture of crystalline and amorphous phases. It describes how polymer chains fold and organize into crystalline lamellae and spherulites. The degree of crystallinity affects various material properties, and can be measured using techniques like DSC and X-ray diffraction. A higher crystallinity leads to properties like increased hardness, strength and barrier properties.
Brief intro about crystalline and amorphous structures,
glass transition temperature,
free volume theory of glass transition temperature,
factors effecting glass transition temperature etc.
A polymer is a large molecule, or macromolecule, composed of many
repeated subunits. The structure of a polymer is defined in terms of
crystallinity. This might also be thought of as the degree of order or regularity
in how the molecules are packed together. A well-ordered polymer is
considered crystalline. The opposite is an amorphous polymer. Almost
all amorphous polymers possess a temperature boundary. Above this
temperature the substance remains soft, rubbery and flexible, and below
this temperature it becomes hard, glassy and brittle.
The temperature, below which a polymer is hard and above which
it is soft is called the glass transition temperature.
For example:-
When an ordinary natural rubber ball if cooled below -70oC becomes so
hard and brittle that it will break into several pieces like a glass ball falling on a
hard surface.
This happens because there is a temperature boundary for amorphous.
The transition from the rubber to the glass-like state is an important feature of
polymer behavior, marking as it does a region where dramatic changes in the
physical properties, such as hardness and elasticity, are observed.
The hard, glassy, brittle state is known as the glassy state and the soft,
rubbery, flexible state is the rubbery or viscoelastic state. The glass transition
temperature is denoted by Tg.
Tf is another term for temperature, when a polymer is heated further, it forms
a viscous liquid and starts flowing, this state is known as viscous-fluid state
and the temperature is termed as flow temperature (Tf).
Tg is an important characteristic property of any polymer as it has an
important bearing on the potential application of a polymer.
Brief intro about crystalline and amorphous structures,
glass transition temperature,
free volume theory of glass transition temperature,
factors effecting glass transition temperature etc.
A polymer is a large molecule, or macromolecule, composed of many
repeated subunits. The structure of a polymer is defined in terms of
crystallinity. This might also be thought of as the degree of order or regularity
in how the molecules are packed together. A well-ordered polymer is
considered crystalline. The opposite is an amorphous polymer. Almost
all amorphous polymers possess a temperature boundary. Above this
temperature the substance remains soft, rubbery and flexible, and below
this temperature it becomes hard, glassy and brittle.
The temperature, below which a polymer is hard and above which
it is soft is called the glass transition temperature.
For example:-
When an ordinary natural rubber ball if cooled below -70oC becomes so
hard and brittle that it will break into several pieces like a glass ball falling on a
hard surface.
This happens because there is a temperature boundary for amorphous.
The transition from the rubber to the glass-like state is an important feature of
polymer behavior, marking as it does a region where dramatic changes in the
physical properties, such as hardness and elasticity, are observed.
The hard, glassy, brittle state is known as the glassy state and the soft,
rubbery, flexible state is the rubbery or viscoelastic state. The glass transition
temperature is denoted by Tg.
Tf is another term for temperature, when a polymer is heated further, it forms
a viscous liquid and starts flowing, this state is known as viscous-fluid state
and the temperature is termed as flow temperature (Tf).
Tg is an important characteristic property of any polymer as it has an
important bearing on the potential application of a polymer.
Average molecular weight of polymer
-Number average molecular weight
-Weight average molecular weight
Properties of Polymer
Uses/Application of Polymer
It consists classification of polymerization techniques. What is bulk polymerization, how will the reaction proceed, and what are the advantages, disadvantages, and applications. Similarly, what is solution polymerization and how it will be carried out, what are the advantages, disadvantages, and applications behind it everything is explained in detail. Some of the related questions are also included for practice. All the contents taken from different websites and books are also mentioned.
poly styrene is a synthetic aromatic polymer made from the monomer styrene. Polystyrene can be solid or foamed. General purpose polystyrene is clear, hard, and rather brittle. It is an inexpensive resin per unit weight. polystyrene is in a solid (glassy) state at room temperature but flows if heated above about 100 °C, its glass transition temperature. It becomes rigid again when cooled .
Lecture notes on Structure and Properties of Engineering Polymers
Course Objectives:
The main objective is to introduce polymers as an engineering material and emphasize the basic concepts of their nature, production and properties. Polymers are introduced at three levels; namely, the molecular level, the micro level, and macro-level. Through knowledge of all three levels, student can understand and predict the properties of various polymers and their performance in different products. The course also aims at introducing the students to the principles of polymer processing techniques and considerations of design using engineering polymers.
polymerization is a process of bonding monomer, or "single units" together through a variety of reaction mechanisms to form longer chains named Polymer.
Average molecular weight of polymer
-Number average molecular weight
-Weight average molecular weight
Properties of Polymer
Uses/Application of Polymer
It consists classification of polymerization techniques. What is bulk polymerization, how will the reaction proceed, and what are the advantages, disadvantages, and applications. Similarly, what is solution polymerization and how it will be carried out, what are the advantages, disadvantages, and applications behind it everything is explained in detail. Some of the related questions are also included for practice. All the contents taken from different websites and books are also mentioned.
poly styrene is a synthetic aromatic polymer made from the monomer styrene. Polystyrene can be solid or foamed. General purpose polystyrene is clear, hard, and rather brittle. It is an inexpensive resin per unit weight. polystyrene is in a solid (glassy) state at room temperature but flows if heated above about 100 °C, its glass transition temperature. It becomes rigid again when cooled .
Lecture notes on Structure and Properties of Engineering Polymers
Course Objectives:
The main objective is to introduce polymers as an engineering material and emphasize the basic concepts of their nature, production and properties. Polymers are introduced at three levels; namely, the molecular level, the micro level, and macro-level. Through knowledge of all three levels, student can understand and predict the properties of various polymers and their performance in different products. The course also aims at introducing the students to the principles of polymer processing techniques and considerations of design using engineering polymers.
polymerization is a process of bonding monomer, or "single units" together through a variety of reaction mechanisms to form longer chains named Polymer.
Crystallization is a separation process very commonly used in the industry of many different materials, from commercially very common chemicals to very specific ones. It also plays an important role in the pharmaceutical industry, as more than 90% of active pharmaceutical ingredients (API) are synthesized as a crystalline product. Crystallization may have a significant direct and indirect influence on the quality of a product; therefore, it is one of the most important purification and separation methods in the production of APIs.
Definition
Application
Difference between molecular and Colloidal dispersion
Characteristics of dispersed phase
Classification of colloidal dispersion
Purification of colloidal dispersion
State of matter and properties of matter (Part-7)(Solid-crystalline, Amorpho...Ms. Pooja Bhandare
CRYSTALLINE SOLID, Types of Crystalline solid, AMORPHOUS SOLID, Difference between crystalline solid and amorphous solid, Why does the amorphous form of drug have better bioavaibility that crystalline couterpaerts?, Polymorphism,
TYPES OF POLYMORPHISM, PROPERTY OF POLYMORPHS, Methods of preparation of Polymorphs, Methods to determine Polymorphism Characterization of Polymorphs, Pharmaceutical Application
Effect of Atomic Structure of Solids on its Property ppt Presentation file | ...Sandeep Kumar
This is a ppt presentation file on the topic- EFFECT OF ATOMIC STRUCTURE ON PROPERTY OF SOLIDS. It give info. about what are solids, their Atomic Structure, and what is the basic difference between Solids and other Materials &
What are Effect of Atomic Structure of Solids on its Property.
Hope It'll be helpful.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
3. SOLIDS
• CRYSTALLINE SOLIDS :
A crystal or crystalline solid is a solid
material whose constituents (such as atoms,
molecules or ions) are arranged in a highly
ordered microscopic structure, forming
a crystal lattice that extends in all
directions.
• AMORPHOUS SOLIDS : An amorphous
solid is any non-crystalline solid in which
the atoms and molecules are not organized
in a definite lattice pattern. Such
solids include glass, plastic, and gel.
4. BASIC DIFFERENCES
CRYSTALLINE SOLIDS AMORPHOUS SOLIDS
They have characteristic geometrical
shape
Solids that don't have definite
geometrical shape
T hey have sharp melting point They melt over a wide range of
temperature
Physical properties of crystalline
solids are different in different
directions. This phenomenon is
known as Anisotropy.
Physical properties of amorphous
solids are same in different
direction. amorphous solids are
isotropic.
When crystalline solids are rotated
about an axis, their appearance does
not change. This shows that they are
symmetrical.
Amorphous solids are
unsymmetrical.
Crystalline solids cleavage along
particular direction at fixed cleavage
planes.
Amorphous solids don't break at
fixed cleavage planes.
5. INTRODUCTION
• Properties of textile fibers are determined by their chemical
structure degree of polymerization, orientation of chain
molecules, crystallinity, package density and cross linking
between individual molecules. Polymer crystallinity is one
of the important properties of all polymers. Polymer exists
both in crystalline and amorphous form.
6. • Figure shows how the arrangement of polymer chain
forming crystalline and amorphous regions. It can be
seen that part of molecules are arranged in regular
order, these regions are called crystalline regions. In
between these ordered regions molecules are arranged
in random disorganized state and these are called
amorphous regions.
• Crystallinity is indication of amount of crystalline
region in polymer with respect to amorphous content.
7. DEGREE OF CRYSTALLINITY
• The degree of crystallinity is defined as the fractional amount of
polymer that is crystalline and it is either expressed in terms of the
mass fraction or the volume fraction.
• For semi-crystalline polymers, the degree of crystallinity is one of its
most important physical parameters since it reflects the sample’s
morphology and determines various mechanical properties, such as
the Young modulus, yield stress as well as the impact strength.
• Differential scanning calorimetry is widely used to determine the
amount of crystalline material. It can be used to determine the
fractional amount of crystallinity in a polymer sample. Other
commonly used methods are X-ray diffraction, density measurements,
and infrared spectroscopy.
8. CRYSTALLISABLITY
• Crystallisabilty is the maximum crystallinity that a polymer
can achieve at a particular temperature, regardless of the
other conditions of crystallization.
• Crystallisablity at a particular temperature depends on the
chemical nature of the macromolecular chain, its geometrical
structure, molecular weight and molecular weight
distribution.
9. POLYMER CRYSTALLISATION
• Crystallization of polymers is a process associated with partial
alignment of their molecular chains.
• These chains fold together and form ordered regions
called lamellae, which compose larger spheroidal structures
named spherulites.
• Polymers can crystallize upon cooling from the melt,
mechanical stretching or solvent evaporation. Crystallization
affects optical, mechanical, thermal and chemical properties of
the polymer.
11. CRYSTALLIZATION BY STRETCHING
• Crystallization occurs upon extrusion used in making fibers
and films.
• In this process, the polymer is forced through, e.g., a nozzle
that creates tensile stress which partially aligns its molecules.
Such alignment can be considered as crystallization and it
affects the material properties.
• Anisotropy is more enhanced in presence of rod-like fillers
such as carbon nanotubes, compared to spherical fillers.
• Polymer strength is increased not only by extrusion, but also
by blow molding, which is used in the production of plastic
tanks and PET bottles.
12. • Some polymers which do not crystallize from the melt, can be
partially aligned by stretching.
• Some elastomers which are amorphous in the unstrained state
undergo rapid crystallization upon stretching.
13. CRYSTALLIZATION FROM
SOLUTION
• Polymers can also be crystallized from a solution or upon
evaporation of a solvent. This process depends on the degree of
dilution.
• In dilute solutions, the molecular chains have no connection
with each other and exist as a separate polymer coils in the
solution.
• Increase in concentration which can occur via solvent
evaporation, induces interaction between molecular chains
and a possible crystallization as in the crystallization from the
melt.
• Crystallization from solution may result in the highest degree
of polymer crystallinity.
14. • The crystal shape can be more complex for other polymers,
including hollow pyramids, spirals and multilayer dendritic
structures.
• The rate of crystallization can be monitored by a technique
which selectively probes the dissolved fraction.
15. HELICAL STRUCTURES
• To facilitate closer packing of molecules in the crystalline
phase , many polymers tend to assume a helical structure.
• Isotactic vinyl polymers has helical structures.
• Helical structure has a special significance in polymers of
biological origin.
• DNA structure also have helical structures.
• This DNA structures was determined by Watson and Crick.
• Hydrogen bonding plays an important role in the formation of
the double helix of the DNA molecules.
17. SPHERULITES
• Spherulites are spherical semicrystalline regions inside non-
branched linear polymers.
• Their formation is associated with crystallization of
polymers from the melt and is controlled by several parameters
such as the number of nucleation sites, structure of the polymer
molecules, cooling rate, etc.
• Spherulites are composed of highly ordered lamellae, which
result in higher density, hardness, but also brittleness of the
spherulites as compared to disordered polymer.
• The lamellae are connected by amorphous regions which provide
certain elasticity and impact resistance.
18. • Alignment of the polymer molecules within the lamellae
results in birefringence producing a variety of colored
patterns.
• Birefringence is the optical property of a material having
a refractive index that depends on the polarization and
propagation direction of light.
• If a molten polymer such as polypropylene is made into thin
film between to hot glass plates and cooled, it is seen that,
from different nucleation centres, spherulites start developing.
20. • Mechanical properties : Formation of spherulites affects many
properties of the polymer material; in particular,
crystallinity, density, tensile strength and Young's modulus of
polymers increase during spherulization. This increase is due
to the lamellae fraction within the spherulites, where the
molecules are more densely packed than in the amorphous
phase.
• Optical properties : Spherulites can scatter light rays and
hence the transparency of a given material decreases as the
size of the spherulites increases. Alignment of the polymer
molecules within the lamellae results
in birefringence producing a variety of colored patterns when
spherulites are viewed between crossed polarizers in
an optical microscope.
21. LAMELLAR STRUCTURE
• Lamellar structures or microstructures are composed of
fine, alternating layers of different materials in the form
of lamellae.
• Such conditions force phases of different composition to
form but allow little time for diffusion to produce those
phases equilibrium compositions.
• Fine lamellae solve this problem by shortening the
diffusion distance between phases, but their high surface
energy makes them unstable and prone to break up
when annealing allows diffusion to progress.
22.
23. LEFT TO RIGHT: SPHERULITES; BLOCK
COPOLYMER MICRODOMAINS; LAMELLAR
CRYSTALS; CRYSTALLINE BLOCK UNIT CELL.
24. FOLDING OF CHAIN DURING
CRYSTAL FORMATION
• For a standard polymer, the lamellar thickness is around 100
Å and the molecular chain length is around 1000 to 10000 Å .
• The accommodation of the long chain into the narrow lamella
is by assuming that chain folding takes place during the
process of crystallization.
• Many experimental techniques such as electron diffraction
prove beyond any reasonable doubt that the chains in a
crystal are folded and oriented perpendicular to the plane of
the polymer crystal lamella.
27. DIFFERENTIAL SCANNING
CALORIMERTY (DSC)
• DSC can be used to determine amount of crystallinity in a
polymer.
• Instrument is designed to measure amount of heat absorbed or
evolved from sample under isothermal conditions.
• DSC contains two pans, one reference pan that is empty and the
other pan has polymer sample.
• In this method polymer sample is heated with reference to a
reference pan. Both polymer and the reference pan are heated at
same rate.
• The amount of extra heat absorbed by polymer sample is with
reference to reference material
32. X-RAY DIFFRACTION(XRD)
• X-Ray diffraction is also used to measure the nature of
polymer and extent of crystallinity present in the Polymer
sample.
• Crystalline regions in the polymer seated in well-defined
manner acts as diffraction grating .
• So the Emerging diffracted pattern shows alternate dark and
light bands on the screen.
• X-ray diffraction pattern of polymer contain both sharp as
well as defused bands.
• Sharp bands correspond to crystalline orderly regions and
defused bands correspond to amorphous regions
34. • Crystalline structure is regular arrangement of atoms.
Polymer contains both crystalline and amorphous phase
within arranged randomly.
• When beam of X-ray passed through the polymer sample,
some of the regularly arranged atoms reflect the x-ray beam
constructively and produce enhanced intense pattern.
• Amorphous samples gives sharp arcs since the intensity of
emerging rays are more, where as for crystalline samples, the
incident rays get scattered.
• Arc length of diffraction pattern depends on orientation. If the
sample is highly crystalline, smaller will be the arc length.
35. • X-ray diffraction pattern of (a) amorphous sample and
(b) Semi crystalline polymer sample
36. CRYSTALLINITY CALCULATIONS
• The crystallinity is calculated by separating intensities due to
amorphous and crystalline phase on diffraction phase.
• Computer aided curve resolving technique is used to separate
crystalline and amorphous phases of diffracted graph.
• After separation, total area of diffracted pattern is divided into
crystalline (Ac) and amorphous(Aa).
• Small Angle X-ray Scattering (SAXS), Infrared Spectroscopy, can
also be used to measure crystallinity.
• Percentage of crystallinity Xc % is measured as ratio of crystalline
area to total area.
XC = AC /(AC +AA)
AC = Area of crystalline phase
AA = Area of amorphous phase
37. PROPERTIES AFFECTED BY
CRYSTALLINITY
• HARDNESS : The more crystalline a polymer, the more
regularly aligned its chains. Increasing the degree of
crystallinity increases hardness and density.
• YOUNG’S MODULUS : There is steep increase in young's
modulus with increase in amount of crystalline component in
the sample.
• TENSILE STRENGTH : This property is directly proportional
to the crystalline structure of a component.
• PERMEABILITY : Crystalline polymers are far less
permeable than the amorphous variety. It means as the
polymer crystallinity increases with decrease in permeability.