1. • Pollution: Traditional plastics amount to 32 million tons of
waste annually, equivalent to 13% of municipal solid waste
stream. With a 9% plastics recycling rate, the consequences of
accumulation include plastic waste pollution that will pollute
the environment and remain in landfills for centuries.
• Halogenated Flame Retardants: Most current flame
retardants are halogenated, a chemical quality linked to
diseases such as autism, obesity, and hindered
neurodevelopment.5
Halogenated flame retardants also degrade
into other toxic compounds that cause contamination of
ecosystems and their wildlife.
• Fire Problem: Deaths from fires and burns are the 3rd leading
cause of fatal home injuries. To protect customers, we must
improve our flame retardancy standards in everyday products.
Methods
Conclusions
Investigating the Application of Cellulose in Biodegradable Flame Retardant Polymer Blends
Shira Li, David Lin
Mentors: Harry Shan He, Dr. Miriam Rafailovich
Department of Materials Science and Engineering, Stony Brook University, Stony Brook, NY
• Mixing/Blending: First, cellulose was soaked in RDP in a 2:3 ratio
of RDP to cellulose and mixed. Then, the RDPCellulose blend was
mixed with PLA and PBAT in varying ratios as shown below.
Introduction Results & Analysis
Materials
• Cellulose: Cellulose is an organic
carbohydrate found primarily in plant
cell walls and the most abundant
organic polymer on Earth. Cellulose is
used as the thermostabilizing
absorbent base for the soaking of
RDP.
• PLA: Poly(lactic acid) is a biodegradable
polyester extracted from renewable
resources such as corn starch or sugar cane.
PLA is easy to produce, has high strength
and durability, and can biodegrade to
carbon dioxide, water, and humus.1,4
• PBAT: Polybutylene adipate co-terephthalate is a
biodegradable copolymer that is both flexible and tough,
making it an ideal blending complement to PLA.1,4
• RDP: Resorcinol bis(diphenyl
phosphate) is a non-halogenated
organophosphorus flame retardant
additive that creates a thermal
insulation barrier between the burnt and
unburnt polymer to prevent the flame
from spreading.
• AFM: Atomic force microscopy nanoindentation utilizes a
cantilever tip to probe a material’s surface and determine
micromechanical properties such as the modulus of elasticity.
• FTIR: Fourier transform infrared spectroscopy uses infrared
radiation to compare the polymer’s surface chemical composition
before and after burning.
• Tensile Test: Examines a material’s stiffness, Young’s modulus,
and yield strength by applying a controlled tension to the material
until mechanical failure.
• Impact Test: Examines a material’s flexibility by measuring its
ability to absorb energy and plastically deform before fracturing.
• UL-94 Flame Test3
: Examines the flame retardancy of plastics by
measuring how long a polymer takes to self-extinguish and
whether the melted polymer drops ignite a cotton wad below.
Results & Analysis
Tensile Test:
•Increasing % of PLA
increased polymer stiffness
•Increasing % of RDP
decreased polymer stiffness
due to RDP’s liquid nature
•Increasing % of cellulose
increased polymer stiffness,
mitigating RDP’s negative
effects
•Cellulose fibers stabilized the
polymer by reducing phase
separation and homogenizing
the blends
Impact Test:
•Increasing % of PBAT in
blends increased flexibility
•Increasing % of RDP in blends
decreased flexibility
•Increasing % of cellulose in
blends improved mechanical
stability and polymer flexibility
UL-94 Flame Test:
• All ratios of PLA/PBAT control blends were highly flammable
• Addition of RDP increased flame retardancy
• However, phase separation between liquid RDP and solid PLA or
PBAT reduced cohesion and induced extensive drippage
• Addition of cellulose decreased drippage
• Cellulose fibers acted as thermomechanical stabilization,
reducing phase separation between materials
• Together, RDP and cellulose maximized flame retardancy and
mechanical strength
• To reduce embrittlement, we reduced the proportion of additive
• 50/50/8 PLA/PBAT/RDPCellulose obtained maximum V0 grade,
self-extinguishing <1s and dripping minimally without ignition
AFM:
•Burning the polymer blends increased mechanical strength
•Burnt polymer blends had an elastic modulus 22x stronger than those
of unburnt samples
FTIR:
• Before burning, the polymer primarily had PBAT and RDP at the
surface while the presence of PLA and cellulose were undetectable
• After burning, PLA and RDP dominated the surface composition
• The emergence of PLA to the surface corresponds with the
hardening of the polymer after burning
• Amplification of RDP peaks after burning illustrates that more
RDP was secreted to form a layer of phosphoric acid that slowed
heat transfer
Unburnt Polymer Blend
Burnt Polymer Blend
1. Kanzawa, T., & Tokumitsu, K. (2011). Mechanical properties and morphological
changes of poly(lactic acid)/polycarbonate/poly(butylene adipate-co-terephthalate)
blend through reactive processing. Journal of Applied Polymer Science, 2908-2918.
2. Pack, S., Bobo, E., Muir, N., Yang, K., Swaraj, S., Ade, H., ... Rafailovich, M. (n.d.).
Engineering biodegradable polymer blends containing flame retardant-coated
starch/nanoparticles. Polymer, 4787-4799.
3. UL 94: Standard for tests for flammability of plastic materials for parts in devices
and appliances (3rd ed.). (1985).
4. Weng, Y., Jin, Y., Meng, Q., Wang, L., Zhang, M., & Wang, Y. (n.d.).
Biodegradation behavior of poly(butylene adipate-co-terephthalate) (PBAT),
poly(lactic acid) (PLA), and their blend under soil conditions. Polymer Testing, 918-
926.
5. Windham, G., Pinney, S., Sjodin, A., Lum, R., Jones, R., Needham, L., ... Kushi,L.
(n.d.). Body burdens of brominated flame retardants and other persistent organo-
halogenated compounds and their descriptors in US girls. Environmental Research,
251-257.
Bibliography
Flame retardants are the hidden protection against the
potentially devastating impact of fire in many plastic products. We
looked to solve two major problems regarding flame retardants:
eliminating their chemical toxicity and making them biodegradable
and thus, environmentally friendly. The combination of PLA and
PBAT provided a biodegradable polymer blend base with an ideal
balance of flexibility and strength. Adding cellulose soaked in
RDP increased mechanical stabilization and made the polymer
flame retardant. Among all the blends we experimented with, the
50/50/8 PLA/PBAT/RDPCellulose blend was able to maintain the
highest flame retardancy grade of V0 while achieving optimal
mechanical properties.
The application of cellulose to our polymer blend resulted in
greater mechanical stability, mitigating the negative effects of
liquid RDP on polymer phase separation. We also discovered that
our blends containing cellulose hardened significantly with
minimal charring after burning, in contrast with previous research
done using starch in biodegradable flame retardant polymer
blends.2
For different practical industrial applications, the desired
mechanical properties of this polymer can be obtained by varying
the ratio of PLA to PBAT to increase either tensile strength or
impact toughness, respectively.
Future Work
In the future, we would like to continue testing more polymer
blends. We aim to minimize the amount of liquid RDP to further
increase the polymer’s mechanical strength while maintaining the
highest flame retardancy grade of V0. We would also like to
conduct further chemical analysis to determine why the polymer
hardens after burning, why the polymer does not char, and the
mechanisms behind the polymer’s self-extinguishing properties.
EDX Analysis:
•After burning, the
polymer showed
minimal charring
•Chemical analysis
indicated greater
phosphorous content
at the surface,
suggesting the
formation of a
thermal shield that
limits flame and heat
transfer
• Goal: To construct an environmentally-friendly, biodegradable
flame retardant polymer blend that maximizes mechanical
properties by minimizing additives.
• Once flame retardancy is attained, we will compare the
physical and chemical properties of the burnt and unburnt
samples to understand the effects of burning on the polymer.
• Hypothesis: A polymer blend of PLA and PBAT with some
proportion of RDP and cellulose additives will achieve these
objectives.
Objectives