BIODEGRADABLE POLYMERS
ONE OF THE MANY SOLUTIONS TO THE WORLD’S PLASTIC
POLLUTION CRISIS
AN INTRODUCTION
A current world renowned problem we have right now are plastics
that are endlessly polluting the land as well as the seas. We may
think that most waste management companies are constantly
scraping through the rubbish we throw out.
However, we were quite wrong. Only a fraction of all plastic waste are
recycled. The rest are possibly floating somewhere in the ocean or
sitting on land continuously without decaying. This is rather harmful
to the environment, as plastics can be accidentally eaten by animals
and contaminate our waters in the form of microplastics.
AN INTRODUCTION
A solution was required to solve the plastic pollution crisis. Something
that can keep the plastics industries going without having to harm
the waters. One of the many proposed solutions were
Biodegradable Plastics, or to be more general, Biodegradable
Polymers.
Biodegradable Polymers are special type of polymer that decompose
in the presence of bacteria or microorganisms, releasing natural
byproducts such as gases, biomass, water and inorganic salts.
AN BRIEF HISTORY
• The use of biodegradable polymers dates back to as early as 100
AD. It was first used as catgut suture, extracted from sheep
intestines.
• Synthetic biodegradable polymers weren’t contrived until the 1980s.
Testing protocols, definitions and standards came into place in 1992
by leaders in biodegradable polymers
• It wasn’t until the 2010s, biodegradable plastics were being utilized
and popularized by clothing and grocery store chains
POLYMER STRUCTURE
• Biodegradable polymers are generally made up of ester, amide, or
ether bonds.
• They can be classified into two groups: agro-polymers and
biopolyesters
• They are grouped based on the chemical structure of the polymer
and the way it is synthesized.
POLYMER STRUCTURE GROUPS
Agro-polymers Biopolyesters
Microorganisms
Polysaccharides
Proteins Monomers
(Synthetic & Natural)
Agro-polymers are usually developed from Biopolyesters are made from
biomass and renewable natural resources microorganisms or synthetically made
of various kind. from monomers, both synthetic and
natural
SYNTHESIS / HOW IT’S MADE
• Industrially, one of the most important biodegradable polymers, polyesters,
are usually synthesized from direct condensation of alcohols and acids, ring
opening polymerizations and reactions involving metal catalysts.
• Various monomers can be used as the starting point of the reaction, with
each of them resulting in a polymer chain with different characteristics.
SYNTHESIS / HOW IT’S MADE
• In order to produce a polymer with excellent properties, three conditions
must be taken into consideration during polymerization:
TEMPERATURE
AGITATION PRESSURE
DEGRADATION MECHANISM
• Degradation of biodegradable polymers usually results in the release of
natural byproducts such as gases, water, salts and biomass.
• The degradation process depends on the properties of the polymer itself as
well as factors from its surrounding environment.
• Polymer properties include copolymers, bond type and solubility
• External environmental factors include pH, temperature, microorganisms,
and water
DEGRADATION MECHANISM
• Biodegradation occurs in two primary mechanisms.
• One is done chemically by reactions such as hydrolysis &
photogdegradation
• The other mechanism involves biological processes, which are further
broken down to aerobic and anaerobic processes
AEROBIC
ANAEROBIC
These processes mostly work for natural polymers. Whereas for newly
made synthetic polymers, it will take millions of years before microorganisms
can adapt to degrade these new synthetic polymers.
PROPERTIES - MECHANICAL
• Since biodegradable polymers can be used as bone supports in the medical
field, it should be strong and durable enough to withstand the applied load
• The unreinforced polymer PLA (polylactic acid) exhibits 36% strength in
tension and 54% in bending when compared to annealed stainless steel.
• Rapid loss in strength and slow loss in stiffness occurs in biodegradable
polymers that consist of carbon or nonorganic composites.
PROPERTIES - CHEMICAL
• They key factor that makes a great biodegradable polymer is its stability and
durability in their application and degradability after its specified use.
• Importantly, the polymer should : 1) be non toxic 2) maintain integrity until
degraded 3) able to control rates of degradation
• The rate of degradation of the polymer depends upon the crystallinity,
molecular weight and hydrophobicity.
APPLICATIONS AND USES
• In the medical field, it is used in drug delivery and tissue engineering. The
ability of the polymer to target a specific site in the body and degrade into
nontoxic materials makes it ideal for drug delivery.
• They are also used in tissue engineering as they also serve as a
biodegradable scaffold for building new biological structures, hence making
less likely to be rejected from the immune system.
APPLICATIONS AND USES
• Aside from medicine, biodegradable polymers are used to replace non-
degradable plastics used for packaging in order to reduce waste. PLA
(Polylactic Acid) is the most widely used polymer as it can adapt physical
properties through processing methods
REFERENCES
• https://en.wikipedia.org/wiki/Biodegradable_polymer
• https://www.sciencedirect.com/topics/materials-science/biodegradable-polymer
• https://www.visionlearning.com/en/library/Biology/2/Biological-Proteins/243
• https://www.britannica.com/science/microbiology/Types-of-microorganisms
• https://en.wikipedia.org/wiki/Methacrylate
• http://semesters.in/definition-and-types-of-agro-polymers-notes-pdf-ppt/
• P. Janarthanan, A.K. Veeramachineni, X.J. Loh “Biodegradable Polysaccharides”
https://www.sciencedirect.com/science/article/pii/B9780128035818092183
• https://www.pouchworth.com/compostable-plastic-bags/
• https://www.uweb.engr.washington.edu/research/tutorials/drugdelivery.html
