Biodegradable Thermoplastic Starch
TPS
Thermoplastic Starch
TPS
High demand of biodegradable substances
Replacing macromoleculr substances that originate from fossil fuels
Structure of Starch
- Hydrophillic-Readily oxidised and reduced
- Amylose-Low molecular weight, long chain
- Amylopectin-High molecular weight, short branched molecules
Molecular Motion
- Rigid and radom conformations
- Molecule movements initiated by heat
- Becomes more flexible and viscous
Molecular
Retrogradation
- Replenish/preserve water content
Retrogradation
- Metabolises into carbon dioxide and water
Physical and Chemical blends
Biodegradable starch blends
Physical blending of polymers
Physical blending is the simple technique of mixing of polymeric materials in a melt state with no chemical reactions taking place.
Physical blends
Main goal of physical blending polymers includes
- Improvement of mechanical properties
- cost reduction
- tailoring of properties to a certain application
Blends with synthetic degradable polymers
To obtain starch based biodegradable thermoplastics the starch component are usually blended with aliphatic polyesters, PVA, and biopolymers.
The commonly used polyesters are:
- Poly Beta-hydroxyalkanoates (PHA)
- Polylactide (PLA)
Biopolymers blends
Biopolymers blends
Natural starch blends
Natural polymers such as starch and chitosan are inherently biodegradable.
Benefits of natural polymers:
- Readily available
- Cheap
- Non-toxic
- Renewable
- Biodegradable
Chemical derivatives
A particular problem of starch-based blends is that many starch blends are non-miscible which leads to poor mechanical properties.
To enhance the mechanical properties of these blends chemical strategies are considered.
These strategies includes:
- Substituting the hydroxyl group
- Graft copolymerization
Agricultural
- Lots of plastics used in agriculture
Agricultural
Packaging & Containers
- Makes up significant amount of our plastic waste
Packaging & Containers
- Increase appeal to consumers
- Suitable for non-liquid foods
Medical
- Non-toxic, resorbable and biodegradable
Medical
- Manufacturing of capsules for drug delieveries
- Film to assist in the healing of wounds
By:
Anton Van
Johnson Wang
Helen Zeng
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