Bioplastics

Synthetic plastics
- 80% of polymers are produced from non-renewable fossil resources. Mass consumption of products with short lifespan (e.g. disposal utensils). Disposed items are transported to landfills; in Singapore, the landfill is currently Pulau Semakau.
- However, this creates garbage patches in the sea, where the plastic breaks up into tiny pieces too small to be scooped up, and forms patches of plastics floating at the surface of the water. Ingestion of these tiny pieces of plastic by the marine animals is detrimental to their health. There is little we can do to clean up the patches. The only solution is to prevent throwing plastic waste into the sea.
- Not all plastics can be recycled.

Bioplastic (made from starch and protein)
- Bioplastics consists of biodegradable plastics and plastics from renewable resources. Hence, not all bioplastics are biodegradable; it depends on the chemical structure
- Natural polymers: produced in growth cycles of cells of living organisms. E.g. proteins, fats, nucleic acids, cellulose, starch, polyesters. Materials created by nature can also be degraded by nature.

- Amino acids: Plastics are formed by polymerisation (addition polymerisation or condensation polymerisation). 2 amino acids can form a peptide bond through condensation polymerisation, with water being the by-product. The OH comes from the carboxyl group, while the H atom comes from the amino group of the 2nd amino acid. In this way, bioplastics can be made from proteins. 

• 80% of 2% cow's milk is made up of the polymer casein, a protein. This protein can go through polymerisation to create a natural plastic, as the casein molecules are condensed into long chains. 
• Addition of acid (vinegar) causes casein to denature and unfold, to rearrange into the chains of a polymer. 
• Straining the curds using a cheesecloth causes casein to precipitate, discard the clear watery substance (whey). Repeat straining process 3 times. 
• Shape casein into desirable shape before letting it dry into a bioplastic 

- Starch: consists of amylose (linear) and amylopectin (branched). After starch is dried from an aqueous solution, it forms a film due to hydrogen bonding between the chains of polymers. Amylopectin inhibits the formation of film, add acid to break down amylopectin. 

• Potato or cornstarch 

- Results of experiment: Cornstarch plastic most durable, hard but brittle. Potato plastic too thin layer, could not peel out of petri dish. Casein plastic very brittle

Benefits of bioplastics: 

• most plastics are made from crude oil and the process produces pollutants such as carbon dioxide which contribute to climate change. Crude oil is also in great demand throughout the world
• bioplastics circumvent these issues by involving the use of plants as the raw material instead of crude oil
• by converting the sugar present in plants into plastic, bioplastics are renewable 

Limitations of bioplastics: 

• hidden environment costs, such as toxic pesticides sprayed on the crops and carbon dioxide emissions from harvesting vehicles
• although fossil fuels are not used to make many bioplastic products, they are typically used to power manufacturing plants
• production requires nearly as much energy as producing conventional plastics 
• a number of bioplastics are compostable. With suitable conditions, microbes will break down the bioplastic into plant material, water, and carbon dioxide. This carbon dioxide goes back into the atmosphere as greenhouse gas emissions 
• might decompose in landfill, giving off methane, a greenhouse gas 20 times more potent than carbon dioxide 
• ineffective labeling keeps many compostable plastics out of the composting mix 
• recycling a mixture of plastics is not possible because different plastics have different melting points 

Personal reflection: 

I support the use of bioplastics because even though it might not seem like a much better alternative than normal plastic or may even be worse in the case of methane gas emission, but bioplastics have the potential to be further improved upon. For example, companies can invest in research to move from food source such as corn to abundant non-food crops such as switchgrass. There is the potential to leave less environmental impact than the current bioplastics because there might be a possibility of manufacturing bioplastics without using fuel, but using wind power and other renewable energy sources.