Production of Bioplastics from Vegetable Waste

Problem I am trying to solve

Plastic, which are polymers, are made up of repeating units of monomers. Most plastics contain around 500 to 20,000 these repeating units and are made from crude oil. Molecules in crude oil undergo chemical reactions and produce monomers, which then bond to form polymers, that then undergo polymerization to form plastics. Besides crude oil being a non re-plenishable resource, polymerization process produces pollutants such as Carbon Dioxide, that contribute to global warming.

Bioplastics are made from the starch of vegetables such as potatoes and corn. However, some vegetable wastes are also a good source of starch. Could vegetable wastes (which typically becomes garbage in most places) be re-used in making bioplastics?

Goal of my project

Can bioplastics be produced from starch-laden vegetable wastes such as potato peels, banana peels and avocado pits?

Which of the above wastes would produce the best bioplastic in terms of strength, durability and flexibility?


Research

Starch from vegetable wastes can be extracted through grinding, evaporation and, filtration and decantation. The starch molecules consist of amylopectin and amylose. Amylopectin requires to be broken down into amylose monomers which form the polymer chains through hydrolysis. An additive Propan-1, 2, 3- triol is used as plasticizer to improve the flexibility of the plastic.

Method

Collect potato peels leftovers

Collect banana peel leftovers

Grind with water in a blender

Sedimentation to collect starch

Potato starch

Banana starch

Avacado starch

Heat starch with gylerol and vinegar

Pour the gel mixture in petri dish

Bake in oven at 250 deg for 30 mins

Cool and set 2 days

Cut into strips and hold with clips

Testing tensile strength of plastic

Testing decay of plastic over 10 days

Conclusions

The goal of the experiment was to find out if bioplastics could be produced from any vegetable waste that contains starch and to determine which vegetable waste would yield the best bioplastic as defined by strength, flexibility and durability.


All three vegetable wastes produced a bioplastic that had many properties similar to a conventional plastic:

  1. Strength (ability to withstand force)

  2. Flexibility (not easily breakable)

  3. Durability (does not decay at least for 7 days)


The starch content is one of the many factors in determining the quality of the plastic generated. While banana peels showed the highest flexibility, potato wastes yielded the strongest plastic and avocado pits extracted the most plastic. The ratio of the amylose to amylopectin molecules is what gives each plastic its unique property.

Recognition

Castro Family Award for Best Physical Science Projects. Board of Directors Awards - Middle School

1st Award, Physical Science and Engineering Category



  1. First Place, Chemistry Junior division

  2. Clinical Chemistry Award – For interesting and original projects that impact the future of clinical chemistry

2nd place award

Top 300 in Broadcom Masters