Kaien Yang - Part 2: Pumpkin Based Bioplastics

Hi everyone!

I’d like to dedicate this blog to part 2 of my project, focusing on inventing a technically feasible, commercially viable and biodegradable plastic using pumpkin and the glycerin which was produced as a byproduct from the transesterification in part 1 of my project.

Pumpkin starch is primarily composed of two molecules: amylopectin, a branched molecule, and amylose, a linear molecule. In bioplastics, when the starch is heated and gelatinized, the amylopectin and amylose become more organized due to hydrogen bonding, and the resulting molecular organization increases the bioplastic’s strength. Glycerin contains polar hydroxyl groups to increase the flexibility. I added vinegar to institute a stronger bond between the pumpkin and the glycerin.

I tested the strength of the bioplastic using the organic glycerin from pumpkin seed oil vs. the petroleum-based glycerin using a clever device I designed using a bucket, an S-hook, gravel, and a scale. My project involves a somewhat long process, with the pumpkin seed to biodiesel and glycerin process taking up to a week and the bioplastic process taking up to two weeks. Extremely humid and hot summer weather in Virginia this year also posed its challenges in getting my bioplastic dried without developing molds. To speed up the process, I produced many batches in parallel and sequence.

I had great discussions with my mentor Dr. Ali, who encouraged me to look into patent application of my invention.

I can't believe we are one blog and one month away from the final event! Stay tuned and stay curious!