When Bioplastic Goes Bad

Time to try another recipe for bioplastic. I’m still hoping to find a simple, affordable material that can be made from waste ingredients (so we don’t use oil for trivial products) that rots away when no longer required… and that could be manufactured in a cottage industry.

The third recipe for bioplastic that I tried was “microwave bioplastic”, which is typically made from cornstarch (1 tbsp), water (1 tbsp) and vegetable oil (two drops). Bioplastic doesn’t come much simpler than this, nor much quicker. A microwave oven is used to heat the mixture for twenty seconds or so, and then you knead the result, and mould it into shape… and you’re done.

I made a small ball of the material, and set it aside to dry. Once again, it appears we’re looking at a thermosetting process here: the bioplastic doesn’t simply harden as it cools. It took about a day to set, and the ball split apart as it dried. The fragments were hard, like a ceramic, making the first time I’ve been able to report a material with the kind of strength that would be sought in many plastic products… but my sample had distorted beyond any kind of usefulness.

Microwave bioplastic ball

Microwave bioplastic: surprisingly hard… but hopelessly distorted during drying.

“Don’t let it dry too quickly,” is the advice from the Internet bioplastic community. The problem of splitting in microwave bioplastic is well known. I kept the next sample under wraps, with just a few air holes. After a week…

Microwave bioplastic cup, decomposing

Something is rotten in the state of bioplastic

My bioplastic, deliberately kept moist to prevent splitting apart, had begun to rot even before it had dried. I removed the plastic covering and left the festering thing to compost itself… and it promptly split apart.

Microwave bioplastic, broken apart

Not all things that are furry are cute.

Verdict: this isn’t the bioplastic we’re looking for.

It’s said that bad doctors get to bury their mistakes, while bad architects can only recommend that you plant a row of trees. Bad bioplastic engineers have the best of all possible worlds: the evidence of their mistakes removes itself – and surprisingly quickly.


3 thoughts on “When Bioplastic Goes Bad

  1. Hi Richard, I too have been playing with variations of bioplastic for years attempting to find “stovetop” solutions. I’ve tried countless variations of formulas found online and even wandered off on my own formulations after speaking with chemists, food scientists, etc. I’ve gotten close but still haven’t locked it down. I would love to chat and share notes!

    • Hey Logan,

      Do you know how I could turn this into a pellet form? I have used cassava starch, vinegar and water. Heated it and made some good bioplastics. I would like to put it into a blown film machine. But I need the pellet form first. And this is where I run into a problem. I dont know if if I can put in all these wet ingredients into a pelletizer?

  2. Pingback: Bananas for Bioplastic | Capacify

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