Questions about Starch-based plastic

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Why most bioplastics are made of cornstarch? Does the type of starch affects the quality of bioplastics? If so, how does the type of starch affects the quality of bioplastic? Thanks in advance.

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The corn starch contains a sugar called dextrose, which is extracted. Through fermentation, the dextrose is converted into lactic acid, a compound produced when a sugar is broken down and oxidized. This lactic acid becomes lactide, the "cyclic di-ester" of lactic acid. {Extra information: This means that at least one hydroxyl group (a group of an oxygen and hydrogen) was replaced with an alkoxy group (a group with carbon/hydrogen chain attached to an oxygen)}. The lactide is polymerized (many lactides are attached to each other) in order to make long chains of lactide, molecules called polylactide acid (PLA). PLA is a type of plastic.

The type of starch would most likely have an effect if there were differences in the quality/amount of dextrose. I would predict that more sugary corn starch types would produce more plastic, but I am unsure how this would affect the quality of the plastic. This would be interesting to research.

I hope that helps!

-Kayli Masuda