Polymers surround us in nature, so it’s no surprise that researchers are looking to transform more biological polymers and organic waste -- rather than food crops -- into bioplastics. Here are just a few examples:
- Orange peel feedstock. Researchers can derive monomers from the cyclic hydrocarbon limonene, which can be extracted from orange rinds using microwaves.
- PHB from microalgae (diatoms), instead of bacteria. By inserting the right genes to produce the right proteins into microalgae, researchers seem to have found a more efficient way to synthesize the versatile biopolymer PHB (polyhydroxybutyrate), using just sunlight and water.
- Cow plastics? Researchers are looking at using protein-rich by-products from beef production to produce bioresins (more details here). What will vegetarians say?
Meanwhile, natural polymers and fibrous plants are also being turned into plastic alternatives or reinforcing ingredients for biocomposites, as in this research:
- Molded cellulose. After all, plant cellulose is itself a biopolymer. PepsiCo is working with a partner to produce moldable cellulose fiber as an alternative for standard packaging plastics.
- Lignin, a constituent of wood, in new PP composites. A chemical treatment of the natural polymer lignin reportedly make it more compatible with polypropylene, allowing composites with 70% lignin content.
- Bio-nano-fibers made from organic waste – “such as banana leaves, crustaceans, and almond nut shells.” Fibers from these materials could be useful in reinforcing biopolymers such as PLA, researchers say.
Although some of these ideas sound far-fetched, we shouldn’t forget that in a few years the lessons learned from this research might turn out to be extremely valuable in making new and better bioplastics.
Mike Tolinski is the author of Plastics and Sustainability, published in Oct. 2011 by Wiley-Scrivener, and he is Contributing Editor for Plastics Engineering magazine of the Society of Plastics Engineers in the USA. His views have been shaped by his engineering, university, and journalism experience in the plastics and manufacturing industries over the past 21 years.