Plastics made from renewable feedstocks, such as corn, hold an odd place in the engineering playbook. They don’t offer any engineering advantages, and, in fact, offer significantly less heat resistance and mechanical strength than their hydrocarbon brethren, which continue to improve in performance. They also have no economic advantage, and remain, significantly more expensive than hydrocarbon-based plastics, even with oil at $100+/bbl. Yet production plans for bioplastics are rapidly expanding, based on the idea they are good for the environment. Some cities are behind the push, such as San Francisco’s ban on polyethylene bags. That strategy is superficial since paper bags create significantly more air and water pollution, and cost ten times more than plastic bags. Such efforts, however, will create a market for compostable plastics. Fast food chains may use compostable plastics for forks and knives. Will bioplastics reduce our dependence on oil? Even that point is debatable given the energy costs required to create and transport biofeedstocks. And surges in grain prices may be an even bigger penalty than high oil prices. At least we can choose not to drive SUVs; we can’t choose not to eat.
The bans aimed at plastics generally lack technical understanding or context. If you’re looking for some plastic engineering insight, consider attending the Annual Technical Conference (ANTEC) of the Society of Plastics Engineers May 4-8 in Milwaukee. There will be a special session May 6 on “Advances in Polymers from Renewable Resources”. One keynote is: “Bioplastics: New Generation Polymers for Reducing Carbon Footprint and Improving Environmental Performance”, which will be delivered by Professor Ramani Narayan of the Department of Materials Science and Engineering at Michigan State University. Dr. Narayan has put some real science into the carbon footprint debate. Other sessions will tackle nuts and bolds technical issues such as improving the heat performance of PLA. The session has a clear pro-bioplastics feel to it. But this is the place to hear the pitch. There will be plenty of plastics engineers in the audience to keep the presentations on target.