We have developed a process for transforming starch into biodegradable films. The starch is chemically modified and crosslinked. Under ordinary conditions the resulting films would be weak and brittle. However with further processing we have obtained tough films that are hydrophobic and resistant to breakdown during fabrication and normal use yet susceptible to biodegradation after disposal. We have obtained films with tensile strengths of 15 - 47 MPa tensile moduli from 320 - 670 MPa and elongations at break from 5-120% depending on processing conditions. These values fall within the ranges reported for polyethylene films. Areas of Application: Possible uses for our films include disposable trash bags food-service items beverage cups diaper backings packaging films and agricultural mulches.
1) Current technology for plastic films involves materials produced from petroleum-based non-biodegradable plastics. (Even the so-called biodegradable plastics presently on the market which are mixtures of starch with conventional polymers are only partially susceptible to microbial breakdown.) 2) Our films being fully biodegradable and entirely based on starch -- a plentiful inexpensive and renewable resource -- offer significant environmental advantages over existing films at comparable cost.