COMPOSITION FOR PRODUCING STARCH FOAM RESISTANT TO MOISTURE AND FREEZE-THAW CYCLES

摘要

Plastic materials for packaging have increased dramatically in the last two decades, replacing more traditional materials such as paper, glass and metals. Most plastics are made almost entirely from chemicals derived from crude oil that may require hundreds of years to degrade and can kill wildlife if ingested. Disposal of used packaging products has been an ecological problem due to their non-degrability. Agricultural-based materials are beginning to emerge as promising substitutes for petroleum-based plastics. These so-called bio-based materials, such as starch and cellulose, have the advantage of being derived from a renewable source and be biodegradable into a useful compost. The present invention provides starch foam, as biodegradable packaging material, comprising an expanded starch and water batter by thermo process. Starch foam has low-density and closed cell structure and is mechanical resistant in different temperatures, mainly lower and freezing temperatures. The essential feature of this invention is its ability to produce starch foam resistant to freeze-thaw cycles. This ability is due to the higher batter viscosity that produces foams with resistant internal structure. Additive compounds may also be added to the formulation (plasticizers, thickening agents, organic and inorganic fillers, pigments and preservatives) to improve starch foam mechanical properties in freeze-thaw cycles. Starch foam can be coated with hydrophobic film to improve the moisture resistance.