A NEW CLASS OF BIODEGRADABLE MATERIALS - POLY-3-HYDROXY-BUTYRATE STEAM EXPLODED STRAW FIBER COMPOSITES .1. THERMAL AND IMPACT BEHAVIOR

Biodegradable thermoplastic composites reinforced with wheat straw fib ers were prepared. The matrix was an expensive polyester, poly-3-hydro xy-butyrate (PHB), produced by bacterial fermentation. Before being mi xed with the PHB, the wheat straw fibers were subjected to a steam exp losion process that induces morphological and structural changes in li gnocellulosics. Such changes enhance the interaction with the thermopl astic matrix. The two components were melt mixed and the composite mol ded under hot compression. Compared with neat PHB, not only does the c omposite material show better mechanical properties but, moreover, pro duction costs are dramatically reduced because wheat straw is a very i nexpensive product. Finally, FTIR measurements revealed some PHB/straw fiber molecular interactions that interfere with the PHB crystallizat ion. (C) 1993 John Wiley & Sons, Inc.