A new class of biodegradable materials: poly-3-hydroxy-butyrate/ steam exploded straw fiber composites. I thermal and impact behaviour

Biodegradable thermoplastic composites reinforced with wheat straw fibers were prepared. The matrix was an expensive polyester, poly-3-hydroxy-butyrate (PHB), produced by bacterial fermentation. Before being mixed with the PHB, the wheat straw fibers were subjected to a steam explosion process that induces morphological and structural changes in lignocellulosics. Such changes enhance the interaction with the thermoplastic matrix. The two components were melt mixed and the composite molded under hot compression. Compared with neat PHB, not only does the composite material show better mechanical properties but, moreover, production costs are dramatically reduced because wheat straw is a very inexpensive product. Finally, FTIR measurements revealed some PHB/straw fiber molecular interactions that interfere with the PHB crystallization