No abstract

No abstract

No abstract

No abstract

No abstract

No abstract

Consorzio sulle Applicazioni dei Materiali Plastici e per i problemi di Difesa dalla Corrosione, Via P. Castellino, 11 1 801 00, Napoli, Italy, and 'Stazione Sperimentale per la Cellulosa, Carta e Fibre Tessili Vegetali e d Artificiali, Piazza Leonard0 d a Vinci, 26-201 3 3 Milano, Italy SYNOPSISBiodegradable 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.

Isothermal crystallization of a polyoxymethylene copolymer in the temperature range of 423-429 K (150-156 1C) was performed using a differential scanning calorimeter (DSC) and data of crystalline development processed within the framework of a nucleation and growth model. Morphological investigations on DSC crystallized specimens were performed by scanning electron microscopy (SEM) and correlated to DSC data to obtain good estimations of spherulite growth rates in the explored temperature range. The accuracy of the growth rate has been enhanced by Hoffman regime analysis using reliable values of input parameters. Moreover, the function describing the number of growing spherulites as a function of time at constant temperature has been obtained.