The miscibility of melt processed blends of bacterial poly( 3-hydroxybutyrate) (PHB) with poly(epich1orohydrin) (PEC) is investigated over the whole range of compositions by means of differential scanning calorimetry, dynamic-mechanical analysis, and hot-stage optical microscopy. PHB and PEC are miscible in the melt in all proportions. After melt quenching, PHBIPEC blends show a single glass transition that linearly changes with composition between the Tgs of the pure components (PHB = 2OC, PEC = -21OC). At room temperature all PHB/PEC blends are partially crystalline, owing to crystallization of a constant fraction (58%) of the PHB present in each blend. A spacefilling spherulitic morphology develops upon blend crystallization from the melt. Isothermal crystallization measurements show that over the range of crystallization temperatures (4OOC < T, < 130OC) and compositions (20% < PEC < 80%) explored, the spherulite radial growth rate ( G ) decreases with increasing PEC content. Biodegradation experiments, carried out in activated sludge and in enzymatic solution (PHB-13 Copyright 0 1997 by Marcel Dekker, Inc.
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