Preparation and characterization of a biocomposite based on cork microparticles in poly(β-hydroxybutyrate)-co-poly(β-hydroxyvalerate) matrix

Abstract

Poly(b-hydroxybutyrate)-co-poly(b-hydroxyvalerate) (PHBV)loaded with 1 to 10 wt.% of cork microparticles (CM) weremanufactured via compression molding technique. CM wereisolated by alkali, bleaching and acid hydrolysis treatments.They were then added to the PHBV matrices via solution cast-ing technique. The filler microparticles showed typical diameters of 10 to 55 microns. Mechanical tests in tension showed thatin PHBV containing 5 wt.% CM the Young’s modulus andthe tensile strength increased by 50% and 10% respectively.Meanwhile, the elongation at break decreased by 70% forthe same CM content. The mechanical behavior of the reinforced composites was discussed in conjunction with the morphology of the samples studied by optical and electron microscopy. The temperature of initial degradation Tid, thetemperature at 5% weight loss Td 5%and the temperature ofmaximum degradation Tdmaxincrease with increasing CMcontent by up to 13.6ºC, 10.1ºC and 12.3ºC respectively forthe composite of 5 wt.%. The composite with 10 wt.% CMcontent showed the best thermal stability with temperature increments of 20ºC, 14.1ºC and 21.5ºC respectively. DSC re-sults showed that the presence of CM has a very weak influence on the melting/crystallization behavior of the composites.