Chemical Degradation of Poly(hydroxybutyrate-cohydroxyvalerate) Microparticles

摘要

Poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) is a polymer that can be used on preparation of controlled release systems containing actives principles. The release of the compounds encapsulated on those systems can occur by three different forms: diffusion, degradation and matrix polymeric rupture. Therefore, it is interesting to evaluate the behavior of polymeric matrix when it is submitted on a pH change, for example an agricultural soils simulations. The objective of this study is the understanding of the chemical degradation process of microparticles employed with agricultural application. The PHBVmicroparticles were prepared using o/w simple emulsion technique followed by solvent evaporation, using poly(vinyl alcohol) (PVA) as stabilizing agent. The evaluation of polymeric microparticles, submitted to chemical degradation process in pH 5.6 at room temperature, was determined by conventional characterization techniques such as Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and Differential Scanning Calorimetry (DSC). By SEM images it is possible to suggest that the chemical degradation process occurred. The indicatives peaks of crystallinity of the PHBV microparticles decrease and occurred the rise of broader peaks relative at appearance of new amorphous regions. The data obtained by thermal analysis shown thatmicroparticles degradation occurred on amorphous and crystallines portions of PHBV.