Chemical Degradation of Poly(hydroxybutyrate‐co‐hydroxyvalerate) Microparticles

Abstract

Summary 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 PHBV microparticles 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 that microparticles degradation occurred on amorphous and crystallines portions of PHBV.

Characterization Techniques of Polymer Aging: From Beginning to End

“…The chemical aging of poly(hydroxybutyrate-co-hydroxyvalerate) can be triggered in the crystalline and amorphous domains, with the features of deceased intensity at 44°for crystalline domain and 21°for amorphous halo. 195 The new broad peaks appeared after aging, due to the disorganization of polymers. Synchronous aging could also be observed for poly(butylene succinate), as a result of the no-preferentially decreased peaks for the crystalline and amorphous regions.…”

“…In the other cases, the aging occurred simultaneously in the crystalline and amorphous regions. The chemical aging of poly­(hydroxybutyrate- co -hydroxyvalerate) can be triggered in the crystalline and amorphous domains, with the features of deceased intensity at 44° for crystalline domain and 21° for amorphous halo . The new broad peaks appeared after aging, due to the disorganization of polymers.…”