Synthesis of polyblends from polypropylene and poly(R,S)-β-hydroxybutyrate, and their characterization

Blends of modified polypropylene (PP) with poly(R,S)-beta-hydroxybutyrate (PHB) were prepared by casting polymer solutions, followed by compression molding into thin films. The modified polypropylene was obtained by oxidation with hydrogen peroxide. Oxidation of polypropylene produced new functional groups such as carbonyl and hydroxyl groups on the polymer chain, and a decrease in molecular weight and crystallinity of the polymers. Maximum crystallinity and mechanical properties of the polyblends were found with a PP/PHB ratio of 90/10 (w/w), and then decreased with increasing PHB content in the polyblends. Biodegradability of the polyblends was lower than that of bacterial and synthetic PHBs. Furthermore, an increase of PHB proportion in the polyblends resulted in highly non-compatible polyblends. Hence only PHB and small parts of the polyblends were decomposed by microorganisms. (c) 2006 Society of Chemical Industry.