Gamma-ray crosslinking of poly (3-hydroxyoctanoate-co-undecenoate)

The gamma-ray crosslinking of films made of poly(3-hydroxyoctanoate) containing undecenoate moieties (up to 33 mole%) were studied. X-ray diffraction, thermal analysis, dynamic mechanical analysis (DNIA), solid state nuclear magnetic resonance (NMR) spectroscopy and degree of crosslinking (swelling analysis) as a function of irradiation dose were evaluated for treatments in air or in N-2 atmosphere. After uncrosslinked material was isolated by CHO, extraction, solid state NMR data suggested that only a small percentage of the double bonds took part in the formation of irradiation crosslinks. Crosslinking in N2 was more efficient than in air and a 20 kGy dose was sufficient for optimal crosslinking. The X-ray diffraction patterns of the polymer films were unaffected by moderate irradiation. The use of sodium hypochlorite to isolate poly(3 -hydroxyoctanoate-co-undecenoate) samples resulted in partial chlorination of the double bonds and considerable depolymerization. (C) 2001 Elsevier Science BN. All rights reserved.