Crystallization phenomena in bacterial poly[(R)-3-hydroxybutyrate]. 2. Embrittlement and rejuvenation

Poly[(R)-3-hydroxybutyrate] (I) (Biopol) is a bacterial storage polymer, currently receiving much attention because of its potential as a biodegradable plastic. A major drawback of I is its intrinsic brittleness. Although as-molded I shows ductile behavior, upon storage at ambient temp. is detrimental aging process seriously embrittles the material and restricts its application possibilities. This remarkable embrittlement is delineated in the present study and could be attributed to progressive crystn. By using a simple annealing treatment I can be rejuvenated while subsequent aging is prevented to a large extent. This observation might considerably enlarge the applicability of