CRYSTALLIZATION PHENOMENA IN BACTERIAL POLY[(R)-3-HYDROXYBUTYRATE] .2. EMBRITTLEMENT AND REJUVENATION

Poly[(R)-3-hydroxybutyrate] (PHB) is a bacterial storage polymer, currently receiving much attention because of its potential as a biodegradable plastic. A major drawback of PHB is its intrinsic brittleness. Although as-moulded PHB shows ductile behaviour, upon storage at ambient temperature a detrimental ageing 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 crystallization. Strikingly, we found that by using a simple annealing treatment PHB can be rejuvenated while subsequent ageing is prevented to a large extent. This observation might considerably enlarge the applicability of PHB.