| Institution: | 1. Polymer Chemistry Laboratory, RIKEN Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan, Fax: (+81) 48 462 4667;2. Polymer Chemistry Laboratory, RIKEN Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan, Fax: (+81) 48 462 4667
Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502, Japan |
| Abstract: | Uniaxially oriented films of poly(R)-3-hydroxybutyrate] (P(3HB)) and two kind of copolymers, poly(R)-3-hydroxybutyrate-co-8%-R]-3-hydroxyvalerate] (P(3HB-co-8%-3HV)), and poly(R)-3-hydroxybutyrate-co-R]-5%-3-hydroxyhexanoate] (P(3HB-co-5%-3HH)), were prepared by cold-drawing from amorphous preforms at temperatures near to the respective glass transition temperatures. Melt-quenched films in a rubber state could be stretched reproducibly to a draw ratio of 500%∼1800%, and subsequent annealing under tension led to improvement of the tensile strength and Young's modulus. Two-step drawing resulted in further improvement of the mechanical properties. The mechanical properties remained unchanged after storing for 6 months at room temperature, suggesting that high orientation and crystallinity suppress the secondary crystallization. |
