Some dynamic mechanical properties of microbially produced poly-Β-hydroxybutyrate/Β-hydroxyvalerate copolymers

Dynamic tensile modulus and X-ray scattering measurements were made for a series of bacterially produced poly--hydroxybutyrate/-hydroxyvalerate (PHB/HV) random copolymers. The position of the primary relaxation is shifted to lower temperatures by increasing HV content and the material becomes generally softer. Drawn PHB/ 17% HV copolymer shows conventional mechanical anisotropy. Results are presented comparing the dynamic mechanical behaviour of isotropic PHB/HV with that of conventional thermoplastics such as polyethylene terephthalate, isotactic polypropylene and polyethylene.