Mechanical properties and higher-order structures of biaxially drawn bacterial poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanote] films

Bacterial poly(3-hydroxybutyrate-co-hydroxyhexanoate) (PHBH) biaxially oriented films were prepared by combination of the roll and biaxial drawing processes. Compression molded films, which consisted of large spherulite aggregation, were roll drawn up to ×1.4 and further biaxially drawn up to 3.0×3.0. The tensile modulus and the break elongation decreased while the tensile strength increased as the biaxial draw ratio increased. Biaxially drawn films showed two kinds of structures: one in which the c-axis was almost perpendicular to the film surface and the other in which the c-axis was at an incline compared to the normal film surface. The correlation among the processing conditions, higher-order structures, and mechanical properties was investigated using wide-angle X-ray diffraction, small-angle X-ray scattering, and tensile measurements. Open image in new window