Enhanced crystallization and storage stability of mechanical properties of biosynthesized poly (3-hydroxybutyrate-co-3-hydroxyhexanate) induced by self-nucleation

The poor mechanical properties induced by unsatisfactory crystallization ability limit the widespread use of biosynthesized poly (3-hydroxybutyrate-co-3-hydroxyhexanate) (PHBH). In this work, poly (3-hydroxybutyrate) (PHB) with a high melting point was first used as a homogeneous nucleating agent to increase the crystallization rate of PHBH by a self-nucleation method with a wider processing temperature window and crystallization kinetics and storage stability of mechanical properties of the PHBH/PHB mixtures were systematically investigated. By controlling the processing temperature and PHB content, the crystal nucleus density and crystallization rate of PHBH could be greatly increased while secondary crystallization was inhibited. When the processing temperature is 185 °C and PHB content is 20 wt%, the half crystallization time is shortened by 96% and the crystallinity was increased to 37.2%. Meanwhile, the mechanical performance of PHBH and its storage stability are greatly improved. Therefore, this work provides a simple and efficient way to improve the crystallization and mechanical performance of PHBH, which is expected to be applied to industrial production on a large scale.