Enhanced crystallization and storage stability of mechanical properties of poly(hydroxyalkanoate)s in the presence of hydrazide compounds with different configurations

Abstract

Slow crystallization rates and poor storage stability of mechanical properties limit the widespread use of biosynthesized poly(hydroxyalkanoate)s (PHA). Hydrazide compounds (HCn) with a formula of C6H5CONHNHCO(CH2)nCONHNHCOC6H5 (n = 4 and 8) were used as PHA nucleating agents to improve the crystallization and mechanical properties. The effects of HCn structure and self-assembly on the crystallization kinetics and nucleation efficiency of PHA were systematically investigated. Both HCns can be dissolved in the PHA matrix at high temperatures and then self-assemble into rod-like structures to induce crystallization of PHA. The nucleation efficiency of HC8 is much better than that of HC4 at low subcooling. With only 0.75 wt% HC8, the crystallization half-life time t1/2 of PHA at 100 °C decreased by 91 % and the degree of crystallinity increased to 38.2 % with a large number of tiny nuclei. Moreover, storage stability of mechanical properties of PHA was greatly improved due to the better crystallization ability. Therefore, this work provides a basis for the design of high-efficiency nucleating agents for PHA, which is expected to improve the mechanical properties and expand the application fields of PHA.