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

Slow crystallization rates and poor storage stability of mechanical properties limit the widespread use of bio-synthesized poly(hydroxyalkanoate)s (PHA). Hydrazide compounds (HCn) with a formula of C6H5CONHNHCO (CH2)(n)CONHNHCOC6H5 (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 HC(n)s 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 t(1/2) of PHA at 100 degrees 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.

Automated summary

This study aimed to improve the crystallization and mechanical properties of poly(hydroxyalkanoate)s (PHA) by using hydrazide compounds as nucleating agents. The results showed that HC8 had better nucleation efficiency than HC4, and the addition of 0.75 wt% HC8 at 100 degrees C significantly decreased the crystallization half-life time and increased the degree of crystallinity of PHA. The better crystallization ability also greatly improved the storage stability of PHA's mechanical properties.