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Biosynthesized poly(3-hydroxybutyrate- co -3-hydroxyhexanoate) (PHBHHx) has emerged as a promising biodegradable polymer with a great potential to compete with traditional petroleum-based plastics, however, the poor crystallization ability makes it challenge to transform into high-performance products via common melt-processing methods. Herein, we demonstrate that N,N′ -dicyclohexyl-2,6-naphthalenedicarboxamide (TMB) can serve as an efficient nucleating agent to significantly enhance the crystallization and resulting storage stability of PHBHHx. The results indicate that PHBHHx with small amounts of TMB (0.3–0.5 wt%) can crystallize completely even under a rapid cooling rate of 100 °C/min and the isothermal crystallization time is greatly reduced. As a result, the crystallinity of the injection-molded PHBHHx products is increased from 24.5 % to 39.5 %, without secondary crystallization after being stored at room temperature for 6 h. The products exhibit superior dimensional stability and the post-shrinkage can be decreased to as low as 0.1 %. Our work offers a feasible method to develop high-performance PHBHHx materials with remarkably enhanced crystallization ability. [ABSTRACT FROM AUTHOR]

Stereocomplex-type polylactide (SC-PLA) has recently emerged as an up-and-coming engineering Bio-plastic because the SC crystallization between enantiomeric poly(l -lactide) (PLLA) and poly(d -lactide) (PDLA) can substantially enhance the heat resistance and hydrolytic stability. Unfortunately, it is exceedingly challenging for high-molecular-weight PLLA/PDLA blends to preferentially crystallize into SC crystals (SCs) during melt processing and the concomitant formation of homocrystals (HCs) causes a significant deterioration in physio-chemical properties of final products. Herein, a dibenzoylhydrazide compound has been utilized as an efficient nucleating agent (NA) for the SC crystallization of PLLA/PDLA blends. The results indicate that, in both non-isothermal and isothermal crystallizations, the SC crystallization is markedly promoted with the incorporation of 0.2–1.5 wt% NA. Specially, the enantiomeric blends with relatively high amounts (≥0.5 wt%) of NA are found to exclusively crystallize into SCs without any HCs formation. Meanwhile, the NA can accelerate the SC crystallization and reduce the crystal size. The preferential SC crystallization should be associated with the hydrogen-bonding interactions between PLAs and NA molecules, which could lower barriers for the nucleation and crystal growth of SCs. Our work provides a facile yet powerful strategy for the preparation of high-performance SC-PLA materials with exceptional SC crystallization ability. [Display omitted] • TMC can act as an efficient NA to promote the SC crystallization of PLLA/PDLA blends. • Exclusive formation of SCs is achieved after adding 0.5 wt% TMC into the blends. • The crystallization is greatly accelerated due to the increase in nucleation density. • The hydrogen bonding between TMC and PLA is responsible for the enhanced SC formation. • A facile strategy has been proved to develop SC-PLA with exceptional crystallizability. [ABSTRACT FROM AUTHOR]