Effect of cellulose nanocrystals on the crystallization behavior and enzymatic degradation of poly(butylene adipate)

Cellulose nanocrystals (CNCs) are nature-resourced nanoparticles and have been widely used to improve performance of biodegradable polyesters. Two types of CNCs respectively prepared by sulphuric acid hydrolysis (aCNCs) and ammonium persulfate oxidation (oCNCs) processes were incorporated into poly(butylene adipate) (PBA) matrix to regulate its crystallization behavior and enzymatic degradation performance. Thermal and X-ray diffraction analysis revealed that both aCNCs and oCNCs could promote the crystallization ability and lamellar thickening of α-form PBA, while oCNCs showed stronger promotion than aCNCs. Optical morphology study indicated that both two types of CNCs enhanced the nucleation ability of PBA. Furthermore, the mechanism of crystallization promotion of CNCs on PBA was further discussed and attributed to the "memory effect" in the melt state of PBA/CNCs composites, which was originated from the hydrogen-bonding interaction between CNCs and PBA chains. The enzymatic degradation testing proved that CNCs could slower down degradation rate of PBA and PBA/oCNCs composites possessed lower degradation rate than PBA/aCNCs composites.