Effects and mechanism of cellulose acetate butyrate on the crystallization of polylactic acid

Abstract

The effect of cellulose acetate butyrate (CAB) on the crystallization kinetics of polylactic acid (PLA) has been investigated by means of differential scanning calorimetry (DSC), polarized optical microscopy (POM) and scanning electron microscopy (SEM). CAB is essentially immiscible with PLA, as CAB spherical particles with average diameters in the range of 140–185 nm dispersed uniformly in PLA matrix. The incorporation of CAB effectively reduces the crystallization rate of PLA even at a low loading of 0.2 wt%. Moreover, it is particularly interesting to find a critical CAB content (about 5 wt%) which further increase in CAB concentration doesn’t bring significant influence on the PLA crystallization rate. Combined with the results of POM, SEM, DSC and selective dissolving experiment, it is proposed that the coating of CAB on the nuclei which enhanced by the nano-scaled CAB structure could strongly inhibit the nucleation, and thereby reduce the overall crystallization rates of PLA.