Crystallization Temperature as the Probe To Detect Polymer-Filler Compatibility in the Poly(ε-caprolactone) Composites with Acetylated Cellulose Nanocrystal

Poly(epsilon-caprolactone) composites containing the acetylated cellulose nanocrystal (aCNC) with various degrees of substitution (DS) were prepared for the phase compatibility study. An interesting phenomenon around the alteration of crystallization temperature (T-c) was reported here. T-c of PCL increases evidently in the presence of pristine CNC (DS = 0) due to its nucleation effect. However, for the composites with aCNCs, T-c decreases monotonously with increasing DSs of aCNCs and is even lower than that of the neat PCL at higher DSs. This is attributed to the improved compatibility between the matrix and particles, which is further evaluated by the Flory-Huggins parameters. Therefore, the alteration of T-c can be used as the probe to detect the compatibility between two phases in aliphatic polyester composites with chemically modified CNCs. From another perspective, crystallization of aliphatic polyesters can be controlled using aCNCs with different DSs.