Non‑isothermal crystallization kinetics of polycaprolactone-based composite membranes

Nanocomposites have been demonstrated as potential materials for biosensors to biomedicine applications. However, the crystallization mechanism of nanocomposites has not been thoroughly investigated so far. Cellulose nanofiber is used as a new kind of nano-filler to modify the biodegradable polymer to prepare nanocomposites. Banana cellulose nanofibers/polycaprolactone composite membranes (BNCF/PCL) and banana cellulose nanofibers grafted with polycaprolactone/polycaprolactone composite membranes (BGCL/PCL) were prepared, respectively. To explore the effects of BNCF and BGCL on the crystallization properties of PCL. SEM, POM, and DSC were used to study the crystallization of PCL, BNCF/PCL, and BGCL/PCL films. Mo's method was applied to study the non-isothermal kinetics of BNCF/PCL films, Avarmi and Jeziorny's models successfully predict the non-isothermal kinetics of BGCL/PCL films. The results showed that BNCF promoted the crystallization of BNCF/PCL films. The crystallization peak temperature of BNCF/PCL films was 4.11 ℃ higher than pure PCL, and the crystallinity was 5.34% higher than that of pure PCL. The crystallization peak temperature of the BGCL/PCL films decreased slightly, but the crystallinity increased by 3.78%. The crystal growth modes of BNCF/PCL films and BGCL/PCL films were consistent with the three-dimensional growth of heterogeneous nucleation, BNCF/PCL films with average Avrami index n ranging from 2.7 to 3.9, and the BGCL/PCL films with n ranging from 2.5 to 3.2. Furthermore, the micrographs of polarized optical microscopy (POM) supported the kinetics results. This study makes a deep insight into the effect of cellulose nanofiber on the crystallization of biodegradable aliphatic polyesters.