Inorganic WS 2 nanotubes that improve the crystallization behavior of poly(3-hydroxybutyrate)

Tungsten disulphide inorganic nanotubes (INT-WS2) were used to prepare advanced biodegradable polymer nanocomposites. The biopolymer matrix employed, poly(3-hydroxybutyrate) (PHB), is one of the most extensively researched and utilized biodegradable and renewable thermoplastic polyesters. Results from differential scanning calorimetry (DSC) and time-resolved synchrotron X-ray diffraction demonstrate that the crystallization and melting behaviour of PHB/INT-WS2 nanocomposites is dependent on both the INT-WS2 concentration and the cooling rate. The addition of low INT-WS2 loadings strongly increases the crystallization rate of PHB, reducing the activation energy with as little as 0.1 wt.% INT, which is very important for the processing of PHB. The nucleating activity of INT-WS2 in the orthorhombic phase of PHB reaches very low values (φ = 0.45), indicating that INT-WS2 actually acts as a highly efficient nucleating agent for the crystallization of PHB. This corresponds to the lowest value observed to date for PHB formulations using specific nucleating agents or nano-sized fillers, which is of significant importance for extending the practical applications of these biodegradable polymer nanocomposites.