Poly(ethylene succinate) nanocomposites containing inorganic WS2 nanotubes with improved thermal properties: A kinetic study

In this paper, inorganic tungsten disulfide nanotubes (INT-WS2) were incorporated into poly (ethylene succinate) (PES) through a simple solution casting method in order to fabricate new hybrid biodegradable nanocomposites. A detailed study was carried out about effect of INT-WS2 on non-isothermal crystallization along with subsequent melting behaviour using differential scanning calorimetry (DSC). It was found that both crystallization rate of PES and its degree of crystallinity enhance in the presence of WS2 nanotubes. The morphological analysis (SEM and EDX) showed that nanotubes are not uniformly dispersed throughout polymer matrix especially at high loadings but the results confirmed that WS2 nanotubes even in this state could effectively have a nucleating role on PES crystallization. Also, calculation of nucleation activity parameter for nanocomposites indicated quantitatively improved nucleation phenomenon by existence of nanotubes. Among the various kinetic models which were used in this study such as Avrami, Ozawa and Liu models, it was observed that the Avrami model is the best one for simulating the crystallization process. The effective activation energy of non-isothermal crystallization was calculated using differential isoconversional method of Friedman. Moreover, crystalline morphology was explored via wide angle X-ray scattering (WAXS) and it was illuminated that presence of INT-WS2 did not alter α-form crystal structure of PES whereas it just accelerated the crystallization process. TGA results revealed that incorporation of INT-WS2 improved the thermal stability of PES.