Incorporation of inorganic fullerene-like WS2 into poly(ethylene succinate) to prepare novel biodegradable nanocomposites: a study on isothermal and dynamic crystallization

In this study, nanometric-sized inorganic fullerene-like tungsten disulfide nanoparticles (IF-WS2) were used to produce biodegradable nanocomposites based on poly(ethylene succinate) (PES). The nanocomposites were prepared through a solution casting method. Both isothermal and non-isothermal crystallization along with subsequent melting behavior were studied using differential scanning calorimetry (DSC) in detail. Also, the crystalline morphology was explored via a wide angle X-ray scattering (WAXS) method. During the isothermal crystallization process which was performed at different temperatures, a maximum was found in the rate of crystallization. The non-isothermal crystallization peak temperature and overall isothermal crystallization rate of nanocomposites were greater than those of the neat PES. Although the morphological analysis (EDX) showed that dispersion of nanoparticles had unacceptable uniformity, the results confirmed that IF-WS2 nanoparticles, while being not well dispersed throughout matrix, could have a nucleating effect on PES crystallization. The degree of enhancement varied with nanoparticle content, exhibiting a maximum at 0.2 wt% of IF-WS2 loading. Avrami's method was successfully applied to simulate crystallization kinetic data and it was found that the crystallization mechanism of PES was changed in the presence of IF-WS2 nanoparticles. The activation energy of non-isothermal crystallization was calculated using Kissinger and Takhor models. Moreover, according to WAXS results, the presence of IF-WS2 did not alter the a-form crystal structure of PES whereas it just accelerated the crystallization process.