Influence of fullerene-like tungsten disulfide (IF-WS2) nanoparticles on thermal and dynamic mechanical properties of PP/EVA blends: Correlation with microstructure

Compatibilized and non-compatibilized polypropylene/ethylene vinyl acetate copolymer (PP/EVA) blends loaded with 5 wt% of fullerene-like tungsten disulfide nanoparticles (IF-WS2) as an inorganic nano-filler were prepared by melt mixing process and their thermal and dynamic mechanical properties were determined. TEM investigations revealed that the IF-WS2 nanoparticles were mainly located within the EVA phase of the blend. Also, microstructure of blends studied by SEM showed that incorporation of IF-WS2 into the blends led to reduction of dispersed domain size attributed to reduction of interfacial tension due to the filler presence. Melting temperature of PP loaded with 5 wt% of IF-WS2 was increased up to 13 °C as compared to the neat PP. Addition of IF-WS2 and PP-g-MAH as compatibilizer to PP/EVA blend increased melting and crystallization temperatures determined by DSC. DMTA studies showed that addition of IF-WS2 into the blends had no positive effect on the storage modulus of nanocomposites while, their loss modulus were higher than that of the neat PP. Moreover, the β transition temperature of PP phase in the blends loaded with IF-WS2 and compatibilizer was about 6 °C higher than the neat PP. The thermo-oxidative and thermal degradation behavior of developed nanocomposites determined by thermal gravimetric analysis (TGA) showed that thermal stability of nanocomposites was improved and their rate of degradation was reduced which were attributed to network-like structure formation of nano-fillers in the blends.