Propylene-ethylene Copolymer Filled Nanocomposites: Influence of Zn-ion Coating upon Nano-SiO2 on Structural,Thermal, and Dynamic Mechanical Properties

Propylene-ethylene copolymer (EP) nanocomposites based on nano-SiO₂ with and without Zn-ion coating were developed by conventional melt blending technique in a sigma internal mixer. Two composites each with 2.5 wt% filler were developed. The first composite was made by melt blending EP with nano-SiO₂ in a co-rotating sigma internal mixer. The second one was obtained by melt blending the same EP, but with Zn-ion coated nano-SiO₂. In case of Zn-ion coated nano-SiO₂ filled EP, wide-angle X-ray diffraction study (WAXD) showed a decrease in interplanar distance and lamellar polymer crystal size when compared to nano-SiO₂ filled EP. Differential scanning calorimetric (DSC) results showed Zn-ion coated nano-SiO₂ acting more as an effective nucleating agent than that of the nano-SiO₂. Thermogravimetric analysis (TGA) results showed improved thermal stability for EP in the presence of both the nanofillers. However, the thermal stability of Zn-ion coated nano-SiO₂ filled EP is higher than that of the nano-SiO₂ filled EP. Scanning electron microscope (SEM) study reveals that the Zn-ion coated nano-SiO₂ homogeneously distributed in the matrix, whereas nano-SiO₂ forms chainlike aggregates in the matrix phase. Dynamic mechanical analysis (DMA) study indicates that both the fillers increase storage modulus, E′; this increment is more prominent in nano-SiO₂ filled EP due to the formation of chain-type aggregates of nano-SiO₂.