Covalently Bonded PE/SiO2 Nanocomposites Synthesized by Reactive Extrusion

Aseries of PE/SiO2 nanocomposites, namely PE2D, PE5D, PE7D and PE10D,were prepared via reactive extrusion from the mixtures of vinyl functionalizednano-SiO2 (v-SiO2), Dicumyl peroxide and PE. For comparison, PE/SiO2nanocomposite (PE7) was also prepared by the same method from a mixture of v-SiO2and PE. SEM and TEM micrographs showed that the above products were composedof nanocomposite. Xylene extraction results showed that, except PE7, nanocompositescontained gel. FTIR Spectra showed the existence of SiO2 in the gels, meaning thatSiO2 nanoparticles were covalently bonded to PE chains, i.e., PE2D, PE5D, PE7D andPE10D were nanocomposites formed by covalent bonds between SiO2 and PE.Studies based on DSC show that all the nanocomposites have Tm of close values andPE7 has higher crystallinity than other nanocomposites. Mechanical properties wereinvestigated through tensile tests and the results show that covalently bonded PE/SiO2nanocomposites have better performance compared to PE7. In this respect, the tensilestrength, modulus, and elongation-at-break of PE7D are given as 41.5 MPa, 349 MPaand 1060% which are as high as 170%, 126% and 125% of the values for pure PE.While the tensile strength, modulus, and elongation-at-break of PE7 are only 109%,108% and 109% of the values for pure PE, indicating the significant effect of covalentbond between polymer matrix and nanoparticles.