Morphology-controlled synthesis of polymethylsilsesquioxane (PMSQ) microsphere and its applications in enhancing the thermal properties and flow improving ability of ethylene-vinyl acetate copolymer

Here, we reported that by adjusting the stirring speed, condensation pH value, precursor concentration and reaction temperature, the morphologies of the polymethylsilsesquioxane (PMSQ) microsphere could be well controlled through the two-step sol-gel synthesis. Because of the specific structural property and strong hydrophobicity, the obtained PMSQ microsphere dispersed well in the ethylene-vinyl acetate copolymer (EVA) matrix to form EVA/PMSQ hybrid. Subsequently, the thermal properties of both EVA and EVA/PMSQ hybrid were investigated through the TGA and DSC tests. The presence of PMSQ microsphere generates a significant delay in the thermal degradation processes of EVA, thus improving the thermal stability of EVA. The PMSQ microsphere also obviously increases the onset crystallization temperature and the crystallization rate of EVA, meaning that adding PMSQ microsphere enhances the crystallization ability of EVA. Finally, by applying rheological tests and microscopic observation, EVA/PMSQ hybrid was found to further improve the flow behavior of Qinghai waxy crude oil than the neat EVA did. The EVA/PMSQ hybrid can act as heterogeneous nucleation templates of wax crystals, and favor the formation of wax crystal flocs with increased size and compactness, thus inhibiting the continuous wax crystal network structure and further improving the flow behavior of the waxy crude oil.