Hybrid materials based on polyethylene and MCM-41 microparticles functionalized with silanes: catalytic aspects of in situ polymerization, crystalline features and mechanical properties

摘要

New nanocomposites based on polyethylene have been prepared by in situ polymerization of ethylene inpresence of mesoporous MCM-41. The polymerization reactions were performed using a zirconocenecatalyst either under homogenous conditions or supported onto mesoporous MCM-41 particles, whichare synthesized and decorated post-synthesis with two silanes before polymerization in order to promotean enhanced interfacial adhesion. The existence of polyethylene chains able to crystallize withinthe mesoporous channels in the resulting nanocomposites is figured out from the small endothermicprocess, located at around 80 C, on heating calorimetric experiments, in addition to the main meltingendotherm. These results indicate that polyethylene macrochains can grow up during polymerizationeither outside or inside the MCM-41 channels, these keeping their regular hexagonal arrangements.Mechanical response is observed to be dependent on the content in mesoporous MCM-41 and on thecrystalline features of polyethylene. Accordingly, stiffness increases and deformability decreases in thenanocomposites as much as MCM-41 content is enlarged and polyethylene amount within channels israised. Ultimate mechanical performance improves with MCM-41 incorporation without varying thefinal processing temperature.