Evaluation of a new technique for preparation of HDPE / silica nanocomposites

This paper presents a new preparation method of nanocomposites using planetary milling of ceramic nanofiller with polymer matrix. The chosen matrix is High Density Poly Ethylene and the filler is nanometric fumed silica, raw or surface treated with two different silanes surfactants. The idea is to promote the penetration of nanosilica in HDPE grains using the high shear stress occurring during planetary milling. Different fabrication parameters (duration and rotation speed) were tested. Scanning Differential Calorimetry measurements showed that the cristallinity rate is slightly reduced by the inclusion of a nanofiller. Initially, the samples exhibited a loss peak at 0.1Hz at 20°C, due to the water presence at the interface. This peak was removed after a short annealing at 100°C. At higher temperatures, nanocomposites samples should exhibit a Maxwell - Wagner - Sillars loss peak in Dielectric Spectroscopy measurements, from the interface developed in the material between materials with different conductivities (nanosilica and HDPE). In the case of untreated nanosilica, this is the case. But, for treated silica, the peak is shown to disappears when the nanostructure correspond to the better dispersion state, due to overlapping of quasi-conductive regions around the nanoparticles.