Non-isothermal crystallisation kinetics of in situ prepared poly(epsilon-caprolactone)/surface-treated SiO2 nanocomposites

摘要

Poly(epsilon-caprolactone)/silica nanocomposites were prepared by the in situ technique. The molecular weight of the polymer was slightly reduced on increasing the amount of filler. Most likely, the silica nanoparticles affected the action of the polymerisation catalyst. Furthermore, it was found that especially for high filler content the silica nanoparticles showed a trend to form aggregates. The non-isothermal crystallisation of these hybrid organic/inorganic materials was studied. The crystallisation rates seemed to increase upon increasing the content of silica nanoparticles in the composites. When the silica content was above 5 wt.-%, the molecular weight of the polymer in the hybrids decreased, and the increase in the crystallisation rates was attributed to both the nucleating effect of the nanoparticles and the lower molecular weight. The modified Avrami and Ozawa model were used to study the crystallisation kinetics. It was found that both of the models gave satisfactory results. The nucleation activity of the filler was estimated. The effective activation energy for the nonisothermal crystallisation was calculated using the isoconversion method of Friedman and the results were compared to those from Kissinger's method. The activation energy was found to decrease upon increasing the filler content, showing that the crystallisation is favoured.