The Effect of Surface Modification of Silica Microfillers in an Epoxy Matrix on the Thermo-mechanical Properties

摘要

Thermo-mechanical and mechanical studies were carried out on silica rilled epoxy composites. The effects of the filler with and without surface modification were studied. Silica particles were incorporated into the polymer matrix: (i) as received and (ii) surface treated with aminosilane coupling agents, namely 3-aminopropyltriethoxysilane (APTES) and 3-aminopropylmethyldiethoxysilane (APDES). The epoxy matrix consisted of poly (bisphenol A-co-epichlorohydrin) glycidyl end-capped (DGEBA) resin cured with ethylenediamine (EDA). The relaxation temperatures assigned to the glass transition temperatures (T_g) of the composites revealed that the filler both with and without surface treatment greatly affects the polymer network structure. It seems that on filling the epoxy-amine reactive mixture with silica a stoichiometric change in the epoxy/amine mixture occurs, which causes a decrease in the T_g. However, no significant differences were found for the different surface treatments. Assuming the systems were homogeneous a pseudo-fractional free volume was calculated from the superposition in the slow dynamics regime and good correlations between this parameter with the type of surface treatment and with the yield stress were found.