Unsaturated polyester resin/epoxy-functionalised nanosilica composites constructed by in situ polymerisation

A reactable nanosilica surface capped with a silane coupling agent containing the epoxy group (denoted as RNS-E) was allowed to participate in the in situ polycondensation reaction of unsaturated polyester resin (denoted as UPR) thereby affording the UPR/RNS-E composite. The structure of the as-prepared UPR/RNS-E composites was investigated by means of Fourier transform infrared spectrometry, thermogravimetric analysis and scanning electron microscopy, and their tensile strength and impact strength were compared with those of pure UPR cured under the same condition and of UPR/RNS-E composites prepared by mechanical blending. It was found that RNS-E exhibits good strengthening effect and toughening effect for the in situ polymerised UPR/RNS-E composite, which is attributed to the formation of a heterogeneous network structure in the cured UPR/RNS-E composites via the chemical reaction among the epoxy group of RNS-E and the hydroxyl (carboxyl) group of UPR. Particularly, the UPR/RNS-E composite with 0.6% RNS-E nanofiller has the highest tensile strength and impact strength, and it is much superior to the same composite obtained by mechanical blending.