Internal stress of nano-alumina-polyester-epoxy resin ternary system

Nano-alumina particles-polyester-epoxy resin ternary systems were prepared by a melting blend process. The internal stresses of both the modified and the unmodified epoxy resins were measured by the steel ring method during the curing and cooling periods. The results showed that the internal stress due to cooling for cured resin was almost absent during the curing period. With the increase in nanoparticles, the elastic modulus increased linearly and the percentage of bulk shrinkage decreased gradually, both of which could either raise or laver the internal stress of the ternary system. The minimum value of the internal stress corresponds to an addition of 8 g of nano-particles. A dynamic mechanics analysis (DMA) indicated that the flexural storage modulus of ternary system was greater than that of the unmodified epoxy resin.