Investigating curing kinetics and structural relaxation phenomena of unsaturated polyester resin containing silanized silica.

The effect of the incorporation of silica nanoparticles on structural relaxation and curing kinetics of unsaturated polyester resin was investigated. The evaluations were made monitoring the curing behavior of the neat unsaturated polyester resin and the resin containing 3 wt% SiO2 nanoparticles using dynamic differential scanning calorimetry at heating rates of 2, 2.5, 3, and 3.5℃ min−1. Results revealed a salient increase in the redox activation energy of the unsaturated polyester resin containing silica, while the activation energy of thermal decomposition of peroxide did not show any change. On the interface of nanoparticles and matrix resin, the dissociation reaction of cobalt naphthenate reduced the effect of the promoter. Differential scanning calorimetry was also used to estimate the average size of cooperative rearrangement region of the nanocomposite. Results revealed the possible grafting of unsaturated polyester onto the nanoparticle surface. The attractive interaction between the matrix and nanoparticle hindered segmental relaxation of the polymer chains. [ABSTRACT FROM AUTHOR]