Effect of resin composition on curing kinetic of nanoclay-reinforced unsaturated polyester resins

Curing behavior of two resins of different unsaturated polyesters [FARAPOL 101 (UF) and Bushpol 81715 (UB)] containing 3 wt % organically modified clay (OMC), catalyzed with methyl ethyl ketone peroxide as initiator and promoted by cobalt naphtenate accelerator was investigated by dynamic differential scanning calorimetry (DSC) and gel time test methods. Chemical structures of UF and UB resins were characterized by H-1 NMR, XRD and TEM techniques were used for morphology characterization of nanocomposites. DSC results showed that after adding OMC, the redox reaction rate of UF increased less than that of UB resin. Measurements of cloud-point temperature (T-c) indicated that the miscibility of styrene/UB alkyd chains was more than that of styrene/UF alkyd chains. Therefore, the alkyd/styrene ratio inside the platelets in UB would be more than that in the platelets in UF nanocomposite. Among the three factors in redox reaction rate of UB/OMC and UF/OMC systems namely: (1) decreasing alkyd-styrene copolymerization share among platelets of OMC, (2) decreasing the activation energy, (3) decreasing the number of collisions, the first one was more effective in UF/OMC system than in UB/OMC system. Consequently, the difference between redox reaction rates of UF/OMC and neat UF was negligible compared with the corresponding difference for UB/OMC and neat UB system.