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 1H 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.

Post-consumer waste poly (ethylene terephthalate), PET, scraps were glycolyzed at different reaction times and different weight ratios of 37.5 to 62.5% PET by using propylene glycol, PG. It was shown that the effect of catalyst presence is significant upon the acceleraion of depolymerization. Two grades of virgin and waste PET were used to compare the depolymerization behaviour by using PG, which showed the exact similarity. The free glycol of the resulted glyco-esters was removed. FTIR, GPC and DSC techniques were used to characterize the glycolization products, and hydroxyl value determination was used to specify the extent of the reaction. The results showed that the some PET chains have been broken down and hydroxyl-terminated end gropus have been formed on the oligomeric chains. A relative decrease in molecular weight and viscosity at same PET concentrations by increasing the reaction time indicated that the PET chains have been broken The results of free glycol removal and hydroxyl value tests confirmed that about 12 to 25% of PG have been used up to break the PET chains. The resulted oligomeric glycolizates can be readily used in formulation of unsaturated resins and specific types of polyurethanes.

With the development of composite manufacturing processes, such as low-pressure compression moulding of sheet moulding compounds (SMC), resin transfer moulding (RTM) and vacuum infusion moulding processes, low-shrinkage resin which can be processed at low temperatures have attracted considerable interest from the composite industry. In this paper the effect of polyvinyl acetate (PVAc) as a low profile additive (LPA) on shrinkage control of an iso unsaturated polyester resin has been investigated and cure behaviour, morphology and mechanical properties of this system has been studied. Our studies show that the maximum exothermic temperature and the rate of cure decreases with increasing the PVAc concentration. The PVAc content has a significant effect on the resin viscosity. It was found that there are two transitions for UP resin containing PVAc cured at low temperatures. The PVAc content is effective for shrinkage control only in a concentration between these two transitions. Experimental results showed that the mechanical properties of this system decreases by increasing the PVAc content.

In this study, the various combinations of low- and high-decomposition temperature initiators and dual promoters were used to cure an unsaturated polyester resin. Methyl ethyl ketone peroxide (MEKP) and acetyl acetone peroxide (AAP) solutions were used as low-temperature initiators. Benzoyl peroxide (BPO) and t-butyl perbenzoate (TBPB) were used as medium and high-temperature decomposition initiators, respectively. Gel time and pseudo-adiabatic exotherm measurements have been used to study the curing behaviour. It has been demonstrated that the low-temperature initiator decomposition does not interfer with the high-temperature initiator decomposition. It was found that the exotherm peak and cure rate have been affected by the decomposition rate of low-temperature initiator in different ways. It is shown in this study that for cobalt naphthenate and dimethyl aniline (DMA) dual promoter systems that, with the increasing of DMA concentration, namely high reactive promoter, exotherm parameters sharply change. It might be due to the more reactive nature of DMA in comparison with the cobalt naphthenate reactivity. Now we can say, a judicious choice of a dual initiator or a dual promoter can avoid short time exothermic reactions, so a dual system can be much more effective than a single one.