Recently, it has been shown that the addition of a small quantity of nanoclay can greatly enhance the efficiency of low profile additives (LPAs) on volume shrinkage control of low profiled unsaturated polyester (UP)/styrene/LPA systems. In this study, however it was found that the organically-modified nanoclay (Cloisite 15A) can also affect the volume shrinkage control of non-low profiled UP/styrene systems. The effect of nanoclay on volume shrinkage of UP resin was investigated by an inhouse constructed shrinkage measurement apparatus. Experimental results revealed that the nanoclay somewhat decreases the volume change of UP/styrene system. The polymerization kinetics of the nanoclay filled UP systems was studied in a quasi-adiabatic reactor. The quasi-adiabatic exothermic measurements showed that, at higher nanoclay content, the reaction rate increased and the induction time decreased. The reduced viscosity measured by a rheometric dynamic analyzer. The gel time calculated by both quasi-adiabatic reactor and rheometric dynamic analyzer data. Results have showed that adding nanoclay into the UP/styrene mixture makes the onset of the viscosity rise happen much earlier which leads to a higher reaction rate, faster viscosity rise, and earlier gelation. It is clearly observed that measuring the gel time at different level of Cloisite 15A is similar to using rheometry and exothermic experiments.

Chemical recycling of Poly ethylene terphthalat (PET) was undertaken through catalytic glycolysis method and the obtained oligomers were used to prepare several unsaturated polyester resins. First, recycled PET in the presence of diethylene glycol (DEG), triethylene glycol (TEG) and zinc acetate as a catalyst was depolymerized, followed by purification of the products. The products were then reacted with maleic anhydride (MA), phthalic anhydride (PA), ethylene glycol (EG) and propylene glycol (PG) to obtain unsaturated polyester resins.In the glycolysis stage of PET, parameters like the type of glycol used and its molar ratio were examined and the hydroxyl value, free glycol and FT-IR spectrum of products were obtained. In the preparation of resins, parameters like the type of the products of glycolysis reaction and the usage of two different types of anhydride were studied. The prepared resins were then diluted with styrene and cured in the presence of suitable initiator.

In this study, the unmodified graphite and graphite modified with a silane agent have been used to ameliorate the thermal conductivity coefficient and dynamical properties of unsaturated polyester resins. The effect of the addition of the unmodified graphite and modified graphite on the thermal conductivity coefficient and dynamical properties of unsaturated polyester resins in the graphite amounts of 0. 02 % and 0. 3 % by weight were studied using the solid thermal conductivity measuring device and DMA test. The results showed that the silane modifier could help to create strong covalent bonds between graphite particles and the unsaturated polyester resins network and cause changes in thermal and dynamic properties compared to unmodified graphite particles. Adding 0. 3 % by weight of the unmodified graphite to the unsaturated polyester resins resulted in a 7 % raise in the storage modulus in the glassy region. However, adding the same amount of graphite modified using the silane agent increased the storage modulus by 33 % in the glassy region. The silane modifier caused a better dispersion of graphite particles in the resin structure. The superior dispersion of graphite particles caused more interaction between graphite particles and the resin network, which significantly increased the modulus of the unsaturated polyester resins. In contrast, the better dispersion of graphite particles because of the presence of the silane agent increased the thermal resistance at the surface of graphite particles, which reduced the thermal conductivity coefficient compared to the same regarding unmodified graphite.

Glycolysis of recycled polyethylene terephthalate (PET) from post-consumer soft-drink bottles was carried out with ethylene glycol (EG) at different weight ratios of PET to EG using zinc acetate as catalyst at the boiling point of EG under nitrogen atmosphere for a constant time of 8 h. The results showed that in excess of EG (at mole ratio of PET/EG = 0.12) the glycolyzed products contained predominantly bis(hydroxyethyl) terephthalate (BHET). Kinetics of polyesterification of glycolyzed product, BHET, made from a mole ratio of 0.12 of PET/EG with maleic anhydride was also studied without using acid catalyst. The polyesterification was carried out at different temperatures (135, 160, 200 and 210 °C) comparable to the industrial process scheme. It was observed that the acid value of the reaction mixture decreased and the extent of reaction increased sharply with increasing temperature or time of the reaction. At 135 °C the kinetic plots, using third-order kinetics, were non-linear at initial times.

Glass fiber/unsaturated polyester resin composites are one of the most employed materials due to their excellent mechanical properties, room temperature curing and low cost. In this paper, unsaturated polyester-like resins based on modified castor oil were reinforced with glass fiber. The resin consisting of maleated castor oil methacrylate was homopolymerized or alternatively copolymerized with styrene. The effects of glass fiber content on mechanical and dynamic-mechanical properties were evaluated and compared with a commercial unsaturated polyester resin/glass fiber composite. The addition of glass fiber at 20–, 40 wt% increased flexural properties and impact properties of the composites compared to their neat polymers. At 40 wt% glass fiber, flexural strength and flexural modulus were 235 MPa and 4694 MPa, respectively. These values were near to those obtained for a commercial unsaturated polyester resin with the same fiber load, i. e., 320 MPa and 6843 MPa, respectively. The homopolymer afforded impact strength values of 25–, 44 kJ/m2 that were near to commercial unsaturated polyester resin composites (i. e., 20–, 51 kJ/m2), as well. The triglyceride oil provided ductility and impact strength to composites while styrene as comonomer provided stiffness to copolymer composites but decreased their impact strength. A good adhesion was observed between fibers and matrix in copolymer composites in comparison with their homopolymer composites which was enabled through dilution with styrene.

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.

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.