Effect of methyl methacrylate on the mechanical properties of unsaturated polyesters

Abstract

This research involves the preparation of orthophthalic and isophthalic unsaturated polyesters with the average molecular weights of 3,000 and 10,000 , respectively. The orthophthalic and isophthalic polyester resins was then prepared by dissolving the obtained orthophthalic and isophthalic unsaturated polyesters in a mixture of styrene monomer and methyl methacrylate employed were 65:35:0, 65:30:5, 65:2510,65:20:15, 65:15:20,650:25 and 65:0:35 . From the investigation of the polyester resin’s properties, it was found that the increase of methyl methacrylate in the polyester resin resulted in the decrease of the viscosity, increase of the gel time and cure time and decrease of the exothermic heat from the curing. The thermoset polyesters was then prepared in order to study their mechanical properties and weathering resistance by using methyl ethyl ketone peroxide in the curing process. The mechanical properties of thermoset polyesters studied were tensile strength, hardness, flexural strength and heat distortion temperature, It was found that the increase of methyl methacrylate in the polyester resin resulted in the increase of the weathering resistance but decrease of the mechanical properties. Changes in the amount of methyl ethyl ketone peroxide showed small effects in the thermoset polyester’s properties. The most suitable rations of orthophthalic and isophthalic polyester resins for the industrial applications are 65:30:5 and 65:15:20, respectively.