The waste residue (1) left after dimethyl terephthalate (DMT) had been separated, composed of Me and diMe p- (about 30%), m- (>50%) and o-phthalates (about 10%) and trimelliates (about 1%), was (a) catalytically transesterified (220 degreesC) with ethylene glycol (II) and (b) polycondensed (220degreesC) with maleic anhydride (III) to achieve an intended acid number (AN) The resulting polyester was cooled to 60degrees C and dissolved in styrene containing hydroquinone. The resulting unsaturated polyester resin (UPR) contained 30% styrene. Another trial raw material (DGT) was produced by transesterifying I with II. DGT was heated with III (220degreesC, 1 h); H2O was distilled off; and the reaction was continued to achieve an intended AN. The resulting polyester was cooled to 60 degreesC and dissolved in styrene to yield a UPR containing 30% styrene. Another UPR was prepared by using DGT and waste PET. The DGT-based uncured UPR were less viscous; PET raised the viscosity, reactivity and mech. properties of UPR. The (DGT+PET)-based UPR had the shortest gelling time and the highest T-g. The I-based UPR had always lower T-g, but better Charpy's impact strength and hardness than the UPR prepared from com. raw materials. As the amount of III was raised, the thermal resistance of the DGT-based UPR rose; their properties were more affected by III than those of I-based UPR.