Poly(Butylene Itaconate) (PBI) was synthesized with itaconic acid (IA) and 1,4-butylene glycol (BOD) by direct esterificationpolycondensation (No.1 method) and stepwise feeding process (No.2 method), respectively. The reaction process of two methods was investigated by determining the acid value, the intrinsic viscosity, the relative molecular mass and its distribution. The results showed that the acid value of synthetic PBI by No.1 method was higher than 40 mg(KOH)/g, the intrinsic viscosity was 8.232 1 mL/g, the molecular weight was 2 889, and the molecular weight dispersion coefficient was 1.614. As for No.2 method of synthetic PBI, the acid value was lower than 39.61 mg(KOH)/g, the intrinsic viscosity was 6.697 3 mL/g, the molecular weight was 2 559, and the molecular weight dispersion coefficient was 1.568. The structure of polyester was confirmed by means of Fourier Transform InfraRed (FT-IR). By comprehensive comparison, stepwise feeding process was the better way to synthesize PBI.

With itaconic acid (IA) and 1,4  butanediol (BDO) as the raw materials, the resultant hydroxyl terminated aliphatic unsaturated polyesters (PBI) were prepared. The unsaturated polyurethane was prepared with PBI as the soft segment and toluene diisocynate (T DI) as the hard segment. The effect of its reaction conditions on the mechanical properties of the unsaturated polyurethane was also investigated. It was found that the film products with the optimum properties were obtained under the material mass ratio o f TDI and PBI 1 ∶ 1.5, the reaction temperature 80 ℃ , optimum reaction time 2 h, with dibutyltin dilaurate in an amount of 1% as the catalyst. Combining with benzoyl peroxide in an amount of 1%,as an initiator, the film of the unsaturated polyurethane was smooth, transparent and level. The hardness was 6H, and the adhesion property was A grade.