The Synthesis Of Unsaturated Aliphatic Polyester And Its Dissussion On Polyurethane Adhesives

Polyester was obtained from fumaric acid and diethylene glycol through a two step process containing esterification and polycondensation. Influencing factors including reactant ratios, temperatures, catalysts and inert gases were studied through a series of experiments.The performances of products were characterized by means of polymerization degrees, hydroxyl values, acid values and intrinsic viscosity.The results showed that, the dihydroxy alcohol must be more excessive than biacid to obtain the polyester polyol.When the alcohol-acid mole ratio was closer to 1,the molecular weight and the average degree of polymerization increased with the extent of reaction.The optimal ratio of dihydroxy alcohol and biacid was 6:5.The optimal esterifiction temperature and polycondensation temperature were 140℃and 190℃.The reaction slowed down when the temperature was too low; however some side reaction happened when the temperature was too high.Moreover, nitrogen and vacuum circumstance were both necessary to protect functional groups-the duplet bond in fumaric acid and enhance molecular weights.The enzymatic degradation was studied at 37℃in phosphate buffer solution with porcine pancreas lipase.The unsaturated polyester showed good biodegradation.When the duplet bond was crossed, the polyester had poor biodegradation.Polyurethane was synthesized by unsaturated aliphatic polyester and TDI in solvent. Influencing factors including reactant ratios, temperatures, catalysts and inert gases were studied through polyurethane -NCO conversion rates. The peeling strength and biodegradation were studied.