Study On The Synthesis And Properties Of Polyurethane Materials Based On Aliphatic Diamine

Diverse processing technology and abundant raw materials give polyurethane materials excellent properties such as wear resistance,fatigue resistance,heat insulation and good biocompatibility to meet the needs of different applications.With the rapid development of science and technology,developing polyurethane materials with excellent properties to fulfill the requirements of newly developed fields is of significant importance.Using low molecular weight aliphatic diamines to synthesize polyurethane materials is a good way to improve their physical and mechanical properties and the diversiform structures of diamines will give polyurethane materials a wide range of adjustable properties.But the reactivity of low molecular weight aliphatic diamines is too high to be used in the synthesis of polyurethane elastomers and foams.In order to solve the problem mentioned above,carbon dioxide was used to protect amine groups reversibly.After being protected,low molecular weight aliphatic diamines were successfully applied to produce polyurethane elastomers and foam.Details of research work are as follows:(1)The reversible reaction between carbon dioxide,diamines and carbamate salt is used to cover diamine's reactivity.When being transferred into the hot mold in the plate vulcanizer,diamines gradually release and react with prepolymer under the condition of heating to produce polyurethane-urea elastomer materials.Four kinds of polyurethane-urea elastomers were synthesized with the method mentioned above.Four polyurethane elastomers chain-extended with diols were also prepared as control to investigate the influence of diol and diamine chain extenders on the properties of polyurethane elastomers.Results show that more and stronger hydrogen bonds are formed in the polyurethane-urea elastomers which provide a greater driving force for the formation of better microphase separation and give polyurethane-urea elastomers higher modulus,wider temperature range at rubbery platform and better mechanical properties in comparison to their polyurethane counterparts.This method provides a new avenue to develop polyurethane-urea elastomers with excellent properties which could satisfy the demands of newly emerged fields.(2)The reversible reaction between carbon dioxide,diamines and carbamate salt was utilized to produce polyurethane foams,via varying foaming temperature and the amount of catalyst and carbamate salts used foams with uniform and stable cell structures,excellent mechanical properties and good fatigue resistance were obtained.By contrast,the process of using carbamate salt as foaming agents to produce polyurethane has longer gel time and higher foaming efficiency than that of using water as blowing agents,and the resulting materials give better mechanical and anti-fatigue properties.Using carbamate salts as foaming agent to synthesize polyurethane foam gives guidance to improve the mechanical property of foam and is expected to solve the environmental damage caused by physical foaming agent.