Preparation And Study Of Graphite-based Polyurethane Composites

Polyurethane elastomer(PUE)is a new synthetic polymer material,which is widely used in chemical,electronics,textile,medical,construction,aerospace and aviation fields due to its good mechanical properties,chemical resistance,aging resistance and wide range of performance adjustment.However,there is friction heat generation in ordinary polyurethane screen,resulting in softening of the surface,which reduces the carrying capacity of the screen,and the mesh becomes different sizes,which can not meet the accurate separation of the material.Therefore,the development of polyurethane screen with excellent wear resistance and good comprehensive mechanical strength has become one of the important research directions at present.In order to improve the wear resistance and mechanical properties of PUE,polytetrahydrofuran diol(PTMG),toluene-2,4-diisocyanate(TDI),4,4'-methylene-bis(2-chloroaniline)(MOCA)were used as the main raw materials to synthesize PUE.Furthermore,different types and types of graphite(GP)were added to enhance the wear resistance of PUE composites.On this basis,glass fiber(GF)was introduced to prepare PUE/GP/GF composites with high wear resistance and heat resistance and excellent comprehensive mechanical properties.The main research contents and experimental conclusions are as follows:1.Using PTMG as soft segment,TDI and MOCA as hard segment,PUE was prepared by prepolymer method.A series of PUE materials were prepared according to the content of isocyanate group(-NCO),molecular weight of PTMG,chain extension coefficient and other conditions in polyurethane prepolymer.The effects of different factors on mechanical properties and wear resistance of PUE were clarified.The sliding friction properties of PUE were significantly enhanced by molecular structure optimization and additive modification.The tensile strength of PUE composite prepared in this paper can reach 55 MPa,the friction coefficient is less than 0.57,and the wear rate is less than 20%.After thermal aging,the tensile strength can still reach 35 MPa.Thermogravimetric analysis(TGA)showed that the decomposition temperature of PUE was 298?.2.The wear resistant PUE/GP composite was prepared by using GP as filler to increase the wear resistance of PUE while maintaining its mechanical properties such as high hardness and high elasticity.The effects of different GP content on the properties of PUE/GP composites were investigated by adjusting the GP content of different types and sizes.When the content of scaly 8000 mesh GP is 5wt%,the composite has excellent comprehensive properties.Compared with pure PUE,the tensile strength increases from 55 MPa to 57.8 MPa,the friction coefficient decreases from 0.57 to 0.18,and the wear rate decreases from 20% to 7%.3.Glass fiber reinforced PUE/GP/GF composites were prepared by hot pressing with GF as reinforcement.When GF content was 30%,the friction coefficient remained 0.18 and the tensile strength increased from 57.8mpa to 97.6mpa.TGA results showed that GF could improve the heat resistance of PUE/GP/GF composites.The thermal decomposition temperature of PUE/GP/GF increased with the increase of GF content,and the initial decomposition temperature increased from 298? to 360?.