Research On Thermal Expansion And Tribological Properties Of Filler Modified UHMWPE Composite Materials

Despite the outstanding performance advantages of Ultra-High Molecular Weight Polyethylene(UHMWPE),its sensitivity to temperature changes,poor dimensional stability and large coefficient of thermal expansion limited the application of UHMWPE as friction sub-materials.In order to effectively control the thermal expansion coefficient of UHMWPE and broaden its application scope as friction sub-material,this paper systematically investigates the thermal expansion properties and tribological properties of three different filler-modified UHMWPE composites,and establishes the sliding friction temperature field model of UHMWPE under dry friction conditions for the type of friction contact in the test,and establishes the correlation between thermal expansion properties and tribology.The correlation between thermal expansion properties and tribology was established to provide theoretical guidance and data support for the development of new low thermal expansion coefficient polymer friction sub-materials.The main findings and conclusions of this paper are as follows.(1)Multi-walled carbon nanotubes(MWCNTs),glass fibers(GF),and zirconium tungstate(Zr W2O8)were selected to modify UHMWPE.The hardness,thermomechanical properties,and thermal expansion properties of UHMWPE with different filler contents were investigated;the tribological properties of UHMWPE composites under dry friction environment were examined.The results showed that the MWCNTs/UHMWPE composites obtained by ultrasonic dispersion and regrinding with anhydrous ethanol had good dispersion,and the MWCNTs could effectively improve the thermal expansion properties of UHMWPE,and the composites with 0.8% MWCNTs had better tribological properties;the GF modified with KH570 formed a stable Si-O-Si GF can effectively improve the thermal expansion performance of UHMWPE due to its low thermal expansion coefficient and strong force with polymer chains,and the comprehensive performance of KH570 modified GF composites is better than that of untreated GF composites at the same filler content;Zr W2O8,which has negative thermal expansion characteristics,can significantly reduce the thermal expansion performance of UHMWPE.The friction coefficient of Zr W2O8/UHMWPE composite decreases and then increases with the increase of filler content,and Zr W2O8 significantly increases the hardness of UHMWPE,thus enhancing the resistance to abrasive wear and improving its wear resistance.(2)A sliding friction model under dry friction conditions was established,and the thermal-structural coupling was used to simulate the reciprocal sliding contact process on its surface.As the friction process proceeds,UHMWPE gradually forms a macroscopic three-dimensional temperature field from the highest temperature at the center of the friction contact area to the inner gradient,and the reduction of thermal expansion coefficient helps to reduce the thermal stress and thermal strain during the frictional heating process,thus improving the frictional wear performance to a certain extent.