Preparation,Properties And Rheological Behavior Of Antistatic Nano UHMWPE Composites

Ultra high molecular weight polyethylene(UHMWPE)shows many excellent properties,such as small friction coefficient,strong impact resistance,health,biocompatibility and low temperature resistance.However,UHMWPE products are easy to generate and accumulate static electricity in the process of manufacturing,transportation,and especially using due to its extremely low electrical conductivity.These problems increase the difficulties of manufacturing processes,affect the product appearance and even lead to explosion,fire.Therefore,it is very important and urgent to give UHMWPE used in these occasions antistatic property.First of all,the excellent electrical conductivity of multi-walled carbon nanotubes(MWCNT)and graphene nanosheets(GNS)were used as conductive filler to prepare UHMWPE conductive composites in this paper.It was found that the preparation method requires only a low MWCNT or GNS content(0.5wt%)to reach the percolation threshold of the composites,and then the antistatic modification of UHMWPE can be achieved.At the same time,it was found that GNS had a aggregation in UHMWPE matrix,resulting in decreases of impact and tensile performance of UHMWPE/GNS.In contrast,the dispersion of MWCNT was better than that of GNS,and the impact performance of UHMWPE/MWCNT was improved by 30.1%,and the tensile performance was increased by 23.5%.Secondly,on the basis of achieving antistatic property,we succeed in modifying the MWCNT surface by grafting ODA onto its surface to further improve the mechanical properties of UHMWPE/MWCNT composites.On one hand,the adsorption of MWCNT was weakened,the possibility of MWCNT agglomeration was reduced,and its dispersion in UHMWPE matrix was improved.On the other hand,the interface between MWCNT and UHMWPE was strengthened by surface modification of MWCNT,which was conducive to the transfer of external forces between MWCNT and UHMWPE.The experimental results confirmed that the impact strength of UHMWPE/MWCNT-ODA material was 42.1%higher than that of UHMWPE,and the tensile performance was 21.5%higher than that of UHMWPE.Finally,this paper investigated the rheological properties of UHMWPE and UHMWPE composites.Through the analysis of experimental results,we found:temperature and frequency can affect the range of linear viscoelastic zone;the higher the molecular weight of UHMWPE,the greater the complex viscosity of UHMWPE is,and the higher molecular weight lead to larger storage modulus and greater elasticity of the composites.With the increase of test temperature,the complex viscosity and storage modulus of UHMWPE decreased,the pesk of loss coefficient of UHMWPE had a tendency to move toward the high frequency,and the viscosity of the whole system was improved;In addition,the initial storage modulus was improved due to the introduction of MWCNT.How,ever,MWCNT hindered the process that UHMWPE chains changed from incomplete entangled state toward thermodynamic equilibrium state that UHMWPE chains were completely tangled,which reduced the storage modulus of UHMWPE;By investigating the influence of modified MWCNT on the rheological properties of UHMWPE composites,we found that the proper filler surface modification is effective method to improve the processing rheological properties of UHMWPE composites.