Reinforced Uhmwpe And The Influnce Of Processing Condtions On Its Properties

Ultrahigh molecular weight polyethylene (UHMWPE) is one of thewidely used and promising thermoplastic polymers for mechanical/structuraland wear-resistance applications. The noticeably unique combinations ofUHMWPE properties are high toughness, low coefficient of friction, minimalwater absorption and self-lubricity. But compared with other engineeringthermoplastic, the heat-resisrant property and surface hardness of UHMWPEare lower which limits its use in many applications. In order to expand itsapplied scope, research on how to improve the strength and heat-resistantproperty has become more and more popular.In this work, UHMWPE were modified by adding inorganic fillers and γirradiation crosslinking, which were helpful in improving its heat-resisrantproperty and surface hardness and optimizing the mechanical properties. Inaddition, the influence of compression molding pressure and compressionmolding temperature on its properties were also studied. What’s more, thedifferent properties between compression molding sample and extrusionsample were also studied. Several main conclusions were as follows： (1) With a proper content of needle wollastonite、ultrafine muscovite andOMMT, the tensile strength、surface hardness、heat distortion temperature andwear resistance of UHMWPE could be improved, among which OMMT wasthe best, ultrafine muscovite took the second place and needle wollastonitewas the worst. When UHMWPE was filled with4wt%OMMT, the tensilestrength was increased by33.5%, the wear rate was reduced by66.7%and thecoefficient of friction was reduced by20.7%. When UHMWPE was filledwith6wt%OMMT, the surface hardness was increased by29%and the heatdistortion temperature was increased for22℃.(2) With a proper doesof γ irradiation, the gel content、melting point、crystallinity、surface hardness、tensile strength、heat distortion temperature andwear resistance of UHMWPE could be improved. The heat distortiontemperature of UHMWPE increased by40℃and the crystallinity increasedfrom41.75%to56.76%when the γ irradiation does reached150kGy. Butγirradiation crosslinking reduced its toughness. The tensile elongation at breakdecreased. Remlting could further increase the gel content and enhanced itstoughness, but reducing the melting point, crystallinity, surface hardness,tensile and wear resistanc. γ irradiation crosslinking of UHMWPE filled with5wt%of ultrafine muscovite could further improve its surface hardness andwear resistanc.(3) Compression molding pressure and compression molding temperaturehave an important effect on the properties of UHMWPE. With the increasing of compression molding pressure, the melting point, crystallinity and thetensile elastic modulus inceased, tensile elongation at break decreased. Alongwith the increase of compression molding temperature, tensile elastic modulusand tensile elongation at break decreased. Though the processing conditions ofcompression moldin and exreusion were different, the tensile properties wereapproximately close. The tensile strength and tensile elongation at break ofcompression molding sample were higher than that of extrusion sample whichhad higher tensile elastic modulus and crystallinity and a lower melting point.