Preparation,Friction And Wear Behavior Of Microstructured Polypropylene/Ethylene-Octene Copolymer/Graphene Composite Surfaces

Because of its unique advantages,superhydrophobic materials are gradually becoming practical and industrialized.However,Due to the complicated process,high production cost,and easy damage of the microstructured surface,the application of superhydrophobic materials is limited.Therefore,the use of large-scale and low-cost forming methods to fabricate microstructured surface is conducive to the transformation of superhydrophobic materials from basic research to practical application.Because polypropylene(PP)is a thermoplastic general-purpose plastic with excellent performance,good mechanical properties,easy processing,and low price,PP is selected as the main raw material.Graphene(GP)nano-fillers with lower friction coefficient and ethylene-octene copolymer(POE)with better ductility were added to PP matrix.Microstructured surface of composites are prepared by melt blending and micro-hot embossing,aiming at solving the problem of easy damage of microstructure in demoulding process and obtaining superhydrophobic composite material with good wear resistance.The specific research contents are as follows:1.The PP/GP composites with different GP content are prepared by melt blending method,and the microstructured PP/GP(91/9)surface are prepared by micro-hot embossing.The tensile strength,impact strength,wettability,friction and wear behavior and wetting stability of the samples are analyzed.The results show that the addition of GP can improve the tensile strength,impact strength and hydrophobicity of the materials.The microstructured PP/GP surface is regular after demoulding,which obviously improves the problem of difficult demoulding of pure PP.The water contact angle(CA)on the microstructured PP/GP surface is 153° accompanied with a 10 ?L large droplet and rolling angle(RA)is 0.5°,showing superhydrophobic and low adhesion,i.e.lotus leaf effect.When the microstructured surface are extruded or impacted by droplets,the surface remains stable in Cassie-Baxter state.When the surface are worn by a distance of 1000 mm,the CA on microstructured PP/GP surface is 152.3°and RA is greater than 90°,showing superhydrophobic and high adhesion,namely petal effect.However,due to the low toughness of the microcolumn,the microstructure generated more debris during the wear process.2.The PP/POE blends with different POE content are prepared by melt blending method,and the microstructured surface of PP/POE(70/30)were prepared by micro-hot embossing.The tensile properties,impact properties,wettability,friction and wear behavior and wetting stabilityof PP/POE blends are analyzed.It was found that the toughness,impact resistance and hydrophobicity of PP/POE blends increased with the increase of POE content.During the demoulding process of microstructured PP/POE surfaces,there are too many slender fibers at the top of the microcolumn to reproduce accurately,but the cavitation between the slender fibers can hinder the infiltration of droplets.Even after extrusion or droplet impact,the surface microstructures of PP/POE still present a stable Cassie-Baxter state.The CA of 10 ?L droplets on the PP/POE microstructured surface is 155°,showing superhydrophobic properties.Due to better toughness,there is no fracture in the microstructure during the wear process,and the superhydrophobic property of the microstructured surface can be maintained even after after abrasion length of 2000 mm.3.In order to obtain superhydrophobic materials with easy demoulding and good wear resistance,POE and GP are added into the matrix PP,and a two-step process is adopted.The PP/GP(91/9)composites are prepared first,then PP/POE/GP composites are prepared.Finally,PP/POE/GP microstructural surfaces are prepared by micro-hot embossing.The tensile properties,impact properties,wettability,friction and wear behavior and wetting stability of PP/POE/GP composites are analyzed.The PP/POE/GP sample has a tensile strength of 21.21 MPa,an elongation at break of 520.33%.and the CA of a smooth PP/POE/GP surface is 105.8°,exhibiting hydrophobic properties.The morphology of the microstructured surface after demoulding is regular and can be reproduced accurately.10 ?L droplets rapidly rolls away from the surface,indicating that the microstructured PP/POE/GP surface exhibites superhydrophobic and low adhesion,and the wettability is stronger than that of PP/GP and PP/POE microstructures.Because of the toughness of the microcolumn,there is no serious problem of wear debris and microstructure damage during the wear process.Even if the surface is worn by a distance of 3000 mm,the surface exhibites superhydrophobic and high-adhesion properties.When the microstructured surface is extruded or impacted by droplets,the surface remains stable Cassie-Baxter state.