Performance Evaluation Of UHMWPE Fiber Modified By Functionalized Polyethylene Wax

Ultra high molecular weight polyethylene(UHMWPE)fiber has many excellent properties such as high physical and mechanical properties,chemical resistance,abrasion resistance,and low density,and it has been widely used in various fields.However,UHMWPE fibers exhibit poor interfacial adhesion with polar polymeric matrices due to its high crystallinity,smooth surface,and the lack of polar groups on the surface.Although researchers at home and abroad have adopted a variety of physical and chemical methods to modify the fiber,currently few new modification methods have appeared,and the existing methods have their own shortcomings.Therefore,further development in surface modification of UHMWPE fiber is needed,which is of great significance for further expanding the application fields of fiber.In this study,three different functional polyethylene waxes(PEW)were prepared based on the constructed modification model,and UHMWPE fiber with good interfacial properties was prepared by coating method.The factors affecting the preparation of functional PEW,and the effects of the concentration of treatment solution,the grafting rate of monomer,the addition of dual monomer,the temperature of treatment solution,and the compound treatment with functional PEW/silane coupling agent on the bonding strength between fiber and resin matrix were studied systematically.And the finite element analysis of single fiber pull-out process was carried out by ABAQUS software.The changes of surface chemical composition,mechanical properties,wettability,surface morphology,and single fiber pull-out process before and after modification were discussed.Through the research of this subject,the interface bonding strength between fiber and resin matrix has been improved to a certain extent,which provides a low-cost,controllable and effective treatment method for the surface modification of UHMWPE fiber.The main conclusions drawn from it are as follows:(1)PEW was used as a raw material to perform coating modification treatment on UHMWPE fibers.The results show that the interfacial bonding strength between fiber and resin matrix is improved after treatment with PEW,thereby proving the feasibility of fiber modification model.(2)Maleic anhydride grafted polyethylene wax(PEW-g-MAH),methyl methacrylate grafted polyethylene wax(PEW-g-PMMA),and maleic anhydride/styrene grafted polyethylene wax(PEW-g-MAH/St)were designed and prepared.The study shows that the functional PEW with different grafting rates can be obtained by changing the preparation conditions.And the synergistic effect of St can significantly increase the grafting rate of MAH.And infrared spectral analysis shows that MAH,MMA,and St have been successfully grafted onto PEW macromolecules.(3)Factors such as the concentration of treatment solution,the coating temperature,the grafting rate,the synergistic effect of two monomers,and the type of grafting monomer can significantly affect the bonding strength between fiber and resin matrix.The study shows that after treatment with 9wt% functional PEW,the pull-out strength of fiber is significantly improved,and compared with the original fiber,the pull-out strength of fiber can be increased by 39.80% after treatment with PEW-g-MAH,the pull-out strength of fiber can be increased by 45.11% after treatment with PEW-g-PMMA,and the pull-out strength of fiber can be increased by 57.95% after treatment with PEW-g-MAH/St;And the pull-out strength of fiber gradually increases with the increase of grafting rate and coating temperature.At the same time,the pull-out strength of fiber increases gradually with the increase of dosage of St.Moreover,the type of monomer used will affect the interfacial properties of fiber.Furthermore,there are no significant changes in the mechanical properties and crystallinity of fiber before and after coating modification,but the wettability has been significantly improved.Infrared spectrum analysis shows that functional polar groups derived from MAH,MMA and St have been introduced onto the fiber surface.(4)The compound treatment with functional PEW/silane coupling agent can significantly affect the bonding strength between fiber and resin matrix,durability of surface coating and wettability.The research shows that with the increase of the concentration of silane coupling agent,the pull-out strength of fiber gradually increases,and when the concentration of silane coupling agent is 12wt%,compared with the untreated fiber,the pull-out strength of fiber compound treatment with PEW-g-MAH/silane coupling agent can be increased by 71.38%,the pull-out strength of fiber compound treatment with PEW-g-PMMA/silane coupling agent can be increased by 77.97%,and the pull-out strength of fiber compound treatment with PEW-g-(MAH/St)/silane coupling agent can be increased by 98.59%.At the same time,the weight loss ratio and contact angle decrease with the increase of the concentration of silane coupling agent.Infrared analysis shows that the silane coupling agents introduced into the modified system have reacted with each other to produce a three-dimensional network crosslinking structure,and new functional groups have been introduced onto the fiber surface such as Si-O-C,Si-OH,and Si-O-Si.(5)Functional PEW coating can significantly affect the pull-out process of UHMWPE fiber.Compared with the untreated fiber,the pull-out process of modified fiber can be divided into four stages: A,B,C,and D,and the pull-out stage A of modified fiber has a higher load value,and the pull-out stage B of modified fiber is more obvious.In addition,there will be load fluctuations in the pull-out stages C and D of modified fiber.However,the pull-out stages C and D of of untreated fibers are not distinguished clearly,and load fluctuation does not occur in these two stages.(6)The cohesion model of ABAQUS software was used to simulate the pull-out process of fiber.The results show that the finite element analysis model can effectively express the interface bonding performance between UHMWPE fiber and resin matrix.The presence of functional coating has significant influence on the actual and simulated single fiber pull-out process.The model has a good description of the pull-out stages of A,B and C,but a poor description of stage D.During the fiber pull-out process,the stress on the fiber is transferred from the interface layer to the surrounding matrix.The functional PEW coating and its combination with /silane coupling agent can significantly increase the friction resistance of interface layer.At the same time,the functional PEW coating acts as an intermediate bridge between fiber and resin matrix,which can serve as a stress buffer,thereby preventing the expansion of interfacial cracks and the occurrence of stress concentration.The damage process of functional PEW coated fiber has obvious time lag,and the ability of fiber to resist damage is enhanced.The polarity,number and type of monomer contained in the coating can significantly affect the damage process of the coating.The introduction of silane coupling agent can further improve the ability of the interface layer to resist damage.In addition,the presence of the functional PEW coating can significantly improve the impact resistance of the interface layer,while the introduction of silane coupling agent can further improve the impact resistance of the interface layer.