Study On The Surface Modification Of Uhmwpe Fiber And The Interfacial Adhesion Properties Of Fiber Reinforced Rubber Composites

Fiber reinforced rubber composites have many advantages,such as high specific strength and modulus,environmental chemical corrosion resistance,durability,designability of material structure and properties,so they are widely used in tire,crawler,rubber hose and other fields.In order to meet various technical requirements,adequate interfacial adhesion between fiber and rubber matrix is very important.The adhesion force largely depends on the molecular interface structure and the molecular interface interaction,and the high mechanical properties of fiber reinforced rubber composites mainly depend on the adhesion mechanism between the fiber and the matrix.Chemical interaction can provide higher adhesion,and only in this case,the composite represents the whole,rather than a mechanical mixture of two incompatible components.The adhesion between untreated fibers and rubber substrates is generally low,mainly due to the large differences in polarity and modulus between the two.At present,Resorcinol-Formaldehyde-Latex（RFL）impregnation treatment technology is still the most widely used fiber surface modification technology in industrial production.However,the molecular chain of Ultra High Molecular Weight Polyethylene（UHMWPE）fiber has a linear structure,there are only two elements（Carbon and Hydrogen）on the main chain,the surface is lack of polar groups,and the molecular structure with high crystallinity and high orientation is very dense,resulting in low surface energy,high chemical inertia,difficult to combine with resin latex,rubber and other materials,and poor interfacial adhesion properties.This has greatly limited the surface modification methods of UHMWPE fibers and their promotion and application in the field of materials.Therefore,the purpose of this paper is to modify the surface structure and properties of UHMWPE fiber,combined with the good adhesion of traditional RFL dipping system and rubber matrix,to explore a surface modification method which is more suitable for UHMWPE fiber,so that it has a good adhesion with rubber matrix,while preserving its excellent mechanical properties as much as possible.（1）Based on the adhesion test of a single UHMWPE fiber,the RFL impregnation system,which is traditionally used for the impregnation treatment of aramid and nylon fibers,was applied to UHMWPE fibers.It is found that this system can still effectively improve the surface adhesion of UHMWPE fiber.When UHMWPE fiber is impregnated by RFL impregnation two-bath method,the adhesion of UHMWPE fiber is increased by 36%compared with untreated UHMWPE fiber without losing the mechanical properties of UHMWPE fiber,and the H extraction force is increased from41.2 N to 56 N.（2）Based on the surface pre-modification of UHMWPE fiber,the surface energy of a single UHMWPE fiber pretreated by plasma（P）treatment significantly increased and the contact angle decreased,and functional groups such as-COOH,-C=O,-OH were effectively introduced into the surface.After plasma pretreatment,the RFL impregnation adhesive phase increased by about50%compared with the untreated fiber.The H extraction force increased from41.2 N to 61.6 N.（3）In order to preserve the mechanical properties of UHMWPE fiber more effectively,the surface coating method was adopted,that is,the surface of UHMWPE fiber was functionalized by the reaction of dopamine（DA）,polyethyleneimine（PEI）or PEI/PDA.The experimental results show that the three pretreatment methods can effectively increase the surface energy of UHMWPE fiber,reduce the surface contact angle of fiber,and introduce functional groups such as-C=O,-NH₂and amide group into the fiber surface,and the adhesion is improved most obviously when the ratio of PEI and DA is1.5:1.When the fiber is pretreated with PEI/PDA and then impregnated with RFL,the adhesion of the fiber is increased by about 52%compared with untreated fiber.The H extraction force increased from 41.2 N to 62.5 N.（4）The UHMWPE fiber is blended with the surface highly active fiber nylon 66（PA66）,and active functional groups are introduced into the surface of the UHMWPE fiber through physical weaving.The experimental results show that the surface adhesion of UHMWPE/PA66 blended fabric（impregnated RFL）increases by about 68%compared to pure UHMWPE fabric（impregnated RFL）.