Influence Of Adhesive Rubber On Interfacial Adhesive Properties Of Environmentally Friendly Impregnated Nylon Cords And Its Mechanism

Fiber/rubber composite materials are widely used in high-speed and high-load automobile/aircraft tires,high-pressure resistant special rubber hoses and high-strength special rubber conveyor belts.The interfacial adhesion between fibers and rubber matrix is the key to determining fiber-reinforced rubber.The industrial use of resorcinol-formaldehyde-latex（RFL）system impregnation treatment of fibers can obtain excellent interfacial adhesion properties.However,due to the harmfulness of formaldehyde and resorcinol,countries all over the world are competing to develop new non-RFL environmental protection system impregnation treatment technology to replace RFL technology.This paper is based on the epoxy resin environmental protection system developed by the research team in the early stage of impregnating nylon 66 cords.By changing the composition design of the adhesive rubber,that is,adding a phenolic resin prepolymer to the adhesive rubber,changing the accelerator system,and blending the epoxy natural rubber,a total of three methods,further enhance the interfacial adhesion performance of environmentally friendly impregnated nylon cords and rubber to meet the requirements of large aircraft tires for higher interfacial adhesion performance of fiber/rubber composites.（1）Improve interfacial adhesion by changing the tackifier of the adhesive rubber.Mainly from the amount of phenolic resin SL-3022 and hexamethylenetetramine HMT to explore the changes in the vulcanization properties and mechanical properties of adhesive rubber,as well as the influence on the interfacial adhesion properties of composite materials.By adjusting the amount of SL-3022 and HMT,the H pull out force of the nylon66 cord/rubber composite material reaches 174.5±15.6 N,which is 16%higher than that of standard bonding rubber;the peeling force of a single cord reaches 15.9 N/root,which is 8%higher than that of the standard bonding rubber.At this time,the modulus of the bonding rubber is 7.0 MPa,and the interfacial shear strength of the composite material is 15.2 MPa.Through the analysis of the adhesive rubber modulus,it was found that the H pull out force of the composite was positively correlated with the adhesive rubber modulus.（2）Improved interfacial adhesion by changing the promoter of the adhesive rubber.The changes of the vulcanization properties and mechanical properties of the adhesive rubber,as well as the influence on the interfacial adhesion properties of the composite materials,were mainly explored from the types and amounts of accelerators.Through the analysis of the vulcanization performance of the bonded rubber,it is found that prolonging the rubber scorch time t₁₀can improve the interfacial adhesion of the composite material,and t₁₀is proportional to the H pull out force of the composite material.The sulfur content of the fiber/rubber composite interface was quantitatively characterized by EDS,and it was found that the sulfenamide accelerator NS could significantly increase the sulfur content migrated from the rubber phase to the interface transition layer during the vulcanization process,thereby increasing the interfacial viscosity of the composite.combine.When the amount of accelerator NS is 0.8 phr,the H pull out force of the nylon 66cord/rubber composite reaches 201.7±10.7 N,which is 34%higher than that of the standard adhesive rubber;the peeling force of a single cord reaches 18.6N/root,26%higher than the adhesive rubber with accelerator M.With the increase of the adhesive rubber modulus,the peel force of the composites first increased and then decreased.When the adhesive rubber modulus was 5.8MPa,the interfacial bonding effect of the composite was the best,and the interfacial shear strength of the composite was 13.6 MPa.（3）Improve interfacial adhesion by blending epoxy natural rubber.The effects of the blending ratio of natural rubber/epoxy natural rubber and the amount of curing agent on the interfacial adhesion properties of composites were mainly investigated.It is found that the modulus of adhesive rubber increases first and then decreases with the ratio of ENR/NR.When the NR/ENR is 9:1,the modulus of the bonding rubber is the largest.The modulus of the adhesive rubber is positively related to the H-extraction force of the composite.When NR/ENR is 9:1 and the dosage of HMT is 0.5 phr,the H pull-out force and peeling force of the composite material reach 175.3±11.8 N and 16.4 N/piece,respectively,which are 15%and 11%higher than the standard adhesive rubber.At this time,the bonding rubber is 6.1 MPa,and the interface bonding effect of the composite material is the strongest.