Development And Application Of High Performance Adhesives For Lightweight Composite Materials

Composite materials are far superior to traditional materials in strength,stiffness,fatigue resistance and acid and alkali resistance,among which polymer matrix composites are widely used.The matrix of polymer matrix composites is composed of epoxy resin,unsaturated polyester or polyurethane,and graphite,boron or aramid fibers are used as reinforcements.In practical applications,composite materials are often connected with metal materials to form a complete functional structure.The interface of composite materials will be destroyed by the traditional connection method,and the adhesive can realize the effective connection of composite materials without changing the existing design.In this paper,the removal of resin and the recovery of aramid fiber in composite materials were studied,and the recovered aramid fiber was added to the adhesive,and a one-component adhesive for bonding composite materials was successfully designed.First,the discarded aramid helmet was disassembled,and after the aramid composite was immersed in tetrahydrofuran/dioxane mixed solution for 24 h,the removal rate of resin layer in the composite reached 90.5%.Scanning electron microscope test shows that the surface of recycled aramid fiber is smooth and undamaged,and there is no obvious difference in appearance from Du Pont Kevlar^?964 fiber.Tensile test shows that the monofilament of recycled fiber can reach 81.8%of the breaking strength of Kevlar^?964fiber,and the fiber bundle composed of 20 recycled aramid fiber monofilaments can reach92.1%of the breaking strength of Kevlar^?964 fiber bundle.Secondly,on the basis of recycling aramid fiber,aramid fiber was added to epoxy adhesive as reinforcing material.The influence of the addition fraction of aramid fiber on the shear strength of similar materials such as steel sheet/steel sheet,aluminum sheet/aluminum sheet and carbon fiber sheet/carbon fiber sheet are discussed the effect of aramid fiber addition fraction on shear strength of dissimilar materials such as steel sheet/aluminum sheet,steel sheet/carbon fiber sheet,aluminum sheet/carbon fiber sheet was discussed.The hardness of the cured adhesive was tested by the addition fraction of aramid fiber the thermal stability and thermal aging resistance of the adhesive with aramid fiber were tested.The results show that with the increase of the proportion of aramid fiber in the adhesive,the shear strength of the adhesive to different materials shows a similar trend.When the addition of aramid fiber is 2.0 wt%,the shear strength of the adhesive to different materials is the best,and the comprehensive performance of the adhesive is the best.Compared with the adhesive G 909 of Henkel Le Tai,it is found that the shear performance of aramid fiber adhesive is higher than or equivalent to that of G 909adhesive,and its hardness is similar to that of G 909 adhesive.The thermogravimetric test shows that the addition of aramid fiber has no obvious effect on the thermal stability of epoxy adhesive.Aramid fiber adhesive and G 909 adhesive have similar declining trend at different aging temperatures,but aramid fiber adhesive has higher shear strength.In this paper,the fiber in aramid helmet was successfully recycled,and the recycled fiber was added to the adhesive formula to successfully prepare a high-performance adhesive for bonding lightweight composite materials.