The Synthesis Of E44/KH550Modified Waterborne Polyurethane Adhesives And Their Application On UHMWPE Fiber

Waterborne polyurethane (WPU) adhesive is prepared by dispersing polyurethane particles in the media of water. It not only inherits the excellent properties of abrasion resistance, good flexibility and low temperature resistance, but also shows the advantages of non-flammable, nontoxic, environmental friendly, energy-saving, easy processing and good adhesive, etc. Therefore WPU has been widely used in the fields of aviation, aerospace, automotive, adhesives, wood processing, building materials and paper industries. In particular. WPU can be used as thermoplastic resin to prepare ultra-high molecular weight polyethylene (UHMWPE) fiber reinforced composites which has been widely used in the fields of high strength ropes, bullet-proof materials, cut resistant gloves and so on. However, UHMWPE fibers are non-polar materials, the wetting properties between WPU emulsion and UHMWPE fibers are very poor, the water and thermal resistance of WPU films are also very bad. In this thesis, three kinds of silane coupling agents and a kind of epoxy resin are used to modify WPU emulsion in order to expand their application areas. The main work and research results of the thesis include the following four aspects.(1) Toluene diisocyanate and polypropylene goycol are used as main raw materials.1.4-butanediol and a,a-dimethylol propionic acid (DMPA) are used as chain extender. triethylamine is used as neutralizing agent, the WPU emulsion is prepared using acetone method. The effect of DMPA addition and solid content of emulsion on the particle size and the viscosity of WPU emulsions, the interfacial shear strength of WPU-UHMWPE fiber composites and water absorption of WPU films are discussed. The results indicate that with the increasing of added DMPA content, the particle size of WPU emulsion decreases, the emulsion viscosity increases, the stability of WPU emulsion becomes better, the interfacial shear strength between WPU and UHMWPE fibers increases, the water absorption of WPU film increases. With the increasing of solid content of WPU emulsion, the particle size of emulsion decreases, the emulsion viscosity increases and the emulsion becomes difficult to How and soak the UHMWPE fibers when preparing fiber-reinforced composites. Therefore, comprehensively considering the emulsion performance, film performance and the interfacial adhesive properties between WPU and UHMWPE fibers, the optimal DMPA content is selected as5%, the optimal solid content is controlled as30%.(2) The3-ammonia propyl three ethoxy silane(KH550), γ-(2,3-epoxy propyl) propyl three oxygen base silane (KH560) and N-p-(ammonia ethyl)-γ-ammonia propyl methyl dimethoxy silane (KH602) are used as modifier, toluene diisocyanate and polypropylene goycol are used as main raw materials, KH550, KH560and KH602modified WPU emulsions are prepared by using acetone method. The effects of added content of three kinds of silane coupling agents on the performance of WPU emulsion and WPU film, and the interfacial adhesive properties between WPU and UHMWPE fibers are researched. The results show that with the increasing of added content of silane coupling agent, the particle size of modified WPU emulsion increases, the emulsion viscosity decreases, the stability of WPU emulsion becomes worse. Among the three kinds of silane coupling agents, the effect of KH550on particle size and viscosity of WPU emulsion is the least, the effect of K.H602is the most. Excessive addition of silane coupling agent may reduce the storage stability of WPU emulsion. Therefore, adding5%silane coupling agent is suitable in the preparation of silane modified WPU emulsion. The results also show that with the increasing of added silane coupling agent content, the water absorption of modified WPU film decreases, the tensile properties of WPU film increases, the water contact angle of WPU film increases and the interfacial shear strength between WPU and UHMWPE fiber is improved. The modification effects of different modifiers on the interfacial shear strength of WPU-UHMWPE fibers composites are different:KH550has the optimal modification effect wbile the effect of KH602is not obvious.(3) Epoxy resin of E44is used to modify WPU emulsion. the performance of E44modified WPU emulsions and WPU films are researched. The results show that with the increasing of E44addition, the particle size of modified WPU emulsion increases, the emulsion viscosity decreases gradually; the water resistance and thermal resistance of WPU film are both obviously improved, the tensile strength of WPU films increases, the elongation at break of films decreases; E44modification has only slight improvement on the surface hydrophobicity of WPU film. therefore, it has no obvious improvement on WPU-UHMWPE fiber interfacial adhesive performance.(4) KH550and E44are use to simultaneously modify WPU emulsion, the effects of modifier addition on the performance of compound modified WPU emulsion and film have been studied. The research shows that when the added content of one modifier is fixed, the particle size of WPU emulsion increases with the increasing of another modifier. the emulsion viscosity decreases, the water and thermal resistance increases. the tensile strength of WPU film increases, and the elongation at break of the film decreases. When the added E44content is constant, the water contact angle on the WPU film surface increases and the WPU-UHMWPE fiber interfacial shear strength is improved with the increasing of KH550content.