چكيده لاتين
Epoxy adhesives have attracted much attention in various industries due to their properties such as high strength and good chemical resistance. The film type of these adhesives has attracted the attention of many industries, including the aerospace industry, due to its advantages such as easy use, creating a uniform adhesive line, storage capability, and no waste. Among the important parameters that should be considered for epoxy film adhesives used in this industry are high adhesion strength, thermal resistance, and mechanical strength. Given that few studies have been conducted in the field of designing the formulation of film adhesives used in the aerospace industry, the purpose of this research is to design the formulation of epoxy film adhesives with high strength and thermal resistance. In designing the formulation of these adhesives, a mixture of 4 types of epoxy resins was used. The effect of adding three types of reinforcements including alumina nanoparticles, polymer particles with a core-shell structure (polybutyl acrylate (core)/methyl methacrylate-glycidyl methacrylate copolymer (shell)) and polysulfone in the formulation of these adhesives was investigated in three separate parts on the mechanical, adhesion and thermal properties of epoxy film adhesives. For this purpose, core-shell polymer particles were first synthesized by emulsion polymerization and fully characterized. The surface of alumina nanoparticles was also modified by 3-aminotriethoxysilane. In the first part, it was found that by adding 5 wt.% modified alumina nanoparticles to the epoxy adhesive formulation, the tensile strength, Youngʹs modulus and toughness of epoxy composites increased by 334%, 14% and 1142% respectively compared to pure epoxy. Also, the adhesion strength in single-edge aluminum-aluminum joints increased by 105% compared to pure epoxy. The results of the thermogravimetric analysis (TGA) test showed that the thermal decomposition onset temperature (TIDT) and the maximum thermal decomposition temperature (Tmax) in this sample increased by 97 and 28 °C, respectively, compared to the pure epoxy sample. In the second part, it was found that the tensile strength of epoxy increases with the increase in the core-shell particle fraction, and in the sample containing 10% by weight of the emulsion of these particles, the tensile strength and toughness are 8 times greater than the tensile strength and 129 times greater than the toughness of pure epoxy, respectively. Also, the adhesive strength of this sample increased by 102% compared to pure epoxy. The results of the TGA test showed that the TIDT and Tmax in this sample increased by 48 and 11 °C, respectively, compared to the pure epoxy sample. In the third section, it was found that in the combination of low weight percentages (10% by weight) of polysulfone resin, the tensile strength of epoxy adhesives increases, but with increasing the percentage of this resin, the tensile strength decreases. Also, this additive has an undesirable effect on the adhesion strength. This resin increases Tmax compared to pure epoxy. In examining the effect of all three modifiers on the mechanical and thermal properties of epoxy film adhesives, an equilibrium of mechanical properties was achieved. Also, the results of the TGA test showed that the thermal properties of this sample decreased significantly compared to the samples in which alumina nanoparticles and core-shell particles were used separately.
