| Abstrakt: |
Epoxy adhesives are one of the polymers used as high-performance matrix in adhesives. However, the high brittleness and low toughness of epoxy adhesives are critical challenges during their service in structural applications due to their high-crosslinking degree. The lack of appropriate high-temperature thermal stability is another drawback of these valuable materials. This study addressed the effect of hybrid reinforcement comprising zirconium oxide nanoparticles (NPs), phenolic resin (resol type), and poly (butyl acrylate-block-styrene) copolymer (BCP) on mechanical, adhesion, thermal, and morphological properties of the epoxy adhesive. Mechanical properties, thermal stability, and microstructure of the epoxy adhesive was assessed using tensile test, TGA, and FESEM tests, respectively. The adhesion features of the formulated adhesive were evaluated in lap joint bonding of an aluminum to aluminum. A new approach was developed to design advanced adhesives with high mechanical, adhesion, and thermal properties by adding hybrid additives. Based on the tensile test results, adding 5 phr of zirconium oxide nanoparticles to the epoxy adhesive increased the tensile strength, modulus, and the toughness of the dumbbell-shaped samples by 69, 33 and 175% compared to the neat epoxy adhesive, respectively. Furthermore, the sample containing 10 phr phenolic resin, 5 phr zirconia NPs, and 2.5 phr block copolymer exhibited the highest improvement (420%) in the shear strength in the single lap joint increment compared to pure epoxy, reflecting the synergistic impact of these compounds at the mentioned percentage. The TGA results indicated the highest initial degradation temperature in the sample containing 5 phr zirconia NPs which was 54.4 °C higher than that of the pure epoxy. The images of the fracture surface of the optimal samples in the tensile test showed the cavitation, shear band formation, crack deviation, and crack tip blunting as major mechanisms in the toughness enhancement of the samples. [ABSTRACT FROM AUTHOR] |
Full text from SpringerLink