Synthesis and properties of nanocomposite adhesives

Abstract

A series of acrylic co-polymers and terpolymers from ethyl acrylate (EA), butyl acrylate (BA) and acrylic acid (AA) were synthesized by solution polymerization. Nanocomposite adhesives based on these acrylic polymers and silica or clay were prepared by sol–gel or solution blending techniques, respectively. The effect of nanoparticles on the performance of the hybrid adhesives was investigated by measuring peel strength, lap shear strength or static shear resistance against three substrates having different surface characteristics- aluminum (Al), wood (W) and biaxially oriented polypropylene (PP). The results showed significant improvement in peel strength of Al–Al and PP–PP joints with increase in polarity of the polymer matrix and nanofiller concentration. These results could be explained in terms of higher cohesive strength of the nanocomposite adhesives. The locus of failure also changed from interfacial failure for neat acrylic adhesive to stick–slip failure for the hybrid composites. Both the lap shear strength and static shear resistance of the hybrid nanocomposites also gradually increased with nanofiller loading. Al–Al and W–W joints displayed higher joint strength, because of the interaction of the hydroxyl groups present on the surface of these substrates.