Effect of adhesive application method on lap shear strength of hot-melt adhesive with fracture analysis

Abstract

Polyamide hot melt adhesive was prepared from dimer acid, sebacic acid, ethylenediamine and piperazine. Piperazine content was varied from 12.5 mol % to 37.5 mol %. Prepared polyamides were tested for adhesion property – lap shear strength. Specimens for lap shear strength were prepared by two methods. In first method, lap joint was formed manually using glue gun while in the second method lap shear joint was formed using compression molding machine. It was found that sample prepared by compression molding gave better values of lap shear strength than that prepared using glue gun. Panels were also fracture analyzed, to find the reason for the properties obtained. Adhesion strength of lap joint formed using second method was found to be 5 to 10 times more than that formed using first method. First method is largely used, commercially, in hot-melt adhesive application. For any of the adhesive application method, as the piperazine content increased lap shear strength decreased.