Hot melt adhesive properties of PA/TPU blends compatibilized by EVA-g-MAH

Abstract

A new copolyamide (PA52) with good adhesion to aluminum (Al) sheets was synthesized from caprolactam, nylon 66 salt, nylon 1010 salt, and stearic acid, and a series of PA52/TPU blends compatibilized by maleic anhydride-grafted ethylene vinyl acetate (EVA-g-MAH) were prepared for use as hot melt adhesives. In the ternary blends (PA52/EVA-g-MAH/TPU), the weight ratio of PA52 to TPU was kept constant at 50/50 and the amount of EVA-g-MAH was varied at 0, 2, 4, 6, and 8 wt% over the total weight of the blend, respectively. The solubility parameters were taken into account to describe the partial compatibility of PA52/TPU blends. The effects of EVA-g-MAH content on the melt viscosity, morphology, mechanical and thermal properties of ternary blends were systematically investigated, and the adhesion strength of hot melt adhesives based on the ternary blends were determined in terms of 90° peeling strength tests of Al/adhesive/ABS stacks. The results showed that the melt viscosity of ternary blends were greater than that of PA52/TPU blend, and the blend containing 6 wt% EVA-g-MAH exhibited an optimal miscibility behavior and excellent mechanical properties, at the same time, its peeling strength reached the maximum (120 N/25 mm).