Reactive Interfacial Adhesion between Surface-modified Polystyrene and a Polyamide (nylon 6)

Abstract

We present an investigation of the reinforcement of the interface between a flexible amorphous polymer (polystyrene, PS) and a semi-crystalline polymer (a polyamide, Ny6). Poly(styrene-co-maleic anhydride) was used as the compatibilizer. Fracture toughness was measured using the asymmetric double cantilever beam test (ADCB). For bonding temperatures above 190℃, the adhesion strength was found to increase with bonding time, pass through a peak value, and then reach a plateau. The fracture toughness increased with increasing bonding temperature, passed through a peak near 200℃, and then decreased with further increase of the bonding temperature. This behavior was more obvious for an amorphous polymer / semi-crystalline polymer pair than for a pair of semi-crystalline polymers. The variation of the fracture toughness with bonding time and temperature can be plausibly explained in terms of two different failure mechanisms[1]: adhesive failure at the interface for short bonding times and when the bonding temperature is low, and for longer bonding times and at high temperatures, cohesive failure between chains at the interface and the bulk PS due to decreased chain entanglement. This was also verfied by adopting three different surface functionalization processes (ion beam, plasma, complex ion beam process) for the polystyrene to exclude the complexity of the chain diffusion.