Factors Affecting Adhesion at Copper-Polyamide 11 and Aluminum-Polyamide 11 Interfaces

Abstract

Adhesion at polyamide 11-copper and polyamide 11-aluminum interfaces was studied. Metal-polymer-metal laminates were prepared by compression molding using processing conditions similar to the normal melt processing parameters of polyamide 11. The results show that the time of contact at the molding temperature required to reach contact level of adhesion is significant (several minutes). The state of the metal surface affects adhesion. Mild oxidation (prior to molding) improves adhesion with aluminum; with copper, a monotonous slow decrease of adhesion with oxidation time is observed. The presence of the metal surface affects the crystallization behavior of polyamide. Upon a relatively slow cooling rate (40-50'C/min), a transcrystalline layer about 15 1Lm thick is formed having a degree of crystallinity almost 10% higher than the material away from the interface. In the absence of the transcrystalline layer, the level of adhesion is significantly lower.