Effect of a tie film on the enhanced interfacial adhesion between polyethylene and polyamide-6 in a sequential injection molding

The effect of a tie film consisted of polyethylene (PE) and maleic anhydride functionalized PE (PE‐g‐MAH) on the interfacial adhesion of PE and polymide‐6 (PA6) was studied in a sequential injection molding process. It was found that the interfacial adhesion of PE/PA6 was significantly improved via in situ reactive compatibilization. The results showed that the interfacial adhesion increased with PE‐g‐MAH concentration, and reached a plateau value at the weight fraction of 40%, showed a maximum at a thickness of about 15 μm tie film. Higher the second melt and mold temperature, stronger the interfacial adhesion was obtained. An analysis conducted on the fracture interface by using scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) revealed that the increase of the interfacial adhesion was strongly related to the morphological structure of the fracture interface, which changed from chunks to fibrils, and to a thin layer. The relationship between the interfacial adhesion and interfacial fracture mechanisms was also discussed. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers