Interfacial Characteristics of Film Insert Moldings Consisting of Semicrystalline and Amorphous Polymers

Abstract

Abstract Film insert moldings were produced from amorphous and crystalline polymers, i. e. PC + ABS and PET respectively. The vastly different characteristics of these polymers provide an interesting platform to study the mechanisms that are responsible for interfacial bond formation, particularly when these materials were molded at different molding conditions. It was observed that intermolecular diffusion between amorphous polymers takes place at virtually any temperature as long as it is kept above the glass transition temperature of the material, though higher temperatures are favorable to accelerate diffusion. As for crystalline polymers, there is an initial need to create free and mobile molecular chains by heating the materials to its melting temperature before any significant diffusion takes place. Certain criteria have to be met, irrespective of the materials used, before good interfacial bonding is achieved. Firstly, the injection molding parameters should be optimized to ensure intimacy between the surfaces of the film and injected resin. Once this is achieved, interdiffusion of molecules should be promoted to ensure extensive film-substrate molecular entanglements. The state of molecular entanglement should then be retained for a sufficient amount of time as the material solidifies in order to obtain good film-substrate adhesion.