Separation of Plastic Waste by utilizing Unsteady Heat Transfer and Melt-Sticking Phenomena.

Abstract

This paper deals with a novel process for separating mixed plastics such as found in industrial waste by utilizing unsteady heat transfer to the plastics and so-called melt-sticking between the plastics and a heated solid surface. First the concept of the novel separation process was proposed, and then the feasibility of the concept was experimentally examined by using an experimental setup, in which particles of various types of plastics were pressed against a heated plate. The results clearly showed that the heated plate temperature at which the melt-sticking between plastic particles and the heated plate takes place markedly varies with the types of plastics, and that the temperature is also influenced by the materials of the heated plate. These results suggest that the melt-sticking phenomenon can be applied for separating mixed plastics. Based on a hypothesis that the melt-sticking phenomenon takes place when the interface temperature between the heated plate and plastic particles exceeds a certain temperature, which varies with the types of plastics, and by using a theoretical solution of unsteady heat conduction between two semi-infinite bodies, the heated plate temperature at which the melt-sticking occurs was successfully estimated for various types of plastics and heated plate materials, and separation ability of this process was discussed.