Separation of multi-component parts for mechanical recycling – Study about basic approaches using a heating process.

The recyclability of plastic components has become an important objective in the product development process of packaging and technical products. Especially for multi-component parts which are processed via overmolding technology, mechanical recycling shows several challenges regarding separation, sorting, and the following treatment in recycling plants. Combining different functions in one process step or saving costs by reducing the amount of expensive high-performance thermoplastics are two of possible advantages using multi-component parts. In the context of electric mobility and lightweight engineering, multi-material mixes are very important due to a variety of requirements that cannot be met by a single material. At the end-of-life stage, multi-component parts are mostly thermally disposed of because the substance-to-substance bond of two different types of plastic makes mechanical recycling difficult. A separation of the different materials in such components has to be done to get pure materials for the further recycling process. In this study, the adhesion of plastic materials, which are processed by overmolding, is investigated by using the temperature during testing the bond strength as the main parameter for a simulated separation process. The idea is to conduct the separation process in a hot washing unit in common recycling plants. The bond strength is tested by applying normal, shear, and peel stress to the samples. The temperature is varied from ambient conditions up to 110 °C. The results show a decrease in bond strength for the tested material combinations. A further approach to produce multi-component parts with better recyclability is to use an intermediate layer out of an additional plastic material that shows good adhesion to both main materials. In a recycling process, the two components can be separated by melting the intermediate layer and shearing the parts in recycling machines. The results show the basic feasibility of this approach. [ABSTRACT FROM AUTHOR]