Material recycling of plastics

In the material recycling of plastics, the polymer structure is transferred almost unchanged into the secondary products by remelting. The comparatively low quantities used in this process so far are mainly due to the high purity requirements placed on the plastic waste so that the products made from it can compete with primary products. Even small amounts of impurities can significantly disrupt the reprocessing process or significantly change the physical properties of a polymer material.

From a purely technical point of view, it is possible to separate high-purity plastic products even from a comparatively heterogeneous plastic waste stream. However, this requires a combination of several process steps (e.g. picking, sensor-based sorting, density separation). The higher the increase in the recyclable content between the feedstock and the product is to be, the more increasingly finer process steps are therefore required, resulting in an exponential growth of the processing costs. The sales price of the secondary plastic must bear these and other costs and at the same time be able to compete with that of primary plastic products. Due to the currently rather low primary production costs of most mass plastics, this is only economically feasible for selected types of plastics and waste fractions.