Coextrudierte Zweischichtfolien zur Verarbeitung von Post-Consumer-Materialien im Thermoformen
Due to the lack of raw material and forced by political demand, an increasing percentage of post-consumer materials (PCR) shall be used in all processing methods in polymer technology. Thermo-forming, as one of the oldest polymer-processing methods, has special requirements regarding the melt stability at high temperatures. Low melt stability affects the thermoforming in a negative man-ner, as the low stiffness leads the sheet to sag during the heating phase. New processing strategies for PCR materials in the coextrusion of two-layer films were developed in this study to overcome the low melt stiffness of PCR materials and to produce homogeneous and reproducible products. In thermoforming, the benefit of using a two-layer system for processing PCR materials is also evident. The investigations carried out in this work show the potential of the two-layer film compared to monolayer or blend configurations for processing PCR materials without further modification in thermoforming. A holistic evaluation of the potential of coextruded two-layer sheets for processing PCR materials in thermoforming covers thermal analysis, analysis of rheological behavior and characteristic part properties. Up to 50% of PCR material can be applied in the coextruded two-layer configuration. The use of a two-layer sheets for processing PCR materials in thermoforming can thus make a significant contribution to an increase in the efficiency of resources and sustainability.