Effect of Multiple Recycling on Thermo-mechanical and Rheological Behaviour of PP/EPDM Thermoplastic Vulcanizates

Driven by the need to design sustainable polymeric materials that remain superior mechanical properties after recycling, this work is centred on the effect of multiple recycling of thermoplastic vulcanizates (TPVs). Among thermoplastic elastomers, TPVs combine several favourable characteristics such as damping, light weight, ease of processing by means of injection moulding, design flexibility and recyclability. Multiple processing of a commercially available PP/EPDM TPV by shredding and injection moulding was followed by analytical investigations on rheological and thermo-mechanical properties using melt rheological measurements, dynamic mechanical analysis, differential scanning calorimetry analysis and mechanical tests. The results show that key performance parameters of the TPV such as Young’s modulus, stress at 100% strain as well as stress and strain at break only change slightly. Stress at 100% strain can be used as a quality indicator as it decreases linearly with every recycling step. This study opens new opportunities to increase the content of recycled PP/EPDM TPV and even manufacture technical components with 100% recycled material.