Processing and Mechanical Properties of Highly Filled PP/GTR Compounds

Abstract

Ground rubber from automobile tires is very difficult to recycle due to the cross-linking of the macromolecules and thus the lack of thermoplastic properties. The research consisted of assessing the processing possibility via the injection of highly filled PP/GTR compounds modified with 1.5 wt.% 2.5-dimethyl-2.5-di-(tert-butylperoxy)-hexane. GTR dosing ranged from 30 wt.% up to 90 wt.%. The evaluation of the processing properties of the obtained materials was carried out on the basis of the melt flow index test results and the signals recorded during processing by the injection molding by temperature and pressure sensors placed in the mold. The influence of the applied modifier on the changes in the mechanical properties of PP/GTR was determined with hardness, impact and static tensile tests. Moreover, thermal properties were obtained by the differential scanning calorimetry method. It has been found that it is possible to efficiently process compounds with high GTR content using injection molding. The presence of the filler allows to significantly reduce the cooling time in the injection mold and thus the time of the production cycle. It has been confirmed that 2.5-dimethyl-2.5-di-(tert-butylperoxy)-hexane modifies the rheological properties of PP and thus the PP/GTR composition. The lower viscosity of the matrix results in a more accurate bonding with the developed surface of the GTR grains, which results in better mechanical properties of the rubber-filled polypropylene.

Green Approaches in Rubber Recycling Technologies: Present Status and Future Perspective

“…It can therefore be concluded that by selecting the appropriate cross-linking agent and manipulating the reactive processing parameters, it is possible to obtain products of higher quality without using an additional compatibilization technique. Similar findings were provided by Kosćiuszko et al 146 who compared GTR/polypropylene (PP) systems with and without 1.5 wt % 2.5-dimethyl-2.5-di(tert-butylperoxy)hexane. Except for the enhancement of mechanical properties, a significant improvement in the volume-flow rate (MVR) as a measure of processability was observed after the addition of the peroxide.…”

“…It can therefore be concluded that by selecting the appropriate cross-linking agent and manipulating the reactive processing parameters, it is possible to obtain products of higher quality without using an additional compatibilization technique. Similar findings were provided by Kościuszko et al . who compared GTR/polypropylene (PP) systems with and without 1.5 wt % 2.5-dimethyl-2.5-di­( tert -butylperoxy)­hexane.…”

Sustainable 3D printing with recycled tire rubber-based filaments: an investigation of process parameters and mechanical behaviour

“…Nowadays, the blending of GTR with various polymers, notably polypropylene (PP), polyethylene, polyvinyl chloride and polystyrene (Ramarad et al, 2015a(Ramarad et al, , 2015bJiang et al, 2018;Liang et al, 2020;Kosciuszko et al, 2022), has opened up avenues for shaping and re-melting these materials into a diverse array of extruded and moulded products. Consequently, GTR blends have found practical applications in numerous aspects of everyday life, including running tracks and playground surfaces, to name a few (Toncheva et al, 2021;Ferrao et al, 2008).…”

Cross-Linking, Morphology, and Physico-Mechanical Properties of GTR/SBS Blends: Dicumyl Peroxide vs. Sulfur System

“…The incorporation of modified or unmodified GTR into polymer systems is a topic that has been addressed and studied for many years. GTR is usually added to thermoplastics such as polyethylene (PE) [ 16 , 17 , 18 ], polypropylene (PP) [ 19 , 20 , 21 ], polyvinyl chloride (PVC) [ 22 ], etc. It is also common to create blends based on natural or synthetic rubbers [ 23 , 24 , 25 ].…”