Preparation of Thermoplastic Vulcanizates Based on Waste Crosslinked Polyethylene and Ground Tire Rubber Through Dynamic Vulcanization

An environmental-friendly approach called high-shear mechanical milling was developed to de-crosslink ground tire rubber (GTR) and waste crosslinked polyethylene (XLPE). The realization of partial devulcanization of GTR and de-crosslinking of XLPE were confirmed by gel fraction measurements. Fourier transform infrared spectral studies revealed that a new peak at 1723.3 cm(-1) corresponds to the carbonyl group (-C=O) absorption was appeared after milling. The rheological properties showed that the XLPE/GTR blends represent lower apparent viscosity after mechanical milling, which means that the milled blends are easy to process. Thermoplastic vulcanizates (TPVs) could be prepared with these partially de-crosslinked XLPE/GTR composite powders through dynamic vulcanization. The mechanical properties of the XLPE/GTR composites increased with increasing cycles of milling. The raw XLPE/GTR blends could not be processed to a continuous sheet. After 20 cycles of milling, the tensile strength and elongation at break of XLPE/GTR (50/50) composites increased to 6.0 MPa and 185.3%, respectively. The tensile strength and elongation at break of the composites have been further improved to 9.1 MPa and 201.2% after dynamic vulcanization, respectively. Re-processability study confirmed the good thermoplastic processability of the TPVs prepared. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 2110-2120, 2011