Continuous production of liquid reclaimed rubber from ground tire rubber and its application as reactive polymeric plasticizer

Liquid reclaimed rubber (LRR) was produced from ground tire rubber (GTR) in a continuous operation by using a co-rotating twin-screw extruder. The effects of reclaiming recipe, screw configuration combination, barrel temperature, and screw speed on the degree of reclamation were investigated. Through the adjustment of these conditions, an LRR with a sol fraction of 73.5% was obtained. Characterizations of the LRR by gel-permeation chromatography (GPC), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and re-vulcanized ability tests showed that the LRR had unique properties - low viscosity, good compatibility with natural rubber (NR), and re-vulcanized ability. Because of these properties of LRR, it was used as reactive polymeric plasticizer in NR to replace the conventional oils such as the environmental aromatic oil (EAO) used in this study. The plasticizing effect, acetone extraction, mechanical properties, and thermostability of the LRR/NR compounds were investigated and compared with those of EAO/NR compounds. The results show that the plasticizing efficiency of LRR is somehow lower than that of EAO. In addition, the LRR-plasticized NR has higher tensile strength, modulus at 100% and 300% elongation, hardness, extraction resistance, and thermostability than EAO-plasticized NR.