Abstract: The effect of the screw rotation speed, temperature and pressure of subcritical water, and other additives on the devulcanization in the blends of the SBRbased ground tire rubber (GTR) with PEHD was studied. It showed that the high shear stress imposed by the twinscrew extruder and the subcritical water may promote the devulcanization. The faster the screw rotation speed or the higher the subcritical water temperature and pressure, the stronger the decomposition or degradation reaction. Nbutyl amine may significantly promote the devucanization and at the same time protected the double bond in the blend. When the screw rotation speed was 1000 r/min, the temperature and pressure of subcritical water were 220 ℃ and 2.4 MPa, respectively, a thermoplastic elastomer of DGTR/PEHD containing EPDM and with nbutyl amine provided a tensile strength of 12.8 MPa and an elongation at break of 614.6 %.

Key words: ground tire rubber, subcritical water, devulcanization reaction, thermoplastic elastomer, styrenebutadiene rubber