Cardanol grafted reclaimed rubber by in-situ reaction for better properties

Abstract

Cardanol grafted reclaimed rubber (CGRR) was prepared by in-situ reaction between reclaimed rubber (RR) and cardanol, during reclamation of waste rubber powder (WRP) in an internal mixer at 190 °C. Dicumyl dioxide (DCP) acted as an initiator. The percent grafting, grafting efficiency, structural characteristics, reclamation degree and storage stability of RR, as well as the mechanical properties of re-vulcanized CGRR (rCGRR) were all investigated by the effect of DCP content. The FTIR and 1H-NMR proved that cardanol was successfully grafted onto the backbone of RR. Both grafting reaction and the reclaiming reaction could be affected by DCP content. The percent grafting, grafting efficiency of CGRR increase with DCP content. While DCP over 0.5 phr, the reclamation degree of CGRR decrease which had an adverse influence on mechanical properties of rCGRR. By comparison, the optimum content of DCP should be 0.5 phr. In addition, the CGRR (0.5 phr DCP) shows obviously improved mechanical properties and storage stability (70 days detection) than that of aromatic oil filled reclaimed rubber. The thermal stability of cardanol and WRP, also thermodynamic transformation of CGRR were characterized by TGA and DSC respectively.