Functionalized starch as a novel eco-friendly vulcanization accelerator enhancing mechanical properties of natural rubber

•Functionalized starch (SSX) was prepared by chemically bonding SIBX onto the starch.•The thermal stability of SSX has been significantly improved compared with SIBX.•SSX can be used as a novel eco-friendly vulcanization accelerator.•NR vulcanized by SSX vulcanization system has better mechanical properties. A novel eco-friendly vulcanization accelerator, starch supported sodium isobutyl xanthate (SSX) has been synthesized firstly. The modification of starch using sodium isobutyl xanthate (SIBX) has improved the thermal stability significantly, and the vulcanization process of natural rubber (NR) could be accelerated by SSX at 145 ℃ accordingly. More importantly, SSX can be dispersed into NR matrix uniformly along with the strong interfacial interaction between SSX and NR, as evidenced by the constrained rubber chains around SSX surface. In addition, mechanical properties of the obtained NR have been enhanced remarkably, showing a 22.4 % increase in tensile strength when compared with traditional vulcanization accelerator. Laying on the fact that a novel vulcanization accelerator has been fabricated successfully using SIBX functionalized starch, new strategies for the preparation of green vulcanization accelerators and the functional application of biopolymers can be provided.