Improvement of the properties of natural rubber/ground tire rubber composites through biological desulfurization of GTR

The surface desulfurization of ground tire rubber (GTR) had been carried out via a biological treatment by Thiobacillus sp. with strong sulfur oxidizing capacity. The bonding states and element content on the surface of GTR and desulfurated GTR (DGTR) were evaluated using an X-ray Photoelectron Spectroscopy (XPS). The contact angle of GTR was 120.5 degrees and decreased down to 93.5 degrees after treatment. The cure characteristics, swelling behavior, and crosslink density of natural rubber (NR)/GTR and NR/DGTR were examined. The improvement in mechanical properties was observed for NR/DGTR vulcanizates, which was attributed to the enhanced interfacial interaction between DGTR and NR matrix. The dynamic mechanical analysis (DMA) results showed that NR/DGTR vulcanizates had a reduction of molecular chain friction resistance during glass transition region and Scanning electron microscopy (SEM) studies further indicated a good coherency and homogeneity between DGTR and NR matrix.