Preparation and properties of modified porous starch/carbon black/natural rubber composites

Starch is considered as a cost-effective, abundant, renewable and environmental-friendly filler for rubber reinforcement via proper modification. In the present study, porous starch (PS) was modified by esterification with dodecenyl succinic anhydride (DDSA) for preparation of DDSA-modified porous starch (DDSA-PS). The suitable esterification conditions (e.g., temperature, time and dosage of DDSA) were discussed by single-factor experiments as 40 °C, 8 h, and 8 wt % (based on porous starch dry weight), respectively. Later on, a series of DDSA-PS/carbon black (CB)/natural rubber (NR) composites were prepared from the mixture of carbon black and DDSA-PS/NR compound that was pre-processed by co-coagulation of DDSA-PS and rubber latex. When the total filler dosage is constant as 60 parts per hundred rubber (phr), various properties of DDSA-PS/CB/NR composites were investigated by varying the composition ratio of DDSA-PS/CB. The results showed that when the ratio of DDSA-PS/CB was increased, the Payne effect of rubber compounds was attenuated to a large extent as well as the reduction of mechanical properties of vulcanized rubbers. Notably, the rolling resistance and hysteretic property were improved, reflected as the reduction of heat built-up, by incorporation of modified porous starch into the final NR composites. Therefore, DDSA-PS could be served as a promising filler for rubber industry partially instead of carbon black.