Pretreatment of Hevea Latex by Sorbitol: Improving the Efficacy of Silica Dispersion by a Biomimetic Approach
Abhijit Bera, Bharat Manna, Debabrata Ganguly, S. K. P. Amarnath, Samik Nanda, Amit Ghosh, Santanu Chattopadhyay
Abstract
Incorporating a high amount of silica in cis-1,4-polyisoprene (CPI) by conventional dry mixing is a Herculean task. A biomimicking approach is adopted herein through incorporation of a bio-based sugar alcohol (sorbitol) into the CPI latex, which creates protein–carbohydrate interactions in the latex called protein–sugar conjugates. These treatments unveiled a significant improvement in key properties of the CPI vulcanizates, like >15% reduction in tan δ at a high temperature, besides better dispersion as evident from morphological studies. The protein and phospholipid ends were cleaved by respective enzymes for a clearer percipience of their individual effects on compounds’ key properties. The molecular dynamics study reveals a faster convergence of root-mean-square deviation (RMSD) and maximum radius of gyration (Rg) values of the sorbitol-treated latex, confirming a stable conformation of the CPI matrix in the presence of silica. Subsequently, a greater number of hydrogen bonds between the functional groups of protein and sorbitol demonstrates successful blocking of the functional groups (protein–sugar conjugates) of CPIs’ unwanted substances.