Cardanol Functionalized Carboxylated Acrylonitrile Butadiene Rubber for Better Processability, Technical Properties and Biocompatibility

Abstract

The present investigation deals with the latex stage functionalization of carboxylated acrylonitrile butadiene rubber (XNBR) by chemically grafting cardanol onto its backbone main chain to impart multifunctional characteristics to it. The grafting of cardanol onto XNBR in the latex stage has been accomplished successfully using benzoyl peroxide (BPO) as a free radical initiator. Cardanol grafted XNBR (C-g-XNBR) exhibited an increase in molecular weight (7.5%) with an increase in PDI (polydispersity index). The optimum grafting parameters were found to be of 1 phr BPO with 15 phr cardanol at a reaction temperature of 80 °C and a reaction time of 10 h using “Taguchi methodology”. The maximum percentage grafting (PG) and grafting efficiency (GE) were estimated to be 13.8 and 92.8%, respectively at the optimum combination of the reaction parameters. Differential scanning calorimetry and dynamic mechanical analysis results exhibited a decrease in Tg value for the functionalized elastomer. Thermogravimetric analysis displayed an increase in the thermal stability of C-g-XNBR. MTT [3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide] assay and hemolysis studies proved that functionalized rubber as biocompatible. Moreover, functionalized XNBR exhibited a potential bactericidal effect against Staphylococcus aureus and Escherichia coli strains. Fire and flame retardancy study revealed an increased LOI (limiting oxygen index) for C-g-XNBR.