FUNCTIONALIZATION OF ACRYLONITRILE BUTADIENE RUBBER WITH META-PENTADECENYL PHENOL, A MULTIFUNCTIONAL ADDITIVE AND A RENEWABLE RESOURCE

Abstract

ABSTRACT The present invention deals with the functionalization of acrylonitrile butadiene rubber (NBR) by chemically grafting meta-pentadecenyl phenol (cardanol) onto the backbone chain. This imparts inherent multifunctional characteristics to the nitrile rubber. The grafting of cardanol onto NBR was accomplished successfully in emulsion stage using benzoyl peroxide (BPO) as a free radical initiator. The grafted NBR is characterized by ultraviolet–visible, Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and gel permeation chromatography. Cardanol grafted NBR (CGNBR) shows an increase in molecular weight (6.6%) with an increase in polydispersity index value. The optimal conditions of grafting are found out to be, “1 phr BPO, 15 phr cardanol, at a reaction temperature of 60 °C and a reaction time 10 h” by using the “Taguchi L9 orthogonal array” method. The grafting efficiency and percentage grafting are calculated to be 79.2% and 7.1%, respectively, at the optimum combination of parameters. The CGNBR shows an increase in molecular weight and reduction in Wallace plasticity number as well as Mooney viscosity, but exhibits a higher plasticity retention index value, as compared to ungrafted NBR. The rheological characteristics of CGNBR exhibit a better flow behavior index than NBR. Differential scanning calorimetry, dynamic mechanical analysis results exhibit a decrease in Tg value for grafted NBR. Thermogravimetric analysis results displayed an increase in thermal stability of the functionalized NBR than that of raw NBR.