Highly improved compatibility and mechanical properties of carboxylated nitrile rubber/styrene butadiene rubber by incorporating modified Kevlar nanofibers

Abstract

In this work, water-dispersible modified Kevlar nanofibers (m-KNFs) were successfully prepared through grafting Kevlar nanofibers (KNFs) with epichlorohydrin (ECH). Then m-KNFs were incorporated into the compound of carboxylated acrylonitrile butadiene rubber (XNBR)/styrene butadiene rubber (SBR) thanked to a facile latex co-coagulation method. The interactions among m-KNFs, XNBR and SBR as well as the compatibility and mechanical properties of XNBR/SBR/m-KNFs blends were investigated. The dynamic mechanical analysis and differential scanning calorimetry analysis showed that the glass transition temperature (Tg) shifted mutually between XNBR and SBR confirming enhanced compatibility between XNBR and SBR. Moreover, Fourier transform infrared spectra demonstrated that m-KNFs might form covalent bonding with XNBR, while Raman spectra indicated that m-KNFs were ability to interact with the aromatic structure of SBR via π-π conjugation, which was responsible for the improved mechanical behaviors and compatibility of blends. With the addition of only 0.3 phr (parts per hundred rubber) m-KNFs, the tensile strength and tear strength of XNBR/SBR/m-KNFs blend were improved by 87.2% and 194.7%, respectively, compared with those of neat XNBR/SBR blend.