"Effect of graphene oxide on mechanical properties of carboxylated nitrile butadiene rubber/styrene-butadiene rubber blend: Experiment and molecular simulation"

"Rubber blending was an effective way to develop new rubber materials that could achieve better properties than those of single components. The properties of blend could be precisely controlled by using different types of rubbers. However, most blends tended to phase separation, which led to deterioration in mechanical properties. Graphene oxide (GO) could be used as a novel compatibilizer to improve compatibility between rubbers［1-2］. 　In this work, GO was added to the blends of carboxylated nitrile butadiene rubber (XNBR) and styrene-butadiene rub-ber (SBR). The XNBR/SBR blend with different blend ratios were designed, and the effect of GO on the mechanical properties of GO/XNBR/SBR blended systems was analyzed in detail by a combination of molecular dynamics (MD) simulations and experiments. The formulation of rubber compounds was XNBR/SBR 100 phr (in mass, the same below), GO 0 or 3.0 phr, antideteriorant 4010 NA 2.0 phr, zinc oxide 2.0 phr, stearic acid 2.4 phr, accelerator CZ 2.2 phr and sulfur 1.5 phr. The mass ratios of XNBR/SBR were 25/75, 50/50 and 75/25, respectively. 　Through MD simulation, the number of hydrogen bonds of GO/XNBR/SBR blends was shown in Fig 1. The results showed that plenty of hydrogen bonds existed in GO/XNBR/SBR blends, and both the total number of hydrogen bonds and the number of interfacial hydrogen bonds increased with increasing XNBR content, indicating that the interfacial interaction of GO/XNBR/SBR blends was enhanced. After adding 75 phr of XNBR, the number of hydrogen bonds was the highest［3］. ■ Fig 1 Number of hydrogen bonds of GO/XNBR/SBR blends 　Tensile strength of XNBR/SBR and GO/XNBR/SBR blends were shown in Fig 2. It could be seen that the tensile strength of XNBR/SBR blend increased gradually with the growing of XNBR content, mainly due to the higher strength of XNBR compared to SBR. The higher the proportion of XNBR rubber was, the better the mechanical properties of the blends were. Compared to that of XNBR/SBR blend, the tensile strength of GO/XNBR/SBR blend increased by 86% when adding XNBR of 75 phr. The strong interfacial interactions, such as hydrogen bonds, may lead to a remarkable increase in the mechanical properties of the blend. ■ Fig 2 Tensile strength of XNBR/SBR and GO/XNBR/SBR blends"