A facile strategy to reinforce styrene butadiene rubber with modulus domain

The reinforcement of sulfur-crosslinked styrene butadiene rubber is of great importance. In this paper, styrene butadiene rubber with high modulus domains was prepared by a simple rubber processing process through the in situ reaction of epoxy resin and 4,4'-diaminodiphenylmethane (DDM), and satisfactory enhancement of mechanical properties was obtained. With the increase in epoxy resin from 5 to 15 phr, atomic force microscopy confirmed that the size of the dispersed phase increased from 400 nm ~ 1 μm to 750 nm ~ 2 μm, as well as the modulus increased from 90.1 to 279.3 MPa. Besides, the modulus of the SBR matrix was maintained at 11–15 MPa. It is proved that the dispersed phase forms a high modulus, low adhesion "domain" in the matrix. The 300% modulus, strength, and fracture toughness of the specimens significantly increased to 3.58, 6.34 MPa, and 17.41 MJ/m³, which are 2.50, 3.30, and 3.03 times higher than those of SBR, respectively, when the epoxy resin load was 15 phr. This strategy provides a cost-effective approach to obtain high strength rubber materials at high efficiency.