A facile strategy to reinforce styrene-butadiene rubber with modulus domain

Abstract The incorporation of fillers into the elastomer matrix is universally acknowledged as an effective strategy for fabricating superior-performance rubber materials, which depends on filler dispersion and interfacial interaction. In this work, styrene-butadiene rubber (SBR) with high modulus domains were prepared via the in situ reaction of epoxy resin (E51) and 4,4'-diaminodiphenylmethane (DDM) and a satisfactory mechanical properties reinforcement effect. The crosslinked network was confirmed by high-temperature infrared spectroscopy, vulcanization properties and activation energy. Scanning electron microscopy (SEM) demonstrated that the dispersed phase formed by the in situ reaction of E51 with DDM was uniformly dispersed in the matrix. Furthermore, with the loading of E51 from 5 phr to 15 phr, Atomic force microscopy (AFM) further confirmed that the size of the dispersed phase increased from 400 nm ~ 1 µm to 750 nm ~ 2 µm, and that the dispersed phase formed a high-modulus “domain” with low adhesion in the matrix, and the modulus increased from 90.1 MPa to 279.3 MPa, whereas the modulus of the SBR matrix was maintained at 11 ~ 15 MPa, and there was an interfacial layer with a thickness of 304 nm ~ 470 nm between the domain and the SBR matrix. At E51 loading of 15 phr, the 300% modulus, strength and fracture toughness of the specimen was significantly increased to 3.58 MPa, 6.34 MPa and 17.41 MJ/m³, respectively, which were 2.50, 3.30 and 3.03 times higher than those of SBR. The approach suggested in this research introduces an innovative method for reinforcing unfilled rubbers.