Surface modification of commercial carbon black by silane coupling agents for improving dispersibility in rubber compounds

Abstract The dispersion of a filler in a rubber matrix is a crucial parameter affecting the mechanical and dynamical properties of a rubber compound. It is the current issue of the rubber compounding industry because, most fillers are categorized as a mineral, while the rubber is an organic material. The surface modification of the filler has been accepted as an effective technique for the improvement of the abovementioned parameter. First, the surface premodification of commercial carbon black with a grade of N660 (CB) was implemented by four different oxidation methods. After that, among of used methods, the oxidation method using citric acid was selected to produce modified carbon black (CB‐Oxi) for further treatment. Subsequently, the coupling agent, Bis[3‐(triethoxysilyl)propyl] tetrasulfide (TESPT) was functionalized on the surface of CB‐Oxi to produce modified‐CB‐Oxi. Also, for comparison purposes, the TESPT functionalization was accomplished on untreated CB to form modified‐CB. The FTIR spectra of CB‐Oxi showed using the premodification method introduced the hydroxyl and carboxyl groups on the surface of CB. The correspondent spectra for modified‐CB‐Oxi confirmed the existence of silane groups on the surface of the carbon black. However, the mentioned silane groups were not observed on the surface of modified‐CB. The findings were strengthened by several characteristic techniques including, FESEM, XRD, EDS, CHNS elemental analysis, and RAMAN spectra. The FESEM graphs and elemental mapping showed homogeneous dispersion and uniform distribution of sulfur and silicon elements on the modified‐CB‐Oxi surface. According to RAMAN spectra, the disturbance in the structure of carbon black graphite was reduced after surface modification. modified‐CB‐Oxi is proposed as a potential substitute filler for current commercial carbon black in rubber compounding.