Evidence of silane coupling in torrefied agro‐industrial residue‐filled poly(styrene‐co‐butadiene) rubber compounds

Abstract

AbstractHeat‐treated rice hull residues were evaluated as fillers in poly(styrene‐co‐butadiene) rubber (SBR) compounds. The currently used precipitated silica filler was replaced with torrefied filler in concentrations varying from 0 to 100 wt%, and the influence of coupler concentration varying from 0% to 3% (7 parts per hundred rubber or phr total) on the filler‐rubber interaction was investigated. The curing process, dynamic properties, and mechanical properties of the SBR compounds were examined for silica‐filled and torrefied rice hull (TRH)‐filled materials with and without the coupling agent. Partial or full replacement of silica with TRH resulted in a systematic decrease in compound viscosity. Longer scorch (ts2) and shorter cure times (t90) were also observed. Incorporation of TRH increased compound modulus (stress at 100% elongation or M100 and Young's modulus) but decreased tensile strength and elongation. The presence of coupler brought about improved dynamic and mechanical properties and 30% lower tan δ at 3 phr level. Results provided the first evidence that, when used as a filler in an SBR compound, torrefied rice hulls can be chemically coupled to the SBR polymer, resulting in increased polymer‐filler interactions analogous to the conventional silica‐coupler‐polymer system.