materialsParticle sizes of nanofillers were determined using a light-scattering instrument (Zeta Sizer Nano-ZS90) for stable mixedsuspensions of silica and MoS2, which were diluted to a con-centration of 0.5 mg/mL, followed by sonication for 1 h at roomtemperature.UV–vis spectra of the suspensions of MoS2and its mixtures withsilica were collected on a Scinco S-3150 spectrometer. Raman spec-tra of MoS2and its model mixtures with silica were taken using aLabRAM Aramis of HO RIBA Jobin Yvon, equipped with a He–Ne ionlaser (532.0 nm) as the excitation source.The optimum cure time (tc90) of the NR compounds were deter-mined at 143◦C using a UR-2030SD vulcameter (U-CAN DynatexInc., Taiwan). The tensile properties of crosslinked composite mate-rials were determined using a Gotech testing machine, accordingto ISO 37-2005. Hardness was tested using a hardness meter,following ISO standard 48:1994. The crosslinking densities ofthe vulcanizates were determined using the equilibrium swellingmethod and calculated using the Flory–Rehner equation [27,28].The dynamic mechanical spectra of the uncured and cured com-pounds were obtained using a Netzsch 242C instrument. Thespecimens were examined from −100 to 80◦C in tensile mode, witha strain of 0.5%. The frequency and heating rate were set as 10 Hzand 3◦C/min, respectively. Strain sweeping of the composites wasconducted using an RPA2000 rubber process analyzer (RPA; AlphaTechnology Inc., USA). The frequency and temperature were fixedat 1 Hz and 60◦C, respectively. The heat build-up and dynamic com-pression set of the vulcanizates were determined using a Goodrichflexometer (RH-2000N, Gotech Testing Machines Inc., Taiwan). Thedynamic compression test was the modified version of ISO4666/3-1982. The load was 0.5 MPa as the samples were relatively soft.The dispersion of silica and MoS2in the rubber matrix were exam-ined using transmission electron microscopy (TEM; JEOL2100) atan accelerating voltage of 30 kV.