Effect of in situ bonding system and surface modification of montmorillonite on the properties of butyl rubber/montmorillonite composites

Isobutylene–isoprene rubber (IIR)/nanoclay composites were prepared by solution intercalation method. Cloisite Na⁺ montmorillonite and organo‐modified montmorillonite (OMMT) nanoclays, namely, cloisite 10 A, cloisite 15 A, and cloisite 20 A were used in this study. The effect of in situ bonding system HRH (hexametylene tetramine: resorcinol: hydrated silica) on the dispersion of used nanoclays in the rubber matrix were examined by X‐ray diffraction and scanning electron microscope (SEM). Both techniques showed complete exfoliation of the clays silicate layers in IIR/OMMT/HRH nanocomposites (NCs). Rheometeric and mechanical properties (tensile strength, elongation at break%, and E‐modulus) of the NCs were studied. The addition of HRH system to IIR/OMMT NCs improves their mechanical properties. Moreover, IIR/clays/HRH NCs showed a decrease in the scorch time (t_S2) and the cure time (t_C90), which is an industrial privilege for saving time and energy. Swelling measurements were used to determine the filler–rubber interaction (Q_f/Q_g), the molar mass between cross‐links (Mc) and the cross‐linking density (ν) for each composite. The presence of HRH system enhances the rubber–filler interaction; in addition to an increase in the cross‐link density values. POLYM. COMPOS., 34:1559–1565, 2013. © 2013 Society of Plastics Engineers