چكيده به لاتين
Silicone rubber (SR) and ethylene propylene diene monomer (EPDM) blends are immiscible due to their different polarity. In this study, SR/EPDM/nanoclay nanocomposites containing 10, 20 and 30 phr EPDM and 3,6 and 9 phr nanoclay were prepared by two-roll mill and then cured with 1 phr DCP. Compatibilizing effect of the nanoclay and EPDM-g-MA addition to the blend were studied by viscoelastic and morphology characterization. Curing behavior of the samples showed that the vulcanization rate and crosslink density of the blends increased by increasing SR content. Morphological studies were carried out via XRD, SEM and EDX and the results revealed that the nanoclay was inclined to reside in the EPDM dispersed phase and form intercalated and exfoliated structure and consequently, increase the hardness and elasticity of this phase in the nanocomposites, while agglomerated in SR. Tensile test results of the samples indicated a good fitting of experimental results and Maxwell and Kelvin-Voigt models in the initial time of deformation for all the blends. Close fitting of the tensile properties based on the experiment and Maxwell model is related to the good dispersion of the nanoclay in the blends. Using rheological models including Cole-Cole, Han plot and van-Gurp, showed the good dispersion and homogeneous structure of EPDM-based nanocomposites, but according rheological studies, the nanoclay is not able to disperse effectively in SR phase and the best dispersion was obtained in the presence of the compatibilizer. According to the morphology of the nanocomposites and also Palierne model, which used both rheological and morphological data, the addition of nanoclay to the blend decrease the interfacial tension from 0.34 mN/m to 0.06 mN/m and the minimum of the interfacial tension was calculated 0.04 mN/m for the nanocomposite containing both the nanoclay and compatibilizer.
Keywords: SR, EPDM, Nanoclay, Rheological properties, Morphology, Maxwell model
