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In the present work, the effect of distribution of Carbon Black (CB) and rubber viscosity over the conductivity of rubber blend composites was studied. Preferential location of CB predicted by surface tension measurements and calculation of interfacial energy (wetting coefficient) was corroborated by dynamic analysis (DMA) as well as bound rubber experiments. In this respect, the employment of the DMA technique to infer preferential distribution of CB, through the following of changes in the loss tangent (Tan δ), were proposed and successfully assessed in this study. A double percolation effect was evidenced by the appearance of a maximum in conductivity at relatively low EPDM content and CB concentration; however, when blend viscosity increases due to the addition of EPDM (the most viscous rubber), the double percolation effect is suppressed and the conductivity falls due to the prevailing dispersion effect of CB particles. According to these results, the blend viscosity was found to play a major role in the final conductivity of the studied composites.

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Silver/carbon nanoparticles (9 nm) were incorporated, as reinforcements, into a matrix of poly(methyl methacrylate) via in situ miniemulsion polymerization. It was found by differential scanning calorimetry that the glass‐transition temperature of the poly(methyl methacrylate) showed an improvement of 14 °C with only 0.5 wt % nanoparticles in comparison with a pure poly(methyl methacrylate) control, which was also obtained by miniemulsion polymerization under the same conditions. This increase was related to a polymer chain mobility restriction due to a combination of bound plastic and joint plastic shell effects at the interphase and the surrounding regions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 511–518, 2007.

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Expanded graphite (EG) was added to polylactic acid (PLA) and then fully mixed in a novel elongational mixing device (RMX) to obtain PLA/EG nanocomposites. The operation of the new mixer device is based on the induced multiple passages of material (by means of reciprocating pistons) at different flow speeds through a short capillary die, thus creating convergent/divergent elongational flows. Highly homogeneous materials were obtained at all mixing conditions and particle size ranged from hundred to several hundreds of nanometers. Also, X-ray diffractograms showed different intensity of the characteristic peak of EG (3% wt/ wt EG was kept constant), suggesting partial exfoliation. Furthermore, the molecular weight of processed neat PLA samples was assessed in order to correlate the PLA degradation to morphology and reinforcement mechanisms in the nanocomposites, as a function of the RMX parameters. As well, final flow properties of neat PLA and EG compounds were obtained by dynamic rheology. Thermomechanical degradation of PLA was found to play a major role in the rheology of mixing. On the other hand, PLA nanocomposites presented a storage modulus between 20 and 40% higher than neat PLA. Finally, morphology comparison between the RMX and an internal mixer, at the same mixing energy input, demonstrated a higher dispersive mixing efficiency for the RMX. POLYM. ENG. SCI.,

Ionic liquid modified multiwalled carbon nanotube (MWCNT) based styrene–butadiene rubber (SBR) nanocomposites were prepared with the two-roll mill mixing method, and the rheological measurements were used to study the dispersion of MWCNTs on a microscopic scale and its compatibility with the SBR matrix. Viscous liquid-like rheological behavior at low MWCNT loadings and pseudo-solid-like rheological response at high MWCNT loadings were observed, showing the gradual transformation from individual structures of MWCNTs to polymer bridged MWCNT networks. A decrease in the mobility of SBR macromolecular chains by the geometric confinement of three-dimensional networks of MWCNTs further confirms the interdeveloped pseudo-solid behavior of filled composites. Dynamic viscoelasticity data have been compared with the theoretical Carreau–Yasuda equation. Transmission electron microscopy of the samples reveals that MWCNTs are randomly dispersed in the rubber matrix. Finally the nature of the filler association and its role in the nonlinear viscoelastic properties at large strain amplitudes were investigated.