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Dynamically vulcanized blends of 85/15 polystyrene (PS)/natural rubber (NR) were prepared by melt mixing in an internal mixer at I70°C using dicumyl peroxide (DCP). The concentration of DCP was varied from 0 to 4.2 milliequivalents (meq). It was found that dynamic vulcanization of the blend with 2.8 meq DCP significantly enhanced the Young's modulus, flexural modulus, and impact strength, with a marginal improvement in tensile and flexural strengths. The SEM studies revealed that the morphology of the blends changed drastically on dynamic vulcanization. The dynamic mechanical studies showed that the storage modulus and the loss modulus were better for dynamically vulcanized blends with 2.8 meq DCP in comparison to other blends. The rheology studies reveal that the damping of the blend was reduced at the melt processing conditions at a DCP content of 2.8 meq and the blend was pseudoplastic in nature. The thermal stability of the dynamically vulcanized blend improved on dynamic vulcanization. Thus, dynamic vulcanization can be employed as a means of technological compatibili-zation technique for 85/15 PS/NR blend for overall improvement in properties.

The incorporation of hybrid fillers such as conducting polymer/graphene in polymer matrices affords promising materials with high dielectric constant suitable for electronic devices. Initially PANI/GO hybrid was prepared via in situ oxidative polymerization of aniline on GO. The hybrid was dispersed in dichlorobenzene and then incorporated in epoxy resin. The evaporation of the solvent resulted in in situ reduction of GO and the mixture was cured. The effect of PANI/rGO hybrid filler on the morphology, electrical conductivity, dielectric, dynamic mechanical, and thermal properties of epoxy nanocomposites was evaluated. The electrical conductivity of the nanocomposite containing 9 wt% of the filler (EPG9) enhanced by five orders of magnitude compared to neat epoxy, that is, from 5.6 × 10−13 to 1.27 × 10−8 S/cm. A high dielectric constant (ε′) of 208 was achieved for EPG9. The dielectric loss tangent (tan δ) was low for the hybrid nanocomposites at 103 Hz. DMA studies revealed that the storage modulus (E′) increased significantly with the incorporation of hybrid fillers. The tensile strength and Young's modulus of the EPG3 nanocomposites improved by 14.3% and 33.1%, respectively compared to neat epoxy. SEM and TEM studies revealed the uniform dispersion of the hybrid filler at 3 wt% in the epoxy matrix. The addition of PANI/rGO filler also improved the thermal stability of the epoxy nanocomposites.

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In this work, polyaniline nanorod adsorbed on reduced graphene oxide (P@G) hybrid filler was prepared via in situ polymerization of aniline monomer in the presence of reduced graphene oxide as template. Fourier transform infrared, X‐ray diffraction, field emission scanning electron microscopy, and high‐resolution transmission electron microscopy images revealed the formation of P@G hybrid. The P@G hybrid was dispersed in dichlorobenzene and then introduced into epoxy resin at different loadings. The epoxy nanocomposites containing 9 wt% P@G hybrids (E/P@G9) exhibited a maximum DC conductivity of 1.34 × 10−5 S/cm that is eight orders higher compared to pure epoxy. At 103 Hz, a dielectric constant (ε′) of 163 was attained for E/P@G9, nearly 34 times higher than pure epoxy. A percolation threshold of 4 vol% was observed for ε′. Dynamic mechanical studies showed that significant enhancement in storage modulus values were exhibited for 3 and 5 wt% of hybrids. The glass transition temperature showed a maximum shift of 10°C to higher temperatures at 3 wt% loading of P@G hybrids (E/P@G3). The tensile strength, Young's modulus, and impact strength of the E/P@G3 nanocomposites enhanced by 19.7, 72, and 12%, respectively. The thermal stability of the epoxy nanocomposites also enhanced with the addition of P@G hybrid.

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Epoxy/conducting filler nanocomposites with high dielectric performance have emanated as a promising material in electronic and electrical industry. In this work, a facile and low-cost method, that is, thermal reduction at 400°C was adopted for the preparation of reduced graphene oxide (rGO) from graphene oxide (GO). The rGO was characterized by X-ray diffraction analysis, Fourier transform infrared spectroscopy, Raman spectroscopy, Field emission scanning electron microscopy and Transmission electron microscopy. Epoxy nanocomposite presented a dielectric permittivity of 35 at 1.8 vol.% loading of rGO (Ep/G-1.8) at 103 Hz, which was 5 times higher than neat epoxy and with a low dielectric loss. With the addition of 0.3 vol.% of rGO (Ep/G-0.3), the mechanical properties such as tensile strength, Young’s modulus and impact strength were enhanced by 34%, 56% and 54%, respectively. Dynamic mechanical analysis (DMA) revealed that in comparison to epoxy, there was a tremendous enhancement of storage modulus (55%) and the glass transition temperature (Tg) exhibited a remarkable shift of 39°C towards higher temperature for Ep/G-0.3. Cross-link density and coefficient of effectiveness (C-factor) estimated from the storage modulus improved significantlyfor Ep/G-0.3. Theoretical modelling was done on the viscoelastic properties of the composites. SEM studies indicated the uniform dispersion of rGO throughout in the epoxy matrix. Thermogravimetric analysis revealed that inclusion of rGO improved the thermal stability of epoxy nanocomposites.