This paper focuses on the preparation and characterization of Poly(methyl methacrylate)/multi-walled carbon nanotube composites through ex-situ and in-situ processes. The extent of dispersion and fracture morphology was studied by TEM, AFM, SEM and FESEM. The increase in conductivity at percolated loading of 2.91 wt% was more for in-situ prepared PMMA/MWNTs nanocomposite as compared to ex-situ prepared nanocomposites. The dielectric constant of pure PMMA was increased from 5 to 72 in the ex-situ prepared PMMA/MWNTs nanocomposites with 4.76 wt% of MWNTs loading. Moreover, for the ex-situ nanocomposites containing 2.91 wt% of MWNTs, the dielectric constant was 15, but in-situ prepared PMMA/MWNTs nanocomposite showed two times increase at same loading of 2.91 wt% of MWNTs. Dielectric constant of PMMA/MWNTs nanocomposites loaded with (< 4.76 wt%) of MWNTs remained almost constant with frequency. Dynamic mechanical analysis showed remarkable increase in storage modulus, especially at higher temperatures with 4.76 wt% loading of carbon nanotubes as compared to pure PMMA. The presence of additional peak before T(g) indicated that CNTs could be used to wake up secondary relaxations, which were inactive in pure PMMA. Thermogravimetric analysis (TGA) showed that thermal stability of PMMA/MWNTs nanocomposites increased by 45 degrees C (in N2) and 27 degrees C (in air) at 4.76 wt% of MWNTs as compared to the pure PMMA.

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The mechanical, morphological and thermal properties of the binary and ternary blends of a fluorocarbon elastomer (FKM), an acrylic elastomer (ACM) and a liquid crystalline polymer (LCP) were investigated. The ternary blends were prepared by varying the amount of the LCP but fixing the ratio of the FKM and ACM. Addition of a third component, a polyacrylic rubber which interacted with the LCP, facilitated the structural development of the LCP phase by acting at the interface. The mechanical properties of the ternary blends were substantially improved because of both the fibril generation and adhesion of rubber particles on the LCP fibrils, which were attributed to the ACM interaction. Morphological investigations suggest that the fine fibrillation of the LCP domains is more apparent in the ternary blends than in the binary blends of FKM and LCP prepared under the same processing conditions. Thermogravimetric analysis (TGA) revealed an improved thermal stability of the FKM in the presence of the LCP for the binary blends, but a lower thermal stability for the ternary blends. Copyright © 2005 Society of Chemical Industry

This paper demonstrates the effectiveness of polyphosphazene elastomer as compatibilizer on the properties of Nylon 6,6/thermotropic liquid crystalline polymer blends. In situ fibrillation of thermotropic liquid crystalline polymers develops in the shear flow field in presence of thermoplastic matrix. The addition of polyphosphazene into the blend facilitates the structural development of thermotropic liquid crystalline polymer. Polyphosphazene elastomer reacts at the interface resulting in reduction of viscosity, which in turn reduces the droplet size enabling fine dispersion of the Liquid Crystalline Polymer (LCP) fibrils. Thermal stability does not change appreciably, but in case of ternary blend T g value slightly shifted towards the higher side compared to pure matrix indicating the increase in miscibility in the ternary blends. Morphological study demonstrates the significance of compatibilization in immiscible polymer blends.