Acrylic elastomer/filler nanocomposite : effect of silica nanofiller on thermal, mechanical and interfacial adhesion

Silica fillers are often added to elastomer to improve performance in commercial applications. Mixing with different nanofillers in the presence of different curative systems is expected to improve interchain crosslinking between the filler and the elastomer. ZnO is a common curative for many functional elastomers, the authors have tried the possibility of using nanosilica filler and surface modified (Zn ion coated) nanosilica filler in the presence of different curative systems. The surface modified silica offers good results in the development of advanced materials for enhanced mechanical properties and thermal stability. The use of Zn ion coated nanosilica filler led to an increase in the adhesion at interfaces between the modified filler and elastomer matrix. The modified nanosilica filler (Zn ion coated), showed high tensile strength, tensile modulus, hardness, thermal stability and dynamic modulus in the presence of ammonium benzoate curative system as compared to hexamethylenetetramine (HMT) and 4,4′ methylene-bis-(cyclohexalaminecarbamate) (diak IV). The modified silica filler containing composites clearly revealed the predominant interfacial adhesion rather than chemical crosslinking in the presence of ammonium benzoate curative system

Mechanical and morphological study of polyphenylene sulfide/liquid crystalline polymer blends compatibilized with a maleic anhydride grafted copolymer

Blends of thermotropic liquid crystalline polymer (LCPA‐950), based on a copolyester of hydroxynapthoic acid and hydroxybenzoic acid with an engineering thermoplastic, poly(phenylene sulfide) (PPS), were prepared using a corotating twin‐screw extruder. Addition of a third component, a functionalized polypropylene (maleic anhydride grafted polypropylene, MA‐PP), that interact with the thermotropic liquid crystalline polymer (TLCP) facilitates the structural development of the TLCP phase by acting as a compatibilizer at the interface. Differential scanning calorimetry and dynamic mechanical thermal analysis results, however, show that there is an interaction between the polymers in the presence of compatibilizer. This means that MA‐PP can be used as a compatibilizer for the PPS/LCP in situ composite system. The viscosity of the compatibilized in situ composite was decreased by the compatibilizer, and this is mainly due to the fibrous structure of the LCP at the high shear rate. The mechanical properties of the ternary blends were increased when a proper amount of MA‐PP was added. This is attributed to fine fibril generation induced by the addition of MA‐PP. Morphological observations determined the significance of the third component in immiscible polymer blends, and an optimum amount of MA‐PP exists for the best mechanical performance

Flexible composite of PEEK and liquid crystalline polymer in presence of polyphosphazene

Binary blends of a reactive ketone based polymer with liquid crystalline polymer (LCPA‐950) were studied. The main properties required are flexibility and thermal resistance of material in presence of polyphosphazene, which acts as a compatibilizer. It has been observed that with the addition of LCP the composites showed reduced viscosity during blending and changes in the crystallization of the LCP phase. FTIR study showed that there was a partial interaction between the PEEK and LCP in presence of polyphosphazene. Polyphosphazene is miscible with both PEEK and LCP, which was evident from DMA results. The thermal stability of the composites has been studied by DTA/TGA. The thermal analysis of the blends showed that the degradation process is accelerated by blending, but with the addition of polyphosphazene the onset temperature of first degradation slightly shifted towards higher side than the PEEK/LCP blend. Measurement of the tensile properties showed an increase in the elongation as well as enhanced modulus and strength. From SEM micrographs of tensile fractured surfaces, it was revealed that there is good adhesion between the matrix and dispersed phase upon addition of polyphosphazene to ketone based polymer (PEEK) with LCP