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The paper demonstrates the efficacy of natural rubber-g-poly (styrene-co-acrylonitrile) (NR-g-SAN) copolymers as impact modifier for SAN. The impact behaviour of SAN /NR-g-SAN blends were studied as a function of cross-link density of NR, percent grafting, rubber content in the blend and the AN content in the grafted chain. The cross-link density of NR had no significant effect on impact strength of the blends whereas increase in percent grafting (PG) of the rubber significantly improved the impact strength. Thus the impact strength increased four times when the PG of the rubber was increased from 34.2 to 65%. Further increase in PG decreased the impact strength. Similar trend was observed on increase in the rubber content, the maximum impact strength was observed at 20% rubber. The impact strength also depended on the acrylonitrile content of the grafted chain. Tensile and flexural strength and modulus of these blends were not influenced by PG and AN content in the grafted chain whereas these properties decreased with the increase in the rubber content. Scanning electron microscopic studies of the impact fractured surfaces showed cavitation of rubber particles and craze induced matrix deformation. Dynamic mechanical studies confirmed the two-phase structure of these blends. [ABSTRACT FROM AUTHOR]

The sulphonation of commercially available PEEK in powder form (Gatone™, Gharda Chemicals Limited, India) was carried out using conc. H2SO4 under different reaction conditions. The duration of reaction was varied from 3-5 h, polymer concentration 4-10% (w/v) and temperature 35-50°C. Structural characterisation of sulphonated polymers was done by elemental analysis, FT-IR and1H-NMR spectroscopy. The degree of sulphonation as calculated from1H-NMR and elemental analysis (S-content) was found to be in the range of ~ 50-80%. Multistep mass loss was observed in thermogravimetric traces (recorded in N2 atmosphere). The first step (50-225 ± 25°C) was due to loss of moisture (1-10%) and second step (250-425 ± 25°C) has been attributed to volatilization of SO3 from the sulphonic group. The backbone degradation takes place above 450°C. The mechanical properties and proton conductivities of various sulphonated samples was also evaluated. [ABSTRACT FROM AUTHOR]

Structurally different poly(arylene ether sulphone) (PES) copolymers were synthesized by reacting stoichiometric amount of dichlorodiphenyl sulphone (DCDPS) with bisphenols. The molar ratio of bisphenol-A and phenolphthalein (ESP)/hydroquinone (ESH)/resorcinol (ESR) was varied to prepare nine copolymer samples. Structural characterization was done by FT-IR and 1H-NMR studies. The initial decomposition temperature as well as temperature of maximum rate of mass loss in ESR and ESH copolymers were similar and a marginal decrease in these decomposition temperatures were observed by increasing the isopropylidine units in the backbone. High char residue at 800°C was observed in polymers having high content of phthalein units. [ABSTRACT FROM AUTHOR]

Thermal behaviour of blends based on N,N'-bis(4-itaconimidophenyl) ether (IE) and 4,4'-bis(4-allyl-2-methoxyphenoxy) benzophenone (R1) or 4,4'-bis(2-allylphenoxy) benzophenone (R2) are described in this paper. The reactive diluent content was varied from 5-50% (mass/mass) in these blends. A decrease in the melting point and exothermic peak temperature was observed with increasing mass percent of reactive diluent. Thermal stability of blends was affected at high mass percentage of reactive diluents. [ABSTRACT FROM AUTHOR]

Optimum temperature and pH for the isolation of soy protein isolate (SPI) from soy protein concentrate (SPC) were established. Enzymatic hydrolysis of SPI with enzymes of different specificities such as trypsin, chymotrypsin, papain and urease was carried out and the products of hydrolysis were characterized by molecular mass determination [sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)] and thermal techniques [differential scanning calorimetry (DSC) and thermogravimetric analysis (TG)]. Enzymatic hydrolysis resulted in a significant reduction in molecular masses. However the thermal stability of hydrolysed SPI was similar to native SPI indicating that it is independent of molecular mass. DSC studies indicated an increase in temperatures of endothermic transition associated with SPI denaturation and loss of absorbed moisture in samples of lower molecular masses. [ABSTRACT FROM AUTHOR]