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Highlights: [•] Blend membranes are produced from carboxy methyl cellulose and polyvinyl alcohol. [•] Mixed matrix blend membranes are also produced by incorporating bentonite fillers. [•] These membranes are used for pervaporative separation of acetic acid and water mixtures. [•] Sorption thermodynamics and diffusion characteristics of membranes are discussed. [Copyright &y& Elsevier]

Cu-Cr-Zr-Ti alloy (Cr: 0.5-0.7, Zr: 0.02-0.05, Ti: 0.02-0.05, Fe: 0.015 and balance Cu) is a candidate material for the inner wall of the double-walled and regeneratively cooled combustion chamber of cryogenic rocket engine. Low cycle fatigue (LCF) behaviour of the alloy was investigated in the solution annealed (1253K for 10min. followed by air cooling) condition. Fully reversed, strain controlled LCF tests were performed in air at total strain amplitudes varying from±0.25% to±1.0%. Different temperatures over 300 to 900K range were employed for the tests. Additionally, a few tests with fully compressive strain cycling were performed, employing strain amplitudes ranging from -0.5 to -2.0% at a constant temperature of 900K. All tests were carried out using a fixed strain rate of 3×10−3 s−1. The stress response behaviour under fully reversed and mean compressive cycling conditions was observed to be similar for a given total strain range and was seen to be strongly dependent on the temperature of testing. Mean compressive cycling yielded marginally better lives compared to fully reversed cycling. A pronounced initial cyclic hardening followed by a regime of saturation characterised the behaviour at room temperature. However, in the temperature range of 673-773K, a secondary hardening stage following a saturated stress response was observed. The extent of secondary hardening was seen to be maximum at 673K. The magnitude of the initial hardening was seen to decrease with increasing temperature. A continuous softening upto failure characterised the stress response behaviour at 900K. The results are explained in the light of detailed optical and SEM investigations. [ABSTRACT FROM AUTHOR]

Low cycle fatigue tests were carried out on 316 L(N) stainless steel at room temperature employing strain amplitudes ranging from ± 0.3 to ±1.0% and a strain rate of 3×10−3s−1. The material showed initial hardening for a few cycles followed by prolonged softening, saturation and final failure. The fatigue life was found to decrease with increase in strain amplitude. The analysis of stable hysteresis loops showed non-Masing behaviour for this material. The elasto-plastic response of the material under cyclic loading was characterized taking into account isotropic and kinematic hardening occurring during cycling. The material parameters were obtained from the experimental hysteresis loops and cyclic stress response of the material. Finite element analysis of elasto-plastic deformation was carried out to obtain the stabilized hysteresis loop and cyclic stress response of the material. The predicted hysteresis loops showed good agreement with experimental results. The low cycle fatigue life prediction was carried out based on plastic strain energy dissipation with cycling. [ABSTRACT FROM AUTHOR]

Abstract: Nanocrystalline La0.65Sr0.35MnO3 powders were synthesized by modified solution combustion route. The X-ray diffraction patterns of powders calcined at different temperatures were analyzed by Rietveld programme. The synthesized bulk polycrystalline sample were in 100% perovskite phase and showed an increase in particle size from 22.9nm to 55.9nm with the increase in the calcinations temperature from 650°C to 850°C. The grain boundary of sintered pellet observed under electron microscope was devoid of any precipitation related to MnO2, SrO and the La–Mn–Sr–O phases. The core level photoelectron spectra of lanthanum, strontium, manganese and oxygen were studied in detail. The average chemical composition obtained from the XPS measurement was found to be La0.62Sr0.38Mn1.11O3.44. Curie temperature for the 50nm powder was around 365K and saturation magnetization at 100K was 60emu/g. [Copyright &y& Elsevier]

Abstract: Polyvinyl alcohol (PVOH) was chemically modified by crosslink copolymerization of acrylic acid (AA) and acrylamide (AM) in aqueous solution of PVOH and finally crosslinking the copolymer of AA and AM designated as PAAAM with N,N′-methylenebisacrylamide (NMBA) and PVOH with glutaraldehyde to produce a full interpenetrating network (FIPN) membrane. Accordingly, a membrane containing PVOH:PAAAM of 1:0.5 designated as FIPN500 was synthesized. Filled FIPN membranes were synthesized by in situ incorporation of highly hydrophilic aluminosilicate filler during copolymerization of the monomers in PVOH matrix to produce three filled membranes designated as FIPN502, FIPN505, and FIPN510 containing 2, 5 and 10mass%, respectively (of total polymer) of the filler. PVOH membrane cosslinked with 2mass% glutaraldehyde, PAAAM copolymer modified PVOH membrane i.e. FIPN500 and the three filled FIPN membranes were used for sorption and pervaporative dehydration of acetic acid. The filled IPN membranes were found to show higher flux and water selectivity than the unfilled membranes. Among the three filled membranes, FIPN510 was found to show the highest flux (6.612kgm2 h−1 μm) and water selectivity (325.53) at 0.953mass% water in feed. Interaction parameters, partial permeability, intrinsic membrane selectivity and concentration average diffusion coefficients for all the membranes were also evaluated. [Copyright &y& Elsevier]

Abstract: Poly vinyl alcohol (PVOH) membrane, was crosslinked with 2, 4 and 6 mass% of four different kinds of crosslinkers i.e. glutaraldehyde (GLU), oxalic acid (OA), dimethylol urea (DMU) and tetra ethyl ortho silicate (TEOS) to produce four different kinds of crosslinked PVOH membranes termed here as PVGLU, PVOA, PVDMU and PVTEOS membrane, respectively. These membranes were first used for pervaporative separation of azeotropic feed concentration of 87.7mass% of isopropyl alcohol (IPA) in water. Among all of these membranes PVOH membrane crosslinked with 2mass% (of PVOH) GLU i.e. PVGLU2 was found to show optimum flux and water selectivity (79.75g/m2 h and 45.23, respectively, at 40°C) for separation of this IPA–water azeotropic mixture. This PVGLU2 membrane was further filled with 2, 4, and 6mass% hydrophilic aluminosilicate filler to produce three different filled membranes i.e. F2PVGLU2, F4PVGLU2 and F6PVGLU2, respectively. These three filled membranes were used for separation of the same azeotropic IPA–water mixtures and F6PVGLU2 membrane was found to show optimum flux and selectivity (109.84g/m2 h and 72.71, respectively, at 40°C). This F6PVGLU2 membrane crosslinked with 2mass% glutaraldehyde and filled with 6mass% aluminosilicate filler showing optimum flux and selectivity for azeotropic IPA–water mixture was used for dehydration of IPA using IPA–water mixtures containing 75.87–99.36mass% IPA in water. All of the filled and unfilled membranes synthesized were also characterized by various conventional methods. [Copyright &y& Elsevier]

Abstract: Polyvinyl alcohol (PVOH) has been chemically modified by crosslink copolymerization of acrylic acid (AA) and acrylamide (AM) in aqueous solution of PVOH and finally crosslinking the copolymer with methylene bis acrylamide (MBA) and PVOH with glutaraldehyde to produce a full interpenetrating network (FIPN) membrane. Accordingly, three such fully crosslinked IPNs i.e. FIPN25, FIPN50 and FIPN75 have been synthesized with different mass ratio of PVOH:copolymer i.e. 1:0.25 (FIPN25), 1:0.50 (FIPN50) and 1:0.75 (FIPN75). These full IPN membranes were used for pervaporative dehydration of ethylene glycol (EG). All of these IPN membranes were characterized with various conventional methods like FTIR, mechanical properties, DTA and SEM. The performances of the membranes were evaluated in terms of sorption and pervaporative dehydration of EG. The IPN membranes were found to show preferential sorption and diffusion for water. Flux and water selectivity of these membranes were found to increase with increasing amount of copolymer in PVOH matrix. However, among the three membranes, FIPN75 were found to show the highest flux but lower selectivity for water while FIPN50 membrane showed optimum performance in terms of both flux and selectivity. Diffusion coefficient and plasticization interaction of water and EG through all the IPN membranes were determined using modified solution-diffusion model. [Copyright &y& Elsevier]

Abstract: The leak before break analysis of SS 316L(N) components of the prototype fast breeder reactor requires the elastic plastic fracture toughness parameter J for 0.2mm crack extension, J 0.2, especially for the welds, at the operating temperatures. The J–R curves for the welds produced using the consumable developed by Indira Gandhi Centre for Atomic Research, were determined in the as-welded condition as well as after thermal ageing (923K/4200h) conditions at 298K and 643K, using unloading compliance method for 298K and normalization method for 643K. The aged material exhibited pop-in crack extensions of magnitudes that, according to ASTM E1820 standard, could be ignored for multi-specimen data analysis for determining J 0.2. Therefore, for this condition, Jnom–Δa curves were established using the multiple specimen method and also single specimen normalization method; for the latter, a modification earlier developed by the authors for accounting for small pop-in crack extensions was used. The value of J 0.2 from both methods showed excellent reproducibility. Ageing is seen to reduce the toughness of this material considerably at both the testing temperatures. [Copyright &y& Elsevier]

Abstract: Tetrahydrofuran (THF) is an important volatile intermediate used in chemical industries and its separation from water is encountered in many application. Three different copolymers of acrylamide with increasing amount of 2-hydroxyethyl methacrylate (HEMA), i.e. PAMHEMA-1, -2 and -3 were synthesized and the crosslinked (gelled) copolymer membranes made from these sol copolymers were used for pervaporative dehydration of THF over the concentration range of 0–14wt% water in feed. These extremely hydrophilic gel copolymer membranes were found to be highly water selective in both sorption and diffusion through the membranes. Water flux was found to decrease with increase in degree of crosslinking from PAMHEMA-1 to 3 copolymer membranes. Among the three membranes PAMHEMA-1 membrane showed very high water selectivity (216) and reasonable flux (570gm/m2 h for 0.56wt% of water in feed at 50°C temperature). Water was also found to have a strong positive coupling effect on THF permeation. The membranes were found to show both sorption as well as diffusion selectivity for water. [Copyright &y& Elsevier]

Abstract: For a modified 9Cr-1Mo (P91) grade steel in the normalised and tempered (NT) condition and also after accelerated thermal ageing (2900h at 923K), the elastic–plastic fracture toughness parameter J for 0.2mm crack extension, J 0.2, has been determined at 653 and 803K, and compared with J 0.2 of the NT material at 300K. It is concluded that this thermal ageing does not significantly influence the toughness at 653 and 803K. Also testing temperature has a marginal effect on J 0.2 at 300 and 653K. At 803K, however, creep effects become so prominent that a basic premise for J-controlled crack growth, namely rate-independent plasticity, is seriously violated, giving rise to anomalously high values of J 0.2. [Copyright &y& Elsevier]

Abstract: Ba0.8Sr0.2TiO3 (BST) nanocrystalline thin films were deposited on n-type silicon substrates by radio-frequency magnetron sputtering technique at various deposition temperatures. X-ray diffraction confirmed that the deposited BST films were polycrystalline possibly due to recrystallization. Scanning electron microscopy study showed the evidence of resputtering in the films deposited at a high substrate temperature (600 °C). The electrical properties of the films were measured using an aluminum/BST/silicon metal-insulator-semiconductor capacitor configuration. Annealing seemed to enhance the dielectric constant of the as-deposited film. The film deposited at 300 °C showed the highest dielectric constant. Three-dimensional Monte-Carlo simulation confirmed that 300-350 °C would be the optimum deposition temperature range for the sputtering of BST films. [Copyright &y& Elsevier]

Quantum dot (QD) superluminescent diodes (SLDs) exhibiting 8 mW and 95 nm full-width at half-maximum centered at 1270 nm are demonstrated with a flat-topped spectral profile. This is achieved using 3 times 2 dots in compositionally modulated wells technique. Furthermore, techniques for realization of high-power SLDs are also demonstrated. A continuous-wave output power of 42 mW is achieved for narrowband devices centered at 1250 nm. [ABSTRACT FROM PUBLISHER]

Abstract: Natural rubber (NR) and poly(styrene-co-butadiene) rubber (SBR) were crosslinked chemically with sulfur and accelerator by efficient vulcanization. These were then compounded for physical crosslinking with high abrasion carbon black filler (grade N330) with three different doses, i.e. 5, 10 and 20phr to obtain three filled membranes from each of these two rubbers (NR-5, NR-10 and NR-20 and SBR-5, SBR-10 and SBR-20). These six filled rubber membranes were used for pervaporative separation of toluene–methanol mixtures up to 11wt% of toluene in feed. It has been found that with increase in filler doses from membrane-5 to membrane-20, the selectivities and mechanical properties of the membranes increase. All of these membranes showed reasonably good range of flux (20.814g/m2 h for SBR-5 to 10.26g/m2 h for NR-20) and separation factor (286.4 for NR-5 to 183.7 for SBR-5) for 0.55wt% of toluene in feed. Among these membranes NR-20 and SBR-20 with highest crosslink density showed maximum separation factor for toluene along with good flux. It has also been found that for comparable crosslink density NR membranes showed better separation factor than SBR membranes. [Copyright &y& Elsevier]

Abstract: Dynamic strain ageing (DSA) behavior of a 20% prior cold worked titanium modified austenitic stainless steel (Alloy D9) was investigated in the temperature range 300–1023K at a constant (nominal) strain rate of 1.33×10−3 s−1. Serrated plastic flow was observed in a narrow temperature region of 773–873K. Anomalies characteristic of DSA were observed in the variations of strength, ductility, and strain hardening parameters with temperature. Specifically, the difference between ultimate tensile stress and yield stress indicated that a single DSA mechanism is operative over the range of observations. Plastic strain energy density for uniform deformation showed a peak in the DSA temperature range, suggesting that in this material, DSA should enhance the ductile fracture resistance. [Copyright &y& Elsevier]

Abstract: Methyl tertiary butyl ether (MTBE) is now being extensively used as a lead-free octane enhancer for green fuel. Pervaporative separation process is used for separation of methanol–MTBE mixtures encountered during manufacturing of MTBE. Three different copolymers of acrylamide with increasing amount of 2-hydroxyethyl methacrylate (HEMA), i.e. PAMHEMA-1, -2 and -3 were synthesized and the cross-linked (gelled) copolymer membranes made from these sol copolymers were used for pervaporative separation of methanol from its mixtures with MTBE over the concentration range of 0–10wt.% methanol in feed. These hydrophilic gel copolymer membranes were found to be highly methanol selective in both sorption and diffusion through the membranes. Methanol flux was found to decrease with increase in degree of cross-linking from PAMHEMA-1 to -3 copolymer membranes. Among the three membranes PAMHEMA-3 membrane showed highest selectivity and acceptable flux (511.7, 9.9g/m2 h for 0.53wt.% of methanol in feed) while maximum flux with high selectivity was shown by PAMHEMA-l membrane (18.48g/m2 h, 243 for 0.53wt.% of methanol in feed). MTBE was also found to have a negative coupling effect on methanol permeation. The membranes were found to show both sorption as well as diffusion selectivity for methanol. [Copyright &y& Elsevier]

Abstract: Temperature dependent infrared study of water adsorption on the bc-plane of a Bi2Sr2CaCu2O8 (Bi2212) single crystal reveals that water is molecularly physisorbed, and forms hydrogen-bonded clusters in the temperature range of 85–150K. Although dissociative adsorption is expected on surfaces terminated with Ca–O and Cu–O groups, no dissociated species is detected. The main absorption bands occur between 3200 and 3500cm−1 and are assigned to the O–H stretching and the overtone of O–H bending. For exposures higher than 1.0L, the sticking coefficients are similar for different temperatures. The features in the O–H stretch region for water clusters red-shift as a function of temperature between 85 and 140K. Water clusters have an amorphous structure between 85 and 140K, and form a crystalline structure at 150K. [Copyright &y& Elsevier]

Abstract: For 20% cold worked 15Cr–15Ni–Ti modified austenitic stainless steel (Alloy D9), the Larson–Miller parameter can be used to describe the effects of prior thermal exposures to different time–temperature combinations on the 0.2% yield stress σ YS, ultimate strength and total elongation in subsequent tensile tests at 300, 723 and 923K. A single master plot for all the tensile test temperatures was obtained by plotting the Larson–Miller parameter against the ratio S YS=(σ YS of thermally aged material)/(σ YS of un-aged material) at identical tensile testing temperature. [Copyright &y& Elsevier]

Abstract: Natural rubber (NR) and poly(styrene-co-butadiene) rubber (SBR) has been crosslinked with sulfur and accelerator with three different doses of varied accelerator to sulfur ratios to obtain three crosslinked membranes from each of these two rubbers (NR-1, NR-2 and NR-3 and SBR-1, SBR-2 and SBR-3). These six rubber membranes were used for pervaporative separation of toluene–methanol mixture up to 10wt% of toluene in feed. It has been found that with increase in accelerator to sulfur ratio from membrane-3 to membrane-1, the vulcanization system shifts from conventional to efficient system resulting in higher degree of crosslink density and permeation selectivity. All of these membranes showed reasonably good range of flux (45.26gm/m2 h for NR-3 to 12.0gm/m2 h for SBR-1) and separation factor (162 for SBR-1 to 35.12 for NR-3) for 0.55wt% of toluene in feed. Among these membranes NR-1 and SBR-1 with highest crosslink density showed maximum separation factor for toluene along with good flux. It has also been found that for comparable crosslink density SBR membranes showed better separation factor than NR membranes. [Copyright &y& Elsevier]