Showing papers by "Indian Institute of Technology Kharagpur published in 1983"
TL;DR: In this article, a triethanolamine complex of cadmium ions, ammonia and thiourea solutions was used for thin films of CdS and CdSe on glass substrate.
126 citations
TL;DR: In this paper, detailed viscometric and ultrasonic velocity studies have been conducted on solutions of blends of poly(methyl methacrylate) with poly(vinyl acetate), poly (vinyl chloride) and poly(polystyrene) over an extended range of concentrations and temperatures.
108 citations
TL;DR: Rubber vulcanizates can be reclaimed by milling them with curing ingredients as discussed by the authors, but their physical properties are inferior to those of the control vulcanizeate and they exhibit poor processing characteristics.
Abstract: Rubber vulcanizates can be reclaimed by milling them with curing ingredients. Physical properties of the RR vulcanizates are inferior to those of the control vulcanizate. RR compounds exhibit poor processing characteristics. Poor physical properties and processing characteristics can be improved by blending with fresh rubber. However, a higher proportion of RR increases the stiffness and causes brittle failure.
99 citations
TL;DR: In this article, a solid solution of Bi2S3SbS3 was prepared in the form of polycrystalline films on glass substrates by the dip-dry process using BiCl3, SbCl3 concentrated hydrochloric acid and thiourea.
83 citations
TL;DR: In this paper, the resorcinol-hexa-silica bonding system is essential for NR-silk fiber systems, and the aging resistance of silk fiber-reinforced NR composites is excellent only beyond a fiber loading of 20 phr.
Abstract: (1) The resorcinol-hexa-silica bonding system is essential for NR-silk fiber systems. (2) Mechanical anisotropy is observable only at higher fiber loadings (20 phr and above) in NR-silk fiber systems. (3) In composites containing a sufficient amount of bonding agents and fibers for tensile anisotropy to be observed, tensile failure occurs by both fiber breakage and debonding. (4) Addition of silk fiber to NR causes (a) increase in hardness, (b) reduction in resilience and elongation at break, (c) increase in heat buildup and set, and (d) increase in tear resistance. (5) The aging resistance of silk fiber-reinforced NR composites is excellent only beyond a fiber loading of 20 phr. (6) Mill shrinkage and green strength of NR improve, while Mooney viscosity and scorch time increase with the addition of silk fiber to NR.
68 citations
TL;DR: The Banded Gneissic Complex (BGC) of Rajasthan, considered to form the basement underlying the Precambrian (Proterozoic) Aravalli metasediments, shows an erosion surface marked by a conglomerate and an angular unconformity.
55 citations
TL;DR: In this article, a silane coupling agent (Si-69) was used to reduce the viscosity and increase the scorch lime in silica-and clay-filled EPDM.
Abstract: 1. A silane coupling agent (Si-69) reduces the viscosity and increases the scorch lime in silica- and clay-filled EPDM. The cure lime of silica-filled mixes remained unchanged and that of ...
49 citations
TL;DR: In this paper, the changes in network structure and fracture mode of natural rubber vulcanizates, during ageing at 100°C have been studied by chemical analyses and scanning electron microscopy.
38 citations
TL;DR: In this paper, a solution growth technique was developed for the deposition of thin films of copper(II) selenide on glass substrate using a copper salt solution, triethanolamine, ammonia, and sodium selenosulfate as the reacting agents.
37 citations
TL;DR: In this paper, the properties of compatible and incompatible poly(methyl methacrylate)-poly(vinyl acetate)-polystyrene blends have been studied by ultrasonic velocity measurements.
36 citations
TL;DR: In this paper, the authors show that the improvement in technical properties in the presence of silane coupling agents is more in the peroxide vulcanization system and is accompanied by enhanced polymer-filler interactions.
Abstract: The presence of silane coupling agents do not cause a change in network structure in clay-filled natural rubber vulcanizates, both in sulfur vulcanization and peroxide vulcanization systems. However, the improvement in technical properties in the presence of silane coupling agents is more in the peroxide vulcanization system and is accompanied by enhanced polymer—filler interactions. Scanning electron microscopy (SEM) studies have been made in order to understand the failure behavior.
TL;DR: In this article, the effect of reinforcement fillers on the performance of styrene-buatadiene rubber (SBR) vulcanizates has been studied with respect to the following parameters: (a) the nature of cross-links (flexible sulphur (-Sx-) type and rigid carbon-carbon (-C-C-) type); (b) the impact of reinforcement filler, ISAF carbon black (N 220) in both cross-linking systems; and (c) the effects of crosslink density in the case of sulphur-cured
Abstract: Scanning electron microscopy (SEM) studies on tear fracture of styrene-buatadiene rubber (SBR) vulcanizates have been made with respect to the following parameters: (a) the nature of cross-links (flexible sulphur (-Sx-) type and rigid carbon-carbon (-C-C-) type); (b) the effect of addition of reinforcing filler, ISAF carbon black (N 220) in both cross-linking systems; and (c) the effect of cross-link density in the case of sulphur-cured vulcanizates. It was observed that peroxide-cured SBR (unfilled) vulcanizate undergoes brittle fracture whereas the optimum cross-linked sulphur-cured unfilled vulcanizate undergoes fracture in the shear planes and with branching of the tear path. In the case of sulphur-cured SBR (unfilled) vulcanizate with a higher cross-link density the fracture pattern is similar to that of the vulcanizate which has an optimum cross-link density. When the cross-link density is increased or the nature of cross-link is changed to the rigid C-C type, stress dissipation becomes difficult and hence the tear resistance decreases. Peroxide-cured SBR (filled) vulcanizate shows a typical stick-slip mode of fracture as well as steady tear and microfolds over the surface. Sulphur-cured SBR (filled) vulcanizates show short and curved tear lines. Fillers help to arrest crack growth and to increase stress dissipation, thereby increasing tear resistance.
TL;DR: In this article, electrical conductivity of pure and ZnO doped SnO2 has been measured at different temperatures and oxygen partial pressures and three partial pressure ranges have been identifieD.
Abstract: Electrical conductivity (σ) of “pure” and ZnO doped SnO2 has been measured at different temperatures and oxygen partial pressures (\(p_{{\text{O}}_{\text{2}} } \))- From the variation of electrical conductivity of these materials three partial pressure ranges have been identifieD. In the high partial pressure rangeσ increases with decreasing\(p_{{\text{O}}_{\text{2}} } \) followed by a\(p_{{\text{O}}_{\text{2}} } \) independent region at lower\(p_{{\text{O}}_{\text{2}} } \) ´s and finally increases once again with a further decrease of\(p_{{\text{O}}_{\text{2}} } \). These variations have been explained on the basis of an anti-Frenkel type defect structure and an interstitial solid solution of ZnO in SnO2. The activation energy for the conduction process has been estimated and the values are found to differ in two different temperature ranges. In the low temperature range the conductivity is attributed mainly to the chemisorption of oxygen on the surface of the specimen.
TL;DR: In this article, the authors considered the thermal instability of a rotating, heat conducting, micropolar fluid layer heated from below and confined between two rigid boundaries, and the onset of thermal instability was governed by a linear eigenvalue problem.
TL;DR: The abrasion of NR/BR blend vulcanizates has been studied in three different testing machines and the abraded surfaces have been observed in a scanning electron microscope as mentioned in this paper.
Abstract: The abrasion of NR/BR blend vulcanizates has been studied in three different testing machines and the abraded surfaces have been observed in a scanning electron microscope. The ranking of the unfilled blends obtained from Akron abrader is different from that obtained from Du Pont and DIN abraders, while in the case of the black-filled vulcanizates the same ranking can be obtained from all the three machines. Tensile and fatigue properties are believed to play major roles in determining abrasion loss in the Akron abrader, while the effect of friction is more pronounced in the other two machines. The slip angle of 20° and the deformation of the surface layer of rubber during abrasion accounts for the difference in the direction of the abrasion pattern observed in the case of Akron abrader. The carbon black-reinforced vulcanizates give rise to a fine abrasion pattern. Because of the continuous change in the direction of abrasion in DIN abrader, a well-defined pattern was not observed. The very low abrasion loss of 50/50 blend vulcanizates in Du Pont abrader is also evident from the nature of the abraded surface.
TL;DR: SrVO 3, a cubic perovskite binary oxide, has been investigated as a catalyst for the oxidation of methanol and of benzene as mentioned in this paper, and a comparison has been attempted between the catalytic activities and selectivities for the two reactions.
TL;DR: In this article, the diacid chloride of 2-(3-carboxy vinyl)phenyl-1,3-dioxoisoindoline-5 carboxylic acid with m-phenylenediamine and 2-(4-Carboxy phenyl)-1, 3-doxoindol-5-car boxylic acids with 1,5-bis(3-aminophenyl)1,4-pentadien-3-one was carried out in polar solvents to produce new unsaturated polyamide-im
Abstract: Polycondensation of the diacid chloride of 2-(3-carboxy vinyl)phenyl-1,3-dioxoisoindoline-5-carboxylic acid with m-phenylenediamine and the diacid chloride of 2-(4-carboxy phenyl)-1,3-dioxoisoindoline-5-carboxylic acid with 1,5-bis(3-aminophenyl)1,4-pentadien-3-one was carried out in polar solvents to produce new unsaturated polyamide–imides. The solution and the thermal, electrical, and a few other properties of the polymers were studies. The polymers were soluble in highly polar solvents. The solubility parameter of the polymers was calculated from the Small's group contribution. The polymers were fairly thermostable and underwent crosslinking creaction when heated, preferably in the presence of a suitable catalyst. The crosslinked polymers were in soluble even in highly polar solvents and possessed higher thermal stability. The swelling behavior of the polymers was studied and the molecular weight between two consecutive crosslinks was determined. X-ray diffraction and the dielectric properties of the polymers and their crosslinked products were also studied.
TL;DR: In this article, the effects of carbon black on polymer-filler interaction, technical properties and fracture mode of carboxylated nitrile rubber (XNBR) cured by different curing systems have been studied.
TL;DR: A boundary scalar transform technique, wherein the pattern boundary is expressed in finite Walsh series expansion, is presented for the description and discrimination of polygonal curves and the effectiveness of the normalization of the starting point is discussed.
TL;DR: In this article, a method was developed for chemically depositing thin films of TlS onto glass substrates using a thallous nitrate solution, ammonia and thiourea as the reacting agents.
TL;DR: In this article, an extension of earlier work is made to determine both theoretically and experimentally the coefficient of discharge and spray cone angle of a swirl nozzle using a time-independent purely viscous power-law non-Newtonian fluid.
Abstract: An extension of earlier work is made in the present paper to determine both theoretically and experimentally the coefficient of discharge and spray cone angle of a swirl nozzle using a time-independent purely viscous power-law non-Newtonian fluid. The theoretical predictions are made through an approximate analytical solution of the hydrodynamics of flow inside the nozzle. Experiments are carried out with aqueous solutions of CMC (carboxymethyl cellulose sodium salt) powder of various concentrations as the working fluids. The rheological properties of the working fluids are established by a capillary tube viscometer. From both the theoretical and experimental analyses, the pertinent independent input parameters are recognised as the generalised Reynolds number at inlet to the nozzle ReGi, the flow behaviour index of the fluid n, length-to-diameter ratio of the swirl chamber L1/D1, spin chamber angle 2α and the orifice-to-swirl-chamber-diameter ratio D1/D1. Although the theory predicts the correct qualitative trend in all cases, it does not agree well with the experimental results. Therefore, on the basis of the theoretical results, emperical relationships between nozzle characteristics and input parameters heve been established. Finally it is recognised that, regarding the injection conditions and fluid properties, the generalised Reynolds number at nozzle inlet ReGi and the flow behaviour index n have inverse and direct effects, respectively, on the coefficient of discharge, but have a negligible influence on the spray cone angle. Amongst the nozzle geometries, an increase in the values of D2/D1 and 2α or a decrease in the value of L1/D1 decrease the coefficient of discharge and increase the spray cone angle.
TL;DR: A theoretical analysis for the problem of wave propagation in arteries is presented and results indicate that phase velocities increase with the increase of transmural pressures.
Abstract: A theoretical analysis for the problem of wave propagation in arteries is presented. Blood is treated as a Newtonian, viscous incompressible fluid. On the basis of information derived from experimental investigations on the mechanical properties of wall tissues, the arterial wall is considered to be nonlinearly viscoelastic and orthotropic. The analysis is carried out for a cylindrical artery, under the purview of membrane theory, by taking account the effect of initial stresses. The motion of the wall and that of the fluid are assumed to be axisymmetric. Particular emphasis has been paid to the propagation of small amplitude harmonic waves whose wavelength is large compared to the radius of the vessel. By employing the equations of motion of the fluid and those for the wall, together with the equations of continuity, a frequency equation is derived by exploiting the conditions of continuity of the velocity of the arterial wall and that of blood on the endosteal surface of the wall. In order to illustrate the validity of the derived analytical expressions a quantitative analysis is made for the variations of the phase velocities as well as the transmission coefficient with frequency corresponding to different transmural pressures which relate to different initial stresses. Computational results indicate that phase velocities increase with the increase of transmural pressures.
TL;DR: In this article, a poly crystalline molybdenum disulphide was prepared by high-pressure reduction of M 2 trisulphides at 200°C, and a band gap of 1.18 eV was obtained and n-type conductivity found.
TL;DR: In this paper, a complex plane impedance analysis has been carried out using different electrode materials like silver, graphite and lithium ion conducting glasses in the system LiF-Li 2 O-A1(PO 3 ) 3 have been investigated.
TL;DR: In this paper, the concept of isoparametry in finite difference energy method making it more powerful and versatile to tackle complex plate bending problems with curved boundaries is introduced, and the accuracy and reliability of the present formulation several isotropic plates with a variety of planform are solved.
TL;DR: In this article, changes in crystallographic, electrical, and thermal properties of CuCr2O4 spinel were investigated by replacing Cu with Mg, i.e., Cu 1−xMgxCr 2O4, and Cr with Al.
TL;DR: The high sulfur (HS) vulcanization system gives rise to higher apparent crosslink density and improvement in modulus, resistance to abrasion, compression set, heat buildup, rebound resilience, and dynamic set than that of the low sulfur (LS) system as discussed by the authors.
Abstract: The high sulfur (HS) vulcanization system gives rise to higher apparent crosslink density and improvement in modulus, resistance to abrasion, compression set, heat buildup, rebound resilience, and dynamic set than that of the low sulfur (LS) vulcanization system. Tensile strength, tear strength, and flexing resistance were found to be better for the low sulfur (LS) vulcanization system. Rupture energy during tensile and tear failure determined from the Universal Testing Machine (Instron 1195) also reveals a similar phenomenon. Studies on fracture mode during different types of failure have been done by using a scanning electron microscope (SEM).