bluuebunny/crossref_metadata_2025_split huggingface dataset:
Removal and recovery of nickel ion in sodium citrate solution with chelating resin containing triethylenetetramine side chain
Authors: Maeda Hironori , Egawa Hiroaki 
Published: April 2003

AbstractRemoval and recovery of nickel ion in sodium citrate solution with the macroreticular chelating resin containing triethylenetetramine side chain was investigated. The resin (RMT) exhibited high affinity for nickel ion in a solution containing 100 mmol/dm3 of sodium citrate over the pH range of 7.4–11.5. The adsorption of nickel ion was above 98%. In the column method, the breakthrough capacity of the RMT for nickel ion was 3.0 g/dm3‐resin, when the solution containing 0.5 mmol/dm3 of nickel (II) nitrate and 100 mmol/dm3 of sodium citrate was passed through the RMT column at a space velocity of 7.5 h−1. The nickel ion adsorbed was eluted by allowing 1 mol/dm3 hydrochloric acid to pass through the column. The recycle of adsorption and elution was found to be satisfactory.
Self‐vulcanizable rubber blend system based on neoprene and carboxylated nitrile rubber
Authors: Mukhopadhyay Sujata , De Sadhan K. 
Published: April 2003

AbstractA novel rubber blend system has been developed that is self‐vulcanizable. No rubber chemical was required for vulcanization, and the mixing operation could be completed in less than 14 min. Such a clean rubber blend system can be reinforced by carbon black filler, and physical properties are comparable to those of conventional rubber vulcanisates. Differential scanning calorimeter studies and dynamic mechanical analysis show that neoprene and carboxylated nitrile rubber are not miscible at the segmental level.
Solution of free radical polymerization
Authors: Venkateshwaran G. , Kumar Anil 
Published: April 2003

AbstractThe steady state approximation in free radical polymerization is known to break down during the operation of commercial reactors, in which case the unsteady mole balance of polymer radicals have to be solved numerically. We observed that the differential equations governing the zeroth, first, and second moments of polymer radicals in free radical polymerization are nonlinear in nature. The numerical solution of these is “stiff” because the concentration of polymer radicals is very small. Assuming an isothermal reactor, in the absence of the gel effect, these differential equations can be transformed in a suitable new domain where they are linear and can be solved analytically. We have subsequently developed a computer program for nonisothermal reactors in the presence of the gel effect using the analytical solution between any time increment. The results have been compared with those obtained from the fourth order Runge‐Kutta technique. We show that when the temperature changes are fast, the Runge‐Kutta technique cannot handle the stiffness, and the results begin to deviate from the exact solution. We find that our computer program is computationally efficient in handling this stiffness, takes considerably less time, and can be adapted to any personal computer.
Effect of microenvironment of oxirane groups on the immobilization of penicillin G acylase
Authors: Bahulekar R. V. , Ponrathnam S. , Ayyangar N. R. , Kumar K. K. , Shewale J. G. 
Published: April 2003

AbstractMacroporous beaded terpolymers containing oxirane groups were synthesized for immobilization of penicillin G acylase. The effect of incorporation of various monomers such as hydroxyethyl methacrylate and methyl methacrylate, and the effect of crosslinking agents such as ethylene glycol dimethacrylate and divinyl benzene on binding and expression of penicillin G acylase were studied. The terpolymers were modified to varying extents by treating with polyethyleneimine. The influence of the microenvironment around the oxirane group on the binding and expression of penicillin G acylase was investigated.
Kinetics and mechanism of oligomerization of cardanol using acid catalysts
Authors: Manjula S. , Kumar V. G. , Pillai C. K. S. 
Published: April 2003

AbstractThe kinetics and mechanism of oligomerization of cardanol over acid catalysts were studied. GPC results showed the formation of a mixture of oligomers such as dimer, trimer, tetramer, etc. IR spectra of the products of oligomerization showed a decrease in the intensity of the double bond absorption band at 1630 cm−1 and the disappearance of terminal vinyl bands at 895 cm−1 and 907 cm−1. 1H NMR spectra showed drastic changes in the unsaturated proton resonance signals at 5.5δ with respect to saturated protons at 0.2–2.5δ. The ratio of resonance integrals of unsaturated to saturated protons decreased from 1 : 6.5 to 1 : 20 after oligomerization. GPC studies showed that the rate of formation of the dimer, trimer, tetramer, etc. follow an identical path and that the individual oligomers are formed in the same weight percentage at any time during the reaction. A kinetic scheme is proposed to explain this phenomenon. Kinetic studies showed that the oligomerization reaction follows first order kinetics with respect to the monomer concentration and the rate constant is K = 6.6 × 10−5s−1. A probable mechanism for the oligomerization of cardanol is proposed.
Determination of methylene bridge type of mixed meta and para‐cresol–formaldehyde novolaks by 13C‐NMR spectroscopy
Authors: Fitzgerald E. A. , Tadros S. P. , Almeida R. F. , Sienko G. A. , Honda K. , Sarubbi T. 
Published: April 2003

AbstractCresol–formaldehyde resins are important components of photoresists for semiconductor fabrication. The type of methylene bridge and relative amounts thereof are key structural features that determine resin properties. Several model compounds were prepared that represent the various types of methylene bridges that are possible from condensation of meta‐ and para‐cresol with formaldehyde. The methylene bridges were characterized by 13C‐NMR spectroscopy, and the assignments made were used to analyze spectra of cresol–formaldehyde novolak resin and several oligomer types. The effect of complexation with metal ion on the methylene bridge chemical shift was investigated for one oligomer. The effect of bridging position on the intramolecular hydrogen bonding of the phenolic hydroxyl group was investigated by infrared spectroscopy.
Thermal aging of impact‐modified polycarbonate
Authors: Cheng T. W. , Keskkula H. , Paul D. R. 
Published: April 2003

AbstractGlassy polymers undergo relatively rapid physical aging just below their glass transition temperatures that can lead to embrittlement of normally tough materials like polycarbonate (PC). One approach for solving the embrittlement problem is to incorporate an impact modifier that can cause toughening when the matrix loses its inherent ductility due to physical aging. The effects of thermal aging below the glass transition temperature of polycarbonate on selected properties of blends of PC with various core‐shell impact modifiers have been studied. Observed changes in mechanical properties are related to rubber content, free volume, fracture morphology, discoloration, enthalpy relaxation, glass transition temperature, intrinsic viscosity, and dynamic mechanical behavior. Blend mechanical properties are affected by chemical changes in the impact modifier that occur simultaneous with the physical aging of the PC matrix. The degradation mechanisms involved reduce the effectiveness of the modifier for toughening and also lead to a loss of molecular weight of the PC matrix. Blends containing 10% methacrylated butadiene‐styrene (MBS) core‐shell impact modifiers give the maximum extension of time to embrittlement at 135°C in air. More thermally stable modifiers are required for further extending the ductile mode of failure for physically aged PC blends.
Graft copolymerization of butyl acrylate onto pullulan using manganic pyrophosphate as initiator
Authors: Tian R.‐C. , Gao J.‐P. , Yu J.‐G. , Duan M.‐L. 
Published: April 2003

AbstractThe graft copolymerization of butyl acrylate onto pullulan using manganic pyrophosphate as initiator in aqueous medium was studied. The effects of concentration of initiator, monomer, pullulan, and sulfuric acid on the percentage of grafting, the grafting, efficiency, as well as the rate of graft copolymerization were investigated. The rate equation was derived and a suitable reaction mechanism was proposed. Finally, the grafted samples were characterized by IR spectral measurement.
Acoustic emission in bonded elastomer discs subjected to compression. I
Authors: Kakavas P. A. , Chang W. V. 
Published: April 2003

AbstractThe apparent initial stiffness, M, of a rubber disc subjected to compression was experimentally determined. It was found that the experimental value of M is different than the value theoretically predicted according to Gent's equation. The aim of this study is to prove that this difference in the apparent modulus is due to the existence of microcavities within the testing rubber discs. The microvolds are formed along the curing process of the samples. A new nondestructive experimental technique, the Acoustic Emission (AE) technique, was used for the analysis of microcavitation within rubber discs subjected to compression. The count, event average count rate, amplitude, duration time, and rise time distributions of the received acoustic emission signals from the buckling of voids in the deformed solid, give more insight about the phenomenon of microcavitation.
Starch urea formaldehyde matrix encapsulation of solid agrochemicals. II. Release mechanism and release modeling
Authors: Kulkarni N. V. , Rajagopalan N. , Kale R. P. , Khilar Kartic C. 
Published: April 2003

AbstractBased on experimental observation, a mechanism is proposed to describe the release of carbofuran from a starch‐UF matrix. A simple mathematical model is developed to describe the diffusion‐controlled release of a solid insecticide from a porous starch‐UF matrix undergoing both volume and surface erosions. The model is tested with the release data collected for different matrices and with different pH values of the environmental liquid. The comparison between the model predictions and data is found to be reasonably good. The model describes the release process at different pH values by accounting for the influence of pH on the erosion rates.
Plasma polymerization of metal acetylacetonates and application for gas sensor devices
Authors: Inagaki N. , Tasaka S. , Nozue Y. 
Published: April 2003

AbstractPlasma polymerization of five metal acetylacetonates (MAcAc), aluminium acetylacetonate (AlAcAc), copper acetylacetonate (CuAcAc), titanium acetylacetonate (TiAcAc), zinc acetylacetonate (ZnAcAc), and magnesium acetylacetonate (MgAcAc), were investigated for the application of CO gas sensor devices. Plasma polymerization deposited thin films with metal elements as well as carbon and oxygen elements. The polymer deposition rate in the plasma polymerization was a function of the rf power, the system pressure, and the nature of the MAcAc. The elemental composition of the deposited films was fairly different from that of the starting materials, MAcAc. The complexing bonds of the MAcAc between acetylacetone and the metal element occurred in the plasma zone. The cleavage was closely related to the delocalization of electrons on the complexing of the MAcAc. The plasma polymer films prepared from TiAcAc and ZnAcAc in the presence of Pt catalyst showed a response toward CO gas. The plasma polymer films, especially prepared from TiAcAc, are potential materials for a CO sensor device with both sensitivity and selectivity.
Premembranes for porogen‐derived membranes and thermal decomposition of porogens
Authors: Eyal A. M. , Hazan B. , Hajdu K. , Edelstein D. 
Published: April 2003

AbstractVarious t‐butyl and di‐t‐butyl esters, N‐boc and di‐N‐boc amines, metal salts of N‐boc amino acid, and glycerol–formic acid esters are potential porogens for porogen‐derived membranes. Introduction of more than 20 such compounds into polysulfone or poly(vinyl chloride) films was studied. Transparency, IR spectra, changes in glass transition temperature, and differential scanning calorimetry were used to differentiate between molecular dispersion and formation of micro phases. The results show that for many of the studied additives more than 10% by weight can be practically molecularly dispersed in the polymers. The upper limit of porogen concentration in premembranes depends on characteristics of the polymer and of the porogen, on casting solvent composition, and on drying procedure. Metal salts of N‐boc amino acids were found to be suitable heat‐decomposable porogens. Their decomposition in premembranes proceeds in two stages, in the first of which 2 C4H8 + 2CO2 are released per salt molecule. The metal complex formed goes through decarboxylation at a higher temperature. A heating procedure for completion of the first decomposition stage and for avoiding the second was determined.
Characterization of natural polyisoprenes and synthetic polybutadiene
Authors: Vangani Veena , Rakshit Animesh Kumar 
Published: April 2003

AbstractSynthetic polybutadiene (PBR) and natural rubbers from India (InR) and Guyana (GR) have been characterized in detail. The characterization includes IR, NMR, GPC, DSC, TGA, contact angle, and viscosity measurements. Spectroscopic characterization helped in the differentiation of InR and GR. Viscosity data is used in the evaluation of activation parameters at infinite dilution of the viscous flow. Viscosity data is also used for the determination of the conformation of the macromolecules in various solvents. Surface characterization confirms the total hydrophobic nature of the three rubbers. Thermal analysis shows different degradation pattern for natural rubbers than for the synthetic rubber.
The effects of functional azo initiator on PMMA and polyurethane IPN systems. III. Tear resistance and crack growth of PBD(1,2)‐PU/PMMA (50%) blends
Authors: Roha M. , Dong F. 
Published: April 2003

AbstractThe tear strength and crack growth mechanism of PBD(1,2)–PU/PMMA (50%) IPN systems were studied by the trouser tear test and single edge notched (SEN) tensile test. It was found that these blend systems showed similar structures and properties to particulatereinforced elastomers. The tear strength was dominated by the structure of the rubber matrix. The PMMA phase increased the tearing resistance by increasing the hysteresis of the IPN systems. Chemical bonding between the PMMA‐rich particle and PU‐rich matrix prepared by using a reactive azo initiator inhibited the initiation of the fracture nucleus, decreased the intrinsic flaw size, and increased the tear strength. The crack growth of these IPNs was dependent on both the fracture energy available for crack propagation and the hysteresis of the material. The similar structure of these two blends resulted in the similar crack growth behavior.
New results on the kinetic aspect of the permeation resistance of elastomers, using an original testing cell and methanol as model permeating fluid
Authors: Forte R. , Leblanc J. L. 
Published: April 2003

AbstractThis work describes a method developed to study the permeation of fluids through rubber membrane in a semiautomatic manner, in such a way that information regarding the complete process is obtained. Using this technique, several permeation parameters were assessed with fluoroelastomer and hydrogenated nitrile rubber membranes. A phenomenological model for the permeation process is proposed that includes two concomitant physical phenomena: the swelling of the membrane and the permeation itself. Simple mathematical relationships are derived from the experimental data, with the permeation rate as the key parameter.
Study of curative interactions in cis‐1,4‐polyisoprene. XI. Network maturing reactions in the cis‐1,4‐polyisoprene–sulfur–zinc dimethyldithiocarbamate and cis‐1,4‐polyisoprene–sulfur–zinc dimethyldithiocarbamate–ZnO systems
Authors: Kruger F. W. H. , McGill W. J. 
Published: April 2003

AbstractThe network maturing reactions of the inefficient cis‐1,4‐polyisoprene (IR)–sulfur–zinc dimethyldithiocarbamate (ZDMC) and IR–sulfur–ZDMC–ZnO vulcanization systems were discussed. The Moore–Trego efficiency E was exceptionally high and increased, for example, from 13.0 at 132.4°C to 49.9 at 170.0°C in the IR–sulfur–ZDMC mixture. Calculations showed that ∼ 60% of the elemental sulfur was combined in the network in the form of cyclic sulfides and/or vicinal crosslinks at 148.2°C. The inefficient use of sulfur at the initial cure stages may be attributed to the insolubility of ZDMC in rubber. The increase in E at the later stages of vulcanization was attributed to a decrease in the total number of polysulfidic crosslinks, as the number of mono‐ and/or disulfidic crosslinks remained constant. The destruction of polysulfidic crosslinks was enhanced in the absence of ZnO, due to the catastrophic attack of thiophilic species such as Me2NH. The Me2NH resulted from the rapid decomposition of dimethyldithiocarbamic acid, which formed as a by‐product in the initial crosslink reactions. No evidence was found for the participation of ZDMC in crosslink desulfuration. ZDMC is not a vulcanizing agent.
Synthesis and fluorescence properties of rare earth metal ion–polymer ligand–low molecular weight ligand ternary complexes
Authors: Wang Yunpu , Lei Ziqiang , Feng Hanyu , Bao Jiuntang , Wang Yaobin 
Published: April 2003

AbstractEu3+‐containing polymer ternary complexes were synthesized using different kinds of functional polymers such as poly(benzylmalonic acid styrene) (PBMAS), poly(benzylacetone styrene) (PBAAS), and poly(benzyl‐azo‐o‐hydroxybenzoic acid styrene) (PBAHBAS) as polymer ligands. The structures of the complexes were investigated by elemental analysis and IR spectroscopy. The fluorescence intensity of Eu3+–polymer–TTA (2‐thenoyltrifuoroacetone ion) complexes was decreased in the order PBMAS(61) > PBAAS(42) > PBAHBAS(32). In system of Eu3+–PBMAS–low molecular weight ligand, the emission spectrum shape, the fluorescence intensity, and the wavelength of the maximum emission peak were changed when the low molecular weight ligand was varied. The fluorescence intensity of the Eu3+–PBMAS–TTA ternary complex was 610 times stronger than that of the Eu3+–PBMAS binary complex and 160 times stronger than that of Eu3+–PBMAS–oxine complex. The fluorescence intensity of the Eu3+–PBAAS–TTA complex was enhanced greatly when the proper mol ratio of HTTA/Eu3+ and pH in the reaction were chosen.
Thermogravimetric determination of starch content in starch–polyethylene blend films
Authors: Nakatsuka S. , Andrady A. L. 
Published: April 2003

AbstractThermogravimetric analysis as a technique for rapid determination of starch content in LDPE/starch blend films was investigated. The percent weight loss in a specified temperature range, under a constant heating rate, correlated well with the starch content of films in the range of 0–12 wt % starch, as determined by chemical analysis. The method was used to estimate the residual starch content of LDPE/starch films, containing approximately 6.0% starch, exposed under several biotic exposure conditions. Generally 87–88% of the initial starch content was present in the films after different types of environmental exposures.
Enhanced reactivity of melamine–formaldehyde resins by fractionation. Crosslinking at ambient temperature
Authors: Samaraweera Upasiri , Gan Shubang , Jones Frank N. 
Published: April 2003

AbstractA commercial hexakis(methoxymethyl)melamine (HMMM) resin was fractionated (1) by crystallization of the hexane–soluble fraction from hexane and (2) by partitioning the hexane–soluble and hexane–Insoluble fractions between alumina and various solvents. Crystallization afforded hexakis(methoxymethyl)melamine (1) of 90 to 95% purity. Partitioning afforded 12 fractions with altered proportions of polar and nonpolar species; the least polar fraction was spectroscopically and chromatographically similar to the crystallized material. Relative reactivities of certain fractions were estimated by 1H NMR studies of the rates of reaction with neopentyl alcohol in the presence of catalytic amounts of p‐toluenesulfonic acid (p‐TSA). It was found that the reactivity of fractions, rich in less‐polar species, was substantially greater than that of the commercial HMMM resin, whereas reactivity of fractions, rich in polar species, was less. Reactivity was especially enhanced by removal of all active hydrogen species, notably those containing NH groups. A practical consequence of this result was that fully formylated and alkylated melamine resins could crosslink with polyols at substantially lower temperatures than the commercial HMMM resin, which contained NH groups. Therefore, room‐temperature crosslinking was feasible.
Solution copolymerization of alkyl methacrylates and N–vinyl carbazole: Reactivity ratios
Authors: Ryttel Anna 
Published: April 2003

AbstractThe copolymerization of ethyl methacrylate and n‐butyl methacrylate with N‐vinyl carbazole was studied at 60°C, using AIBN as the initiator. The reactivity ratios of the monomers were determined in benzene, ethyl acetate, acetone or (N,N–dimethylformamide) solutions. The values of r1 and r2 were calculated by the Fineman–Ross and Kelen–Tüdös methods and were compared with those obtained earlier in bulk copolymerization.
Thermal conductivity of polyethylene/polystyrene blends containing SEBS block copolymer
Authors: Agari Y. , Ueda A. , Nagai S. 
Published: April 2003

AbstractWe measured the thermal conductivity of a polyethylene/polystyrene blend containing SEBS block copolymer, which has two components of polystyrene block and hydrogenated polybutadiene block, and discussed the effect of phase inversion on the thermal conductivity by observing the morphorogy of the blend. Further, we examined the applicability of the thermal conduction model for composites, which was proposed in our previous reports, to this blend system. By plotting the logarithm of the thermal conductivities of the blends vs. the weight content of polyethylene, it was found that the experimental data lie approximately on a straight line with an increase in polyethylene until the range of dual–phase continuity (phase inversion), and then the data move on another straight line beyond the range of dual–phase continuity. Thus, our model to explain the thermal conductivity of the polymer blend was proved. Further, both coefficients A and B in our model took linear relations with the weight content of the block copolymer, and the model was, thus, more strongly confirmed to be applicable to thermal conductivity of polymer blends.
Studies on the sorption of lipids in segmented polyurethanes. II. Effect of hard‐segment content
Authors: Sreenivasan K. , Jayabalan M. , Rao K. V. C. 
Published: April 2003

AbstractDiffusion and absorption, of a few representative components found in blood, in segmented polyurethane are studied. The absorption of the components, confined to the soft segment, is found to be Fickian. Both diffusion coefficients and equilibrium absorption was found to decrease with % hard‐segment content. An empirical equation has been proposed to visualize the absorption behavior with soft/hard‐segment content.
Studies on semi‐interpenetrating polymer networks from poly(vinyl chloride‐co‐vinyl acetate) and poly(butyl acrylate)
Authors: Mathew Annakutty , Deb P. C. 
Published: April 2003

AbstractA series of semi‐interpenetrating polymer networks (semi‐IPN) based on linear poly(vinyl chloride‐co‐vinyl acetate) and cross‐linked poly(butyl acrylate) were synthesized. The copolymer was swelled in butyl acrylate monomer containing azobisisobutyronitrile (AIBN) initiator and tetraethylene glycol dimethacrylate cross‐linker and later polymerized in situ. Variation in composition of the IPN was achieved by varying the copolymer/monomer ratio. The semi‐IPN was found to exhibit two distinct glass transitions as measured by differential scanning calorimetry and dynamic mechanical analysis. The tan θ values were found to be dependent on the composition. The tensile strength was found to be higher for semi‐IPNs containing a higher percentage of copolymer.