bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental investigation of vinyl chloride polymerization at high conversion—conversion and tracer response relationships
Authors: Xie T. Y. , Hamielec A. E. , Wood P. E. , Woods D. R. , Westmijze H. 
Published: April 2003

AbstractA model for suspension polymerization which relates the conversion of vinyl chloride monomer (VCM) to polymerization conditions and a tracer response measured by online gas chromatography has been developed. This model can be used to determine monomer conversion with measurements of tracer response by gas chromatograph. A series of experiments using inert mixtures of H2O/PVC/VCM/n‐butane and using suspension polymerization of VCM with n‐butane as tracer were carried out to evaluate the model. The solubility of n‐butane in vinyl chloride was determined in the temperature range 40–70°C. The solubility of n‐butane in polyvinylchloride (PVC) was estimated using nonlinear regression comparing model and experimental data for both inert mixtures and for suspension polymerization. Correlations of the solubility constants of n‐butane in VCM and PVC, respectively, were obtained from the experimental data. Under the present experimental conditions, conversions can be measured online every 7–8 min using the n‐butane tracer method.
Mössbauer studies of styrene–acrylonitrile copolymers containing ferric nitrate
Authors: Brar A. S. , Sunita  
Published: April 2003

AbstractStyrene (St)–acrylonitrile (AN) copolymers were prepared with and without ferric nitrate by free radical polymerization at 70°C. TGA studies showed that the addition of ferric nitrate has some effect on the thermal behavior of the copolymer. Mössbauer, studies of the copolymer, heated at 150, 250, and 480°C for 15 min showed that during the thermal degradation Fe3+ species was reduced to Fe2+, and then, finally, it formed α‐Fe2O3. The mechanism of thermal degradation has been proposed on the basis of IR, TGA, and Mössbauer studies.
Properties of cation exchange membranes obtained in the presence of diluents
Authors: Alexandrova I. , Dimov A. 
Published: April 2003

AbstractThe effect of inert diluents on the properties of cation exchange membranes had been studied. The membranes were prepared by modification of high‐molecular polyethylene (M̄n = 1.19 × 106) with styrene and divinylbenzene in the presence of toluence or heptane and following sulphonation. In the monomer mixture the diluent content was in the range of 5–30 wt. % and divinylbenzene was 3 or 7 wt %. The results obtained indicate that the properties of thus obtained membranes depend on the kind and amount of the diluent. It was found that the membranes, obtained in the presence of toluene, have much better transport properties than the membranes obtained in the presence of heptane at the same concentration in the monomer mixture. The best diffusion coefficient for sodium chloride was found for the membranes, obtained in the presence of 5 or 10 wt % toluene.
Synthetic resins. X. Resin copolymers from hydroxy phenacyl bromide, substituted benzoic acid/formaldehyde
Authors: Nayak Pramod K. , Lenka Subasini , Nayak Padma L. 
Published: April 2003

AbstractA number of resin copolymers have been synthesized by condensing p‐hydroxy phenacyl bromide, substituted benzoic acids, and formaldehyde catalyzed by acids. The resin copolymers were characterized by IR spectra. The solution, thermal and chemical properties of the resins have been investigated. Ion exchange selectivity with respect to Cu2+ and Co2+ has been studied at different pH. Bacteriocidal and fungicidal properties of the resins have also been evaluated.
Cupric ion removal by dyed cellulosic materials
Authors: Shukla S. R. , Sakhardande V. D. 
Published: April 2003

AbstractFour different cellulosic materials namely cotton fibers, bamboo pulp, jute fibers, and saw dust were dyed with monochlorotriazine type reactive dyes. The cupric salts, viz., copper nitrate, copper sulphate, copper chloride, and copper acetate were adsorbed from their aqueous solutions of about 250 ppm strength by both undyed and dyed substrates. It was observed that although the undyed substrates do adsorb the metal salts significantly, their capacity increases greatly on dyeing with reactive dyes. Thus, in many cases, the different dyed substrates show an adsorption level of above 90%. Since the substrates chosen differ from each other in a number of ways, the actual adsorption values show wide variation.
Incompatible ternary blends containing unsaturated polyester resins. II. Interfacial properties
Authors: Suspene L. , Sage D. , Pascault J. P. 
Published: April 2003

AbstractThe interfacial tension (γ) in ternary blends of unsaturated polyester (UP) and rubber oligomers in styrene have been measured using three different techniques: tensiometric plate, capillary height, and drop profile methods. These experimental methods give similar results, but it has been shown that γ values “with or without skimming” are very different. The presence of small molecules, inhibitors, impurities, etc., in the interphase region can explain this discrepancy. We have observed a good correlation between γ and the Flory‐Huggins interaction parameter. The elastomer chain ends have an influence on the interfacial tension: γ is reduced when the oligomers possess hydroxyl groups. An epoxy terminated butadiene–acrylonitrile copolymer, ETBN, was prepared from a large excess of diglycidyl ether of bisphenol A, DGEBA, and carboxyl terminated butadiene–acrylonitrile copolymer, CTBN, at 150°C, and without a catalyst. The excess of DGEBA was eliminated by successive precipitation in the selective solvent ethanol. Since the DGEBA blocks are miscible with the UP resin, the introduction of the ETBN copolymer drastically reduces the interfacial tension of the ternary blend of UP and rubber in styrene.
Acrylonitrile–triethylene tetramine adduct hardener systems for epoxy resin
Authors: Mukherjee G. S. , Saraf M. N. 
Published: April 2003

AbstractTriethylene tetramine (TETA) has been chemically modified to different extents using acrylonitrile (AN) as chain extender for the hardener system of epoxy resin. The modified hardeners have been characterized and used to make epoxy casting and glass reinforced composites. The neat epoxy matrices have been evaluated in terms of mechanical and thermal properties, while their glass fibre reinforced composites have been characterized mechanically. It has been observed with neat resin casting that the Izod impact strength increased from 14.89 to 67.17 kJ/m2, but the Rockwell hardness and glass transition temperature decreased from 83.1 to 30.8 and 146.2 to 59.7°C, respectively, as the extent of modification of TETA increased through the utilization of 0 to 3 mol AN for epoxy curing. Hardener based on adduct of 1 mol TETA and 3 mol AN was found most suitable for making epoxy prepreg with 1 month shelf life at −5°C.
Uphill and selective transport of alkali and alkali earth metal ions through 2,3‐epithiopropyl methacrylate–2‐acrylamide‐2‐methyl propane sulfonic acid copolymer membranes
Authors: Nonaka Takamasa , Ogawa Hirofumi , Egawa Hiroaki 
Published: April 2003

AbstractCationic exchange membranes were prepared with 2,3‐epithiopropyl methacrylate (ETMA)‐2‐acrylamide‐2‐methyl propane sulfonic acid (AMPS) copolymers. Transport of alkali and alkali earth metal ions against their concentration gradient through the membranes was investigated by using the system, where one side (L side) of the membrane in a diaphragm cell was acidic and the other (R side) alkaline or neutral, under various conditions. The ETMA‐AMPS copolymer membranes transported rapidly alkali and alkali earth metal ions against their concentration gradient even from their neutral salt solution. The transport rate and transport fraction of metal ions were greatly affected by the composition of the copolymer membranes and H+ concentration in the L side. The transport selectivity between alkali metal ions was affected by the composition of the copolymers and the selectivity between alkali and alkali earth metal ions was affected by initial H+ concentration in the L side.
Preparation and properties of UV‐autocurable BTDA‐based polyester multiacrylates. I. Effects of acrylic functionality and polyol molecular weight
Authors: Chiang Wen‐Yen , Chan Shao‐Ching 
Published: April 2003

AbstractA series of UV‐autocurable benzophenone tetracarboxylic dianhydride (BTDA)‐based polyester multiacrylate oligomers was synthesized and the effects of acrylic functionality and molecular weight on their physical properties were investigated. The multiacrylate oligomers were prepared by the ring‐opening reaction of glycidyl methacrylate and diacrylate oligomers containing pendant acid groups. The latter was prepared from BTDA, PEG, and hydroxyethyl acrylate (HEA). The obtained autocurable oligomers are cured rapidly when exposed to ultraviolet (UV) without the addition of photoinitiator or photosensitizer. Increasing the mole percentage of GMA in oligomer led to higher acrylic functionality and photocuring rate. The increasing in the functionality of acrylic oligomer was reflected in higher crosslinking density of the cured film which resulted in an increase in Young's modulus and breaking strength, while elongation at break decreased. On the other hand, increasing PEG molecular weight led to a decrease in Young's modulus and breaking strength due to existence of a small amount of acrylate phase and a larger chain length between crosslinks. The dynamic mechanical analysis results showed that storage modulus (E') and glass transition temperature (Tg) were affected by the mol % of GMA and the molecular weight of PEG in the cured oligomers. With increasing mol % of GMA in the oligomers, the storage modulus and Tg shifted to higher temperatures; however, storage modulus and Tg decreased with increasing PEG molecular weight.
A melt prepolymerization of poly(ethylene terephthalate) in semibatch stirred reactors
Authors: Lei G. D. , Choi K. Y. 
Published: April 2003

AbstractA semibatch melt prepolymerization of poly(ethylene terephthalate) (PET) is studied. Being characterized by complex reaction pathways leading to various functional end groups and side products, PET prepolymerization process poses a challenging modeling problem. Ten distinct polymeric species have been defined in accordance with the type of functional end groups and the corresponding mass balance and moment equation are developed to estimate the progress of reaction and polymer molecular weight. The effect of various reactor operating conditions on the performance of the polymerization process has been examined through numerical simulation of the molecular species model developed. In particular, the effect of incomplete transesterification of methyl ester groups on the polymer molecular weight has been investigated in detail.
The effect of type and amount of carbon black on the interaction between polychloroprene rubber and motor oil
Authors: Lawandy S. N. , Botros S. H. 
Published: April 2003

AbstractThe interaction constants between polychloroprene rubber, containing different amounts and types of carbon black, and a motor oil were experimentally determined. It was found that the interaction constant values are not affected by the type of carbon black as long as the mixes contain the same filler concentration and category, whereas mixes containing the same filler type but of different concentrations show different interaction constants.
Dilute solution properties of flexible polymers in toluene: A comparison of commercially available photometers
Authors: Kim Seong H. , Cotts Patricia M. 
Published: April 2003

AbstractDilute solution properties of polystyrene and poly(α‐methylstyrene) in toluene have been measured using several of the commercially available instruments for intensity light scattering. Results are compared among the instruments used and with literature values. Relative advantages and disadvantages of the instruments are discussed.
The rate of ethylene polymerization initiated by various chelating tertiary diamine : n‐butyllithium complexes
Authors: Marshall W. B. , Brewbaker J. L. , Delaney M. S. 
Published: April 2003

AbstractThe initial rates of ethylene polymerization initiated by 13 chelating tertiary diamine:n‐butyllithium complexes were determined under a standard set of conditions. Complexes of the cyclic diamines 1,2‐dipyrrolidinoethane, sparteine, and 1,2‐dipiperidinoethane resulted in higher polymerization rates and larger ultimate polymer yields than did complexes of acyclic diamines such as N,N,N′,N′‐tetramethylethylenediamine. The rates of polymerization and also the polymer yields were also strongly affected by the length of the chain segment connecting the two amino groups in the diamine. Two carbon segments were superior to three carbon segments which were better than one or four carbon segments. The decomposition rate of n‐butyllithium was also strongly accelerated by the presence of many of these diamines.
Immobilization of papain on crosslinked polymer supports: Role of the macromolecular matrix on enzymic activity
Authors: Jayakumari V. G. , Pillai V. N. Rajasekharan 
Published: April 2003

AbstractPapain was immobilized on polymer supports with spacer arms of varying nature and length. As the length of the spacer arm increased, there was a marked increase in the extent of enzyme immobilization and activity of immobilized enzymes. When a long, flexible and hydrophilic polyethylene glycol spacer was introduced between the polystyrene backbone and the functional group used for immobilization, the extent of coupling and enzyme activity increased. Dependence of enzyme activity on the nature and extent of crosslinking and on the nature of the polymeric backbone was investigated. Hydrophilic polyacrylamide‐based supports were found to be more efficient supports for immobilization compared to hydrophobic polystyrene‐based supports.
Acrylic block copolymer analysis by adsorption chromatography with evaporative light scattering detection
Authors: Neff B. L. , Spinelli H. J. 
Published: April 2003

AbstractBlock copolymers of methyl methacrylate and butyl methacrylate are characterized using silica adsorption chromatography with a toluene‐2‐butanone solvent gradient. Evaporative light scattering is the detection method for these otherwise hard to detect acrylic polymers. The homopolymer contamination in the diblock materials are well resolved from the diblock in the separation. The major separation mechanism is composition controlled, but the results also indicate a block length dependency on the separation mechanism.
Characterization of acetylene terminated sulfone (ATS) resin. I. Chemical characterization of the resin
Authors: Stevenson W. T. K. , Goldfarb I. J. 
Published: April 2003

AbstractAn acetylene terminated sulfone resin mixture, prepared under contract for the Air Force, was subjected to a fairly extensive compositional analysis. Monomer, dimer, higher oligomers, solvents, and anomalous side products of synthesis were isolated, identified, and quantified using separatory procedures such as column chromatography and thin film flash distillation, in conjunction with techniques of chemical analysis such as infrared and nuclear magnetic resonance spectroscopy, size exclusion chromatography, and elemental analysis. By these means we were able to precisely characterize the resin mixture and, by so doing, identify some side products of synthesis; most notably, a class of abnormal coupling product able to chelato palladium (a catalyst used in acetylation of the resin) and, therefore, accelerate subsequent acetylene polymerizations in the resin mixture.
Study of the synthesis and properties of PBA/PS/PMMA latex interpenetrating polymer networks
Authors: Liucheng Zhang , Xiucuo Li , Tianchang Liu 
Published: April 2003

AbstractIn this article, we use the technique of multistage emulsion polymerization to synthesize the LIPN PBA/PS/PMMA and use the gravimetric analysis method to study the apparent kinetics of the reaction process and to investigate the influence of the concentration of the initially emulsifying agent, the initiator, and the extent of the crosslinking on the distribution of the particle diameter and the dynamic mechanical properties of the products.
Wholly aromatic polyamide‐hydrazides. V. Preparation and properties of semipermeable membranes from poly[4‐(terephthaloylamino) benzoic acid hydrazide]
Authors: Dvornic Petar R. 
Published: April 2003

AbstractEffects of several processing parameters on the properties of poly[4‐ (terephthaloylamino) benzoic acid hydrazide] semipermeable membranes were investigated. The membranes were prepared using a polymer phase inversion method that consisted of the following sequence of steps: casting of thin, neutralized polymer solution layers on suitable solid support; thermal treatment of the obtained layers to form viscous liquid protomembranes; coagulation of the protomembranes into solid semipermeable membranes; and, when that was additionally desired, posttreatment of the obtained membranes in order to further affect their final separation properties. The processing parameters investigated included temperature and time of exposure to thermal treatment during the preparation of protomembranes, nature of the employed medium, time of exposure, and temperature of the posttreatment of coagulated membranes. In addition, particular attention was devoted to the effect of polymer molecular weight on the properties of the membranes, and for that purpose a series of five polymer samples with molecular weights that ranged from about 17,000 to about 64,500 was prepared using the previously described viscometrical method to monitor the polymer forming polycondensation reactions. The results obtained showed that membrane performance was very much influenced by all of the examined processing variables and that products with considerably different properties could be obtained from the same polymer sample by using different processing parameters. Thus, the use of higher temperatures and longer exposure times in the protomembrane forming thermal treatment step gave higher rejection and lower permeability of the finished membranes, although there seems to exist limiting “ceiling conditions” above which this trend rather abruptly ceases to continue any further. It appears that these conditions correspond to the onset of irreversible changes, either in the polymer chemical structure or in the membrane supermolecular organization. Posttreatment of the prepared membranes was found essential for useful properties in the single‐stage separation applications, which require high membrane selectivity. Of the investigated possibilities, annealing in boiling deionized water was crucial, while exposure to concentrated acids was also important in the case of HCl but rather deleterious in the case of H2SO4. Most significantly, the membrane properties clearly depended on the polymer molecular weight, and it was found that there was a critical polymer molecular weight above which this dependence ceased to be important for practical purposes. It is suggested that this may be a general phenomenon, characteristic for all membrane forming polymer materials, and a possible explanation of its nature is tentatively offered.
Investigation on the kinetics of the adsorption process of aliphatic amidpolyamine on cellulose
Authors: Nedelcheva Margarita Petkova , Mladenova Stefka Marinova , Valcheva Eva Todorova 
Published: April 2003

AbstractInvestigation has been carried out on the kinetic dependences of the adsorption process of aliphatic amidpolyamine (lamide‐1, L‐1) on three kinds of bleached pulp (sulfate pulp of hard wood and sulfate and sulfite pulp of soft wood) at temperatures of 0, 20, 40, and 60°C within a concentration interval of 0.030 g/liter + 0.500 g/liter. It has been established that the kinetic process can be described by the Elovich–Tyomkin exponential kinetic equation. The activation energy is of the order of 4.12–4.42 kJ/mol and the entropy factors substantially affect the process speed. The coefficients of the correlations describing the effect of the L‐1 solution concentrations on the coefficient of heterogeneity (α) and the initial adsorption speed (V0) have been determined.
Durability properties of γ‐radiation‐induced polymer‐modified mortar. I. Effect of sodium sulfate
Authors: Ismail M. R. , El‐Hemaly S. A. S. 
Published: April 2003

AbstractThe influence of sodium sulfate solutions on the physicomechanical properties of neat and modified cement mortar has been investigated. The samples were immersed in sodium sulfate solutions having different concentrations between 0.5 and 2.5% and immersion times from 20 to 100 days. The effect on the compressive strength, weight loss, bulk, density, and water absorption and the microstructure (scanning electron microscopy) were studied. The results indicate that the compressive strength and loss in weight decrease with the increase in sodium sulfate concentration and immersion time. The bulk density increases and then decreases as a result of the increase in sodium sulfate concentration and the time of storage, whereas water absorption behaves in an opposite direction, probably due to partial dissolution of the hydrated products. SEM study showed the formation of new products and voids between the particles were pronounced.
Syntheses and properties of cationic amine–epoxy adducts and their use in electrodeposition: I. Diethanolamine/diethylamine terminated cationic epoxy with pendant 2‐ethylhexanol‐blocked TDI groups
Authors: Yang Chin‐Ping , Chen Yahn‐Haur 
Published: April 2003

AbstractAlkyl partially blocked toluene diisocyanate (PBTDI) and hydroxyl group‐containing polyepoxide were mixed to produce a blocked TDI–epoxy resin and then reacted with secondary amine and treated with acetic acid to give a cationic resin. In this study, six cationic resins (IV‐A and IV‐B, two series) were synthesized from three diglycidyl ethers of bisphenol A with different epoxy equivalent weights of 508, 650, and 950, and two secondary amines (diethylamine and diethanolamine). Acetic acid was used as the neutralization agent and ethylene glycol mono‐n‐butyl ether (butyl cellosolve, BCS) and deionized water were utilized as the emulsion solvents. Some properties of electrodeposition, such as throwing power and rupture voltage, and some physical and chemical properties of the deposited films were investigated.It was found that the appearance of emulsion, deposition yields, and quality of the deposited films are strongly dependent on pH, BCS, and resin contents. To obtain suitable deposition properties and stable emulsions from IV‐A and IV‐B systems, the aqueous dispersion should meet the following conditions: pH, 5.5‐6.0; BCS contents, 3.0–5.0 wt %; and resin concentration, 7.0–9.0 wt %. For both systems, the deposited films had good appearance, adhesion, hardness, and alkali reagent resistance. The salt spray resistance and acid resistance of films deposited from series III‐A (epoxy resin formulations containing diethylamine) are superior to films deposited from series III‐B (epoxy resin formulations containing diethanolamine).
Terpolymerization studies: IV. Terpolymerization of ethyl acrylate, ethyl α‐cyanocinnamate, and styrene
Authors: Angelovici Mose M. , Kohn David H. 
Published: April 2003

AbstractEthyl acrylate, ethyl α‐cyanocinnamate, and styrene were terpolymerized by free radical initiation at 60°C up to low conversion. The relationships between monomer feed and compositions of the terpolymers were determined by a triangular graph according to Slocombe. The terpolymers were characterized by their IR and Proton NMR spectra, intrinsic viscosity, and thermal behaviour. For a selected terpolymer, its adhesive properties for a number of substrates was investigated.