bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and fundamental structural analysis of composite PVC latices
Authors: Omi Shinzo , Shiiyama Eisuke , Aita Kazuyoshi , Matsumoto Masatoshi , Iso Mamoru , Sakaya Mitsuro , Nakano Akira , Imazawa Yasuta
Published: April 2003

Syntheses of various combinations of composite particles were carried out employing PVC‐based latices, PVC, PVC–VAc and PVC–VD, as seed particles. Monomers for seed polymerization were chosen so that the solubility in water and the compatibility with seed polymer may influence the features of products. MMA, whose coverage improves the flow characteristics of PVC plastisols to a great extent, was most investigated along with MMA‐ST, BMA, and ST. Smaller monomerpolymer feed ratio (M/P), smaller seed size, and the employment of monomers sparsely soluble in water were the key factors in preventing the nucleation of secondary particles during the seed polymerization. A quantitative correlation to evaluate how effectively monomer is converted for the formation of composite particles was proposed. Analyses by means of the electron microscopy (TEM and SEM), GPC, DSC, and TLC strongly anticipated the development of IPN structure and the formation of graft linkage between PVC–VAc core and PMMA.
Polysulfone hollow fiber membranes spun from aliphatic acid (C2—C4): N‐methylpyrrolidone complexes—structure determination by oxygen plasma ablation
Authors: Fritzsche A. K. , Cruse C. A. , Kesting R. E. , Murphy M. K.
Published: April 2003

Polysulfone hollow fiber membranes with increased free volumes as reflected by elevated glass transition temperatures can be obtained from a spectrum of Lewis acid : N‐methylpyrrolidone (NMP) complexes provided that the complex is readily dissociated by water. The upper limit of the candidate Lewis acid for suitable complexes is an acceptor number between 49.1 (propionic acid) and 52.9 (acetic acid). Although the enhanced free volume yields an increase permeability with maintenance of selectivity, a knowledge of the structure and morphology of both the active separating layer and the substructure is needed to understand the performance of the membrane. Oxygen plasma ablation experiments have shown that the active separating layer of these membranes decreases in the order NMP/FA > acetic acid : NMP > propionic acid : NMP, butyric acid : NMP, and isobutyric acid : NMP with the differences among the last three being too small to resolve by the current experiment. Also, the surface and internal pore size and internal porosity appeared to increase in the order NMP/FA < acetic acid : NMP < propionic acid : NMP < isobutyric acid : NMP < butyric acid : NMP.
Grafting onto isotactic polypropylene. III. Gamma rays induced graft copolymerization of water soluble vinyl monomers
Authors: Mehta I. K. , Kumar Sunil , Chauhan G. S. , Misra B. N.
Published: April 2003

Graft copolymerization of water soluble vinyl monomers such as acrylic acid and acrylamide onto isotactic polypropylene by the pre‐irradiation method has been studied. Grafting was carried out in a water and water‐methanol solvent system. The percentage of grafting has been determined as a function of (i), total dose (ii) concentration of monomers, (iii) reaction time, and (iv) the composition and amount of water‐methanol solvent system. Water was found to be the best solvent for affording maximum grafting. The grafted samples were characterized by spectroscopic and thermogravimetric methods. Acrylic acid was found to be more reactive than acrylamide towards graft copolymerization.
The effect of compounding ingredients on microbial degradation of vulcanized natural rubber
Authors: Tsuchii Akio , Hayashi Kouji , Hironiwa Tadashi , Matsunaka Hiroshi , Takeda Kiyoshi
Published: April 2003

A series of natural rubber vulcanizates containing varied amounts of sulfur and an accelerator (N‐cyclohexyl‐2‐benzothiazyl sulfenamide, CBS) were prepared and their resistance to attack by a strain of Nocardia, capable of utilizing natural rubber as carbon substrate, was examined. The higher the content of sulfur or CBS, the less the weight loss of the vulcanizates after microbial attack. In this system of curing without a filler, the rate of microbial degradation was suggested to depend on the cross‐link density estimated from the swelling. Addition of calcium carbonate as a filler did not affect the microbial degradation, and in some cases slightly enhanced it. Addition of carbon black, however, made the vulcanizate apparently more resistant to microbial attack. The specimens with HAF grade carbon black loading were more resistant than those with SRF grade.
Synthesis and characterization of conjugates of poly(α‐amino acids) and manganese (III) protoporphyrin IX as relaxation enhancement agents for MRI
Authors: Spaltro Suree M. , Foster Natalie
Published: April 2003

Polymers are finding increasing use in medicine, and conjugates of paramagnetic species and polymers are now being studied as relaxation enhancement agents to improve contrast in magnetic resonance imaging. To assess the potential of such agents, the enhancement of proton relaxation by paramagnetic species bound to macromolecules has been observed for four conjugates of amino acid polymers and manganese (III) protoporphyrin IX. The conjugates all differ in their abilities to enhance the relaxation of water protons in solution; values of relaxation rates range from 3.2 to 9.1 s−1 mM−1. The rotational correlation times and volumes of the kinetic units within the macromolecules have been determined by fluorescence depolarization in an effort to understand the range of relaxation rates observed for the conjugates. The metalloporphyrins bound to the polymers all have very similar dynamic characteristics.
Aromatic copolyimide membranes for high temperature gas separations: H2/CH4, H2/N2, and O2/N2
Authors: Buys H. C. W. M. , van Elven A. , Jansen A. E. , Tinnemans A. H. A.
Published: April 2003

A series of high‐molecular weight condensation polyimides prepared from pyromellitic dianhydride (PMDA) or 3,3,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA) with 4,4′‐oxydianiline (ODA) and/or 1,5‐diaminonaphthalene (NA), and a series of high‐molecular weight condensation poly(amide–imides) prepared from trimellitic anhydride acid chloride (TMAC) with ODA and/or NA were evaluated to determine, in the temperature region 50–250°C, the effect of polymer molecular structure on the permeability and ideal permselectivity of hydrogen, oxygen, nitrogen, and methane. Replacement of ODA with NA generally decreases the permeability of each gas but it increases the permselectivity, which is explained by suppression of both the packing disruption effect and intrasegmental mobility of the amine segments. In general, the overall lower permeation values for the TMAC series of polyimides are much lower than the BTDA‐derived series, being the highest for the PMDA‐derived series. Permeation data were used to calculate the performance of a hollow fiber module on an industrial scale. It is shown that hydrogen can be efficiently recovered (> 90%) with a purity of at least 95% from ammonia synthesis off‐gas with a feed concentration of 61 mol % of hydrogen.
Flame retardancy effect of crosslinking of lignocellulose materials
Authors: S̆imkovic Ivan , Pastýr Jan , Csomorová Katarína , Balog Karol , Micko M. M.
Published: April 2003

Dynamic and isothermal thermogravimetry (TG) was used for the study of flame retardancy effects caused by crosslinking of lignocellulose materials. This effect was also checked with the limited oxygen index (LOI) method. It was found that dynamic TG measurements run to 400°C could indicate the decrease of flame retardancy effect when lower residues are observed for samples measured in oxidative in comparison to inert environments. The isothermal TG data of initial reactions are not suitable for the prediction of flame retardancy effects. Epichlorhydrin (E) is a suitable chemical for the flame retardancy of wood. The addition of polyethyleneimine (PEI) decreases the flame retardancy of wood. On the other hand xylan crosslinked with E gives lower LOI values than the xylan crosslinked in the presence of PEI.
Novel rheological model for the gelation kinetics of ionic polysaccharides
Authors: Lapasin Romano , Pricl Sabrina , Paoletti Sergio , Zanetti Flavio
Published: April 2003

Homogeneous networks of an ionic polysaccharide (namely pectate) in the presence of divalent ions were prepared in situ by proper procedure and the kinetics of the gel formation was studied by means of a coaxial cylinder rheometer in oscillatory flow conditions. The stress response was expanded in a Fourier series and the variation of the components of the fundamental harmonic with time during the gelation process were examined. A model is proposed for the correlation between kinetic parameters such as the concentration of the species active during the gel formation and the rheological parameters that can be experimentally determined, like G′ and G′′. Considerations are developed concerning the mechanism that governs the gelation process under dynamic conditions.
Environmental effects on latex paint coatings. I. Base polymer degradation
Authors: Patil D. , Gilbert R. D. , Fornes R. E.
Published: April 2003

Films of the base polymer used in a latex paint have been exposed to various combinations of UV/SO2/H2O/air. The polymer is primarily a terpolymer of butyl acrylate, vinyl acetate, and vinyl chloride. Reported here are results from dynamic mechanical analysis (Tg), sol‐gel analysis, intrinsic viscosity and contact angle measurements. Exposure without the presence of UV and causes virtually no change in the properties of the films. In the presence of UV and clean air containing O2. there is evidence of both chain scission and crosslinking. When films are exposed to combinations of either UV/SO2 or UV/SO2H2O, a dramatic increase in the rate of change in the properties is observed, indicating a synergistic interaction between UV and SO2. The gel fraction increases from about 20% for the control to about 65% in samples exposed to UV/SO2 or UV/SO2/H2O for as little as 24 h. In the latter exposed samples, there is a corresponding precipitous drop in the intrinsic viscosity of the soluble fraction, a significant increase in the surface polarity of the films, and a large increase in the Tg. Reaction mechanisms for changes resulting from the various exposure conditions are proposed.
Organic polymer analysis by laser ionization mass spectrometry and pattern recognition techniques
Authors: Di Brozolo Filippo Radicati , Odom Robert W. , Harrington Peter de B. , Voorhees Kent J.
Published: April 2003

Results obtained by combining pattern recognition techniques with the organic microanalysis capability of laser ionization mass spectrometry (LIMS) for identifying and classifying the mass spectra produced from 19 different polymer formulations are reported. The data demonstrates that the LIMS mass spectra of many polymers are sufficiently unique to permit accurate classification of different polymers. The results obtained also suggest that pattern recognition procedures combined with laser microprobe analyses could provide a routine and reliable method of performing microanalytical characterization of unknown polymers.
GPC studies on the cationic polymerization of cardanol initiated by borontrifluoridediethyletherate
Authors: Antony Rosy , Pillai C. K. S. , Scariah K. J.
Published: April 2003

The cationic polymerization of cardanol using borontrifluoridediethyletherate as initiator has been investigated by gel permeation chromatographic techniques. The molecular weight and molecular weight distribution of the polymer at different temperatures and various initiator concentrations were studied, and the polymerization conditions have been optimized as 140°C with an initiator concentration of 1%. The reaction was found to follow first‐order kinetics with respect to the monomer. The activation energy and rate constants for the system have also been evaluated. The polymer has been characterized by IR, 1H and 13C‐NMR spectra.
Comparison of the properties of thermotropic liquid crystalline copolyesters containing different disymmetrical units
Authors: Kim H. D. , Paul D. R.
Published: April 2003

The effect of dissymetrical units on the properties of thermotropic liquid crystalline copolyesters based on hydroxybenzoic acid (HBA), terephthalate) acid (TPA), and poly(ethylene terephthalate) (PET) units was examined. The dissymmetrical units employed included 2,7‐dihydroxynaphthalene (2,7‐DHN),1,4‐dihydroxynaphthalene (1,4‐DHN), and bromo‐hydroquinone (Br‐HQ). All of these polymers exhibited turbid melts. The flexible PET units lower the melting and/or stick temperature, and between 10 to 20 mol % is a critical level to achieve values in the range of 250°C or lower. The copolyesters based on 2,7‐DHN have the highest glass transition temperatures and maintain stiffness to the highest temperatures. The properties of each series of copolyesters are discussed in terms of the efficiency of molecular packing. The effects of chemical and physical inhomogeneity are emphasized.
Polyglycol modified poly(ethylene ether carbonate) polyols by molecular weight advancement
Authors: Harris Robert F.
Published: April 2003

Poly(ethylene ether carbonate) polyols can be modified by chemical reactions with polyglycol modifiers under conditions of elevated temperatures and reduced pressures, where diethylene glycol is removed as distillate. Molecular weight builds in a predictable manner and can be controlled by the amount of distillate removed. A reaction pathway for this transformation is proposed. It is important that the modifier be stable to reaction conditions and have a higher boiling point than diethylene glycol. The process has been characterized by following the distillate formation and composition as a function of reactor temperature and product molecular weight build. The product has been characterized by molecular weight, CO2 content, carbon–13 NMR and viscosity/temperature relationships. Carbon–13 NMR of the carbonyl and methyl regions of the spectra are particularly useful for following the chemical changes. A new family of modified poly(ethylene ether carbonate) polyols has been prepared which was not available with prior technology. The modification procedure permits the control of properties such as modifier type and content, molecular weight, CO2 content, viscosity, Tg, density, etc., in the resultant polyol. Since poly(ethylene ether carbonate) polyols have predominantly polyester polyol properties, modification with polyether polyols can be used to adjust properties. These polyols are useful in polyurethane applications.
A durability index in the weathering of low‐density polyethylene (LDPE) films
Authors: Gonzalez A. , De Saja J. A. , Requejo A. , Barahona F. J.
Published: April 2003

Degradation resulting from weathering in low‐density polyethylene (LDPE) films used in agricultural applications was investigated by a series of mechanical and spectroscopic characterization techniques. An easy, nondestructive, and comparatively sensitive test for measuring the durability of these films based on microhardness indentations is presented.
Dicumyl peroxide‐modified cellulose/LLDPE composites
Authors: Sapieha S. , Allard P. , Zang Y. H.
Published: April 2003

The present study reports results on the processing and mechanical properties of composites modified by the addition of dicumyl peroxide (DCP). The addition of minute amounts of peroxide to the cellulose/polymer system during processing has been shown to significantly improve the physical properties of composites. SEM micrographs of fracture surfaces of the peroxide modified composites reveal direct grafting of polyethylene onto cellulose fibers. The existence of a critical peroxide concentration indicates that the grafting reactions terminate when cellulose surfaces are no longer accessible. Possible mechanisms involved are discussed.
Interaction of some highly aggressive solvents and effect of temperature on the transport characteristics of polyurethane
Authors: Aminabhavi T. M. , Aithal U. S.
Published: April 2003

A number of highly interacting liquids have been used as penetrants to study their transport characteristics into a commercial polyurethane membrane. The penetrant‐polyurethane interaction is strongly dependent on the nature of the interacting molecules. With tetrahydrofuran, dioxane, cyclohexanol, acetophenone, and benzyl alcohol the polymer swells greatly even at room temperature, and in such cases, sorption experiments were not carried out at higher temperatures. In a few other cases like pyridine, aniline, etc., thea polymer loses its shape and physical integrity leading to chemical degradation reactions. Some of the otherwise normally behaving liquids like n‐butanol, 1,4‐dichlorobutane, anisole, toluene, chlorobenzene, and nitrobenzene did not reach equilibrium at high temperatures (70–90°C) even after prolonged exposure, making it difficult to interpret the sorption data. The results of this study may be useful to make an overall assessment about the application of polyurethane under extreme service conditions. Furthermore, concentration‐independent diffusion coefficients have been calculated for those penetrant—polymer systems which exhibited the least amount of swelling. For highly swelling liquids, the transport mechanism deviates from the normal Fickian mode and diffusion coefficients for such systems have not been obtained.
Magnetic field effect on photocrosslinking reaction of directly excited azidomethylated polystyrene
Authors: Morita Hiroshi , Uchino Noriaki
Published: April 2003

Gel fractions of thin films of poly(styrene‐co‐vinylbenzyl azide) (AZMS) irradiated with a low pressure mercury lamp were measured in the absence and in the presence of an external magnetic field. By the application of a magnetic field of 0.089 T, the gel fraction of AZMS decreases, and the efficiency of photocrosslink formation decreases by ≈︁ 20%, in contrast to the case of sensitized photocrosslinking of AZMS where the efficiency increases by the application of a magnetic field. Based on the photocrosslinking mechanism of directly excited AZMS, it is concluded that the singlet nitrene which is produced from the singlet excited AZMS abstracts a hydrogen atom from the AZMS polymer to form the singlet radical pair, and that the magnetic field decreases the singlet–triplet intersystem crossing rate of the radical pair.
Thermal behavior and cured products of mixtures of two different bismaleimides
Authors: Nagai Akira , Takahashi Akio , Suzuki Masao , Katagiri Junichi , Mukoh Akio
Published: April 2003

The thermal behavior of a new Bismaleimide, 2,2‐bis[4‐(4‐maleimidophenoxy)phenyl]propane (BBMI) and its mixtures with a conventional monomer, bis(4‐maleimidophenyl)methane (BMI) were investigated by differential scanning calorimetry. The melting point of BBMI was 142°C, lower than that of BMI, although its molecular weight is about twice that of BMI. Each of these bismaleimides and their mixtures showed a melting point when heating, but did not have a distinct freezing point when cooling because of vitrification. The unobserved freezing curve was estimated by calculation based on Schröder's equation using melting point and molar heats of fusion in both bismaleimides. The cured product of BBMI has thermal stability as good as that of BMI. Moreover, the cured product of BBMI has a high flexurai strength and a high flexural elongation owing to the introduction of flexible ether bonds and long phenoxy groups within the monomer structure.
Synthesis and properties of new tetrafunctional epoxy resins containing oxyethylene units
Authors: Iijima Takao , Hiraoka Hideki , Tomoi Masao , Kakiuchi Hiroshi
Published: April 2003

Tetraglycidyl ethers of 2,2′,2″,2‴[sulfonyl bis(4,1‐phenylenenitrilo)] tetrakisethanol and 2,2′,2″,2‴[methylene bis(4,1‐phenylenenitrilo)]tetrakisethanol were synthesized and characterized. Curing reactivities of these new epoxy resins are investigated by differential scanning analysis. The mechanical, thermal, and dynamic mechanical properties of these resins cured with p,p'‐diaminodiphenylsulfone were examined and compared to those fo the conventional tetrafunctional epoxy resin (MY‐720). These new epoxy resins have the advantages of being easier to handle, having higher curing reactivities, and giving cured resins with higher toughness, compared with MY‐720 resin.
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

A 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

Styrene (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

The 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

A 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

Four 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

The 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

Triethylene 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

Cationic 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

A 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

A 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

The 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

Dilute 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

The 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

Papain 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

Block 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

An 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

In 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

Effects 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

Investigation 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

The 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

Alkyl 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

Ethyl 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.
Interaction of poly(methyl methacrylate) and manganese chloride
Authors: Wilkie Charles A. , Leone Joseph T. , Mittleman Martin L.
Published: April 2003

The thermal degradation of poly(methyl methacrylate) (PMMA), in the presence of manganese chloride has been studied by sealed tube reactions and thermogravimetric analysis coupled to FT‐IR spectroscopy. From sealed tube reactions it was found that the degree of mixing of the MnCl2 and PMMA has an important effect on monomer formation. In systems where the two components are simply poured together, the amount of monomer is about half that observed for the thermolysis of PMMA alone; when the two components are thoroughly mixed by dissolution in solvent, the monomer yield fails to zero. The TGA–FT‐IR experiment on solvent mixed material does show the presence of monomer. In sealed tubes, monomer may not escape and must repolymerize, while in the TGA experiment the monomer is swept out before reaction may occur. Monomer production also commences at temperatures lower than those for degradation of PMMA alone. It is apparent that manganese chloride catalyzes both the degradation of polymer to monomer and the reoligomerization of this monomer. The gases that are produced include CO, CO2, CH3Cl, HCl, and CH4. A mechanism is proposed to account for all of these products and a manganese ionomer is the final product of the reaction.
Photochemistry and photopolymerization activity of perester derivatives of benzophenone
Authors: Allen N. S. , Hardy S. J. , Jacobine A. F. , Glaser D. M. , Yang B. , Wolf D. , Catalina F. , Navaratnam S. , Parsons B. J.
Published: April 2003

The spectroscopic properties and photopolymerization activities of a mono‐ and tetraperester derivative of benzophenone are examined and compared with those of benzophenone. Their photopolymerization activity in methyl methacrylate (MMA) and an ethoxylated bis‐phenol‐A diacrylate have been studied using a combination of gel permeation chromatography (GPC), and real time Fourier transform infrared spectroscopy (RTFTIR) as well as the commercial pendulum hardness test. Using GPC analysis on the poly(methyl methacrylate) samples the tetra‐‐t‐butyl perester derivative of benzophenone is found to give a higher weight average (Mw) and number average (Mn) molecular weight polymer than that produced using the mono perester. For the two peresters of benzophenone photopolymerization efficiency using real time FTIR increases with increasing initiator concentration, and no self‐termination is observed up to 0.75% w/w concentration with the mono perester derivative being the more efficient initiator. Similar results were obtained using the commercial pendulum hardness tester with a triacrylate/epoxyurethane acrylate resin with benzophenone exhibiting the lowest activity. Photopolymerization activities of the initiators correlate well with their spectroscopic properties. The phosphorescence quantum yield is higher for the monoperester than the tetraperester derivative and is consistent with a shorter lifetime and lower photolysis quantum yields in 2‐propanol. Compared with benzophenone, phosphorescence analysis indicates that the perester groups impart a degree of charge‐transfer content to the molecule which is consistent with the degree of substitution. Ketyl radical formation on microsecond flash photolysis follows the order benzophenone > mono‐ > tetraperester derivative and is consistent with the phosphorescence quantum yields. On nanosecond laser flash photolysis in nitrogen‐saturated acetonitrile, triplettriplet absorption is extremely weak for both the perester derivatives, being stronger for the monoperester.