bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aminimide as hardener/curing promotor for one part epoxy resin composition
Authors: Niino Hideki , Noguchi Saburo , Nakano Yoshitomo , Tazuke Shigeo 
Published: April 2003

AbstractThree kinds of aminimide compounds were examined as latent hardeners/promotors for epoxy resins. Since aminimides are thermolyzed to generate tertiary amine and isocyanate, the compounds are useful as polymerization initiators for the epoxy group as well as promotors for epoxy–acid anhydride reaction. The pot life was over 30 days at 40°C for a formulated one‐part epoxy resin system. In comparison with epoxy resins cured with conventional hardeners, several interesting characteristics of the mechanical and electrical properties were observed. In particular, the epoxy resins cured by aminimides exhibited high tensile strength and high impact strength, which make them excellent curing agents for adhesive applications. The reasons for these unique properties are discussed.
Graft copolymerization of methyl methacrylate onto wool by use of ferrous ion–peroxodiphosphate
Authors: Subhan Jahanara , Saccubai S. 
Published: April 2003

AbstractPolymethyl methacrylate has been graft copolymerized onto wool using a ferrous ion–peroxodiphosphate initiator system in an aqueous methanol medium. Graft copolymerization was carried out at 20°C, 30°C, 40°C, and 50°C. The rate of grafting was found to be dependent on the concentrations of monomer (MMA), ferrous ion (Fe2+), peroxodisphosphate (PP), wool (w), and reaction temperature. [Acid], solvent composition and ionic strenghth were also varied to study their effect on grafting. Based on the experimental results, a suitable kinetic scheme was proposed. Rate and thermodynamic parameters were also varied to study their effect on grafting. Based on the experimental results, a suitable kinetic scheme was proposed. Rate and thermodynamic parameters were also evaluated.
The rejection of polar organic solutes in aqueous solution by an interpolymer anionic composite reverse osmosis membrane
Authors: Koyama Kiyoshi , Nishi Takao , Hashida Isao , Nishimura Masato 
Published: April 2003

AbstractReverse osmosis separation for many kinds of polar organic solutes (alcohols, phenols, monocarboxylic acids, amines, and ketones) was examined by an anionic charged composite membrane. The solute permeation was carried out in single‐solute aqueous solution (200 mg/L) under applied pressure of 7.88 MPa at 25°C. The correlation between the solute rejection and polar parameters for these organic solutes have been investigated. For n‐alkyl alcohols, monocarboxylic acids, and ketones, the solute rejection increases with molecular weight and/or molecular branching. For undissociable polar organic solutes such as alcohols and ketones, solute rejections are closely related with the Taft's number. For dissociable polar organic solutes, solute rejections depend greatly upon the dissociation constant and the degree of dissociation of solute. This membrane showed higher rejection (80%) for phenol in an undissociated state at a 98% rejection level of NaCl. Also, rejections of phenolic derivatives depend upon the pH value of the feed solution and the polar effect of substituted groups. For acetic acid and methylamine, the solute rejection increases proportionally to the degree of dissociation of solute. From these facts, the main factors in reverse‐osmosis separation by an anionic composite membrane are discussed.
The rate of plasticizer uptake by suspension PVC
Authors: Davidson John A. 
Published: April 2003

AbstractA microscopic technique employing image analysis was developed to measure the rate of swell of suspension PVC particles in both excess and finite amounts of plasticizer at temperatures below the crystalline melting point. The rates of plasticizer uptake derived from these swell measurements were found to be dependent upon the concentration of plasticizer and the rate of heating. A high value for the activation energy for plasticizer uptake was observed (60–100 kcal/mol) in agreement with earlier work. Each resin was also characterized by a total capacity for plasticizer (TC) which was found to be dependent on the resin type, the plasticizer type, and the maximum temperature achieved. An expression was derived for the rate of plasticizer uptake in a Brabender powder mix experiment. In this case the dry time is controlled by a single rate up to the maximum capacity for plasticizer of the resin (Gmax). Values of Gmax and TC were found to correlate on a one‐to‐one basis when measured at the same temperature. In all the cases investigated the rate of plasticizer uptake in the Brabender was found to correspond to a rate derived from image analysis swell at a plasticizer level of 0.25 cc/g. This behavior was in apparent contradiction to the concentration dependence generally observed and was demonstrated to be due to the large thermal gradients which exist in the Brabender powder mix head during the experiment. This work illustrates that Brabender powder mix times may have no relationship to dry times in a high speed mixer where heating is both even and higher temperatures are achieved.
Modelling of condensation polymerization of novolac‐type phenol–formaldehyde in homogeneous, continuous‐flow, stirred‐tank reactors
Authors: Kumar Anil , Phukan Uzzal K. , Gupta Santosh K. 
Published: April 2003

AbstractA detailed kinetic model for the novolac‐type phenol–formaldehyde polymerization has been proposed in terms of five reactive sites. These sites have been shown to have different reactivities. Mass‐balance equations for homogeneous, continuous‐flow, stirred tank reactors (HCSTR) for each of the species have been written, and these have been solved numerically. A comparison of the results with those for the batch reactor shows that, for a given residence time, smaller but more polydispersed and branched chains are formed.
Alternating copolymers of butadiene and propylene: Properties and characterization
Authors: Wieder W. , Kroemer H. , Witte J. 
Published: April 2003

AbstractAlternating copolymers of butadiene and propylene (BPR) made by a solution polymerization technique with a modified catalyst of the Furukawa type have highly regular structures. The constitutional repeating unit consists of one propylene and one 1,4‐trans‐butadiene unit. No chain imperfections were detected, except for ≦2% 1,4‐cis‐butadiene units. The configurations of the chiral tertiary carbon atoms in the propylene units could not be directly determined by spectroscopic methods. The intrinsic viscosities of the samples studied lie between 1.1 and 1.8 dL/g. The high molecular weight fractions (M > 2 × 105) show long‐chain branching. Crystallization effects, namely, a decrease in specific volume with time, and melting are observed after annealing unoriented samples at temperatures between −30 and −50°C. X‐ray diffraction shows that the structure of the ordered phase depends on polymerization conditions, varying between a liquid crystal‐like close packing of parallel chain segments and imperfect crystalline, three‐dimensionally periodic arrangements of chains. Both in the noncrystalline and crystalline ordered phases, the molecules are arranged in layers with a spacing of 0.47 nm. The crystalline chains have nonplanar and not fully extended conformations with a repeat distance of 0.72 nm. The rate of crystallization and the relative decrease in volume (≦1.3%) are small compared to stereoregular polymers like natural rubber and high‐cis polybutadiene. In crosslinked specimens, stretched 1:6 to 1:10, the crystalline or liquid crystal‐like structure persists up to +60°C. The imperfect nature of the crystallization of BPR is caused by stereoisomerism of the chiral carbon atoms. The chains are probably composed of short tactic sequences separated by tactic arrangements.
Graftability of beaten pulps and acetylated pulps
Authors: Heikal Salwa O. , El‐Shinnaway Nabila A. , Elkalyoubi Samera F. 
Published: April 2003

AbstractCe(IV)‐induced polymerization of acrylonitrile with acetylated bagasse and wood pulps, having different acetyl contents, has been investigated. The graft yield is dependent on the acetyl content as well as the origin of the pulp. Increasing the acetyl content of pulps caused a significant decrease in the polymer loading. However, the rate of polymerization of acetylated wood pulp is much higher than that of acetylated bagasse pulp. The ceric consumption during grafting decreases as the acetyl content of the pulp increases. The effect of beating of the pulps, to various degrees of freeness, on their reactivity toward grafting process has also been studied. Generally, the state of cellulose, as defined by its degree of beating, and the origin of the pulp strongly influenced the graft yield. In creasing the beating degree of bagasse pulp resulted in a decrease in graft yield, while beating of wood pulp, to a definite degree, inhibits the polymerization reaction. The consumption of Ce(IV) by the beaten pulps during oxidation is somewhat greater than that consumed by the unbeaten pulps, whereas the consumption during grafting of acrylonitrile onto beaten pulps depends on the initial concentration of ceric solution. Also, the effect of grafting of acrylonitrile onto acetylated wood and bagasse pulps on their strength properties as well as the effect of grafting onto beaten pulps on their properties has been investigated. Grafting of acrylonitrile onto acetylated bagasse pulp decreased its strength properties, but improved its beatability comparatively to those of original pulp (0 acetyl content). On the other hand, grafting of acrylonitrile onto acetylated wood pulp resulted in a great improvement in its strength properties compared to those of grafted unacetylated pulp. Grafted unbeaten pulps gave thinner and weaker paper than the original pulp (without grafting). Beating of bagasse pulp before grafting gave pulp which possessed a higher strength properties, at low °SR, than those of pulp beaten after grafting. Raising the °SR by rebeating the pulp after reaction up to the original value had an adverse effect on the strength. Beating of bagasse pulp before grafting did not accelerate the reaction rate, but it saved some power consumption, since the time required for beating of grafted pulp to a given °SR was lower than that of ungrafted pulp.
Synthesis and physicochemical studies of some new amphoteric ion exchangers
Authors: Kapadia R. N. , Dalal A. K. 
Published: April 2003

AbstractSome new amphoteric ion exchangers have been synthesized by condensing salicylic acid, p‐hydroxybenzoic acid, sulfosalicylic acid, gallic acid, 3‐hydroxy‐2‐naphthoic acid, β‐resorcylic acid, and resacetophenone with epichlorohydrin employing ethylenediamine as a crosslinking agent. Some of the physicochemical properties, such as moisture content, true density, apparent density, void volume fraction, concentration of ionogenic groups, exchange capacity, rate of exchange, pH‐titration curves, pK values, isoionic point, thermal stability, oxidation resistance, and swelling behavior in different solvents, have been investigated.
Studies on synthetic‐polymer plates with high surface energy. V. Diethylene glycol bis(allyl carbonate)–acrylic acid copolymer plate by vapor‐phase transfer process
Authors: Kaneko Norio , Takahashi Akira , Ohtsuka Yasuji 
Published: April 2003

AbstractSynthetic‐polymer plates with carboxyl group on their surface were prepared by a two‐step copolymerization process transferring M2 monomer via vapor phase. Diethylene glycol bis(allyl carbonate) (CR‐39) was used as M1 monomer, and acrylic acid was acid was used as M2 monomer. The relations between the experimental conditions and the surface properties of the resulting plates were examined in the following terms: (1) composition of CR‐39 prepolymer gel plate used and (2) concentration of benzoyl peroxide as the initiator. The plates had good water wettability and an excellent antifogging property.
The effects of oxygen diffusion on the surface photooxidation of polystyrene
Authors: Ito Masayoshi , Porter Roger S. 
Published: April 2003

AbstractThis paper further illustrates the applicability of multiple internal reflectance infrared spectroscopy to the analysis of near‐surface photooxidation. The results are compared with transmission infrared spectra to evaluate compositional gradients resulting from photooxidation and the influence of oxygen diffusion. The sample was a solvent‐cast film of atactic, narrow distribution polystyrene, Mw of 100,000, that had been drawn to a ratio of 3.0 at 110°C by solid state coextrusion. Irradiation of these thin films, ∼25μm thickness, was performed on exposure to air at 35°C for periods of up to 6 h using a mercury source emitting at 254 nm. On photooxidation, a board peak appears at 3200–3500 cm−1, attributable to hydroperoxide formation. The most dramatic increase in the infrared spectra is found for a carbonyl band at 1730 cm−1. It appears to result from an aromatic acid group since it is shifted to 1660 cm−1 on immersion of the oxidized polystyrene films in aqueous ammonium hydroxide. It is confirmed that the photooxidation of polystyrene occurs preferentially at the surface and that this reaction rate is greatly reduced in the drawn polystyrene film.
Chemical modification of polystyrene. II. A cation exchange resin from polystyrene electrophilically substituted with pyromellitic dianhydride
Authors: Biswas Mukul , Chatterjee Shakuntala 
Published: April 2003

AbstractCrosslinked polystyrene based on condensation of polystyrene and pyromellitic dianhydride has been processed into a sulfonic acid cation exchange resin of improved thermal properties. The resin has been characterized in respect to its structure ion exchange and thermal stability by IR and elemental analysis data, total and salt‐splitting capacity measurements, pH‐titration characteristics, and TGA and DTA studies.
The influence of thermal properties on the glass transition temperature in styrene/divinylbenzene network–diluent systems
Authors: Ellis T. S. , Karasz F. E. , Brinke G. Ten 
Published: April 2003

AbstractThe depression of glass transition temperature in polystyrene and styrene/divinylbenzene networks, by the addition of ethylbenzene, ethyl acetate, and m‐diethylbenzene, respectively, has been investigated by differential scanning calorimetry. The predictive quality of the Couchman–Karasz treatment for the composition dependence of Tg in compatible systems was found to provide excellent agreement with experimental results for the depression of Tg by ethylbenzene, provided certain modifications were made. Qualitatively, the theory predicts that for a given diluent, the depression of Tg is particularly sensitive to the incremental change in heat capacity of the pure polymer or network. The behavior of ethylbenzene provided good quantitative agreement with the theory, provided that the incremental change in heat capacity of the diluent at its Tg was approximated by ΔCp = constant/T and that the incremental change in heat capacity of the network at Tg represents only those units capable of thermal activation. The anomalous behavior observed on plasticization by ethyl acetate and m‐diethylbenzene could in part be explained by a reduction in solvent quality or syneresis of diluent in the highly crosslinked samples.
Compatibility of some fluorosubstituted styrene polymers and copolymers in blends with poly(2,6‐dimethyl‐1,4‐phenylene oxide) and with polystyrene
Authors: Vukovic Radivoje , Karasz F. E. , Macknight W. J. 
Published: April 2003

AbstractBlends of poly(p‐fluorostyrene) (PpFS), poly(o‐fluorostyrene) (PoFS), poly(styrene‐co‐p‐fluorostyrene) (SP46), poly(styrene‐co‐o‐fluorostyrene) (SO49), with poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) and with polystyrene (PS), have been prepared by compression molding of coprecipitated polymers. Compatibility of these systems has been studied by differential scanning calorimetry. Detection of one or two glass transition regions was used to classify the blends as compatible or incompatible. Homopolymers of pFS and oFS were found to be incompatible with PPO and PS. The SP46 copolymer and SO49 copolymer were compatible with PPO in all proportions.
Selective synthesis of isobutene trimers and hexamers with oxo acid catalysts
Authors: Higashimura Toshinobu , Miyoshi Yoshihiro , Hasegawa Hiroshi 
Published: April 2003

AbstractThe reaction of isobutene (IB) with its dimers (IB2) catalyzed by CF3SO3H yielded isobutene trimers (IB3) in high yield in nonpolar solvents at 0°C. The initial feed of isobutene, in the presence of equimolar IB2 or more, was selectively converted into IB3 without loss or accumulation of IB2. After complete consumption of the isobutene, however, the remaining IB2 rapidly dimerized to isobutene tetramers (IB4). 13C‐NMR analysis of the products showed that the IB3 was formed via addition of the t‐butyl cation (protonated isobutene to 2,4,4‐trimethyl‐1‐pentene (an IB2 isomer); the trimer fraction was free from isomers arising from addition of the t‐butyl cation to 2,4,4‐trimethyl‐2‐pentene (another IB2 isomer) or addition of the IB2 cation to isobutene. The IB3 thus obtained was further oligomerized with CF3SO3H catalyst in nonpolar media in the range of 0 to −25°C to give a mixture of IB5, IB6, and IB7 in high yield. With EtAlCl2 as catalyst, reaction of isobutene with IB2 and oligomerization of IB3 both resulted in products with a broad molecular weight distribution containing higher oligomers and complex hydrocarbons formed via cracking of the intermediate carbocations.
Fungal degradation of polycaprolactones
Authors: Benedict Christine V. , Cook William J. , Jarrett Peter , Cameron J. A. , Huang Samuel J. , Bell James P. 
Published: April 2003

AbstractThree high molecular weight polycaprolactones (M̄w= 35,000, 18,600, and 7,130) were utilized as the sole carbon source by five of six fungi tested by the American Standards for Testing and Materials (ASTM) agar plate method. The fungi wereAspergillus flavus, A. niger, A. fumigatus, Chaetomium globosum, Pencillium funiculosum, and aFusarium sp.Quantitative analysis of degradation was performed using gel permeation chromatography (GPC). GPC analysis demonstrated differences between the activities of organisms which appeared similar by the ASTM method, and showed that, while all molecular weight species within each polymer were hydrolyzed, in several cases low molecular weight end products were not assimilated. Depending on the organism, the dominant factor determining degradability was either polymer molecular weight or degree of crystallinity.
Polyphenylquinoxalines containing pendant phenylethynyl groups: Preliminary mechanical properties
Authors: Hergenrother Paul M. 
Published: April 2003

AbstractPolyphenylquinoxalines (PPQ's) containing various amounts of crosslinkable pendant phenylethynyl groups were prepared from the reaction of 3,3′,4,4′‐tetraaminodiphenyl ether, 4,4′‐oxydibenzil, and 4,4′‐oxybis(4″‐phenylethynylbenzil). The distribution of the pendant phenylethynyl groups along the polymer chain was varied in an attempt to alter the properties of the polymers. Preliminary film, adhesive, and laminate properties of PPQ void of pendant crosslinkable groups and containing pendant phenylethynyl groups were determined. The thermally induced reaction of the phenylethynyl group crosslinked the polymer which resulted in better dimensional stability at elevated temperatures.
Gel permeation chromatography: The effect of flow rate on efficiency. II
Authors: Chuang Jau‐Yi , Johnson Julian F. , Cooper Anthony R. 
Published: April 2003

AbstractThe effect of flow rate on efficiency in gel permeation chromatoraphy has been examined over wide ranges of flow rate, i.e., linear flow velocities using columns of different diameters using both organic and inorganic packings. The results indicate a considerable increase in efficiency at flow velocities below 0.02 cm/s. No lower limit to this increase could be determined due to experimental difficulties. Between flow velocities of 0.02–0.2 cm/s little efficiency is lost.
Synthesis and properties of photosensitive rubbers. IV. Photosensitive rubbers from hydroxyethyl cinnamate and polyisoprene modified with maleic anhydride
Authors: Azuma Chiaki , Hashizume Naoko , Sanui Kohei , Ogata Naoya 
Published: April 2003

AbstractPolyisoprene in o‐dichlorobenzene solution were reacted with maleic anhydride at 180°C under nitrogen atmosphere to form modified polyisoprene with α‐substituted succinic anhydride groups. These groups were converted by reaction with hydroxyethyl cinnamate in pyridine at 25°C to cinnamate groups. Various amounts of cinnamate groups as photosensitive groups could be easily introduced into polyisoprene up to 75 mol % toward polyisoprene repeating units. Polymer glass transition temperatures of the products rose linearly from −70°C for polyisoprene to 60°C with increasing amounts of the side groups. The solution viscosity of the products in chloroform decreased from 9.34 for polyisoprene to 0.77 with increasing amounts of the side groups. The photosensitivity of the polyisoprene, which is based on the photodimerization of the cinnamate groups, was higher than that of polypentenamer having cinnamate groups due to the interaction by the free carboxylic acids neighboring with the cinnamate groups. The photosensitivity of the cinnamate group was kinetically evaluated in terms of the dependence on the polymer glass transition temperature. The interaction by the free carboxylic acid groups in the polyisoprene reduced the dependence of the photosensitivity on the mobility of the polymer segments. Linear relationship between observed rate constants of the photodimerization and (TUV − Tg + 50)−1 was obtained and the slope of the line changed and became very small at higher glass transition temperatures.
Simulation of reversible AA + B′B″ polycondensations in wiped film reactors
Authors: Gupta Santosh K. , Kumar Anil , Ghosh Anup K. 
Published: April 2003

AbstractWiped‐film reactors carrying out AA + B′B″ type reversible polycondensations (where A, B′, and B” are functional groups, with B′ and B” reacting with A at different rates) have been simulated. The governing mass balance equations have been solved for two transport models of this reactor (one by Ault and Mellichamp and the other by Amon and Denson) using a combination of finite difference and the Runge–Kutta methods. The increase in the number‐average chain length μn of the polymer formed in the reactor is computed as a function of the various rate constants and the parameters characterizing the reactor. μn is found to be most sensitive to the surface area of the film and to the temperature used, both for the equal reactivity as well as for the unequal reactivity cases. For the latter, the effect of the reactivity ratio for the forward rate constants is more significant than that of the equilibrium constants. Results of the two models are also compared under similar conditions and it is found that under equivalent conditions, the Amon–Denson model gives slightly higher μn than the Ault–Mellichamp model.
The characterization of styrene–β‐pinene polymers
Authors: Sheffer Howard , Greco Gary , Paik George 
Published: April 2003

AbstractStyrene was polymerized with β‐pinene at 30°C and −50°C in methylene dichloride and in m‐xylene solvents. The styrene‐to‐terpene ratio on pyrolysis suggests that the polymers made at 30°C are copolymers, whereas most of the polymers made at −50°C are not copolymers. On the other hand, ethylene, ethane, and propylene analysis suggests that more of the polymers made at −50°C are copolymers.