bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reactions of halogenated 1,2‐epoxypropanes and diethylaminoethyl cotton
Authors: Soignet Donald M. , Benerito Ruth R. 
Published: April 2003

AbstractDiethylaminoethyl (DEAE)‐cotton has been reacted with epichlorohydrin (1,2‐epoxy‐3‐chloropropane) neat, in alcoholic solvents, and in aprotic solvents at temperatures ranging from 25 to 95°C. Fabric properties and electron micrographs of fibers removed from these chemically treated DEAE cottons have been compared with those obtained when DEAE‐cottons were treated under similar conditions with other halogenated 1,2‐epoxypropanes, and with 1,2‐epoxy‐4,4,4‐trichlorobutane. For comparative purposes, epichlorohydrin was reacted with an aminized cotton containing primary amine groups, with cotton containing quarternary ammonium groups, and with DEAE‐cottons in which the tertiary amine groups had been quaternized. For reaction at 95°C with net epichlorohydrin, greatest increase in conditioned wrinkle recovery was observed with DEAE‐cottons. Only with DEAE‐cottons were the add‐ons and recovery angles imparted by epichlorohydrin affected by the anion associated with the amine groups. None of the halogenated 1,2‐epoxypropanes reacted with unmodified cotton in the absence of a basic catalyst. Those that reacted with unmodified cotton in the presence of an external base catalyst did not improve conditioned recovery angles. The mono‐, di‐, and trichloro‐1,2‐epoxypropanes all increased the conditioned and wet wrinkle recovery of DEAE‐cotton when reacted neat at 95°C. The type of oxirane ring opening of epoxypropanes was shown to be influenced by the degree of chlorination of the carbon alpha to the ring. Both primary amine groups and quaternary amine groups catalyzed the epichlorohydrin–cellulose reaction. Dilution of epichlorohydrin with alcohols or decreasing reaction temperature lowered add‐ons and improvements in wrinkle recovery properties. Use of aprotic solvents for the DEAE‐cotton‐epichlorohydrin reaction gave finished cotton fabrics having only high wet wrinkle recovery properties.
Diethylaminoethyl cellulose–anhydride reactions
Authors: Soignet Donald M. , Benerito Ruth R. , Pilkington Mary W. 
Published: April 2003

AbstractTertiary amine groups of diethylaminoethyl cotton are internal catalysts for the reaction of cellulose hydroxyls with anhydrides to form esters. These cellulose esters are stable to mild acid steeping but hydrolyze under mild basic conditions. Anhydrides containing halogen atoms yield products with increased resistance to rot. None of the anhydrides employed produced fabrics with increased crease recovery, abrasion resistance, or breaking strength.
Substituted aliphatic polybenzimidazoles as membrane separator materials
Authors: Trischler Floyd D. , Levine Harold H. 
Published: April 2003

AbstractWhen initially evaluated as potential membrance separators for a heat‐sterilizable silver‐zinc battery, aliphatic polybenzimidazoles (PBI) proved to be unsatisfactory because of their excessively high resistivity. Later, various polymer modifications such as sulfonation, N‐hydroxyethylation, N‐cyanoethylation, and N‐carboxyethylation were made in an attempt to increase the hydrophilicity of the PBI's. As a result of these efforts, an N‐carboxyethylated, suberic acid‐based PBI shows promise as a sterilizable battery separator material.
Copolymers of starch and polyacrylonitrile: The dilution effect
Authors: Fanta George F. , Burr Robert C. , Russell C. R. , Rist C. E. 
Published: April 2003

AbstractIn the ceric ammonium nitrate‐initiated graft polymerization of acrylonitrile (AN) with starch, grafting frequencies and molecular weights of grafted polyacrylonitrile changed from 600 anhydroglucose units (AGU)/graft and 120000 to 280 AGU/graft and 36000 when concentrations of starch and AN were varied from 0.27 and 1.20 to 0.023 and 0.235 moles/l. of water, respectively. The influence of variety of starch, size of the starch granules, and reaction time was studied, and possible reasons for the influence of reactant concentration on the composition of the copolymer are considered.
Telechelic elastomers
Authors: Uraneck C. A. , Hsieh H. L. , Sonnenfeld R. J. 
Published: April 2003

AbstractTelechelic elastomers, polymers with reactive terminal groups, can be prepared in emulsion and solution systems. Examples of characterization of the polymers and preparation of a mercapto telechelic copolymer in an emulsion system and of mercapto‐, hydroxy‐, and aziridinyl‐telechelic elastomers in solution systems are given. The elastomers were cured in peroxide or sulfur‐accelerator formulations. The telechelic polymers exhibited enhanced stress‐strain and dynamic properties in comparision to those of the controls. In tread formulations, outstanding properties were obtained for the mercapto‐and azieridinyl‐telechelic butadiene‐styrene copolymers.
Performance of solution‐cast membranes of poly(hydroxythyl methacrylate) in osmosis and reverse osmosis
Authors: Bloch R. , Vieth W. R. 
Published: April 2003

AbstractNoncrosslinked copolymers of hydroxyethyl methacrylate (HEMA) with ethyl methacrylate (EMA) were prepared and investigated as candidate materials for reverse osmosis membranes. Water and salt flux were calculated from the results of osmosis experiments, compared with cellulose acetate and found to be somewhat smaller. The mobility of water varies by several orders of magnitude between a high flux cellulose acetate membrane and a low flux HEMA‐EMA membrane.
Comparaison des méthodes de fractionnement par chromatographie de perméation et par gradient d'elution pour la détermination des répartitions moléculaires des polypropylénes
Authors: Crouzet P. , Fine F. , Mangin P. 
Published: April 2003

AbstractMolecular weight distributions for polypropylene samples have been determined by a permeation fractionation method (GPC). Porous silica beads were used as a packing material for the columns. The set of columns allows a good separation of the polypropylene macromolecular chains in a range of molecular weights from 5000 to 1.5 × 106, and the thermal and mechanical stabilities of these beads are very good. The calibration has been carried out with fractions of polypropylene of narrow molecular weight distribution prepared by a large‐scale column fractionation. The molecular weights M̄w and M̄n and the ratios M̄w/M̄n calculated from the GPC curves show, in general, good agreement with the ones calculated from the column fractionation curves. However, the M̄w/M̄n ratios are always highter in the case of GPC fractionation. This could be due to diffusion phenomena.
Storage‐stable epoxy B‐stage resins
Authors: Aelony David 
Published: April 2003

AbstractN‐Substituted β‐aminopropionhydrazides, RNHC2h4CONHNH2, were prepared by the Michael addition of primary amines to acrylic esters. The adducts were converted to the corresponding hydrazides. The aminohydrazides react readily with terminal epoxides at moderate temperatures yeilding B‐stage resins of excellent storage stability. When powdered B‐stage resins are sprayed on hot metal (150‐230°C.), a smooth cross‐linked coating is formed in less than 3 min. The coatings have unusually high elasticity, they pass the Olson button test. For best performance the amine used should have the primary amino group attached to either a primary carbon atom or directly to an aromatic nucleus. Aminohydrazides with the following R. Groups have been prepared: methyl, n‐butyl, sec‐butyl, tert‐butyl, phenyl, cyclohexyl, benzyl, octyl, dodecyl, and octadecyl.
Reversible melt flow rate increase of branched acetal polymers
Authors: Prichard J. H. , Wissbrun K. F. 
Published: April 2003

AbstractContinued shearing of molten long‐chain branched acetal polymers raises their melt flow rates manyfold. The increase is not due to molecular degradation, as evidenced by constancy of inherent viscosity, and by the ability to reverse the increase by dissolving and reprecipitating the polymer. Shearing was found to have only a relatively small effect upon the melt viscosity but a very large effect upon the entrance correction for capillary flow. It is suggested that crystallization of branched polymers from solution creates an exceptionally strong entanglement network, and that the observed rheological changes reflect the disruption by shear of this network.
Oxygen consumption during induction period of a photopolymerizing system
Authors: Chong J. S. 
Published: April 2003

AbstractBased on a simple, general kinetic scheme for the inhibition reaction of a photopoly‐merizing system, a solution is obtained for the differential equation which describes the oxygen concentration profile as a function of exposure time, light intensity, and absorption coefficient. The effect of the absorption coefficient on the oxygen concentration in a polymer slab is evaluated by numerical computation.
Decomposition of burning polytetrafluoroethylene
Authors: Fenimore C. P. , Jones G. W. 
Published: April 2003

AbstractPTFE rods, 0.6–3.8 cm diameter, were burnt from the top downwards in a gently rising atmosphere of oxygen. The burning was only possible in concentrated oxygen, or at elevated temperature or pressure. At its surface temperature of 920 ± 25°K, the polymer evolved monomeric C2F4 which oxidized in a surrounding gas flame; 15–35% of all the carbon in the gas was found present as monomer just above the larger rods. Depolymerization of the solid was not its only mode of decomposition, however. The heat radiated and conducted from the flame into the condensed phase was too little to depolymerize it completely, and heterogeneous reactions with species from the gas phase must also have contributed to the decomposition. Overall, the polymer burnt in O2, but the gaseous reactant which attacked the surface need not have been O2 or O in all cases, for these rare species just above the larger rods. Elemental fluorine was present in the gas even when elemental oxygen was absent, and calculations indicate that F atoms would be a major flame species at equilibrium. It is possible that heterogeneous attack by flame generated F atoms consumed part of the polymer and also supplied energy to help depolymerize the rest.
Chemistry of epoxide resins. XVII. Influence of structure and curing conditions on the density, degree of cure, and glass transition temperature during the curing of epoxide resins
Authors: Fisch W. , Hofmann W. , Schmid R. 
Published: April 2003

AbstractDuring an investigation of various epoxide resin systems, some cases were found in which the room temperature density decreased with increasing curing temperature and increasing degree of cure. In other systems the density was found to be independent of the curing temperature. In these cases it is possible by deliberately stopping the reaction to measure density values which also decrease as the curing progresses. This unexpected behavior can be explained in a purely physical manner from the pattern of the density changes during an entire curing cycle. The density decrease of the noncured mixture, which is due to the increased curing temperature, outweighs all contraction effects consisting of isothermal chemical and cooling shrinkage, whereby the latter is dependent to a great extent on the glass temperature. In those cases where the glass temperature exceeds the curing temperature, the chemical reactions come to a standstill, when the temperature difference reaches a certain value, i.e. it “freezes chemically”. By means of values that can be measured readily at low temperatures, it is possible to construct diagrams from which the variation of the density at higher temperatures of the curing cycle can be estimated.
Studies in chemically modified celluloses. I. Oxidative susceptibility of chemically, modified cellulose
Authors: Kangle P. J. , Nabar G. M. 
Published: April 2003

AbstractThe oxidative susceptibility to different oxidizing agents such as dichromate–sulfuric acid, dichromate–oxalic acid and sodium hypochlorite in presence of leuco Cibanone Orange R of cellulose oxidized with sodium metaperiodate and its corresponding borohydride‐reduced product was studied and compared with that of cellulose. From the changes in the chemical properties of the oxidixed products, an attempt was made to study the mechanism of oxidation of periodate oxycellulose and sodium borohydride‐reduced periodate oxycellulose with the above mentioned oxidizing agents.
Practical use of intrinsic viscosity for polyethylenes
Authors: Quackenbos H. M. 
Published: April 2003

AbstractAlthough usually derived from measurements at several concentrations, intrinsic viscosity (IV) can be determined with good precision from a single measurement. IV tends to be a regular and distinct function of melt index (MI) for each family of high‐density polyethylenes. The tendency to regularity suggests a use in routine control, uniform production being marked by a small scatter about the IV–MI line. The distinctiveness marks one family of medium high and high‐density resins from another, and becomes a rapid means of identifying the production method of a resin. Further, IV at a given MI correlates roughly with properties, and can be used to characterize a resin. These attributes of the IV–MI relationship arise from the correlation of IV a t a given MI with width of molecular weight distribution. Such width varies considerably among commercial high‐density polyethylenes, causing a commensurate variation in IV. Among low‐density polyethylenes the IV–MI relationships is less useful, being confused by long‐chain branching.
Methods of fractionating polymers by ultrafiltration
Authors: Baker R. W. 
Published: April 2003

AbstractPolyvinylpyrrolidone and dextran polysaccharides have been fractionated by ultrafiltration by using newly developed membranes with sharp molecular weight cutoffs. Three different experimental techniques were employed: (a) batch ultrafiltration by using progressively more retentive membranes; (b) continuous ultrafiltration by using several similar membranes in series; (c) variable pressure ultrafiltration by using a single membrane and varying the applied pressure. Ultrafiltration is shown to be a technique of preparative fraction having the advantages of simplicity, speed, and economy.
Thermal degradation of phenolic resins. V
Authors: Learmonth G. S. , Searle D. P. 
Published: April 2003

AbstractThe effect of varying the nature of crosslinks in phenolic resins has bee studied with the use of resins made from phenol, p‐cresol, and bisphenol A. Thermal analysis showed that the methylene bridge was stronger under nonoxidative conditions than the isopropylidene linkage. The result is somewhat affected by the degree of crosslinking.
Failure loci for a thermoplastic at various temperatures
Authors: Golden J. H. , Hammant B. L. , Hazell E. A. 
Published: April 2003

AbstractCorresponding flexural stress and strain data for polycarbonate failure (at yield or break when brittle), at various temperatures are reported. It is shown that a specific failure locus is obtained at each temperature examined and that the results provide a means of construction of an appropriate locus for any temperature within the range 77–373°K investigated.
Tetrabromophthalic anhydride in self‐extinguishing polyesters
Authors: Narkis M. , Grill M. , Leeser G. 
Published: April 2003

AbstractPolyesters based on tetrabromophthalic anhydride are self‐extinguishing in the range of 8–12% bromine content and nonburning at higher levels of the latter. An increase in bromine content results in higher flexural and tensile strenght and flexural modulus, while impact resistance is slightly reduced. Mechanical Properties vary with bromine content in the 0–12% range and remain practically unaffected at higher levels up to 23%.
Diffusion of m‐nitroaniline into polyacylonitrile
Authors: Hossain Talukder Mohamed Abul , Iijima Toshiro , Morita Zenzo , Maeda Hirokuni 
Published: April 2003

AbstractThe diffusion of nonionic penetrant, m‐nitroaniline, into polyacrylonitrile was studied in detail on a range of temperature from 50.6°C to 95.0°C. The penetrant distribution in polymer is Fickian, which is different from that of cationic dye, Malachite Green reported earlier. The diffusion coefficient D increases with the rise of temperature. The sharp inflection point (72°C) of the Arrhenius plot, log D versus 1/T, corresponds to Tg of polyacrylonitrile in the presence of water, which is lower than that measured in the dry state by a dynamic mechanical testing method. The activation energy is constant below Tg (ca. 10 kcal/mole), suddenly reaches a maximum at Tg and then gradually decreases with increasing temperature. General trends of Arrhenius plot for different polymer–penetrant systems are discussed. The temperature dependence of penetrant diffusion above Tg can be described by a general form of the WLF equation, log aT = log (DTg/DT) = − C1g(T − Tg)/(C2g + T − Tg), where the values of C1g and C2g were calculated to be 4.03 and 24.54, respectively. A comparison was made between m‐nitroaniline and Malachite Green. The difference in the respective Tg and the constants C1g and C2g of the WLF equation in polyacrylonitrile is attributed to the size of the penetrants and their ionic character. The surface concentration increases below Tg and decreases above Tg with rise in temperature.
Analysis of condensation polymerization reactors. III. Continuous reactors
Authors: Szabo T. T. , Leathrum J. F. 
Published: April 2003

AbstractThe kinetic model for polycondensation reactions has been derived and techniques for validating the model have been described in Parts I and II of this work. This paper is concerned with using the results of Part I and II for the analysis and design of continuous polycondensation reactors.
Structure–property relationships for liquid transport in modified polypropylene membranes
Authors: Michaels Alan S. , Vieth Wolf , Hoffman Allan S. , Alcalay Haim A. 
Published: April 2003

AbstractIn view of the intensifying interest in the application of polymeric membranes in mixture separation processes, the permeation and permselective properties of polypropylene films toward several candidate organic liquids and vapors were investigated. Polymer films were subjected to solvent and thermal treatments, and the effects of these treatments on film morphology and transport properties were studied. Structure–property relationships for membrane permeation were then developed. Polypropylene films were found to be selective toward toluene, relative to isooctane, and p‐xylene relative to o‐xylene. Liquid flux rates were found to depend primarily upon the solubility of the permeants in the films and the absolute difference in the solubility parameters of the polymer–liquid pair provided a good basis for correlation of this effect. Considering liquids of closely similar solubility parameters, fluxes were found to be dependent upon the apparent molecular cross sections of the permeants. Films annealed in various organic solvents at temperatures of 60–100°C exhibited enhanced permeability, with up to fifteenfold increase relative to untreated membranes, but with reduced selectivity towards the permeants. A mechanism to account for these effects through consideration of the influence of treating solvent type on polymer morphology is proposed. It postulates the formation of more open or coarser spherulitic structures as a result of recrystallization in the presence of solvent during annealing. The enhanced flux rates in the treated films are attributed to the changes in the spherulite textures and to diminished intercrystalline tie chain constrainment within the spherulitic substructure.
Effect of molecular weight on changes produced in the surface layer of polystyrene film in a nitrogen atmosphere by ultraviolet irradiation
Authors: Kato Koichiro 
Published: April 2003

AbstractThe effect of molecular weight on the changes in the surface layer of polystyrene films on near‐ultraviolet irradiation has been studied in a nitrogen atmosphere at 25°C. Changes produced by irradiation were followed by determining the amount of solvent‐insoluble portions, the molecular weight changes, and the intrinsic viscosity changes. Most crosslinking took place in the range of the transmissible depth of 2537 Å light. Low molecular weight samples formed a small amount of solvent‐insoluble material. High molecular weight samples formed a large amount of solvent‐insoluble material. In the range above a certain molecular weight, the amount of solvent‐insoluble material approached an asymptotic value with increasing molecular weight, because of the limited penetration of 2537 Å light. Since most crosslinking took place in the range of the transmissible depth of 2537 Å light, the average number of crosslinks in the solvent‐soluble portions was influenced by the amount of solvent‐insoluble material. Low molecular weight samples produced many crosslinks. High molecular weight samples produced a few crosslinks. In the range above a certain molecular weight, the average number of crosslinks in the solvent soluble portions approached an asymptote with increasing molecular weight. Chain scission seems to have occurred in every sample.
Preparation of block copolymers of styrene and methacrylic acid
Authors: Brown C. W. , Taylor G. A. 
Published: April 2003

AbstractA range of block copolymers of styrene and methacrylic acid has been prepared by the suspension method involving migration of a growing radical across a phase boundary. The way in which copolymer composition varies with change in the amount of the two monomers in the reaction mixture has been studied, and explanations are suggested to account for these variations. Two methods, involving calculation from solubility data and thermogravimetric analysis respectively, have been used to give an estimate of the length and composition of the blocks.
Visible dichroism of the poly(ethylene terephthalate)–disperse dye system at high temperatures
Authors: Nakayama Kazuo , Okajima Saburo , Kobayashi Yasuji 
Published: April 2003

AbstractThe dichroic behavior of PET film dyed at 70°C with Disperse Red 17 or Disperse Yellow 7 was investigated in the temperature range 20–200°C with a view to studying the changes in amorphous region of PET at high temperatures. The dichroic orientation factor D versus temperature plot is expressed by a straight line with negative slope; two breaks appear at 80 (Tg) and 120°C. So long as the amorphous structure does not change irreversibly, the values of D change reversibly with the temperature. Hence, if a change in D after heating is observed at room temperature, it is evidence that an irreversible change occurred in the amorphous structure during the heating. The break at 120°C is a new amorphous transition point of PET existing along with Tg, although the Tg can hardly be observed after the cold crystallization; some phenomena reported in the literature are proposed as evidence.