bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phosphine‐based flame retardants for polypropylene
Authors: Savides Chris , Granzow A. , Cannelongo J. F. 
Published: April 2003

AbstractFlame retardant formulations for polypropylene are described that comprise a heat‐stable phosphonium bromide or phosphine oxide, containing cyanoethyl substituents, in combination with ammonium polyphosphate. At additive levels of (20–30)%, flame‐retarded polypropylene, with an Underwriters' Laboratories UL 94 V‐0 rating is obtained with little effect on thermal and mechanical properties of the polymer. A characteristic property of this flame retardant mixture is low smoke generation during burning. Mechanism studies indicate that the organophosphorus component alone acts as an inhibitor in the gas phase, whereas the ammonium polyphosphate alone acts in the condensed phase. The synergistic effect observed by the combination of these two components is due to the formation of a phosphorus‐rich char which forms an insulating layer.
Mechanical properties of SBS block copolymers. II. Effect of structure and selective solvent casting on stress–strain properties and mechanical hysteresis
Authors: Kalfoglou Nikos K. 
Published: April 2003

AbstractNear‐equilibrium stress–strain properties were obtained for poly(styrene–b–butadiene) copolymer films cast from different solvents at 35°C. The solvents used were methyl ethyl ketone and cyclohexane, selective for PS and PB, respectively, and toluene, a common solvent for both copolymer components. Tensile properties were studied at two successive loading cycles up to a maximum elongation ratio of λmax = 7.0. At constant composition, the results were interpreted on the basis of the available morphology for these systems. The effect of hard block content (35% to 45% styrene) and at constant composition (39% styrene) of block length was also examined on such properties as elasticity and mechanical hysteresis. The results indicate that at constant composition the PB block length influences elasticity and mechanical hysteresis, also that films cast from a common solvent have higher tensile strength and increased mechanical hysteresis presumably because of a more effective load transfer between phases.
The effect of casting solvent on the sorption and diffusion of water vapor in poly(γ‐methyl L‐glutamate)
Authors: Minoura Norihiko , Nakagawa Tsutomu 
Published: April 2003

AbstractWater vapor permeability of poly(γ‐methyl L‐glutamate) (PMLG) membranes prepared by using dichloroethane, trifluoroacetic acid, and formic acid as solvents was studied. The membranes prepared by casting dichloroethane and trifluoroacetic acid solutions of the polymer, designated as PMLG–DCE and PMLG–TFA, respectivley, had α‐helical structures according to infrared absorption spectra, while the membranes prepared by allowing the PMLG–TFA membranes to swell in formic acid, designated as PMLG–FA, had mainly a β‐sheet structure. The amounts of water sorbed by PMLG–DCE, PMLG–TFA, and PMLG–FA increased in that order. The isotherms of PMLG–TFA and PMLG–FA were sigmoidal‐shaped isotherms, and the heat of sorption for PMLG–TFA and PMLG–FA was larger than that for PMLG–DCE, which suggested the presence of the sorption sites. The diffusion coefficients of water for PMLG–DCE increased and then decreased with increasing concentration. On the other hand, the diffusion coefficients for PMLG–TFA and PMLG–FA increased with concentration. The activation energies of diffusion for PMLG–DCE, PMLG–TFA, and PMLG–FA increased in that order. These results were discussed in connection with the molecular conformations of poly(γ‐methyl L‐glutamate) in the membranes. From these results, it is assumed that the molecular chains in the PMLG–TFA membranes are mainly in α‐helical and partly random‐coil conformations.
Effects of gamma radiation on two aromatic polysulfones. II. A comparison of irradiation at various temperatures in air‐vacuum environments
Authors: Brown J. R. , O'Donnell J. H. 
Published: April 2003

AbstractThe aromatic polysulfone poly(oxy‐1,4‐phenylenesulfonyl‐1,4‐phenyleneoxy‐1,4‐phenyleneiso‐propylidene‐1,4‐phenylene) (I) showed no change in flexural yield strength after doses of γ‐radiation up to 600 Mrad in vacuum at 35,80, and 125°C (Tg = 190°C)). However, the flexural strength decreased markedly with doses above 100 Mrad on irradiation in air, to 40–60% of the initial value after 200–400 Mrad, depending on the sample and the irradiation conditions. Chain crosslinking was predominant over scission for irradiation in vacuum at all temperatures; (G(X), G(S), and G(S)/G(X) increased with the irradiation temperature, but G(S)/G(X) decreased to zero above Tg. Poly(oxy‐1,4‐phenylenesulfonyl‐1,4‐phenylene) (II) behaved similarly, except that the flexural strength was found to be very dependent on the thermal treatment of the sample. This polymer showed a remarkable retention of its mechanical properties on irradiation up to 200°C (Tg = 230°C) in the absence of air, the flexural strength being retained up to 500 Mrad. Radiation annealing occurred at 35°C in vacuum and air and combined radiation and thermal annealing at 125 and 220°C. Progressive removal of surface layers from flexural test bars of I irradiated in air showed that the decrease in flexural strength with dose could be explained by a decrease in the molecular weight towards the surface resulting from radiation‐oxidation reactions.
Plasma polymerization of tetrafluoroethylene. III. Capacitive audio frequency (10 kHz) and AC discharge
Authors: Morosoff N. , Yasuda H. , Brandt E. S. , Reilley C. N. 
Published: April 2003

AbstractThe plasma polymerization of tetrafluoroethylene (TFE) is studied in a capacitively coupled system with internal electrodes using a 10 kHz (af) and a 60 Hz (ac) source. The emphasis is on identifying conditions that are compatible with continuous coating of plasma polymer on a substrate moving through the center of the interelectrode gap. Operation at a pressure below 100 mTorr is most favorable for deposition of a substantial portion of the plasma polymer on this substrate. Plasma polymer deposited in this way is characterized by ESCA and by deposition rate data and compared to that deposited using rf power in both capacitively and inductively coupled systems. The polymers found in all systems are broadly similar and completely different from conventional poly(TFE). The distribution of power density in the various systems has been identified and compared. This is accomplished by using the known susceptibility of fluorine‐containing polymers (including plasma polymer) to a high‐power plasma as a probe of plasma power density within the interelectrode gap in the capacitively coupled system. The most active zone of the af or ac plasma is close to the electrode at a plasma pressure of approximately 40 mTorr. The use of a magnetic field leads to an intense localized glow such that etching by active fluorine atoms occurs at a specific locus on the electrode. By contrast, the low‐pressure rf capacitively coupled glow discharge is the mildest of those investigated, and its most active zone is further from the electrode and much more diffusely localized by a magnetic field.
GPC: Use of automatic weighing to determine elution volumes
Authors: Moebus Gerhart A. , Crowther John A. , Bartick Edward G. , Johnson Julian F. 
Published: April 2003

AbstractAn automatic balance has been designed, constructed, and tested for continuous determination of the weight of the eluent in chromatography. This balance is considerably more precise than the frequently used automatic siphons. As the elution volume for any molecular species is independent of flow rate over a considerable range, the balance can be used with relatively inexpensive pumps, and thus highly precise constant volume pumps are not required.
Polyimide fibers: Structure and morphology
Authors: Goel R. N. , Hepworth A. , Deopura B. L. , Varma I. K. , Varma D. S. 
Published: April 2003

AbstractPolyimide fibers were prepared by wet spinning of poly(p,p′ ‐diaminodiphenylmethanepyro‐mellitamic acid). Density measurements and x‐ray diffraction studies were carried out to study the structure of the resultant polyimide fibers. Polyamic acid as well as undrawn polyimide fibers were essentially amorphous with two amorphous haloes. Hot drawing of the fibers at 300°C resulted in increase in crystallinity, and a simultaneous decrease in density also took place. X‐ray data revealed that meridional reflections correspond to the repeat unit length in the fiber. Scanning electron micrography studies indicated that polyamic acid fibers prepared by a wet‐spinning technique developed voids during spinning which increased on cyclodehydration to the polyimide state. Hot drawing of fibers resulted in enlargement of these voids. However, a highly fibrillated structure was developed during drawing which could account for the strength of the fibers.
ESR studies of the photodegradation of cellulose graft copolymers
Authors: Hon David N.‐S. 
Published: April 2003

AbstractUltraviolet light induced free radicals in cellulose and cellulose graft copolymers were studied by means of ESR spectroscopy. At least six kinds of free radicals were formed in cellulose when the polymer was irradiated with ultraviolet light. Polystyrene and poly(methyl methacrylate) are more resistant to ultraviolet light than cellulose; however, the cellulose graft copolymers of polystyrene and poly(methyl methacrylate) were degraded by ultraviolet light. ESR studies revealed that photoinduced free radicals in cellulose graft copolymers were formed at the grafting branches of the copolymers rather than the cellulose backbone. The mechanisms of light stabilization and energy transfer reactions of cellulose and cellulose graft copolymers are discussed.
Impact resistance and secondary transitions
Authors: Hartmann Bruce , Lee G. F. 
Published: April 2003

AbstractInstrumented Charpy impact measurements were made on polycarbonate from liquid nitrogen temperature to room temperature. The polymer had a transition from brittle fracture to ductile failure at −130°C. Scanning electron micrographs of the fracture surfaces did not correlate with the secondary transition or test temperature. A Fourier analysis of the impact pulse covers a wide range of frequencies, but the dominant frequencies at room temperature are below 200 Hz. Time–temperature superposition shows that the secondary transition occurs over a broad frequency range centered at 7 MHz at room temperature. Impact strength and the secondary transition (at impact frequency) both have a maximum value around −75°C.
Pneumacel: Basic technology and applications
Authors: Bonner W. H. , Fish F. H. , Webb M. Q. 
Published: April 2003

AbstractPneumacel, a new kind of resilient closed‐cell foam, has characteristics especially useful for firm cushioning materials. A fluorocarbon inflatant in addition to air present in the closed cells provides a mechanism for recovery from long‐term loading for nonelastomeric polymer foams such as poly(ethylene terephthalate). The basic structural features characterizing pneumacel contribute to its performance as a resilient foam. Important principles in selecting the optimum combination of polymer and inflatant are described, as well as the process for making pneumatic cellular products. Development work on applications of pneumacel fibers has led to its utilization in cushions for under carpets, padding for use over springs in mattresses, automobile seats, and furniture. Properties of the assemblies of fibers for such uses are described.
Carboxyl‐containing starch graft polymer: Preparation and use in heavy metal removal
Authors: Rayford W. E. , Wing R. E. , Doane W. M. 
Published: April 2003

AbstractWater‐insoluble carboxyl‐containing starches were prepared by grafting acrylonitrile onto a highly crosslinked starch followed by base saponification to convert nitrile groups into a mixture of carboxamide and carboxylate groups. Ceric ammonium nitrate or ferrous sulfate–hydrogen peroxide was used to initiate graft polymerization of acrylonitrile. The isolated products were evaluated for the removal of Cd2+, Cu2+, and Pb2+ from aqueous solution.
Copolymerization of ethylene chlorophosphonite with 2‐phenyl‐1,3‐dioxolane and its flame‐retardant effect on polyester fabric
Authors: Inagaki Norihiro , Katsuura Kakuji 
Published: April 2003

AbstractCopolymerization of ethylene chlorophosphonite (ECP) with 2‐phenyl‐1,3‐dioxolane (PhD) and the flame‐retardant effect of the copolymer on polyester fabric were investigated. (1) Copolymerization occurred without added catalyzer. The number‐average molecular weight ranged from 600 to 1000. 1H‐nmr and ir spectra for the copolymers showed that their structures varied depending on feed composition (ECP/PhD ratio): ECP/PhD less than or equal to 1 yielded an alternating copolymer having the structure
magnified image
and at ECP/PhD ratios greater than 1, some insertion reaction of ECP into polymer I occurred. (2) Selectivity of flame retardation could be observed. The copolymer with structure I was an effective flame retardant for polyester fabric but useless for cotton fabric. Its effectiveness in polyester fabric
was superior to that of TBPP.
Complex‐forming polymeric sorbents with macromolecular arrangement favorable for ion sorption
Authors: Kabanov V. A. , Efendiev A. A. , Orujev D. D. 
Published: April 2003

AbstractCrosslinked polymeric sorbents with macromolecular arrangement favorable for sorption of copper ions have been obtained obtained on the base of copolymer of diethyl ester of vinylphosphonic acid with acrylic acid. The general principle involves interaction of linear polymer and sorbing ions in solution where the segments of the macromolecules are still mobile enough, subsequent fixation of optimal ion uptake conformations of macromolecules by crosslinking of metal polymer complexes, and removal of ions from crosslinked sorbent. Such treatment increases the exchange capacity of the sorbents more than twice and improves essentially its kinetic characteristics in comparison with the same copolymer crosslinked by conventional methods without special arrangement of macromolecules. The rate of the uptake on the sorbents with macromolecular arrangement favorable for ion sorption first increases with increase in the degree of crosslinking and then decreases. Apparently the jise of the crosslinking degree leads to more rigid fixation of the optimum ion uptake conformations of the macromolecules' segments. Further increase of the crosslinking degree alongside with fixation prevents ions from diffusion into the sorbent.
Polymer deposition in sisal fibers: A structural investigation
Authors: Barkakaty B. C. , Robson A. 
Published: April 2003

AbstractSisal (Agave sisalana) fibers were graft copolymerized with certain vinyl monomers (methyl acrylate, ethyl acrylate and methyl methacrylate) using gamma irradiation and ceric ammonium nitrate as initiation techniques. Examinations of the surface topology and the internal structure of the grafted fibers made by scanning electron microscopy. The results derived from the SEM observations on transverse sections of the grafted fibers were supplemented by information obtained by polarized light microscopy. Polymer was deposited not only on the surface of the fiber substrate, but also in the lumen, the middle lamellae, and throughout the cell wall network of the multicellular aggregates. The degree of polymer inclusion in the lumen (which is the most conspicuous of all the available internal sites) was found to depend on the percentage graft copolymer add‐on, as well as on the previous history of the fiber (natural or chemically modified). The mechanical properties of the grafted fibers were investigated (by means of an Instron tensile tester).
Accuracy of the parallel‐plate analogy for representation of viscous flow between coaxial cylinders
Authors: Worth R. A. 
Published: April 2003

AbstractThe accuracy of the parallel‐plate approximation to represent various viscous flows of non‐Newtonian fluids between coaxial cylinders is investigated. Four types of flow are considered: tangential drag flow, tangential pressure flow, and axial pressure flow. The solutions for flow between parallel plates are compared with the exact solutions, and the errors are plotted against radius ratio for a number of values of the power‐law index to provide an indication of the range of usefulness of the parallel‐plate analogy.
Kinetic studies on the condensation reaction of 2‐methylol‐4‐t‐butylphenol with 4‐t‐butylphenol using acid catalysts. I
Authors: Reddy B. Siva Rami , Rajadurai S. , Santappa M. 
Published: April 2003

AbstractThe rates of the individual reactions of 2‐methylol‐4‐t‐butylphenol with 4‐t‐butylphenol were measured under varying mole ratios of reactants in the presence of different acid catalysts (5.0 × 10−3 N to 2.0 × 10−4 N) at five different temperatures (60, 65, 70, 75, and 80°C). In all the experiments, the reactions were found to obey second‐order rate law. The values of the Arrhenius parameters and the entropy of activation for the overall reaction were calculated. The relative catalytic efficiencies of the acid catalysts followed the order HNO3 > HCl > H2SO4.
Gel permeation chromatography of poly(dimethyl siloxane). I. The universal calibration
Authors: Mandík Lumír , Foksová Alena , Foltyn Josef 
Published: April 2003

AbstractThe Benoit universal calibration method has been tested for evaluation of GPC data of polydimethylsiloxane (PDMS) in toluene at 60°C. For the conversion of the calibration curve for polystyrene to the PDMS calibration curve, the Mark–Houwink equation for PDMS in toluene at 60°C was derived: [η] = 9.77 × 10−5 M0.725. The applicability of this universal calibration was proved by the experimental results on five PDMS model samples. For the correct evaluation of the PDMS elution curve, the use of the true calibration is inevitable, because the hydrodynamic volume of PDMS molecular weight unit is somewhat different from the polystyrene one.
Statistical methods for comparing GPC curves
Authors: Füzes László 
Published: April 2003

AbstractThe possibilities of comparing the GPC curves of two or more polymers were studied, and the method of “distinguished points” (DPs) is suggested for this purpose. The features of these DP values as random variables were investigated. According to the experimental results they meet the requirements of the statistical tests applied in this text. In order to indicate the significant deviation or the agreement of the DP values of GPC curves of two polymers, the sequential U and t tests are suggested, because with these methods the number of the necessary parallel measurements is considerably decreased, and one can also decide on the magnitude of the variation on must be able to detect, while in the case of more than two polymers the methods of the analysis of variance can be utilized. The molecular weight ranges in which significant differences occur can also be determined. The described methods were tested by materials of known molecular weight distributions.
Polymer film‐type channel electron multipliers: Their characteristics and comparison with bulk‐type flexible multipliers
Authors: Kishimoto Yoshio , Hayashi Tomonao , Hashimoto Masashi , Ohshima Tsutomu 
Published: April 2003

AbstractPolymer film‐type channel electron multipliers (CEMs) were developed and their characteristics investigated in comparison with bulk‐type flexible CEM. As film‐type CEMs, a paint‐coating‐type CEM and a solvent‐etching‐type CEM were fabricated. The paint‐coating‐type CEM is made by coating a “paint” which is prepared by dissolving in a solvent an electronically conductive polymeric composition having a high secondary electron emission yield. Up to the present study the mean gain of the film‐type CEM, in spite of the lower resistivity of the dynode, seems to be slightly more dependent on the count rate than that of the bulk‐type CEM made of the same material. However, the convenience of fabricating the dynode film by coating the dynode‐forming paint on the internal surface of any shaped tube or a flexible polymer tube would overcome the slight disadvantage mentioned above.
Flow visualization of cellulose acetate–acetone solutions
Authors: Boudreaux Edwin , Cuculo John A. 
Published: April 2003

AbstractThe flow behavior of four cellulose acetate–acetone solutions varying from 20.00% to 28.18% solids concentration was observed using flow visualization techniques at 24°C with an industrial‐type dry spinning system. Fibrous particulate matter entertained in the solutions and crossed polars revealed the streamlines and the birefringence due to flow in glass spinnerets. The streamlines of the four solutions were radially convergent at all obtainable throughputs. The crossed polars revealed a cone of birefringence with the order of the interference colors decreasing upstream of the capillary inlet. The intensity and extent of birefringence varied somewhat with concentration and throughput. Except for kneeing, the emerging extrudates were undeformed. The kneeing was not a result of flow instability a t the capillary inlet but was due to another, undetermined instability. A separate study of the kneeing revealed both a concentration dependence and hysteresis. The birefringence of the emerging extrudates was a function of both concentration and throughput, and it yielded some information about the structure of the solutions.
Frequency distributions of breaking load, tenacity, and ratio of cell wall thickness to ribbon width for single cotton fibers
Authors: Patel N. C. , Dweltz N. E. 
Published: April 2003

AbstractAnalysis of the frequency distributions of breaking load, tenacity, and ratio of cell wall thickness to ribbon width (C/R) for single cotton fibers in this study has indicated that they can all be represented by β‐distributions. This suggests that a parallel model of element configurations exists in which there is a uniform distribution of elemental strengths in single cotton fibers before as well as after slack mercerization. In the case of breaking load and tenacity, the distributions are positively skewed and the skewness decreases on slack mercerization, suggesting that quite a few potentially weak places have been either completely removed or at least strengthened. The changes in C/R ratio on slack mercerization for cottons having a range of maturity have been examined and discussed. The dependence of properties such as breaking load, tenacity, and linear density on cell wall to ribbon width ratio (C/R) have also been studied.
Influence of drawing and molecular weight on structural‐mechanical properties of acrylic fibers
Authors: Stoyanov A. I. , Kpestev V. P. 
Published: April 2003

AbstractThe influence of drawing and molecular weight in a narrow range on the several structural‐mechanical properties of acrylic fibers have been investigated. Drawing of fibers (λ = 3x–6,5x) leads to a considerable increase of tenacity. These data were explained with the orientation and perfection of structure. It was found that the molecular weight in closer range influences the density, perfection of structure, and the stability of fibers to repetitive deformation. The results show that the diversions of the average molecular weight, in the manufacture of commercial acrylic fibers, must be negligible.