bluuebunny/crossref_metadata_2025_split huggingface dataset:
Direct fiber formation and fiber properties of aromatic polyoxadiazoles
Authors: Imai Yoshio 
Published: April 2003

AbstractA novel and simple fiber formation process has been developed to fabricate aromatic polyoxadiazoles. The aromatic copolyoxadiazole solution prepared from terephthalic acid, isophthalic acid, and hydrazine sulfate in fuming sulfuric acid was utilized directly as spinning solution and was successfully wet‐spun to form fiber into a coagulating bath containing sulfuric acid. In the wet‐spinning process, selection of the coagulating bath was the most important factor, and the best results were obtained by the use of approximately 50 wt‐% aqueous sulfuric acid. It was easy to prepare a polyoxadiazole fiber having a tenacity of more than 4 g/den. and an elongation of more than 10%. In addition, the fiber properties reached to a tenacity of 6 g/den. and an elongation of 12% under optimum spinning conditions. The wet‐spun polyoxadiazole fiber showed an almost round cross section and a clear skin‐core structure by microscopic observation. The fiber had a high level of thermal and dimensional stability and a high proportion of property retention at elevated temperatures, as well as all‐round general fiber properties.
Polyacrylic desalination membranes. II. Reverse osmosis performance
Authors: Hoffman Allan S. , Modell Michael , Pan Peter 
Published: April 2003

AbstractA new class of polyacrylic membranes has been tested under reverse osmosis conditions on dilute (1%–4%) salt solutions. Fluxes up to 0.2 gal‐mil/ft2‐day at greater than 98% rejection have been achieved. The effect of membrane composition on product flux and salt rejection is discussed. Increased fluxes at even higher rejection should be possible by proper selection of the type and concentration of hydrophilic, hydrophobic, and crosslinking monomers. It is concluded that improved membranes should have as high as possible a concentration of hydrophilic groups, distributed randomly through a lightly crosslinked, rubbery polymer matrix.
Discussion of treatments for the kinetics of radical polymerization with primary radical termination
Authors: Ito Katsukiyo , Matsuda Tatsuo 
Published: April 2003

AbstractWithout knowledge of the familiar geometric mean, the following equation was derived for the radical polymerization with primary radical termination under the condition that reaction between primary radicals is negligible:

where both A and B are constants depending on various rate constants. This equation was mathematically and experimentally dealt with.
Structure of biaxially oriented polypropylene film
Authors: Uejo Hirozo , Hoshino Sadao 
Published: April 2003

AbstractIsotactic polypropylene hot‐pressed film was subjected to uniaxial and biaxial stretching. The orientation behavior was investigated by means of x‐ray pole figure technique, birefringence, electron microscope, and tensile tester. From the x‐ray pole figure results it was confirmed that three kinds of crystal orientations, i.e., c‐axis along the stretching direction, b‐axis normal to the plane of the film, and [110] vector weakly normal to the film, accompany the biaxial stretching of the film. Electron micrographs of the surface of biaxially stretched polypropylene film revealed that, as the elongation increased, fibrillar structures became oriented to the stretching directions. From this orientation behavior a new deformation mechanism based on the woven structure presented by Khoury et al. was proposed. In this mechanism the orientation of the crystals is explained as a phenomenon accompanying the rotation and splitting of the woven structure presumed to be the structural element of polypropylene film.
Determination of isopropyl peroxydicarbonate decomposition rate constant using EPR
Authors: Rathke P. P. 
Published: April 2003

AbstractThe decomposition rate constant, kd, of isopropyl peroxydicarbonate in toluene at 23.3°C was determined using electron paramagnetic resonance techniques (EPR). Diphenylpicrylhydrazyl (DPPH) was used to monitor the formation of radicals. Because DPPH has a strong absorption spectrum on the EPR, the accuracy of measuring small changes in the indicator concentration should be greater than measuring small concentrations of primary radicals. A value for kd of 4.5 × 10−7 sec−1 was obtained. This is in good agreement with previously published values.
Combined pyrolysis and radiochemical gas chromatography for studying the thermal degradation of epoxide resins and polyimides. II. Degradation of polyimides
Authors: Bishop D. P. , Smith D. A. 
Published: April 2003

AbstractThe thermal degradation of aromatic polyimides in nitrogen at 700°C was studied using pyrolysis gas chromatography, infrared spectroscopy, and radiochemical techniques. Degradation mechanisms were postulated to account for the breakdown products found and to explain variations in the ratio of carbon monoxide to carbon dioxide.
Acetylation of cotton treated with sodium hydroxide
Authors: Zeronian S. H. 
Published: April 2003

AbstractThe reactivity of mercerized, ethanol‐washed, never‐dried cotton, as indicated by acetylation, is higher than that of mercerized, water‐washed, never‐dried cotton. Hygroscopicity measurements indicate that the ethanol‐washed cotton is not fully amorphous. They also reveal that the accessibility of cotton treated with caustic soda solution of mercerizing strength will be higher than that of cotton treated with ethylamine regardless of whether water or a solvent of lower hydrogen‐bonding capacity is used to extract the swelling agent. Based on microscopic examination, acetylation of mercerized, ethanol‐washed fibers apparently takes place relatively uniformly. The breaking load of cotton fibers is similar to that of mercerized, ethanol‐washed cotton fibers of about 8% acetyl content. However, the crystallinity of these materials, as shown by hygroscopicity studies, is markedly different. This indicates that the fine structure of the cotton fiber can be modified considerably without causing a loss in strength. Yarn tensile tests indicate that mercerized, ethanol‐washed cotton yarn with acetyl content between 10% and 30% has a breaking load which is about 12% lower than that of cotton.
Drag reduction and structural turbulence in flowing polyox solutions
Authors: Little R. C. , Wiegard M. 
Published: April 2003

AbstractStructural turbulence has been detected in dilute aqueous solutions of Polyox Coagulant (also known to be a highly effective drag‐reducing agent). The flow line which characterizes structural turbulence from its onset in the laminar region passes well into the fully turbulent region (Reynolds turbulence) with virtually no change in slope, implying that the same molecular oscillations or segmental motions responsible for structural turbulence are now operative in drag reduction. The persistence of structural turbulence at very low concentrations is rationalized on the basis of Busse's explanation of the role of polymer entanglements in viscosity and elastic turbulence.
Extraparticle diffusional effects in gel permeation chromatography. II. Experimental results
Authors: Ouano A. , Biesenberger J. A. 
Published: April 2003

AbstractExperiments coupled with a systems analysis were conducted on chromatogram dispersion, or zone broadening, in gel permeation chromatography (GPC). Three components of a Waters Associates Model 200 chromatograph, each of which is a potential cause of dispersion, were considered; these are: the packed column, with extraparticle dispersion only; the empty tubing, between pump and columns, columns and detector, etc.; and the detection system, viz., the differential refractometer cell. Toluene solvent was used and the solutes whose dispersion was studied included orthodichlorobenzene (ODCB) and narrow‐molecular‐weight polystyrene standards having molecular weights of 900, 20,400, 51,000, 97,200, and 160,000. Nonporous glass beads, 50 μ in diameter, were used as column packing. Two diameters, 1 mm and 0.5 mm, of stainless steel tubing were studied. In addition to the usual rectangular pulse sample injection, a step input mode for solute introduction was also used. The empty tubing was found to contribute significantly to the degree of dispersion and to skewness of elution curves. Anomalous bimodal characteristics of the elution curves were also observed which could only be ascribed to the empty tubing. These phenomena depended markedly on parameters such as tube diameter and length, and solute concentration and molecular weight. Dispersion in the packed column, although important, was found to be symmetrical (Gaussian) and less sensitive to these parameters than in the empty tubing, especially with respect to molecular weight. Dispersion in the cell was believed to be insignificant relative to the packed column and empty tubing.
Dependence of association in polyacrylonitrile solutions on the molecular volume of the nonsolvent
Authors: Beevers R. B. 
Published: April 2003

AbstractAn examination of data obtained from viscometric measurements of the association occurring in solutions of polyacrylonitrile in dimethylformamide, γ‐butyrolactone, and dimethylacetamide has shown that the solubility parameter of the solvent–nonsolvent liquid mixture at the aggregation point is closely related to the molecular volume of the nonsolvent used to bring about association.
The sorption of ions by polyamides
Authors: McGregor R. , Harris P. W. 
Published: April 2003

AbstractAn analysis is given of the principal thermodynamic factors that influence the distribution of an ion between a macroscopically homogeneous polymer phase and a second homogeneous phase and a general method is proposed for the computation of the equilibrium ion sorptions in well‐defined model systems. Particular attention is paid to the sorption of ions by polymers containing ionizable groups and the method is used to clarify some of the current problems in the theoretical explanation of the mechanism of sorption of acid dye anions by polyamide fibers. The method is applicable in principle to any dyeing system in which the fiber phase may be regarded at equilibrium as a macroscopically homogeneous, equipotential volume.
The effect of styrene grafting on the diffusion and solubility of organic liquids in polyethylene
Authors: Fels Morton , Huang Robert Y. M. 
Published: April 2003

AbstractThe effect of grafting styrene onto low‐density polyethylene on the diffusion and solubility of benzene and n‐hexane in the graft copolymer has been investigated. The diffusion coefficient at zero concentration Dc = 0 for both benzene and n‐hexane decreased with the amount of styrene grafting in the polyethylene–styrene graft copolymer membrane. The free volume parameters of the polyethylene–styrene graft copolymer were calculated using benzene and n‐hexane as the diffusing species. Results show that there is a large decrease in free volume as grafting proceeds and the effect is more pronounced at low levels of grafting. Solubility was found to be a function of the per cent grafting, there being a 50%–90% increase in benzene solubility in a 26% graft compared to polyethylene. The increase in solubility for n‐hexane was considerably lower. The effect of crystallinity on the free volume parameters has also been calculated.
Studies on sublimation of disperse dye out of dyed polymers. I. Rate of sublimation and amorphous transition points of poly(ethylene terephthalate)
Authors: Ito Ichiro , Okajima Saburo , Shibata Fumio 
Published: April 2003

AbstractFour samples of poly(ethylene terephthalate) film of various crystallinities and orientation were dyed with p‐nitroaniline and disperse dyes. When these films were heated under a 2–3 × 10−3 mm Hg vacuum at a specified temperature T, the dye sublimed out of the dyed specimen. The amount (Mt/M∞) of sublimed dye is in linear proportion to the square root of the sublimation time, t½, where Mt and M∞ are the amounts of dye sublimed for times t and t = ∞. The diffusion coefficient D, calculated from the slope of the above plot, is independent of the dye concentration of the film.When log D is plotted against 1/T°K over the temperature range 320–520°K, the relation is composed of two to four intersecting lines with the slope decreasing with elevation of temperature and with the breaks at about 89°–98°, 122°–135°, 155° and 175°–176°C. These breaks are the amorphous transitions: the first is the glass transition temperature Tg, the second and the fourth are the amorphous transitions corresponding to the crystalline transition points, i.e., the cold crystallization temperature and the smectic–triclinic transition temperature. With some exceptions, these amorphous transitions are found also by dilatometry and electrical conductivity measurements. The apparent activation energy for diffusion decreases from about 100 kcal/mole for the glass state to 22–24 kcal/mole for the region above 180°C. The activation energy for each region changes slightly with the size of dye molecule and the crystallinity and orientation of the film.
Some solution properties of fractionated water‐soluble hydroxypropylcellulose
Authors: Wirick Max G. , Waldman Maurice H. 
Published: April 2003

AbstractA solution‐fractionation technique has been developed for water‐soluble (molar substitution, MS, ca. 4) hydroxypropylcellulose (HPC), utilizing mixtures of anhydrous ethanol (solvent) and n‐heptane (nonsolvent) of varying composition. Solubility is primarily an inverse function of chain length, species of highest molecular weight being soluble only in solvent mixtures richest in ethanol. Fractionation data indicate HPC substitution is fairly uniform, although there is a tendency for shorter chains to be more highly substituted than long ones. Some control over the degree of variation is possible by changes in processing conditions. Molecular weight and molecular weight distribution reflect the properties of the cellulose employed in sample preparation and the use or omission of deliberate degradation for viscosity control. A sample of HPC ([η] = 4.2; MS = 4.4) was separated into seven fractions of approximately equal weight and the average molecular weight (Mw), root mean square radius of gyration, and second virial coefficient of each of these fractions in ethanol were determined by light scattering, while molecular weight distributions were investigated by gel permeation chromatography in tetrahydrofuran. The relation between intrinsic viscosity and degree of polymerization (DP) was found to be [η] = 7.2×10−3DP. A comparison of hydrodynamic and configurational parameters for HPC in ethanol with those for hydroxyethylcellulose (HEC) in water indicates these two polymers behave very similarly in solution. In both systems the ratio of the mean square end‐to‐end unperturbed molecular chain length (R) to DP diminishes with increasing molecular weight, reaching a minimum at a DPw of approximately 3000. The ratio [(R)/(R)], where (R)½ is the root mean square end‐to‐end distance for 1,4′‐polysaccharides assuming free rotation of the chain units, also diminishes with increasing molecular weight, reaching a limiting value of 3.5. This relatively high ratio indicates considerable rigidity in the coiled molecule and is believed to be at least partially the result of intramolecular hydrogen bonding.
The photo‐oxidation of poly(vinyl chloride) investigated by a stress relaxation technique
Authors: Cox W. C. , Crawford D. J. , Peill P. L. D. 
Published: April 2003

AbstractA stress relaxation technique was used to study the kinetics of the photo‐oxidation of plasticized poly(vinyl chloride) film. The effects of ultraviolet irradiation were characterized by the slope of a difference line between the stress relaxation curve of an irradiated test sample and that of a nonirradiated control. An activation energy of 12 kcal/‐mole was obtained for the rate‐controlling reaction, which was postulated to be hydrogen abstraction from the substrate by peroxy radicals. The rate of relaxation was dependent on the radiation energy, being greater at lower energies. It was also independent of oxygen pressure at “high” pressures and dependent at “low” pressure. The nature of the plasticizer and the presence of stabilizer and ultraviolet absorbers all affected the relaxation behavior.
The swelling of cotton in cadoxen, ethylenediamine, and cuprammonium hydroxide
Authors: Evans G. M. , Jeffries R. 
Published: April 2003

AbstractThis paper describes the swelling of cotton fiber in solutions of cadoxen, ethylenediamine, and cuprammonium hydroxide. The absorption of swelling agent and the increase in width of the fiber were measured. The degree of swelling in cadoxen solutions, in relation to the composition of these solutions, is complex; very high degrees of swelling can be attained. The effects of these swelling treatments on the fine structure of cotton, as measured by the infrared‐deuteration method, density, acid hydrolysis, and an acetylation technique, are described and discussed in relation to the swelling behavior.
A new synthetic fiber made of nylon 3
Authors: Masamoto Junzo , Sasaguri Kichiro , Ohizumi Chihiro , Yamaguchi Koretaka , Kobayashi Hidehiko 
Published: April 2003

AbstractNylon 3 fibers were produced by wet spinning, and properties and structures of the fibers were investigated. Fiber‐ and film‐forming abilities of nylon 3 dopes in various coagulants, using various solvents, were investigated and it was found that only the nylon 3 spinning dope dissolved in formic acid showed excellent fiber‐ and film‐forming abilities in coagulation baths of ethers, esters, or alcohols. As for mass transportation in these coagulants, solvent (formic acid) was diffused into coagulants, with scarce penetration of the coagulants into protofibers. This was due to the fact that these coagulants had moderate solubility parameter values and moderate proton‐accepting power, which means the existence of some interaction between solvent and coagulants and no interaction between coagulants and polymer. Protofibers thus obtained were already crystallized and stretching them at room temperature was impossible. However, in such media as silicone oil, hot air, and Wood's metal, which were thought to have no interaction with polyamides, nylon 3 fibers were stretchable above their glass transition temperature (170°–180°C), while in such media as hot water, hot glycerin, and hot steam, which were thought to have some interaction with polyamides, nylon 3 fibers could not be stretched. Mechanical properties of nylon 3 fibers were as follow: strength, 2–3 g/d; elongation, 10%–20%; Young's modulus, 11 × 105–17 × 105 psi. High Young's modulus, high transition temperature, and high moisture regain are pointed out as characteristic features of nylon 3 fibers, compared with other synthetic fibers.
Polyester hot‐melt adhesives. I. Factors affecting adhesion to epoxy resin coatings
Authors: Jackson W. J. , Gray T. F. , Caldwell J. R. 
Published: April 2003

AbstractThe peel strength and tensile shear strength of polyester hot‐melt adhesives on metals coated with epoxy resins are affected by four characteristics of the polyester: (1) inherent viscosity, (2) glass transition temperature (Tg), (3) degree of crystallinity, and (4) melting point. The inherent viscosity affects the strength, toughness, and crystallinity of the adhesive. The Tg and degree of crystallinity affect the low‐temperature adhesive properties; the peel strength is relatively low when the Tg is appreciably above the use temperature. The Tg, degree of crystallinity, and melting point affect the high‐temperature adhesive properties. A hot‐melt adhesive with high peel and tensile shear strengths from 0° to 120°C is the polyester of 1,4‐butanediol and trans‐1,4‐cyclohexanedicarboxylic acid.
Polyurethanes with long fluorinated side chains
Authors: Raes M. C. , Boudakian M. M. , Urs S. V. 
Published: April 2003

AbstractCopolymer triols were prepared from propylene oxide and glycidyl (α,α,ω‐trihydrododecafluoroheptyl) ether or pentadecafluoroheptylepoxyethane. Cationic polymerization was used and block copolymers were obtained in the molecular weight range of 1,000 to 3,000. These copolymer triols were reacted with an 80/20 mixture of 2,4‐/2,6‐tolylene diisocyanate, giving polyurethanes with the same polymer backbone as the conventional polyurethanes based on polyoxypropylene triols and tolylene diisocyanate. It was found that these polyurethanes, containing between 0% and 45% fluorine, showed increasing adhesion to anodized aluminum with increasing urea bond content of the polymer. However, the fluorine content did not show the expected effect on adhesion. Isothermal gravimetric analysis showed that the heat stability of the fluorourethanes was lower than for conventional urethanes on a weight basis, only because the segments split off in heat degradation were heavier for the fluorourethane. This phenomenon might possibly also apply to urethanes with a fluorinated backbone. On a mole basis fluorourethanes might be as stable as nonfluorourethanes. It was also found that the thermostability, as measured by weight loss, increased with an increasing degree of crosslink density in the polymers.
Degradation of poly(vinyl chloride)
Authors: Salovey R. , Bair H. E. 
Published: April 2003

AbstractThe decomposition of poly(vinyl chloride) below 155°C has been examined by thermogravimetric analysis. Degradation is enhanced by irradiation with 1 MeV electrons. Later stages of isothermal weight loss for thermal and radiolytic decomposition follow 3/2‐order kinetics and a similar reaction scheme is inferred. A free radical mechanism for dehydrochlorination involving allyl and polyenyl radicals is postulated.
Decomposition kinetics of a phenolic–carbon composite. I. Resin available for volatilization
Authors: Auerbach Irving 
Published: April 2003

AbstractThe isothermal decomposition of a phenolic resin in a phenolic–carbon cloth composite was measured at approximately 0.1 to 0.2 torr over the temperature range of 105°–718°C. The kinetics are initially first order and, in the later stages, second order. An analytic technique is provided for calculating the maximum quantity of resin which will volatilize during decomposition, thereby obviating the necessity of measurements for extended time periods. The amount of resin available for volatilization during decomposition varies with temperature and is in equilibrium with resin, which does not volatilize. Plots of the equilibrium constant versus the reciprocal absolute temperature show that two equilibria are involved: one which predominates up to 352°C and the other above this temperature. The heats of reaction are 2.2 and 15.3 kcal/mole. The first value is associated with hydrogen bonding and the second with decomposition and oxidation activation energies.
Mill behavior of elastomers: Scale‐up criteria
Authors: Wagner Martin G. 
Published: April 2003

AbstractAn investigation into the phenomenon known as “bagging” on a rubber mill was made. Based upon the assumption that bagging is a manifestation of a viscoelastic hydrodynamic instability, a scale‐up criterion for the onset of bagging was developed. The derived scale‐up method was tested over wide ranges of elastomer compounds and mills and found to hold within the estimated experimental error.