bluuebunny/crossref_metadata_2025 huggingface dataset:
Combined pyrolysis and radiochemical gas chromatography for studying the thermal degradation of epoxy resins and polyimides. I. The degradation of epoxy resins in nitrogen between 400°C and 700°C
Authors: Bishop D. P. , Smith D. A.
Published: April 2003

The thermal degradation of a bisphenol A‐based epoxy resin (EP 274) cured with 4,4′‐diaminodiphenyl methane (DDM) and with phthalic anhydride (PA) was studied using a radiochemical pyrolysis gas chromatography technique. Conclusive evidence for some of the degradation mechanisms of these resins was obtained by pyrolyzing samples containing various 14C‐labelled groups and analyzing the products using this method.
Direct fiber formation and fiber properties of aromatic polyoxadiazoles
Authors: Imai Yoshio
Published: April 2003

A 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

A 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

Without 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

Isotactic 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

The 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

The 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

The 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

Structural 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

Experiments 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

An 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

An 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

The 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

Four 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

A 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

A 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

This 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

Nylon 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

The 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

Copolymer 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

The 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

The 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

An 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.
The ultraviolet activation spectrum of polycarbonate
Authors: Mullen P. A. , Searle N. Z.
Published: April 2003

Previous work has shown that a polymeric phenyl salicylate and a polymeric dihydroxybenzophenone are formed during the irradiation of polycarbonate with nonspectrally dispersed ultraviolet light. In the present studies the photodegradation of polycarbonate film has been investigated as a function of irradiating wavelength using spectrally dispersed light from a xenon are between 2300 and 6300 Å. Maximum changes in absorbance at 3200, 3600, and 4000 Å were induced in the sample by irradiating wavelengths between 2800 and 2900 Å. The wavelength sensitivity of an extruded sample of polycarbonate is compared with results obtained for a solution‐cast thin film of the material. The results of the present study support the stepwise photodegradation mechanism of polycarbonate previously reported and suggest the possibility of an additional photodegradation process.
Cellulose graft copolymers. II. Graft copolymerization of ethyl acrylate with γ‐irradiated cellulose from acetone–water systems
Authors: Nakamura Yoshio , Hinojosa Oscar , Arthur Jett C.
Published: April 2003

Ethyl acrylate was graft‐copolymerized from acetone–water systems with γ‐irradiated, purified cotton cellulose. The scavenging of the free radicals in the irradiated cellulose by water, acetone, and water–acetone systems was determined by electron spin resonance spectroscopy. The ESR spectra of free radicals, scavenged by water and acetone, were recorded by the use of a time‐averaging computer attached to the ESR spectrometer, in which the ESR spectrum of the irradiated cellulose, which had been immersed in water and/or acetone, was electronically subtracted from the ESR spectrum of the irradiated cellulose control. For both water and acetone, the ESR spectra of the scavenged free radicals were singlets. This indicated that free radical sites formed on carbon C1 or C4 on radiation‐initiated depolymerization, which would generate singlet ESR spectra, were readily accessible to these solvents. The maximum scavenging of the radicals was observed when irradiated cellulose was immersed in acetone–water solution which had a composition of 25/75 vol‐%. The scavenging of the free radicals in irradiated cellulose when immersed in acetone–water solutions was less than when immersed in methanol–water solutions. Also, the extent of graft copolymerization of ethyl acrylate from acetone solutions with irradiated cellulose was less than that of ethyl acrylate from methanol solutions. These differences were probably due to differences in the diffusion rates of acetone and methanol into the cellulosie structure. The Trommsdorff‐type effect in the acetone solutions would be less than in the methanol solutions, since acetone is a better solvent for poly(ethyl acrylate) than methanol.
Reversible crosslinking in cellulose. II. Mono‐and bifunctional reactions of bis‐β‐isocyanatoethyl disulfide with cotton
Authors: Sakamoto Munenori , Takeda Junichi , Yamada Yoshio , Tonami Hiroaki
Published: April 2003

Bis‐β‐isocyanatoethyl disulfide (BIED) was synthesized from diethyl dithiodipropionate and its reaction with cotton in dimethylformamide was investigated. The sulfur content of the treated cotton decreased by reduction with tri‐n‐butylphosphine. The polarographic and infrared analyses revealed that BIED reacted with cotton both monofunctionally and bifunctionally to form branches and crosslinks, respectively. The ratio of the crosslinks to the total amount of BIED combined increased in general as the reaction progressed. X‐Ray study indicated that the reaction took place mainly in the original amorphous region.
The degradation of polystyrene during extrusion
Authors: Arisawa Kunio , Porter Roger S.
Published: April 2003

An investigation was made of the magnitude and mechanism of shear degradation of a narrow distribution, high molecular weight (Mw = 670,000) polystyrene. An Instron rheometer was used to perform the extrusion at temperatures from 164° to 250°C. The change in molecular weight distribution was studied by gel permeation chromatography. The maximum shear stress employed was 5.83 kg/cm2. It was found that degradation could be induced at high stress at temperatures of 50°C lower than degradation of polystyrene would occur exclusively due to thermal forces. An activation energy for the degradation, calculated at constant shear rate, was +20.2 kcal/mole. The direction and magnitude of this value are consistent with degradation induced through a mechanical reduced activation for thermal degradation.
Mechanism of alkali thickening of acid‐containing emulsion polymers. I. Examination of latexes by means of viscosity
Authors: Verbrugge C. J.
Published: April 2003

Viscosity‐versus‐pH relationships for a large number of methacrylic acid‐containing emulsion polymers have been measured. The monomers chosen for this study were so selected because they represent synthesized latexes of high and low Tg and comparative hydrophilicity. These were styrene, methyl methacrylate, ethyl acrylate, n‐butyl acrylate, and 2‐ethylhexyl acrylate. The postulated mechanism involved in the transition from an unneutralized latex particle to the neutralized species is accounted for in terms of varying degrees of particle swelling. In the limiting case, particle swelling is followed by complete solution of the polymer. The most important variables are the per cent methacrylic acid and the polymer Tg and hydrophilicity as determined by the comonomers present. The degree of particle swelling ranges from none for high styrene‐containing latexes to high degrees of swelling followed by polymer solubilization for high ethyl acrylate‐containing latexes.
Mechanism of alkali‐thickening of acid‐containing emulsion polymers. II. Examination of latexes with the light microscope
Authors: Verbrugge C. J.
Published: April 2003

The mechanism of alkali thickening of acid‐containing emulsion polymers has been confirmed by visual examination of the swelling and disappearance of latex particles with the light microscope. Specially prepared large particle‐sized latexes were used in this study. Each latex was examined from 0%–200% neutralization with base. The particle swelling and dissolution behavior correlated with viscosity measurements, high viscosity being present for swollen particle systems and low viscosity for true solutions. The neutralized state of all acid‐containing latexes can be pictured in a cube with the important variables being per cent acid, hydrophilicity of the comonomers, and Tg. At the bottom will be latexes only slightly affected by neutralization, above this will be a swollen particle zone, and the largest area will be a true solution zone. The true solution zone will be enlarged by lowering the molecular weight of the latex polymer.
Rheological properties of elastomers based on cellulose fibers
Authors: Nakamura Y. , Arthur Jett C. , Negishi M. , Doi K. , Kageyama E. , Kudo K.
Published: April 2003

Elastomers, based on cellulose fibers, were synthesized by grafting ethyl acrylate onto fibers preirradiated by a high‐energy electron beam. The rheological properties and fine structure of the elastomers were investigated in order to determine factors in development of rubber‐like elastomeric behavior. Mechanical properties of the elastomers depended on (1) degree of polymerization of irradiated cellulose molecules, (2) extent of grafting, and (3) experimental methods of evaluation, particularly in varying environmental conditions, for example, in making measurements in air, water, or ethyl acetate. Glass transition temperatures of the elastomers were dependent on the environmental conditions of evaluation; stiffnesses of the elastomers levelled off at about 0°C; and in all environments, a rubber‐like plateau was observed. Poly(ethyl acrylate) separated from the elastomers was not soluble in acetone. The mean molecular weight of the separated poly(ethyl acrylate) of the elastomer was determined in ethyl acetate by the equilibrium swelling method. It was concluded that crosslinks existed in the elastomers. Electron microphotographs of cross sections of the elastomers, which exhibited rubber‐like behavior, indicated that the fibrillar structure of the irradiated cellulose fibers formed a uniform network and that poly(ethyl acrylate) was uniformly distributed among the fibrils.
Effect of tensile strain on the use of the WLF equation
Authors: Adicoff Arnold , Lepie Albert H.
Published: April 2003

The effect of finite elongation on superposed infinitesimal torsional oscillations has been determined on two propellants, a carbon black‐filled rubber and Solithane 113 (Galcit I), as a function of temperature at various fixed frequencies. Torsional storage modulus—temperature data for carbon black‐filled rubber and propellant show that the effect of the imposed tensile elongation cannot be explained by any simple temperature–elongation shift relationship. The shift factors for the torsional moduli of these two polymeric systems have been calculated as a function of temperature at various tensile elongations. The WLF constants C1 and C2 have been computed for these systems as a function of the elongation. The constants decrease with increasing elongation. The values of the constants at 0% elongation are larger than those commonly found in unfilled materials. The temperature dependence of the shift factor of the torsional storage modulus was found to differ from that of the loss modulus in the cases of carbon black‐filled rubber and propellant. This difference is slight for the rubber and large for the propellant. The effect of increased elongation is to increase the difference in the shift behavior of the moduli for each of these filled polymers. The shape of the loss tangent curve of the propellants examined indicates that these propellants are not thermorheologically simple.
The adsorption and absorption of water vapor by polyethylene terephthalate
Authors: Prosser R. A.
Published: April 2003

An experimental technique for the simultaneous determination of the amount of gas or vapor absorbed and adsorbed by a film of material is given. For Mylar film at 40°C it was found that the amount of water at an activity of 0.9 that was adsorbed was about 1 × 10−7 g/cm2. Assuming that a water molecule is cubical in shape and 3.26 Å on an edge and the surface is geometrically flat, this amounts to several layers of water molecules on the surface for any thickness.
Copolymer characterization by surface tension
Authors: Allan G. Graham , Neogi Amar Nath
Published: April 2003

The use of surface tension measurements is proposed as a simple method for the determination of copolymerization ratios. The procedure depends on the parachor of the copolymer in the liquid state (∏), which is defined by ∏ = ∏s + ∏0(wp/ws)(Ms/M0) for solutions and ∏ = [DP]∏0 for liquid or molten polymers, where ∏s is the parachor of the solvent of molecular weight Ms; wp and ws are the weights of the polymer and solvent in solution; while ∏0 and M0 are the parachor and molecular weight of the repeating unit of the copolymer, respectively. The validity of this relationship is demonstrated by analysis of the surface tension properties of liquid silicone polymers, polystyrene–Decalin solutions, and molten polymers as well as by the calculation of the composition of some characterized tetrahydrofuran–propylene oxide copolymers. The application of surface tension measurement is also suggested as a means of estimating the degree of chain branching in a polymer.
Effects of mixing states on physical properties of vulcanizates of polybutadiene rubber‐general purpose polystyrene resin blend
Authors: Satake K.
Published: April 2003

The effects of the continuous phases of general purpose polystyrene resins upon the physical properties of the vulcanizates were studied using the polybutadiene rubber–general purpose polystyrene resin blend. The unvulcanized samples were prepared according to the method already mentioned in our previous report,1 and the radiation cure was adopted so that a change of state during cure might be avoided. Some physical properties like hardness, modulus, elongation, permanent set, and resilience are much influenced by the existence of the continuous phases even if the polymer blend ratios are kept constant, whereas tensile strength at failure is mainly determined by the polymer blend ratio. The physical properties which belong to the former group are found to be controlled more strongly by the polymer which forms the continuous phase.
Some filler effects on diffusion in silicone rubber
Authors: Most C. F.
Published: April 2003

The diffusion of ethyl p‐aminobenzoate in silicone rubber membranes containing varying amounts of a high surface area fumed silica filler is described, as is a new apparatus for assaying multiple samples. It is shown that increased filler loading results in what appears to be a linear decrease in transmission rate, but that apparent diffusivities fall off drastically as a result of adsorption of the permeant on the filler. Distribution coefficient measurements suffer from the same result. The results suggest that neither an unmodified time lag technique nor a direct solubility method can be used to determine diffusivities of polar or unsaturated molecules in silicone rubbers, since they generally contain silica fillers.
Composition of methyl methacrylate‐grafted cellulose
Authors: Ogiwara Yoshitaka , Kubota Hitoshi , Arai Kenichiro
Published: April 2003

Graft copolymerization of methyl methacrylate on cellulose samples was carried out using various initiator systems, and extraction treatment was performed on the copolymers with 50% to 300% grafting by weight. Adding of ceric ion to a suspension of cellulose and methyl methacrylate in water resulted in more efficient grafting than other methods. That is, amount of extracted cellulose from graft copolymers obtained by the conventional ceric ion method was approximately 20%, whereas those obtained either by the hydrogen peroxide method or by the adsorbed ceric ion method amounted to 70% to 80%. However, the amount of extracted homopolymer was approximately proportional to that of extracted cellulose. The composition of refined samples ranged 20% to 30% of cellulose content and 70% to 80% of poly(methyl methacrylate) content throughout all samples, and it was recognized that the proportion of poly(methyl methacrylate) tended to increase slightly with higher per cent grafting. When the structure of refined graft copolymer was derived from these values, it was recognized that the extent of the grafted chain was at most 1 mole per 1 mole of cellulose molecule in the conventional ceric ion method and amounted to only 1/10 mole in the hydrogen peroxide and adsorbed ceric ion methods.
The average molecular structure of base‐catalyzed low‐mole adducts of propylene oxide to glycerin
Authors: Gibson U. H. , Quick Q.
Published: April 2003

The average structure of low molecular weight base‐catalyzed propylene oxide adducts of glycerin have been studied rather extensively using gas chromatographic and HNMR techniques. HNMR analysis of the trifluoroacetyl derivatives of individual adducts provide a useful technique for distinguishing internal isopropoxy units from terminal isopropoxy units. It can also be used to estimate the degree of initiation at the secondary hydroxyl site of the glycerin starter. A surprising amount of initiation at the secondary hydroxyl site was found for the three‐mole adducts and the four‐mole adducts are very highly initiated at this site. Concentrations of the possible contributing structures in fractions of a typical low‐mole weight polyol are tabulated. The higher adducts are envisioned as consisting of three propagating chains of nearly equal length and reactivity.
Dichroism of poly(ethylene terephthalate)‐disperse dye system
Authors: Okajima Saburo , Nakayama Kazuo , Kayama Kazuo , Kato Yoshio
Published: April 2003

As an approach to the basic study on the orientation behavior of amorphous region, the dichroic orientation factor, D, of poly(ethylene terephthalate), PET, fiber or film dyed with disperse dyes was investigated in relation to Δn, birefringence of the crystalline and amorphous regions, and Δna, birefringence of the amorphous region. It was found that D versus Δn plot belonged to a linear relationship passing through the origin but breaking slightly toward the D axis at Δn ≃ 0.14, while D versus Δna plot was expressed by a straight line passing similarly through the origin but with no break. D0, the value of D at the ideal parallel orientation, was obtained by extrapolating the latter plot of the samples stretched with no relaxation: 1.00 and 0.73 for the PET–C.I. Disperse Yellow 7 and PET–C.I. Disperse Red 17 systems respectively. When the sample had been relaxed, the D versus Δna was also linear; however, D0's obtained were smaller than the above mentioned respective values. Even in these cases D for Disperse Yellow 7 versus the corresponding D for Disperse Red 17 belonged to a linear relationship with the slop 1:0.73.

As the result it was concluded that the transition moment of molecule of C.I. Disperse Yellow 7 coincided with the molecular axis and the dye molecule combined parallel to PET chain, while as to C.I. Disperse Red 17 any definite conclusion could not be determined. However, in the both cases the mode of combination of dye molecules with PET is definite and kept unchanged during stretching and heating.
Preparation of a polyimide foam
Authors: Farrissey William J. , Rose James S. , Carleton Peter S.
Published: April 2003

The reaction of phenyl isocyanate with phthalic anhydride to form N‐phenylphthalimide is strongly solvent dependent and catalyzed by tertiary amines. Water and alcohol promote imide formation, but Lewis acids and organometallic compounds are ineffective. In DMSO solvent, benzophenone tetracarboxylic dianhydride (BTDA) and polymethylene polyphenol isocyanate (PAPI) polymerize with the evolution of carbon dioxide to yield a foamed polyimide. The solvent‐freed open‐celled foams exhibit exceptional fire resistance and thermal stability.
The molecular weight of a sodium lignosulfonate in dimethylsulfoxide and in aqueous 0.1M sodium chlorine
Authors: Yean W. Q. , Goring D. A. I.
Published: April 2003

Values of the weight‐average molecular weight for a high molecular weight lignosulfonate were found to be nearly equal in aqueous sodium chloride and in DMSO. Prolonged storage in DMSO produced no perceptible change in molecular weight. The results indicated that the lignosulfonate macromolecule was a truly covalent species and was not an aggregate comprised of many low molecular weight units held together by association forces.
The fracture threshold for an adhesive interlayer
Authors: Williams M. L.
Published: April 2003

Complementing an earlier paper which utilized an energy balance criterion for a continuum mechanics analysis of adhesive failure in a pressurized blister at the interface of an elastic material and a rigid substrate, the analysis is extended to include an additional elastic interlayer between them. An infinite lateral‐length elastic plate strip bonded through a Winkler elastic foundation to a rigid substrate is assumed, in which the plate is separated from the adhesive layer by internal pressure. It is found that the important design parameters are the tensile modulus‐to‐thickness ratio of the adhesive layer and the adhesive fracture energy of separation of the respective materials. The results provide a basis for investigating changes in the chemical microstructure of the adhesive.
Creep and stress relaxation of natural rubber vulcanizates. Part I. Effect of crosslink density on the rate of creep in different vulcanizing systems
Authors: Farlie E. D.
Published: April 2003

The physical creep of unfilled natural rubber vulcanizates, prepared with different vulcanizing systems, has been studied. For each of the three vulcanizing systems chosen there is a strong dependence of creep rate on crosslink density, but the rates for accelerated sulfur vulcanizates are two or three times higher than those of peroxide vulcanizates of similar crosslink density. Supplementary experiments, in which the crosslink structure of sulfur vulcanizates is modified either by chemical treatment or by variations in the vulcanizing conditions, show that the nature of the crosslink itself is not a determining factor in the type of vulcanizate. Other features, such as the type and quantity of extranetwork material arising from the vulcanizing process, contribute significantly to the viscoelastic behavior of accelerated sulfur vulcanizates.
Determination of poly(oxypropylene diol) present in poly(oxypropylene triol) by thin‐layer chromatography
Authors: Mameniskis Walter A.
Published: April 2003

A thin‐layer chromatographic method has been developed for the quantitative determination of poly(oxypropylene diols) present in poly(oxypropylene triols). The polyols are separated on silica gel plates in a modified developing chamber using ethyl acetate as the developer. Quantitative results were obtained by conventional visualization and densitometer techniques. Polyols ranging in average molecular weight from 400 to 3000 have been resolved by this method. Diols present in a mixture with triols can be detected at levels as low as 1.0%.
Ultrafiltration of macromolecular solutions with high‐flux membranes
Authors: Baker R. W. , Strathmann H.
Published: April 2003

Batch and flow recirculation cells were used to study the properties of high‐flux ultrafiltration membranes with different macromolecular solutions. At low pressures, solutions of completely retained macromolecular solutes have a flux which is approximately the same as the flux of pure solvent. At higher pressures, the solution flux levels off. The flux, at the leveling‐off period, is approximately inversely proportional to the solution concentration. In this plateau region the flux increases with temperature and agitation of the solution but decreases with time. These results are explained by the formation of a gel layer on the membrane surface during the filtration of macromolecular solutions. In ultrafiltration, in contrast to dialysis and GPC, a linear polymer penetrates the selective barrier more readily than does a globular protein of the same molecular weight. The difference may arise from the liquid shear stresses within the barrier medium due to the movement of fluid relative to the pore walls, which is large only in ultrafiltration. Also, retention of polymers was found to decrease with pressure and to increase with agitation of the solution.
Studies in chemically modified celluloses. III. Estimation of free carboxylic acid groups in oxycellulose
Authors: Nabar G. M. , Shenai V. A.
Published: April 2003

Various methods suggested for the determination of carboxyl groups in chemically modified celluloses suffer from some drawbacks. Attempts have been made to overcome the drawbacks of some of these methods. The influence of alkali‐sensitive reducing groups, enediol groups, and lactones on the carboxyl estimation is discussed and the importance of borohydride treatment of the oxycelluloses before the estimation of carboxyl groups by alkali titration method or by iodometric method is stressed. The usefulness and the limitations of both methods are pointed out.
The anionic dispersion polymerization of α‐methylstyrene
Authors: Stampa Guido B.
Published: April 2003

A new technique for the anionic polymerization of α‐methylstyrene has been developed. By using an aliphatic hydrocarbon as the diluent, hexamethylphosphoramide as promoter, and a poly(vinyl alkyl ether) as interfacial agent, the high molecular weight polymer is obtained as a uniform dispersion. The advantages of the method are high conversions at low viscosities and an economical isolation procedure.