bluuebunny/crossref_metadata_2025_split huggingface dataset:
Statistical analysis applied to film development: Grafted PVA‐based water‐soluble film
Authors: Bentz Alan P. , Roth Roy W. 
Published: April 2003

AbstractA statistically designed experiment was used to optimize the physical properties of a cold water‐soluble film by establishing reliable estimates of the effects of the independent variables of the system. The system consisted of polyvinyl alcohol (low molecular weight, 88% hydrolyzed) to which is grafted ethyl acrylate by a ceric ion technique. To the grafted PVA is added a higher molecular weight PVA to strengthen film.
Effect of ethylamine treatment on dielectric properties and crystallinity of cellulose. II
Authors: Venkateswaran A. , Akker J. A. Van Den 
Published: April 2003

AbstractInvestigations have been made on the influence of (1) beating on the dielectric properties of cellulose, (2) beating before and after ethylamine treatment of cellulose, (3) compressive stress and moisture on the crystallinity of cellulose, (4) pelletizing cellulose for measurement of crystallinity, and (5) employing different methods of drying the cellulose on the crystallinity of cellulose. It was found that existing formulas involving the 002 peak intensity for estimating the crystallinity index seem to be inadequate. It is suspected that ethylamine treatment does not “decrystallize” cellulose but causes swelling of cellulose, resulting in an alteration in the lateral order structure of the so‐called “amorphous content” of cellulose. It is suggested that the moisture regain method is more suitable for comparing the dielectric constant and accessibility of cellulose.
Oxidation of styrene popcorn polymer
Authors: Chock David P. , Chock Ernest P. , Miller Glenn H. 
Published: April 2003

AbstractStudies have been made of the oxidation of styrene popcorn polymer that was grown on butadiene popcorn seed. It was found that the solubility of the polymer increased after oxidation. This solubility was studied as a function of both temperature and butadiene content of the polymer. Oxidation of the styrene‐on‐butadiene popcorn occurs at the carbon atoms alpha to a double bond in the butadiene portion of the polymer. This is followed by scission of the structure and the separation of linear atactic soluble polystyrene chains.
Butadiene/styrene/2‐methyl‐5‐vinylpyridine terpolymer. Composition–conversion data in comparison with calculated values
Authors: Crescentini L. , Gechele G. B. , Zanella A. 
Published: April 2003

AbstractTerpolymers from 1,3‐butadiene, styrene, and vinylpyridine are important as rubbers, and, in latex form, as components of rubber‐to‐fabric adhesives. Three monomer mixtures having the approximate weight composition butadiene/styrene/2‐methyl‐5‐vinylpyridine 70/15/15, 25/48/27, and 38.5/49/12.5 have been emulsion‐polymerized at 30°C., and the terpolymer composition as a function of the conversion has been studied. The six monomer reactivity ratios have been determined by binary copolymerizations at 30°C. and checked by low conversion bulk terpolymerizations. Average and instantaneous composition–conversion curves have been calculated, on the assumption of a constant reaction volume, by numerical integration of the terpolymerization equations on electronic computer. Details, of general applicability, for calculations are given. The experimental results of the emulsion terpolymerizations fit satisfactorily the calculated curves over a wide range of conversions.
Sulfur group analysis in unaccelerated vulcanization of natural rubber
Authors: Chakravarty Shomnath , Chatterjee Pronoy K. , Sircar Anil K. 
Published: April 2003

AbstractThe reaction of lithium aluminum hydride forming mercaptan with disfulfides and mercaptan as well as hydrogen sulfide with polysulfides has been applied in order to characterize the structure of the crosslinks in the case of unaccelerated vulcanization of natural rubber with sulfur. The mercaptans formed were determined amperometrically, and the hydrogen sulfide was determined as cadmium sulfide. These measurements, coupled with the estimation of total crosslinks as measured by swelling, provide valuable information as to the distribution f different crosslinks (monosulfide, polysulfide, cyclic structures, etc.) in the vulcanizate. When extended to compounds of different sulfur concentrations (2.92‐33.9%) these studies show how the distribution of different linkages changes with sulfur concentration from compositions corresponding to soft rubber to those corresponding to hard rubber. The present study provides conclusive evidence that the long polysulfidic crosslinks first formed during vulcanization decrease in chain length as vulcanization progresses. Polysulfides also increase with the increasing sulfur content in the stock except in the range 6‐10%. Monosulfidic crosslinks increase with increasing sulfur in the stock. In contrast to accelerated vulcanization, a high proportion of combined sulfur was found to be present in cyclic structures, and this increases with temperature of curing. These findings tally with the results of the earlier workers and have been explained with the present day ideas of the vulcanization reaction. Inaccuracies in the measurements and inherent limitations of the method were discussed.
Stress relaxation of polytetrafluoroethylene in the vicinity of its glass transition temperature at about 130°C.
Authors: Araki Yoshio 
Published: April 2003

AbstractMeasurements of compressive stress relaxation for molded polytetrafluoroethylene were carried out at different temperatures over the range 60–150°C., at 5°C. increments under a small strain (less than 0.3%). By the application of the so‐called Ferry's reduction method, three master curves were obtained with good overlapping from a series of stress relaxation curves obtained at different temperatures for the same specimen. This polymer has two temperatures at which the three master curves cross and the reduction method becomes entirely in applicable. Those two temperatures are about 80 and 100°C. It may be concluded that this polymer has two first‐order transitions at about 80 and 100°C., and the states above and below these temperatures are quite different, as in the case of the transition observed for this polymer at about 20°C., which has been confirmed to be a first‐order transition in crystal structure. The reduction factors aT at different temperatures were plotted in logarithmic scale against the reciprocals of the absolute temperatures. From the slope of those three log aT vs. 1/T curves, the diagrams of the apparent activation energy vs. temperature were obtained. There were two sharp maxima at about 120 and 130°C. in the diagram, where this polymer also has two irregular changes in other viscoelastic properties. It is conceivable that these changes at 120 and 130°C. are second‐order transitions occurring in the amorphous region of the polymer.
Filler particle size and mechanical properties of polymers
Authors: Alter Harvey 
Published: April 2003

AbstractLiterature data for the effect of mineral fillers on the mechanical properties of polyethylene at two temperatures, styrene–butadiene rubber, and natural rubber were examined. The data for modulus, tensile strength, elongation at yield, and ultimate elongation could be well represented by linear plots of the relative mechanical property (ratio of the values for the filled to the unfilled) as functions of the reciprocal of the filler particle size. A plot of one of these properties versus reciprocal filler size shows a family of lines, one line for each concentration of filler, and independent from the chemical nature of the filler. The dependence of the mechanical properties on reciprocal particle size may express a dependence on the surface‐to‐volume ratio of the filler, a balance between the effective cross‐linking due to the large surface area of the filler, and the dilution of the polymer by the volume of filler present.
Some relationships between molecular structure and flow in linear polyethylene
Authors: Schreiber H. P. 
Published: April 2003

AbstractThe flow curves of linear polyethylenes are characterized by a set of empirically defined parameters, including the apparent melt viscosity at zero shear stress, the shear stress for onset of non‐Newtonian flow, and the slopes of linear sections fitted to data in three shear stress ranges of the flow curve. Not all of these parameters have theoretical significance but all are easily measured and therefore should be useful for broad, practical application. The dependence of the parameters on molecular weight, shape, and breadth of the molecular weight distribution has been demonstrated by using fractions and blends of fractions of linear polyethylenes. The zero shear viscosity and degree of non‐Newtonian flow at low shear stress depend primarily on polymer molecular weight. The degree of non‐Newtonian flow at higher shear stress can be related quantitatively to molecular weight distribution factors, while the stress for onset of non‐Newtonian flow also correlates with molecular weight distribution. Formally, the derived correlations are specific to the apparatus used, but may in fact have much broader validity because of the minor importance in these polymer samples, of elastic effects such as capillary die entry effects.
Photodegradation of cis‐1,4‐polyisoprene sensitized by the addition of chloronitroso compounds
Authors: Rabek J. F. 
Published: April 2003

AbstractIt was found that chloronitroso compounds with a free non‐conjugated nitroso group show a considerable sensitizing activity in respect to the process of photochemical degradation of dissolved cis‐1,4‐polyisoprene, which is induced by visible radiation (4000–7000 A.). The effect of 10 chloronitroso sensitizing compounds were investigated. The highest sensitizing activity was found with compounds 2,2‐chloronitrosopropane and 1,1‐chloronitrosocyclohexane. The maximum wavelength, of which the decrease of relative viscosity of solutions was the highest, was determined for 2,2‐chloronitrosopropane. The highest sensitizing activity of chloronitroso compounds was found for wavelengths corresponding to the absorption maximum of the sensitizer added. The theory of the sensitizing activity of chloronitroso compounds is proposed.
Anionic heterogeneous polymerization of acrylonitrile by butyllithium. II. Effect of lewis bases on the molecular weight
Authors: Feit Ben‐Ami , Mirelman David , Katz Y. , Zilkha Albert 
Published: April 2003

AbstractThe heterogeneous polymerization of acrylonitrile in petroleum ether by butyllithium in the presence of Lewis bases was investigated. Molecular weights increased sharply on addition of small amounts of Lewis bases. High, maximal molecular weights were obtained at optimal values of [Lewis base]/[BuLi] = 1–2. Beyond this optimum a sharp decrease of molecular weights was observed. The optimal [Lewis base]/[BuLi] ratio was dependent on the Lewis base used and was specifically related to the structure of the complex Li+ Lewis base. The effectiveness of the Lewis bases in obtaining high molecular weights was as follows: DMF ≫ THF ∼ dioxane > dimethylacetamide. A nonterminated “living” polymerization for which DP was given by DP = Rp/Ri was observed with low rates of monomer addition, whereas chain transfer to monomer occurred with high rates. This behavior was qualitatively the same as that found in the absence of any Lewis base. However, under comparable conditions, higher molecular weights were always obtained in the presence of a Lewis base, except for relatively high ratios of [Lewis base]/[BuLi]. It was suggested that at the optimal ratio of [Lewis base]/[BuLi] and beyond it, all the positive Li+ ions in the polymerization mixture were solvated by the Lewis base. This solvation increased the nucleophilic reactivity of the carbanions. On increasing the Lewis base concentrations up to the optimal value of [Lewis base]/[BuLi], Rp increased much more than Ri, which resulted in a sharp increase of molecular weights. Beyond the optimal value of [Lewis base]/[BuLi] where all the positive counterions of the propagating ends were completely solvated, added Lewisbase might cause further dissociation of the associated [BuLi]n, leading to a larger increase of Ri as compared to Rp, and consequently to a decrease of DP.
Determination of primary and secondary xanthate groups in cellulose xanthate
Authors: Dunbrant Stig , Samuelson Olof 
Published: April 2003

AbstractVarious kinetic methods for the determination of primary and secondary xanthate groups have been compared. With certain types of viscoses all methods give an excellent agreement and are superior to the purely chemical methods which are unreliable. The field of application of a kinetic method based upon decomposition in a slightly acid buffer is limited due to the appearance of a turbidity upon prolonged dexanthation. A modified technique in which the decomposition is carried out at elevated temperature in sodium hydroxide solution is both rapid and versatile.
Regulation of molecular weight distribution in the polymerization of butadiene–styrene and butadiene–nitrile rubbers
Authors: Poddubnyĭ I. Ya. , Rabinerzon M. A. 
Published: April 2003

AbstractConditions for the preparation of butadiene–styrene and butadiene–nitrile rubbers with desirable molecular weight distributions were developed; regulators of different activities were used in the polymerizations. The character of the dependencies of properties of the butadiene–styrene rubbers on the molecular weight distribution of the polymers was established. Butadiene–styrene and butadiene–nitrile rubbers with the desired distributions and good elastic‐plastic and physical‐mechanical properties were obtained. These rubbers are now commercially produced on the basis of these findings.
Physical properties and structure of the polyethylene produced by γ‐radiation polymerization
Authors: Machi Sueo , Tamura Takeshi , Fujioka Shuji , Hagiwara Miyuki , Gotoda Masao , Kagiya Tsutomu 
Published: April 2003

AbstractPolyethylene produced by γ‐radiation had short‐chain branching to some extent and a small amount of vinylidene unsaturation. An OH group was found in polyethylene produced in the presence of methanol. The properties and structure of the polymer were found to vary widely with changes in the reaction condition, such as ethylene pressure, reaction temperature, time, and dose rate. Polymer density, an important property, varied from 0.88 to 0.96 g./cc. and crystallinity from 40 to 80%, depending on the reaction conditions. Polyethylene polymerized at room temperature at a pressure of 300–400 kg./cm.2 was shown to have an extremely high molecular weight (up to 300,000) and low methyl content (below 0.5CH3/100C). Density depends solely on the crystallinity of the polymer, which was found to be determined by the degree of short‐chain branching and molecular weight. Quantitative relationships between them were obtained. The use of methanol as a solvent was found to have no effect on short‐chain branching but have a marked effect on molecular weight; hence, high‐density polyethylene could be obtained with the use of methanol solvent. Polyethylenes with a high molecular weight (above 100,000) had a higher melting point than high‐pressure polyethylene. The quantitative correlation between molecular weight and melt index was also determined and found to be similar to that of Sperati. Some mechanical properties were also measured.
Sedimentation analysis of 1,4‐cis‐polybutadiene in a theta solvent, diethyl ketone at 10.3°C
Authors: Abe Mitsuo , Murakami Yuriko , Fujita Hiroshi 
Published: April 2003

AbstractA sedimentation and viscosity study of 1,4‐cis‐polybutadiene (having 95% 1,4‐cis units) in a θ‐solvent diethyl ketone (DEK) at 10.3°C. is reported. The limiting sedimentation coefficient so and the limiting viscosity number [η]θ of the monodisperse sample of this polymer in the given θ‐solvent as functions of its molecular weight M are derived from data on polydisperse fractions by application of the method described by Homma et al. The results are: so = 0.530 × 10−15M1/2 (in sec.) and [η]θ = 1.60 × 10−3M1/2 (in dl./g.). Substitution of the experimental data into the well‐known Mandelkern‐Flory equation yields 1.74 × 106 for the familiar parameter Φ1/3 P−1, which is about 30% lower than the usually accepted value (2.5 × 106).
Suspension polymerization of caprolactam
Authors: Gechele G. B. , Martinis G. F. 
Published: April 2003

AbstractThe anionic polymerization of caprolactam (with sodium hydride and acetyl caprolactam as catalysts) carried out in glass ampules is reported. The effect of the catalyst concentration, polymerization temperature, and other variables was studied. Polymerization of caprolactam at temperatures around 120°C. in a paraffin suspension, in which the paraffin was introduced into a syrupy prepolymer is also reported. The influence of a few variables on conversion, molecular weight, particle size distribution, is discussed. Both viscosity and conversion are always lower in suspension than in bulk polymerization. Polymer granules of a wide range of dimensions which generally contain some residual monomer (unlike the bulk polymerization) are obtained in suspension polymerization. The above results are discussed and some interpretations are suggested.
Apparatus for determining thermal conductivity of insulation materials
Authors: Goldfein S. , Calderon J. 
Published: April 2003

AbstractThe initial object of this investigation was to design and build an apparatus capable of screening insulation materials for use in arctic shelters. A further object was to determine its suitability for determining thermal conductivity. The apparatus comprised a steel heat sink embedded in a 6‐in. core of polyurethane foam coated with glassreinforced plastic. The specimen rested upon the heat sink, and a constant temperature bath rested, in turn, on the specimen. A potentiometer was used to measure the temperature of the sink by means of a connecting thermocouple. After calibration, the apparatus was found to be highly accurate in determining thermal conductivity.
Oxidative stress relaxation of blends of cis‐1,4‐polybutadiene and natural rubber
Authors: Bell C. L. , Tiller R. 
Published: April 2003

AbstractBlends of cis‐1,4‐polybutadiene and natural rubber were vulcanized with dicumyl peroxide and a CBS (N‐cyclohexylbenzothiazole‐2‐sulfenamide) accelerated sulfur system. For the peroxide‐cured systems, soft vulcanizates had the natural rubber component only very lightly crosslinked and showed pronounced flow at room temperature. The oxidative stress relaxation of the hard vulcanizates at 80°C. in air was intermediate between that of the pure polymers. Intermittent stress relaxation measurements on these vulcanizates showed pronounced crosslinking during the aging of the pure polybutadiene and the 50/50 blend. Soft blends prepared by the accelerated sulfur system also showed flow due to the lightly crosslinked polybutadiene component. The unextracted hard blends resembled the pure polybutadiene vulcanizate in oxidative stress relaxation behavior at 80°C. in air, whereas after extraction to remove residual antioxidant and vulcanization products, etc., the blends were similar to natural rubber at all levels.
Rheopexy in some polar fluids and in their concentrated solutions in slightly polar solvents
Authors: Steg I. , Katz D. 
Published: April 2003

AbstractSeveral medium and high molecular weight polar fluids, when subjected to shearing forces above a certain rate of shear, showed a rheopectic behavior. The observation was made on some polyesters, an epoxy compound, and on concentrated solutions of these materials in nonpolar solvents. The experiments were carried out in a rotating type viscometer with cone‐and‐plate arrangements. The following explanation for the observed rheopexy is proposed: above a critical rate of shear, the polar macromolecules after alignment in the field of shear are forming quasicrystallites and a rheological network structure due to intermolecular forces. Because of the simultaneously occurring process of the breaking of structures in the field of shear, a state of pseudoequilibrium is reached. It was found that when the experiments were interrupted at the stage of such a pseudo‐equilibrium for a short time, a thixotropic strengthening of the existing structure occurred; under renewed shear the stress decreased to its value before the interruption. After interruption of shear for longer periods (hours, days), a breakdown of the rheopectic structure was observed.
A simple relation to estimate the maximum tensile modulus of drawn polymer fibers
Authors: Bondi A. 
Published: April 2003

AbstractThe partial unfolding of folded lamellae crystals is taken as point of departure for the development of a model to describe the elastic properties of cold‐drawn polymer filaments. The resulting relation sums the van der Waals tensile compliance and the spectroscopic tensile compliance of the polymer backbone chain in proportion to the length of folded and unfolded crystal lamellae, respectively, in the drawn filament. Many reported tensile moduli of drawn filaments of semicrystalline polymers are substantially below the predicted value. However, specially careful drawing experiments are rewarded with tensile moduli which closely approach the magnitude predicted by the relation presented here.
Method for structural characterization of high polymeric networks by an osmotic pressure technique
Authors: Seeley R. D. , Rand P. B. 
Published: April 2003

AbstractAn apparatus was designed to measure the osmotic pressure of solvent–polymer systems. The method is unique in that semirigid polymers may be incorporated as the solute component without specimen fissures occurring from excessive solvent dilative action. The advantages of this technique are: high polymeric materials both elastomeric and plastic can be structurally characterized by the same technique; the calculated effective molecular weight of the polymer network will reflect a value consistent with the polymer's performance characteristics; and the method is only restricted to lyophilic polymer–solvent systems.
Crosslinked polyacrylamide gel as a dehydrating agent
Authors: Sherr Allan E. , Swift A. M. 
Published: April 2003

AbstractThe dried crosslinked gel prepared from acrylamide and N,N′‐methylenebisacrylamide has been shown to be an efficient drying agent. The effectiveness of the dried gel has been shown to be comparable with that of several inorganic dehydration agents.
FMIR infrared spectroscopy of coatings on fibers and metal plates
Authors: Hermann T. S. 
Published: April 2003

AbstractThe FMIR technique offers a new and improved means of identifying coatings on fibers, elucidating coating–substrate bonds, and determining the nature of absorption sites on substrates by infrared spectroscopy. This technique is based on the internal reflectance of radiation in the middle infrared region. The ability to obtain infrared spectra of surface materials without removing the materials from the fiber gives the FMIR technique a noteworthy advantage over transmission techniques.
Study on ozone treatment of water‐soluble polymers. I. Ozone degradation of polyethylene glycol in water
Authors: Suzuki Junzo 
Published: April 2003

AbstractPolyethylene glycol (molecular weight 8000) was degraded by ozone in 1% aqueous solution of pH 12. Chemical oxygen demand of the solution decreased with increasing ozone consumed. Intrinsic viscosity of the solution lowered exponentially as a result of the ozonization. The number of breaks calculated from the viscosity indicated that two molecules of ozone were consumed for one cleavage of the polymer chain. The molecular weight distribution obtained by gel permeation chromatography was very broadened and molecular weight was lower as well, and the polymer chain was found to be cleaved randomly by ozone. The production of formic ester, ethylene glycol, diethylene glycol, triethylene glycol, and hydrogen peroxide was confirmed by IR, NMR, gas chromatography, and chemical analysis. These observations could be accounted for by electrophilic attack of ozone on the ether bond.