bluuebunny/crossref_metadata_2025_split huggingface dataset:
The relationship between polymer elastic properties and the ability to impart improved wrinkle recovery to cotton fabric
Authors: Rawls H. R. , Klein E. , Vail Sidney L. 
Published: April 2003

AbstractThe wrinkle recovery of polymer‐coated cotton printcloth was generally found to correlate qualitatively with the elastic behavior of the polymer film. Of the several tensile parameters that can describe elasticity, immediate strain and work recoveries and stress decay were found to be the most sensitive indicators of the polymers' performance on the fabric. Delayed recovery, ultimate elongation, and permanent set were found to be important but were less sensitive parameters; while tensile strength and initial modulus appeared to be unrelated. A model is described whereby the polymer provides additional recovery forces when properly coupled to the fabric. High values of stress decay and permanent set diminish the effectiveness of these forces, while high values of immediate, work, and delayed recovery indicate that large portions of the distorting forces are available for recovery.
The significance of the rubber damping peak in rubber‐modified polymers
Authors: Keskkula Henno , Turley S. G. , Boyer R. F. 
Published: April 2003

AbstractDynamic mechanical properties have been used as the basis for some important conclusions with regards to the physical properties of rubber‐modified high‐impact polymers. This paper attempts to show that conclusions of this type should be limited to fairly narrow groupings of polymers. Since the size, shape, and position on the temperature scale of a damping peak are influenced by composition, morphology, and method of polymer preparation, the significance of the damping peak associated with the rubber phase of the polymer has probably been generalized to too great an extent. Two examples of polymer groupings are given to illustrate the need for caution in attaching significance to the dynamic mechanical properties of polymers. Also given are two fairly narrow polymer groupings to show to what extent dynamic mechanical properties can be used for a correlation with impact strength and rubber concentration.
Flow of viscous fluid through a circular aperture
Authors: Chong J. S. , Christiansen E. B. , Baer A. D. 
Published: April 2003

AbstractThe creeping flow of a highly viscous incompressible fluid through a circular aperture located in an infinitely wide horizontal plate is analyzed by solving Navier‐Stokes equations without inertia terms. Solutions for vertical and radial velocities as well as pressure have been obtained in terms of integral equations with an undetermined Kernal function. This function has been evaluated by assuming several different velocity distributions at the aperture, and the corresponding pressure drop for each case has been calculated. The results show that the pressure loss for a given flow rate goes through a minimum as the assumed velocity profile changes from flat to parabolic. Based on the minimum energy dissipation theorem of Helmholtz, the most appropriate velocity distribution is discussed. Experimental data obtained using sharp‐edged orifices are compared with theoretical predictions.
The synergistic effect of benzhydrylation and iodination of the flammability of alpha‐cellulose
Authors: Lipska A. E. , McCasland G. E. 
Published: April 2003

AbstractCellulose samples modified by iodination, benzhydrylation, and benzhydrylation followed by iodination were pyrolyzed to investigate the potential flame retardance of such treatments. Their effect on crystallinity, rate of thermal degradation, char production, and pyrolysis products was determined. Results indicate that in general the crystallinity index varies inversely with the percentage of substitution, rate of weight loss, and amount of residual char. Although the rates of weight loss of the substituted samples increased from 0.3%/min to 108%/min, depending on the type and percentage of substitution, the overall weight loss pattern of the treated cellulose was similar to that of the untreated samples. Of the three treatments, iodination appears to offer the best flame retardance in that the residual char is increased by a much larger factor for a given weight loss rate. On the other hand, addition of the benzhydryl to the iodinated sample decreases the char. All three treatments drastically reduce the number of degradation products of molecular weights lower than 150; untreated cellulose gave 59 components, whereas the substituted cellulose produced five major compounds: water, acetic acid, furfural, 5‐methyl‐2‐furaldehyde, and 1,5‐anhydro‐2,3‐deoxy‐β‐D‐pent‐2‐eno‐furanose. Of these, water and the furanose derivatives were the major components.
Thermal behavior of poly(vinyl alcohol) modified with phosphorous acid
Authors: Łaszkiewicz Bogumił 
Published: April 2003

AbstractThe thermal behavior of poly(vinyl alcohol) (PVA) modified with H3PO3 has been studied. The effect of phosphorus content in the polymer on the dehydration rate is discussed as well as the temperature‐dependent changes in sample weight. It has been shown that the presence of phosphorous acid radicals in PVA causes a lowering in the temperatures of dehydration and pyrolysis and accelerates these processes.
Pyrolysis of poly(methyl methacrylate co ethyl acrylate)
Authors: Ferlauto E. C. , Lindemann M. K. , Lucchesi C. A. , Gaskill D. R. 
Published: April 2003

AbstractAn investigation of the behavior of poly(methyl methacrylate co ethyl acrylate) with a commercially available filament‐type pyrolysis unit and gas chromatogaph was conducted. It has been hypothesized that the quantity of ethyl acrylate monomer produced under the conditions of the experiment is dependent upon the number of ethyl acrylate–methyl methacrylate bonds contained in the copolymer. These observations were made possible by a standardized samples‐handling technique in which a uniformsize disk was pyrolyzed at a maximum pyrolysis temperature of 600°C. This enabled reproducible pyrolysis gas chromatograms to be obtained and permitted pyrolysis products of copolymers containing different ratios of ethyl acrylate and methyl methacrylate to be compared. An examination of sequence distribution data, obtained with the aid of a sequence distribution program for copolymers, showed sufficient agreement with the pyrolysis data to support the hypothesis. It has been demonstrated that pyrolysis gas chromatography may be applied to experimentally determine the sequence distribution of copolymers.
Calculation of stress–strain curves from relaxation data in the rubbery flow region
Authors: Narkis M. 
Published: April 2003

AbstractStress relaxation curves for polysulfone and Lexan polycarbonate are only time dependent at a constant temperature if strain is defined as ϵH = In (l/l0) and the “true” cross‐sectional area A = A0/(1 + ϵ) is used. The strain‐independent stress relaxation curves can be used to calculate stress–strain curves at different rates of strain according to the linear viscoelastic theory. The agreement between experimental and calculated stress–strain curves is good at least up to about 60% strain in the range of 0.01 to 0.2 in./min rate of extension if an average rate of strain defined by ϵH = 1/t ln(l/l0) is used.
Crease recovery and cuprammonium solubility of some crosslinked cotton fabrics
Authors: Head Frank S. H. 
Published: April 2003

AbstractCotton fabrics crosslinked with the pyridinium salts of three di(chloromethyl) ethrse become largely insoluble in cuprammonium hydroxide solution and their wet and dry crease recovery increases. The solubility falls to below 40% under all the conditions studied. Good improvements in crease recovery are observed only when solubility is below 4%, but the reverse does not hold; some fabrics of poor crease recovery may also have low solubility.
Stress–strain behavior of SAN/glass bead composites above the glass transition temperature
Authors: Narkis M. , Nicolais L. 
Published: April 2003

AbstractRelaxation and stress–strain behavior of SAN–glass bead composites are studied above the glass transition temperature. The strain imposed on the polymeric matrix of the composite is defined as ϵp = ϵc/(1 − ϕ⅓). Stress relaxation data for the filled polymer which is independent of strain can be calculated by multiplying the relaxation modulus (at a certain strain) by (1 + ϵp). Stress–strain curves at constant strain rate and for different concentrations of the filler can be shifted to form a master curve independent of filler content if the tensile stress is plotted versus ϵp. The relaxation modulus increases with increasing the filler concentration and can be predicted by a modified Kerner equation at 110°C.
Studies on adhesion of allylic resin. III. Rheological treatment for the adhesion of diallyl phthalate resin
Authors: Nara Shigeo , Matsuyama Kentaro 
Published: April 2003

AbstractRheological treatment was carried out for the joining system of diallyl phthalate resin and dichromate‐treated copper foil. Rotational and diffusional segmental motions in the diallyl phthalate molecule are required to obtain the necessary bonding strength, and this consideration was confirmed by Kanamaru's setting rate theory. Furthermore, the bonding strength was dependent on the setting temperature and time, and these results were investigated by the dynamic properties of diallyl phthalate resin.
The helical structure of cellulose I
Authors: Viswanathan A. , Shenouda S. G. 
Published: April 2003

AbstractThe unit cell dimension along the crystallographic b‐axis of cellulose is widely accepted to be 10.3 Å, as against the distance of 10.3912 Å between the terminal oxygen atoms of a cellobiose molecule, estimated from the now well‐established crystal structure of cellobiose. Since cellulose is only a polymer of the cellobiose residue, it has been possible to derive the crystal structure of cellulose I from that of cellobiose. The strict application of stereochemical principles to the sucessive residues in the cellulose chain and a consideration of the formal geometric characteristics of a helix suggest a helical form to the cellulose molecule, with seven cellobiose residues per turn, radius r = 1.5830 Å, and angle of helix 7°51′ which is close to the x‐ray orientation angle of 8°21′ observed in ramie, the best‐oriented native cellulose. An analysis of intensity data both for the equatorial and for the meridional reflections leads to a unit cell with central reversed and corner chains and a relative shift between them of one fourth of the repeat length along the b‐axis.
Gel permeation chromatography: Physical characterization and chromatographic properties of corning porous glasses
Authors: Cooper A. R. , Bruzzone A. R. , Cain J. H. , Barrall E. M. 
Published: April 2003

AbstractFive porous glasses, manufactured by Corning, reputed to have very narrow pore size distributions, have been characterized by mercury porosimetry, nitrogen adsorption–desorption isotherms, and electron microscopy. The characteristics of these glasses as packing materials in gel permeation chromatography have been determined. Using polystyrene solutes and toluene solvent at room temperature, the glasses in series combination of columns are capable of separating molecular weights from a few thousand to several million. These glasses are compared with other available materials for column packings in gel permeation chromatography.
The conversion of ethylene–vinyl acetate copolymers with aluminum alcoholates
Authors: Rätzsch M. , Schade H. , Pabst P. 
Published: April 2003

AbstractIf ethylene–vinyl acetate copolymers are converted with aluminum alcoholates, crosslinked products will form. This reaction was studied on the basis of the viscosity variation and the amount of acetic acid ester formed. The constants of the reaction velocity for the conversion with various aluminum alcoholates were determined and a reaction mechanism is discussed.
Turbulent flow friction reduction effectiveness and hydrodynamic degradation of polysaccharides and synthetic polymers
Authors: Kenis Paul R. 
Published: April 2003

AbstractTwo water‐soluble synthetic polymers and several polysaccharides were compared for friction reduction effectiveness during increased exposure to turbulent flow. Solutions were passed through a 0.117 × 41.0 cm fine bore tube at a constant solvent wall shear stress of 4200 dynes/cm2 and wall shear rate of 4 × 105 sec−1. After one pass through the tube, greatest friction reduction at low polymer concentrations was in the order poly(ethylene oxide) > polyacrylamide > bacterial polysaccharide from Xanthomonas campestris > guar gum. As a result of mechanical degradation, after 40 passes of 40 ppm solutions, friction reduction effectiveness was in the order polyacrylamide > polysaccharide from Xanthomonas campestris > poly(ethylene oxide) > guar gum. Degradation curves, the effect of concentration on degradation, and boundary layer and pipe flow applications are discussed.
Molded neoprene liner pads for the poseidon missile launcher
Authors: Meier J. F. , Minter H. F. , Connors H. J. 
Published: April 2003

AbstractNeoprene formulations and mechanical designs have been developed to meet special operational requirements for the Poseidon Missile Launch System liner. The liner supports the missile in an aligned position, provides shock mitigation, reacts properly with the missile during launch, and damps vibrations. Operational requirements include static and dynamic compressive stiffness, damping, and water drainability. A mechanical design was evolved that utilized notched, prebuckled struts as supporting members. Compression–deflection characteristics were modified by simultaneous changes in geometrical design and polymer formulation. A study of the effects of variations in polymer compounding and mechanical design on the compressive stiffness, rate sensitivity of the compression–deflection characteristics, and vibrational damping is described. Mold release agents and their role in successful production are discussed.
The fracture toughness and stress corrosion cracking characteristics of an anhydride‐hardened epoxy adhesive
Authors: Mostovoy S. , Ripling E. J. 
Published: April 2003

AbstractThe toughness and stress corrosion cracking characteristics of an epoxy resin (DER 332) hardened with hexahydrophthalic anhydride (HHPA) were investigated. The epoxy was studied in both the bulk and bond form, and its properties were compared with an amine‐hardened (tetraethylene pentamine, TEPA) system. The toughness, 𝒢Ic, of the anhydride system varied less as a function of ratio of hardener‐to‐resin content and postcure temperature than it did in the TEPA‐hardened system. Like the latter, however, its toughness in the bulk and bond forms could not be correlated, but 𝒢Ic of the joints was dependent on tensile modulus and/or yield strength of the bulk epoxy. Both systems were also toughened in the vicinity of the crack tip by water for short‐time loading, but their long‐time load carrying capability was reduced by a water environment. The anhydride hardened system was more sensitive to strength loss in water than the amine system. The fracture morphology for the two systems was the same, i.e., fast cracking occurred cohesively near the center of the bond, and slow cracking occurred at the interface.
Effect of joint geometry on the toughness of epoxy adhesives
Authors: Mostovoy S. , Ripling E. J. 
Published: April 2003

AbstractIncreasing joint thickness was shown to increase the toughness of epoxy joints hardened with either tetraethylenepentamine (TEPA) or hexahydrophthalic anhydride (HHPA). The increased toughness was associated with a marked increase in macroroughness. An upper limit of joint thickness and hence toughness occurred because very thick joints could not be produced. Residual stresses developed during cooling from the curing temperature caused the latter to separate at the interface. Stress corrosion cracking resistance was also found to depend on bond thickness. For the TEPA‐hardened system, bond thickness had only a minor influence for thicknesses up to 25 mils; and for the HHPA‐hardened system, this persisted to bond thickness of 50 mils. Further increases in bond thickness for both systems caused an abrupt rise in resistance to stress corrosion cracking.
Determination of concentration changes on membrane surface as function of time during evaporation of reverse‐osmosis film casting solutions
Authors: Ohya Haruhiko , Sourirajan S. 
Published: April 2003

AbstractData on the activity of acetone for the binary system acetone‐formamide, and a specific ternary system cellulose acetate‐acetone‐formamide are given for the temperature range 0 to 30°C. A method of determining concentration changes occurring on the membrane surface during the evaporation stage in the process of making cellulose acetate reverse osmosis membranes is illustrated.
Pyrolysis of treated rayon fiber
Authors: Duffy James V. 
Published: April 2003

AbstractThe thermal decomposition behavior of rayon yarn which had been treated with various chlorosilanes and boron–phosphorus compounds was determined at temperatures up to 800°C. It was found that 70% of the available hydroxyl groups in rayon would react with dichlorodiphenylsilane and that the treated yarn had an initial decomposition temperature 125°C higher than that of untreated rayon. The weight loss of the treated yarn at 800°C was dependent on the nature of the chlorosilane and the type of posttreatment used. Alkylchlorosilanes produced higher weight losses than did the arylchlorosilane‐treated rayons. Treatment of rayon yarn with bis(chlorodiphenyl‐phosphine)decaborane (BCDPD) or dimeric chlorophospha(III)‐o‐carborane (DCPC) resulted in an increase in the char yield of the pyrolyzed yarns. In the case of untreated rayon, weight retention at 800°C was 20%, whereas the treated yarns yielded boronated residues of 42–53%. Carbon yields as high as 28% were obtained with the BCDPD treatment. This treatment also resulted in substantial improvement in the oxidative stability of rayon at temperatures up to 250°C.
A structure–property rationalization of some poly(carboxyl–epoxy) thermosets
Authors: Fellers J. , Golovoy A. 
Published: April 2003

AbstractThe glass transition temperatures, Tg, and strength properties have been determined for an acrylic‐based prepolymer containing 25 mole‐% carboxyl functionality crosslinked with five different diepoxides. The Tg values vary from 100° to 200°C, and ultimate elongations of 2% to 7% at 25°C are observed with the different crosslinking agents. These variations are rationalized in terms of the structural elements present in the diepoxides. Thermosets possessing rigid structural units at the crosslink points connected by flexible segments have the best all‐around combination of Tg and tensile properties. A decline in these properties was noted when the epoxide/carboxyl ratio exceeded unity owing to the formation of mixed networks and free chain ends.
Radiation protection of poly(vinyl chloride) by N‐methyl dithiocarbamate substitution
Authors: Nakagawa Tsutomu , Hopfenberg H. B. , Stannett V. 
Published: April 2003

AbstractThe effect of N‐methyl dithiocarbamate substitution on the radiation stability of poly‐(vinyl chloride) (PVC) films was studied. PVC containing between 2 and 11 mole‐% N‐methyl dithiocarbamate (PMD) was irradiated with γ‐rays from a 60Co source at 40°C and the evolved gaseous products were measured and analyzed with a mass spectrometer. The apparent G values for gas evolution for PMD decreased remarkably. For example, a G value of 0.28 was obtained for a PMD which contains 11 mole‐% dithiocarbamate group compared with a G value of 10.8 for unmodified poly(vinyl chloride). Furthermore, the mass spectrum of the evolved gas from the same PMD sample (PMD‐44) with 10 Mrad irradiation showed no hydrogen chloride to be present. The external protection was studied using polymer‐blended films of PVC and PMD‐44. The stabilization coefficients for internal protection and external protection in polymer blends were calculated. The ESR spectrum of the irradiated PMD‐44 showed a strong anisotropy with high g values which differed significantly from the spectrum of the irradiated PVC. A suggested mechanism for radiation protection of PVC against γ‐rays irradiation by the N‐methyl dithiocarbamate group is discussed.
Light scattering properties of acacia catechuic acid. Effects of urea and temperature
Authors: Chakravorty J. N. 
Published: April 2003

AbstractAssociation of acacia catechuic acid (ACA) molecules was established in ethanol–water medium2. This association was further tested in pure aqueous medium as well as by using urea in increasing amounts in aqueous solutions. The 5M urea depressed the molecular weight to 2.82 × 106, as against 5.04 × 106 in aqueous solution of NaCl or KCl. This reduction has been explained as due either to rupture of the molecule itself or dissociation of molecules which normally remain associated in water. The diminution of root‐mean‐square end‐to‐end distance in urea from 323 mμ in water3 to 290 mμ has also been attributed to the disaggregation of the associated molecules. To test this point further, the effect of increasing the temperature was next studied. The molecular weight was observed to be lower at higher temperature (actual value at 47°C was nearly half the original value at 28°C). This considerable reduction positively points to a dissociation of the molecule which was first suspected in our study with urea. The root‐mean‐square end‐to‐end distance also diminished to a certain extent, but not so much as the molecular weight. This has been explained as due to the stretching of the molecule when the solvent behaves as a better solvent at higher temperature.
Preparation and properties of poly(acrylic acid) composite membranes
Authors: Sachs S. B. , Lonsdale H. K. 
Published: April 2003

AbstractA new type of membrane has been prepared for hyperfiltration (reverse osmosis) desalination that is essentially a very thin polyelectrolyte membrane. It is prepared by casting an aqueous solution of a polyelectrolyte, specifically poly(acrylic acid) (PAA), directly on one surface of a finely porous support membrane. In hyperfiltration tests, these composite membranes exhibit desalination performance comparable in dilute solutions to that observed with cellulose acetate membranes of the Loeb‐Sourirajan type. The water flux through these membranes is linear in the pressure up to 100 atm. Salt rejection is a function of pressure; it is also a function of the concentration of the feed solution and the charge of the counterion, in qualitative agreement with the Donnan ion‐exclusion mechanism. Typical long‐term results range from water fluxes of 2 × 10−3 g/cm2‐sec (50 gal/ft2‐day) and 80% salt rejection to 0.2 × 10−3 g/cm2‐sec (5 gal/ft2‐day) and >99.5% salt rejection at 1500 psi with 0.3 wt‐% NaCl. These membranes appear to be useful for brackish water desalination.
A rationale for the preparation of Loeb‐Sourirajan‐type cellulose acetate membranes
Authors: Strathmann H. , Scheible P. , Baker R. W. 
Published: April 2003

AbstractAn attempt has been made to rationalize the variables in the preparation procedure of Loeb‐Sourirajan‐type reverse‐osmosis membranes. The quaternary phase diagram of the system cellulose acetate–acetone–formamide–water was determined and has proved a useful tool in the discussion of membrane structures and properties. A mechanism based on differences in the precipitation rate of the polymer during the membrane formation process has been suggested to explain the observed asymmetry in the membrane structure. The porosity of the membrane has been ascribed to the relative rates of water entering and solvent leaving the cast film. The effects of the casting solution composition, the evaporation time, the wash bath temperature, and the annealing procedure have been studied. X‐Ray diffraction and electron microscopy were used to supplement flux and retention data of membranes made from a cellulose acetate–formamide–acetone casting solution.