bluuebunny/crossref_metadata_2025_split huggingface dataset:
Total applied shear in capillary extrusion
Authors: Rudin Alfred , Chee K. K. 
Published: April 2003

AbstractViscoelastic properties of polymer fluids are single‐valued functions of shear stress or shear rate only at high total applied shear. These parameters may vary with applied shear under milder shear histories. The mean total shear in capillary extrusion is shown to be a function of orifice geometry. Apparent flow curves can be measured at various total shear values by changing the length/radius ratio of the capillary. The true shear stress and true shear rate at the orifice wall correspond to infinite total shear conditions. The true flow curve and elastic parameters like die swell are not measured at equivalent total shear unless the capillary is extremely long.
Dynamic shear modulus of polystyrene bead foams
Authors: Rinde J. A. , Hoge K. G. 
Published: April 2003

AbstractThe shear storage modulus has been determined for 0.05, 0.10, and 0.22 g/cc polystyrene bead foams and for the full density polymer at frequencies from 0.005 to 0.5 Hz at temperatures from −5° to 84°C. These data are superposed to form master curves of log modulus versus log temperature‐reduced frequency, using shift factors calculated by the Arrhenius equation. A plot of log modulus versus log density is linear for the three density foams; however, the modulus value for the solid polymer does not follow this relationship.
Reaction of formaldehyde with cellulose in the presence of sulfuric acid
Authors: Nabar G. M. , Shenai V. A. , Shenai V. A. 
Published: April 2003

AbstractThe extent and rate of reaction between cotton yarn before and after slack mercerization and slack mercerization followed by stretching and formaldehyde, in the presence of various amounts of sulfuric acid (5–60% by weight) were studied. Beyond a concentration of 45% sulfuric acid, the reaction takes place very rapidly, and an explanation is put forward in terms of the extent of swelling of the fiber in sulfuric acid solutions. The reaction was also studied in the presence of glycerin, when the combined formaldehyde value is shown to decrease with an increasing concentration of glycerin.
Influence of chain length on the rate of hydrolysis of polyoxymethylene ethers
Authors: Stanonis David J. , King Walter D. , Vail Sidney L. 
Published: April 2003

AbstractFour series of polyoxymethylene ethers (polyformals) [RO(CH2O)nR] where R is isopropyl, ethyl, methyl, or methoxyethyl and n = 1–3 have been prepared, examined by GLC, separated by fractional distillation, and characterized by NMR. Rate constants for the aqueous acid hydrolysis of all the compounds have been determined. The isopropyl series appears to be a special case, and as reported in the literature (but in aqueous dioxane), all members of this series hydrolyze at the same rate. In the other series, there is a definite increase in rate, which never exceeds fourfold, in going from n = 1 to n = 2. This increase differs considerably from the 100‐fold increase reported by others in going from CH3OCH2OCH3 to CH3O(CH2O)2CH3. In all series, the n = 3 compound hydrolyses at practically the same rate as the n = 2 compound.
Some effects of emulsion polymerization conditions on molecular polydispersity and rheological properties of poly(methyl methacrylate)
Authors: Guillod M. S. , Bauer R. G. 
Published: April 2003

AbstractEmulsion polymerization conditions of free‐radical‐polymerized poly(methyl methacrylate) have been examined in relation to the molecular weight and molecular polydispersity of the resulting polymers. In turn, molecular weight and molecular polydispersity have been related to the apparent viscosity and the appearance of the extrudate produced by an Instron capillary rheometer. The length of time for monomer addition to the polymerization medium was found to be a variable of primary concern in the emulsion polymerization. Continuous monomer addition (from 1 to 2 hr) resulted in a poly(methyl methacrylate) with a narrow distribution (∼2.0) and medium molecular weight (∼132 × 103). Both molecular weight and polydispersity were found to significantly affect apparent viscosity and extrudate appearance. Differences in the rheological parameters were most marked at the lowest shear rate run in this study. The poly(methyl methacrylate) samples with medium molecular weight and more narrow molecular polydispersity exhibited the best combination of low apparent viscosity and smooth glossy appearance.
Effect of activated gas plasma treatment time on adhesive bondability of polymers
Authors: Hall J. Richard , Westerdahl Carolyn A. L. , Bodnar Michael J. , Levi David W. 
Published: April 2003

AbstractThe bondability of the following polymers as a function of length of exposure to excited helium or oxygen was investigated: low‐density polyethylene, high‐density polyethylene (two types), poly(4‐methyl‐1‐pentene), poly(vinyl fluoride), poly(vinylidene fluoride), FEP Teflon, poly(oxymethylene) copolymer, nylon 6, nylon 66, poly(ethylene terephthalate), and polystyrene. Generally, the bond strength increase rapidly initially and then remains nearly constant, perhaps decreasing in some cases at long exposure times. A method is presented for calculating bond strength‐versus‐exposure time curves. The calculated curves generally fit the data reasonably well. Polypropylene showed a rapid increase in bondability with exposure to excited oxygen. Helium was ineffective toward this polymer under normal conditions, but could produce good bond strength at higher temperatures.
Rheological properties of molten poly(ethylene terephthalate)
Authors: Gregory D. R. 
Published: April 2003

AbstractThe complete steady‐state flow properties of molten poly(ethylene terephthalate) for shear stresses ≦4.14 × 106 dynes/cm2 were determined. A single, complete master curve had been constructed in earlier work by Gregory and Watson; the curve interrelates the shear stress, shear rate, temperature, and molecular weight (inherent viscosity) by using a temperature superposition scheme from the literature and a similar molecular weight superposition scheme.Equations in agreement with theory and with other published experimental data were derived from the master curve. Results presented here make possible the direct calculation of the melt viscosity of poly(ethylene terephthalate) at shear stresses ≦4.14 × 106 dynes/cm2. The effects of a unit temperature change and/or a unit change in inherent viscosity (I. V.) on the melt viscosity were determined. For poly(ethylene terephthalate) with a 0.6 I. V., a 0.0025 change in I. V. accounts for about the same change in melt viscosity as a 1°C change in temperature.
Melt viscosities of molten poly(ethylene terephthalate) calculated from modified Bueche‐Harding equation
Authors: Gregory D. R. 
Published: April 2003

AbstractThe semiempirical Bueche‐Harding equation was successfully modified to allow the calculation of experimentally verified melt viscosities of molten poly(ethylene terephthalate) (PET) for shear stresses > 9.65 × 105 dynes/cm2 by accounting for the definite Newtonian region in the flow behavior of PET for shear stresses lE; 9.65 × 105 dynes/cm2. Melt viscosity values calculated from the modified Bueche‐Harding equation agreed within ±12% of the values calculated from the equations based on experimental data.
Reversible crosslinking in cellulose. IV. Reactions of tosylcellulose with potassium thiolacetate
Authors: Sakamoto Munenori , Yamada Yoshio , Ojima Nobuko , Tonami Hiroaki 
Published: April 2003

AbstractReactions of tosylated cotton with potassium thiolacetate followed by alkaline hydrolysis yielded products containing both mercaptan and disulfide. The proportion of disulfide in the products depended much on the solvent used for the thiolacetylation. Reactions of tosylcellulose with thiolacetate in various solvents were investigated by polarographic and infrared analyses. Part of the acetylthio groups produced in acetone or in dimethylformamide was found to undergo rearrangement to form mercaptocellulose acetate. On the other hand, acetylthio groups formed in methanol were found to undergo complete methanolysis to form mercaptocellulose, and most of the mercapto groups thus produced were oxidized before hydrolysis treatment to yield the corresponding disulfide. This could account for the high disulfide proportion in the sample obtained through the reaction of tosylcellulose in methanol. Reaction of tosylcellulose with sodium thiosulfate yielded cellulose disulfide without mercaptan formation.
Solubility parameters of two chlorinated polyethylene polymers
Authors: Schneier Bernard 
Published: April 2003

AbstractAn equation that appears adequate for the calculation of the solubility parameter of random copolymers was tested with two nonrandom copolymers, chlorinated polyethylene (CPE) AK 227 and AK 243, containing 27.8% and 42.1% chlorine, respectively. Flory's equation relating the energy of interaction between polymer and diluent to the depression of the melting point of the pure polymer was used to estimate the solubility parameter of the polymers from solution temperature studies in chlorobenzene, toluene, o‐xylene, and p‐xylene. Using data obtained on PE as a criterion, agreement within 3% was obtained between the reported δ‐value and that estimated from solution temperature studies when toluene, o‐xylene, and p‐xylene were used as diluents. In the case of the two CPE polymers, values for the gas constant and for the heat of fusion in units of cal/cm3 polymer °K and cal/cm3 polymer, respectively, were obtained by solving simultaneous equations. From the derived gas constant values, the weight of an average repeating unit of CPE polymer was obtained, 39.38 for AK 227 and 46.95 for AK 243, which compares favorably with values obtained using the expression n1M1 + n2M2 = Mx. For ΔH, the results showed that in going from PE to CPE, a reversal in the sign of ΔH occurs indicating that, in the diluents studied, the value of χ is positive in the case of PE and negative for the CPE polymers. Taking this into account, agreement between calculated δ‐values and those estimated from solution temperature studies is within 2% for AK 227 (toluene, o‐xylene, p‐xylene) and within 1% for AK 243 when toluene and o‐xylene were used as diluents. Anomalous results were obtained in the latter case when p‐xylene and chlorobenzene were used as diluents and from solution temperature studies of PE in chlorobenzene. The results do indicate that the equation used to calculate the solubility parameter of random copolymers may also be used for nonrandom copolymers such as CPE.
Solvent dyeing of acrylic fibers. Process variables and mechanisms based on rates of dyeing and diffusion studies using cationic dyestuffs
Authors: Duffy Edward A. , Olson Edward S. 
Published: April 2003

AbstractDiffusion coefficients of selected cationic dyes are calculated for one aqueous and six organic solvent dye systems. The concentrations of dyestuffs sorbed by the fibers as functions of dyeing times are plotted for the various dyeing systems.
Results indicate that dye sorption decreases and the diffusion coefficient increases as the concentration of the cosolvent increases. The results were determined by comparing the Crank and Olofsson equations for diffusion.
The effect of roughness on the values of contact angles of binary systems measured at atmospheric pressure and ambient temperature on poly(tetrafluoroethylene) surfaces
Authors: Boyes A. P. , Ponter A. B. 
Published: April 2003

AbstractContact angles are reported for the systems ethanol–water, n‐propanol–water, and benzene–cyclohexane measured at atmospheric pressure and 25.0°C, in equilibrium with their vapors, on poly(tetrafluoroethylene) surfaces of known roughness. Comparison of the data with those reported by other workers has shown that the discordancy in values can be attributed solely to the various preparation techniques producing surfaces of differing roughnesses.
Effects of the combination of solvent and nonsolvent on the fractionation of polypropylene
Authors: Ogawa Toshio , Tanaka Shoichi , Hoshino Sadao 
Published: April 2003

AbstractThe effects of the combination of solvent and nonsolvent on the column fractionation of polypropylene were investigated. Decalin, kerosene, and α‐chloronaphthalene were employed as the solvents, whereas ethyl and butyl carbitol were employed as the nonsolvents. It was found that the molecular weight distribution of the fractions was not very significantly affected by the combination of solvent and nonsolvent. By applying Caplan's theory, namely, that M̄‐1/2 is a linear function of the weight fraction of solvent contained in the eluent (where M is the average molecular weight of a fraction), we concluded that to conduct a good fractionation both the solvent and the nonsolvent should be poorer solvents for the polymer.
Characterization of high‐density polyethylene prepared at low pressure
Authors: Hara K. , Kwei T. K. , Schonhorn H. 
Published: April 2003

AbstractA high‐density polyethylene prepared at low pressures is characterized with respect to density, microscopic examination, mechanical properties, and diffusion. The data for the slowly cooled, nonisothermally crystallized polymer clearly indicate that the method of preparation grossly affects the final properties of the polymer.
Influence of structural effects of halogen and phosphorus polyol mixtures on flame retardancy of flexible polyurethane foams
Authors: Papa Anthony J. , Proops William R. 
Published: April 2003

AbstractThe role of mixtures of reactive bromine and phosphorus flame‐retardant polyol intermediates as well as the individual bromine and phosphorus reagents in suppressing combustion of flexible polyurethane foams was investigated by means of the oxygen index flame test and charring techniques. Bromine alone appears to contribute to flame retardancy in the solid as well as the vapor phase. A substantial portion of the bromine from both aliphatic and aromatic bromide flame retardants was accounted for in the char, and this is also true when phosphorus is present. Ionic bromine appears to be the most effective elemental form. Like phosphorus, bromine alone in foams is also observed to increase the yield of char. Aliphatic bromide in mixture with phosphonate or phosphate gave enhanced flame retardancy, whereas, mixtures with phosphite are not beneficial. Maximum flame retardancy and char yields correlate well for bromine mixed with phosphate and phosphonate, whereas the relationship does not hold with phosphites. Charring experiments at 500°C with foams containing both phosphorus and bromine generally afforded a constant P/Br ratio, suggesting a specific chemical interaction for flame retardancy. Phosphate flame‐retardant efficiency was sensitive to concentration of phosphorus in the foams. On the other hand, phosphonate and phosphite exhibited a constant level of fire resistance at phosphorus levels greater than 0.3%.
Effect of rubber on the environmental stress‐crack resistance of polyethylene
Authors: Spenadel Lawrence 
Published: April 2003

AbstractThe property of environmental stress cracking is a critical performance factor in the polyethylene product areas of rigid and flexible containers, wire and cable insulation and pipe or conduit. It has been known for quite some time that the addition of an elastomeric material to polyethylene can improve its resistance to environmental stress cracking. However, the information reported in the literature on the subject is rather limited and as far as can be determined no attempt has been made to determine the rubber variables affecting the environmental stress cracking performance of polyethylene. In studying the effect of rubber on the environmental stress crack resistance (ESCR) of low and high density polyethylene, the choice of base resin is important. With some resins the addition of rubber doubles the ESCR while with others a fiftyfold improvement can be effected. Of the elastomers investigated in this study, Enjay Butyl 007 a copolymer of isobutylene and isoprene gave the greatest stress‐crack improvement in both low and high density polyethylene. Evaluation of a series of polyisobutylenes indicate that the higher its molecular weight the more effective its performance as a stress crack additive. The effect of rubber on other properties of the polyethylenes such as melt index, stiffness, permeability, chemical resistance, brittle point temperature, and impact strength is also discussed.
Fractionation of linear polyethylene with gel permeation chromatography. Narrow molecular weight‐distribution samples
Authors: Nakajima Nobuyuki 
Published: April 2003

AbstractFour samples of narrow molecular weight‐distribution polyethylene were fractionated with gel permeation chromatography (GPC). The polyethylenes had been prepared by hydrogenating linear polybutadienes (products of Phillips Petroleum Company). The values of molecular weights were furnished by the supplier of the samples. They were measured by absolute methods, i.e., light scattering and osmometry. The polydispersities of these polymers by GPC were found to be narrower than those by the absolute methods, when the polydispersity was expressed in the polystyrene equivalent of chain length. Recalculation on the basis of polyethylene standards did not increase the values of polydispersity. Continuous calibration curves were constructed by using a very broad‐distribution polyethylene. The use of these calibration curves gave the polydispersity values in good agreement with those obtained by the absolute methods.
Elektrische Ladungstrennung während der Vernetzung von Duromeren (Costa Ribeiro Effekt)
Authors: Eyerer Peter 
Published: April 2003

AbstractAn einem Epoxidharz–Amid‐System (Metallklebstoff) wurden während der Aushärtung einige Grundlagen eines elektrischen Effektes untersucht, der bisher an Polymeren unbekannt war. Eine anwendungstechnische Ausnutzung dieses Effektes wurde angedeutet. Die wahrscheinliche Grundlage des Effektes sind die in der Physik bekannten Erscheinungen Costa Ribeiro Effekt und Workman‐Reynolds Effekt. Die Grundlage beider Effekte ist eine Ladungstrennung an einer wandernden Phasenfront zwischen zwei Zustandsformen. Verläuft diese Phasenfront parallel und eben zu zwei Elektroden, so kann im äuβeren Stromkreis je nach Meβanordnung eine Spannung oder ein Strom gemessen werden. Nach einer Einführung in den experimentellen und theoretischen Erkenntnisstand, werden die Ergebnisse von elektrischen Messungen während der Vernetzung eines Epoxidharz–Amid‐Systems dargestellt. Dieses System ergibt bezüglich der Elektroden bei symmetrischer Temperaturführung sehr gut reproduzierbare Potentialkurven. Das notwendige Wandern einer Vernetzungsfront in einer Richtung wird durch ein Absinken der Härterkomponente vor dem Polyadditionsbeginn erreicht. Bei einer Aushärtetemperatur von 170°C ergeben sich Potentialmaxima von etwa 90 mV; bei 80°C beträgt das Maximum 15 mV. Ein Vergleich mit verschiedenen Meβmethoden zeigt, daβ das Maximum der Vernetzungspotentialkurven das Vernetzungsende anzeigt. Costa Ribeiro et al. stellten für Naphthalin und Wasser zwei thermodielektrische Gesetze auf. Es gelang, die Gültigkeit eines der Gesetze auch für das Epoxidharzsystem zu bestätigen. Ein exakter Nachweis der Gültigkeit des anderen Gesetzes war wegen der schwierigeren experimentellen Probleme nicht möglich. Der derzeitige Untersuchungsstand erlaubt es nur, einen Zusammenhang zu vermuten.
Oxidative degradation of poly(ethylene sulfide)
Authors: Adamek S. , Mackillop D. , Schnecko H. 
Published: April 2003

AbstractPoly(ethylene sulfide) which is a strong, stiff, solvent‐resistant thermoplastic resin, upon preparation and molding, undergoes rapid degradation upon aging in air with significant loss in impact strength and other physical properties. This is attributed to surface crazing and shrinking caused by molecular breakdown and crystallization.Infrared spectral studies show the rapid formation of sulfoxide, sulfone, and carbonyl moities in the polymer and mass spectral analysis shows the principal gaseous degradation products to be acetaldehyde, carbon dioxide, sulfur dioxide, and water.The addition of antioxidants, blending with other resins, and polymer modification give only minor improvement in oxidation resistance. This poor oxidation resistance has prohibited the development of poly(ethylene sulfide) as a commercial thermoplastic.
Reverse osmosis separation of phenols in aqueous solutions using porous cellulose acetate membranes
Authors: Matsuura Takeshi , Sourirajan S. 
Published: April 2003

AbstractReverse osmosis separations of phenol (9.4 to 108 ppm), p‐cresol (108 ppm), and p‐chlorophenol (129 ppm) were studied using Loeb‐Sourirajan‐type porous cellulose acetate membranes, and single‐solute aqueous feed solutions at 500 psig and the indicated solute concentrations. It was found that, by dissociating the solute by changing the pH of the feed solution, all the above phenols could be separated by reverse osmosis. Solute separation increased with increase in the degree of dissociation of the solute in the feed solution; and, by the appropriate choice of pore size on the membrane surface, separations of phenol approaching the degree of dissociation of phenol in the feed solution could be obtained under the operating conditions used. Similar experiments using aniline (93 ppm) as the solute showed that dissociation of solute molecules in the feed solution could be a technique generally applicable for the reverse osmosis separation of nonionic solutes in aqueous solution. The effects of operating pressure in the range 250 to 1500 psig and pore size on the membrane surface on the separation of un‐ionized phenol and p‐chlorophenol showed that, with respect to single‐solute aqueous feed solutions of phenols, the component whose relative acidity was greater was preferentially sorbed at the cellulose acetate membrane—aqueous solution interface, and the solute concentration in the membrane‐permeated product solution was a function of the extent and mobility of each of the sorbed species.
The UV spectra of cellulose and some model compounds
Authors: Bos A. 
Published: April 2003

AbstractComparison of the reflectance spectrum of cellulose with that of myoinositol, cycloheptaamylose, and other model compounds indicates that the acetal linkage does not contribute significantly to the absorption peak at 260 nm. The spectra of photolyzed and photo‐oxidized cellulose suggest that ketonic carbonyl groups are a more likely cause of this peak. Photolysis of cellulose and amylose under vacuum with 253.7 nm light increases the concentration of ketonic carbonyls and thus promotes yellowing. Photo‐oxidation with 253.7‐nm light bleaches both carbohydrates owing to the formation of carboxyl groups. Other investigators had previously reported that this last reaction yellows cellulose, but it appears that this was an effect caused by the 184.9‐nm component in the light of the lamp used. Comparison of the spectra of thermally and photolytically yellowed cellulose indicates that the end products of the two degradations are quite different.
Measurement of free‐radical concentration in solids by electron paramagnetic resonance comparison technique
Authors: Nanassy A. J. 
Published: April 2003

AbstractA brief theoretical background of free‐radical concentration measurement by electron paramagnetic resonance (EPR) comparison technique is presented to clarify the criteria required for the measurement. Simple experimental methods are suggested to improve the accuracy of the measurement by taking into account the effects of rf power saturation and instrument parameters on the spectral records.