bluuebunny/crossref_metadata_2025 huggingface dataset:
Solubility parameters of two chlorinated polyethylene polymers
Authors: Schneier Bernard
Published: April 2003

An 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

Diffusion 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

Contact 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

The 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

A 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

The 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

The 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

Four 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

An 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

Poly(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

Reverse 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

Comparison 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

A 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.
Determination of the molecular weight distribution of cellulose on calibrated gel columns
Authors: Almin Karl Erik , Eriksson Karl‐erik , Pettersson Bo A.
Published: April 2003

CMC samples obtained by gel filtration on a preparative scale were used to calibrate an agarose column. The relation between molecular weight and the peak elution volume for monodisperse samples were calculated as well as the relation between band broadening and the peak elution volume. In the calculations of the molecular weight distribution curves of the studied CMC samples, consideration was given to the variable band broadening by proper transformations of the experimental data, thus making it possible to obtain numerical solutions free from oscillations. The method admits a rapid determination of the molecular weight distribution of cellulose and related materials.
Thermomechanical and thermogravimetric analyses of systematic series of polyimides
Authors: Gillham J. K. , Hallock K. D. , Stadnicki S. J.
Published: April 2003

Twelve polyimides which differ systematically in chemical structure were investigated in nitrogen through the temperature range −190° rlhar2; 500°C by torsional braid analysis. The degradative regions were also examined in nitrogen by thermogravimetric analysis. Relationships between chemical structure/thermal history, processibility, thermomechanical behavior, and weight loss are discussed. A logical thermal program for converting the precursor polyamic acid solutions to solid polyimides was developed. High‐temperature, thermally induced chemical reactions could be regulated so as to preferentially freeze out longer‐range relaxations and extend the glass state behavior to well above its original load‐limiting Tg. Materials made from more flexible molecules had lower glass transitions, softened more through the Tg, and had simpler damping spectra and lower thermal stability than materials made from more rigid molecules. A commercially available polyimide film and polyimide‐forming varnish of undisclosed structures were examined by torsional pendulum and torsional braid analyses, respectively. The thermomechanical spectra of the film and cured varnish were similar to the spectra of one structural type of polyimide.
Thermo‐oxidative and photo‐oxidative aging of polypropylene under simultaneous tensile stress
Authors: Czerný Jiří
Published: April 2003

The effect of uniaxial tensile stress at constant load in the range of 0 to 6.86 MN/m2 upon the behavior of stabilized and unstabilized types of isotactic polypropylene was investigated in the course of thermo‐oxidative aging at 80° to 130°C and of photo‐oxidative aging in the Xenotest 450 apparatus at 45° and relative humidity of 65%. From kinetic evaluation of the temperature dependence of weight changes of unstabilized polypropylene during thermo‐oxidative aging, it was found that the weight losses of unstressed and tension‐stressed specimens obey the kinetic equations for a reaction of the first order. The degradation of stressed specimens, however, proceeds at a considerably higher rate as compared with the unstressed state and is marked by a decrease in apparent activation energy as well as by an increased rate of crack development. The cracks develop in the direction perpendicular to the tensile stress and have the shape of hollow funnels widening outward. The tensile stressing of stabilized types of polypropylene in thermo‐oxidative and photo‐oxidative environments causes an accelerated embrittlement of the polymer, manifested particularly by a marked decrease of elongation at break. This accelerated embrittlement goes on under the action of tensile stresses exceeding the so‐called safe stress, i.e., the stress below which no acceleration of aging (as measured by the relative decrease in the elongation at break of the stressed and unstressed specimens), can be detected. The values of this safe tensile stress decrease with the temperature and lie well below the tensile strength of the polymer. In the range of tensile stresses exceeding the safe stress, the dependence of the logarithm of time of a 50% decrease of the elongation at break on the applied tensile stress was found to be linear. The findings are in agreement with Zhurkov's kinetic concept of mechanical deterioration of polymers, where the effect of the applied mechanical stress is superimposed on the thermal fluctuation and leads to the scission of chemical bonds and to the formation of cracks in the polymer.
Some observations on the mechanism of action of retarders in rubber vulcanization. A new class of retarder
Authors: Ballard D. G. H. , Myatt J. , Richter J. F. P.
Published: April 2003

Attempts have been made to demonstrate the involvement of free radicals in the benzthiazolesulfenamide‐accelerated vulcanization of natural rubber. Free radicals were only detected by ESR in reaction mixtures containing the retarder N‐nitrosodiphenylamine (NDPA). In addition, NDPA was the only compound found, from the vulcanization accelerator and retarders tested, to affect the free‐radical polymerization of methyl methacrylate. A purely ionic mechanism for sulfur vulcanization of natural rubber accelerated by benzthiazolesulfenamide derivatives has therefore been assumed and used to help in the design of new vulcanization retarders. A new class of retarder has been discovered, consisting of hydrocarbylthio derivatives of trisalkylsulfonyl methane. These retarders are believed to be the first vulcanization retarders to act by cleavage of a carbon–sulfur bond.
Study of structure and thermal properties of polypropylene and chlorinated polypropylene by infrared spectroscopy and differential scanning calorimetry
Authors: Sakai Kazuyuki , Sobue Hiroshi
Published: April 2003

The infrared spectra of chlorinated polypropylene (CPP) are interpreted and tentative assignments of C—Cl stretching vibration of CPP are proposed. Recently, infrared spectrophotometry has been applied as a useful tool for the investigation of polymer transitions. The solid‐state transition in isotactic polypropylene (IPP) was studied by infrared method in the range of −50° to 30°C; and from the temperature dependence of the peak absorbance, transition at ‐10°C was detected. This temperature of ‐10°C agrees well with the Tg2 detected by other methods. From these results, it is presumed that Tg2 is attributed to a motion (thermal expansion) of IPP segments in either crystalline and amorphous region. The thermal transition of chlorinated isotactic polypropylene (CIPP) was also examined with differential scanning calorimetry and infrared method, and two thermal transitions were observed. A higher transition (TH) has a minimum at a degree of chlorination of about 39 wt‐%; and a lower transition (TL) changes linearly with increasing degree of chlorination. Infrared results indicate that TH may be associated with a motion (thermal expansion) in chlorinated segments, and TL may be associated with a motion in unchlorinated segments. These results of infrared studies also suggest that CIPP may have a block structure.
Correlations between chemical structure, stress‐induced crystallization, and deformation behavior of polyurethane elastomers
Authors: Morbitzer L. , Hespe H.
Published: April 2003

The deformation behavior of polyurethane elastomers depends strongly on physical interactions.

In this paper the stress‐induced crystallization of the polyester or polyether segments in investigated in several polyurethane elastomer systems having different chemical structure for the soft segments. The correlation between the tensile properties (hysteresis loss, extension set, modulus) and the stress‐induced crystallization is discussed.
Stabilization of unsaturated elastomers with phenolic antioxidants
Authors: Patel A. R. , Dibattista A. D. , Klemchuk P. P.
Published: April 2003

An investigation of the thermo‐oxidative stabilization of ethylene–propylene–diene monomer (EPDM), polybutadiene, and emulsion styrene–butadiene rubbers (SBR) with a large number of variously substituted phenolic antioxidants disclosed a limited number of specific antioxidants to be remarkably effective as processing and storage stabilizers for the unsaturated elastomers. The most effective antioxidants of this investigation promise to provide better stabilization of unvulcanized rubbers than currently achievable with present stabilizers. Stabilizer performance in EPDM was assessed by both carbonyl absorbance and gel content measurement after oven aging at 100° and 150°C. Gel measurement after oven aging was found most useful for the other two elastomers. In all instances, good correlation was found between onset of gel formation and onset of color development. The specificity of stabilizer performance is interpreted in terms of functionality, compatibility, stability, and volatility.
Salt effect on gel permeation chromatography of partially charged polymers
Authors: Coppola Gerolamo , Fabbri Piero , Pallesi Bice , Bianchi Umberto
Published: April 2003

The effect of the addition of 0.1M LiBr to dimethylformamide (DMF) solutions of charged and uncharged polymers has been studied by GPC and [η] measurements. LiBr has a salting‐out effect on polyacrylonitrile (with (PAN‐S) and without (PAN) sulfonate sulfur), polystyrene (PS), and poly(vinyl acetate) (PVAc), which is seen by a decrease in [η] and an increase in the GPC retention time. The increase in retention time is, however, abnormally high for charged polymers. Association in PAN and PAN‐S solutions in DMF can explain the experimental observations.
Graft copolymers of starch with mixtures of acrylamide and the nitric acid salt of dimethylaminoethyl methacrylate
Authors: Fanta George F. , Burr Robert C. , Doane W. M. , Russell C. R.
Published: April 2003

Mixtures of acrylamide and the nitric acid salt of dimethylaminoethyl methacrylate (DMAEMA·HNO3) have been graft polymerized onto unmodified wheat starch with ferrous ammonium sulfate–hydrogen peroxide initiation. Graft polymerizations were carried out with both unswollen starch granules and granules that had been swollen by heating in water to 60°C. Ungrafted synthetic polymers were removed from graft copolymers by cold‐water extraction and were characterized by their M̄n and DMAEMA·HNO3 content. Graft copolymers were characterized with respect to per cent add‐on, M̄n and DMAEMA·HNO3 content of grafted polymer, and grafting frequency. Ungrafted synthetic polymers contained a mole percentage of DMAEMA·HNO3 equal to or greater than that present in the initial monomer mixtures; whereas in most grafted polymers the mole‐% DMAEMA·HNO3 in the grafted branches was less than that in the starting monomers. At all monomer ratios examined, polymer grafted to swollen starch granules contained a higher percentage of DMAEMA·HNO3 then polymer grafted to unswollen starch. The influence of starch granule swelling on the molecular weight and frequency of grafted branches was correlated with the composition of the initial monomer mixture. It was determined that the effect of granule swelling on graft copolymer structure would be minimal when 25–30 mole‐% DMAEMA·HNO3 was used. In an acetonitrile–water solvent system, reactions with 20 and 50 mole‐% DMAEMA·HNO3 produced graft copolymers with less DMAEMA·HNO3 in grafted branches than corresponding graft polymerizations run in water. The flocculation of 3% aqueous suspensions of diatomaceous silica was examined with selected starch graft copolymers.
Molecular sieves as drying agents for the monomer in the radiation‐induced ionic polymerization of liquid vinyl monomers
Authors: Stannett V. T. , Du Plessis T. A. , Goineau A. M.
Published: April 2003

The factors which influence the drying of liquid vinyl monomers with molecular sieves are discussed. It is found that the best results are obtained by drying the monomer for at least 12 hr at −15°C on molecular sieves that received no pretreatment at elevated temperatures. Although the prepolymerization that takes place on the molecular sieves during the drying can be quite extensive, the excellent reproducibility that can be achieved by using this method makes it a promising drying technique.
Imidazole catalysis in carbamate and polyurethane formation
Authors: Jerussi Robert A. , Orlando Charles M.
Published: April 2003

Polyurethanes have been prepared from the reactions of the diimidazole and ditriazole adducts of 2,4‐toluene diisocyanate and ethylene glycol or polyols. Suitable formulations have been developed from these components which are useful in preparing polyurethane coatings and foams. Imidazole was established as an effective catalyst for the reactions of the diphenol adduct of 2,4‐toluene diisocyanate with polyols. Imidazolecatalyzed polyurethane formation from the phenol‐blocked diisocyanate occurs readily between 100° and 140°C. A mechanism for the catalytic activity of imidazole in these reactions is proposed.
Modifications of the weissenberg rheogoniometer for measurement of transient rheological properties of molten polyethylene under shear. Comparison with tensile data
Authors: Meissner Joachim
Published: April 2003

Improvements to the Weissenberg rheogoniometer are necessary in order to measure the transient rheological properties of polymer melts correctly. The improvements reported concern the mechanical design, a new heating system, a new normal force measuring system, and additional equipment for the relaxation test. Reliable short‐time results require sufficiently stiff torque and normal force springs, and a small radius and relatively large angles of the cone‐and‐plate gap. The behavior of the LDPE melt under test is “linear viscoelastic,” if shear rate or total shear are small: The relaxation modulus, the stress growth at the onset of constant shear rate, the stress relaxation after cessation of steady shear flow, and, in addition, dynamic shear data (from an oscillation viscometer) all show consistent results when correlated by means of formulae from the theory of linear viscoelasticity. Shearing in the nonlinear range with constant shear rate leads to pronounced maxima of the shear stress p12 and of the first normal stress difference p11 − p22 which occur at constant total shear, almost independent of shear rate. Comparison of shear and tensile data (from extensional rheometer) confirms the Trouton relation in the linear‐viscoelastic case. In the nonlinear case, there is a “work softening” in shear and a “work hardening” in extension.
On the initiation of melt fracture
Authors: McIntire L. V.
Published: April 2003

The importance of (τ11 − τ22)/τ12 (sometimes called the Weissenberg number) in determining the onset of melt fracture is examined using classical linearized hydrodynamic stability analysis. The constitutive relation used is that proposed by Bird and Carreau. It is shown that simple shearing flow of a viscoelastic fluid becomes unstable at a critical value of the Weissenberg number. Implications with regard to polymer processing are discussed.
Ultraviolet irradiation of poly(alkyl acrylates) and poly(alkyl methacrylates)
Authors: Morimoto Kazuyuki , Suzuki Soji
Published: April 2003

Acrylic and methacrylic homopolymers containing different side groups were irradiated with ultraviolet light in the presence of air. The changes of molecular weight distributions of the irradiated polymers were analyzed by means of gel permeation chromatography (GPC), and the rates of chain scission and crosslinking were estimated. As the result of this study, it was found that chain scission takes place more easily in polyalkyl methacrylates than in polyalkyl acrylates.
The formation of polyimides from anhydrides and isocyanates
Authors: Carleton Peter S. , Farrissey William J. , Rose James S.
Published: April 2003

The addition of water to the reaction of isocyanates with carboxylic acid anhydrides has been observed to increase markedly the rate of formation of the corresponding imide. This effect has been observed with both monofunctional and difunctional reagents as well as in different solvents. Evidence is presented which suggests that water hydrolyzes the isocyanate either to the corresponding urea or amine.
Spectroscopic investigation of cellulose degraded celluloses, and their phenylhydrazine derivatives in relation to assessment of degradation
Authors: Blair H. S. , Cromie R.
Published: April 2003

The ultraviolet absorption spectra of Cadoxen solutions of hydrocellulose and hydrocellulose phenylosazones are described. With solutions of hydrocellulose no simple relationship between D.P. and absorbance was found. Solutions of hydrocellulose phenylosazone in Cadoxen show well‐defined maxima at 277 nm and 390 nm and do not change over 1 hr when oxygen is excluded. The absorbance of the phenylosazone at 390 nm may be used to determine the D.P. of the hydrocellulose samples.
High‐temperature elastomers: Glass transition–structure correlations for two systematic series of linear poly(carborane–siloxane)s. I
Authors: Roller M. B. , Gillham J. K.
Published: April 2003

Nine linear poly(carborane–siloxane) high‐temperature elastomers which differ systematically in chemical structure were investigated by torsional braid analysis. The structural variations include two different carborane cage structures in the polymer chain (CB10H10C and CB5H5C) and the stepwise increase in the number of Si(CH3)2O linkages associated with each cage in the repeat unit. Poly(dimethylsiloxane) was studied as the compositional limit of both series. The dynamic mechanical relaxations (at about 1 cps) of the materials are reported. These include the melting points of the semicrystalline polymers and the glass transitions and secondary transitions of all the polymers. The glass transition temperatures in each series were systematized using the well‐known copolymer composition‐versus‐glass transition temperature relationship 1/Tg = W1/Tg1 + W2/Tg2.
High‐temperature elastomers: Glass transition–structure correlations for two systematic series of linear poly(carborane–siloxane)s. II. Incompatibility
Authors: Roller M. B. , Gillham J. K.
Published: April 2003

Previously reported results related glass transition temperature to structure in two systematic series of poly(carborane–siloxane)s using a well‐known copolymer composition–glass transition relationship 1/Tg = W1/Tg1 + W2/Tg2. The relationship was originally proposed to apply not only to copolymers, but also to diluent systems. Accordingly, mixtures of polymers within each series were prepared and the thermomechanical spectra were determined by the technique of torsional braid analysis. The binary mixtures included poly(dimethylsiloxane) with polymers in both series and a mixture of two CB10H10C siloxane polymers. In all cases, the thermomechanical spectra revealed only those transition regions characteristic of the individual components. This type of behavior is indicative of phase separation of incompatible polymeric species.
Dynamic mechanical properties of nonstoichiometric, amine‐cured epoxy resin
Authors: Hirai T. , Kline D. E.
Published: April 2003

The dynamic mechanical properties of epoxy resins cured with nonstoichiometric amounts [37%–103% of stoichiometric composition (SC)] of diethylenetriamine at room temperature have been measured in the temperature range 85° to 300°K and correlated to structures of cured resins. The dynamic mechanical behavior changed above and below 62.5% of SC, at which network structures are formed. The intensities of γ‐ and β‐peaks, ∼150° and ∼250°K, respectively, depend upon the concentration of DETA used. The processes of the γ‐ and β‐peaks are discussed.
Improvement of porous cellulose acetate reverse osmosis membranes by change of casting conditions
Authors: Pageau Lucien , Sourirajan S.
Published: April 2003

The effects of temperature of casting solution in the range −10° to 15°C, that of casting atmosphere in the range 10° to 30°C, relative humidity of casting atmosphere in the range 35% to 75%, and solvent evaporation period in the range 0.5 to 3 min were studied on shrinkage temperatures, solute separations, and product rates of Loeb‐Sourirajan‐type cellulose acetate membranes in reverse osmosis experiments. The composition of casting solution used was as follows: cellulose acetate, 17; acetone, 69.2; magnesium perchlorate, 1.45; and water, 12.35 wt‐%. Best performance was obtained with membranes cast under the following conditions: temperature of casting solution, 10°C; temperature of casting atmosphere, 30°C; relative humidity of casting atmosphere, 65%; and solvent evaporation period, 1 min. For a 90% level of solute separation, the productivities of the above type of membranes were 22.9, 61.4, and 64.5 gallons/day‐ft2 at 250, 600, and 1500 psig using 3500 ppm NaCl–H2O, 5000 ppm NaCl–H2O, and 28395 ppm NaCl–H2O feed solutions, respectively. In all cases, the feed flow rates corresponded to a mass transfer coefficient of 45 × 10−4 cm/sec on the high‐pressure side of the membrane. The general specifications of the above type of membranes are given for the operating pressures of 250, 600, and 1500 psig. The effects of the above casting condition variables on the surface pore structure during film formation are discussed.
Fibers from aromatic copolyamides of limited order
Authors: Preston J. , Smith R. W. , Sun S. M.
Published: April 2003

Fibers were spun from six different, wholly aromatic copolyamides of limited order. Tensile properties of the fibers were obtained at standard conditions and, for selected fibers, at elevated temperatures and after heat‐aging at 300°C in air. The dry‐heat shrinkage determined up to 400°C on selected fibers was relatively low; zero‐strength temperatures ranged from 375°C to 495°C. Resistance to numerous chemical reagents was determined for one of the fibers and found to be comparable to that of the fibers from other wholly aromatic polyamides. Resistance to ultraviolet light appeared to be of the same order as that of unstabilized nylon 66.
Thermal analysis of irradiated poly(vinyl chloride)
Authors: Salovey R. , Badger R. G.
Published: April 2003

The thermal decomposition and resultant disposal of waste poly(vinyl chloride) (PVC) is facilitated by preliminary exposure to ionizing radiation, such as energetic electrons, in an oxygen atmosphere. The results of isothermal and temperature‐programmed thermogravimetry, differential thermal analysis, and effluent gas analysis in nitrogen and in oxygen indicate that the major effect of irradiation is to render PVC increasingly susceptible to oxidation. The presence of oxygen during heating enhances the decomposition. Crystalline order in PVC is destroyed by irradiation.
Studies on melt spinning. II. Analysis of the deformation and heat transfer processes
Authors: Lamonte Ronald R. , Han Chang Dae
Published: April 2003

A generalized, empirical equation is proposed which takes into account the dependence of elongational viscosity on both elongation rate and temperature. From this, a mathematical model for simulating the melt spinning process has been developed. The model has been tested against experimentally observed velocity profiles in fibers of polystyrene and high‐density polyethylene spun into an isothermal chamber. It has been found that predicted velocity profiles agree well with experimentally observed ones. The mathematical model has been used to predict velocity and temperature profiles in fibers spun into a cooling medium. The simultaneous solution of momentum and energy balance equations by means of a numerical integration scheme has generated important information such as distributions of force components involved in spinning and distributions of the total rate of heat transfer along the spinning way.
Basic dyeability and acid content of high‐conversion polyacrylonitrile
Authors: Peebles L. H. , Thompson R. B. , Kirby J. R. , Gibson M. E.
Published: April 2003

Previous data have shown that the basic dyeability of acrylic polymers increases at a given specific viscosity as the peroxydisulfate‐to‐bisulfite ratio, that is, the catalyst‐toactivator (C/A) ratio, is increased. This study represents an effort to understand better the role of the initiator system on the basic dyeability, the acid group composition, and the chain composition of acrylic polymers by preparing model polymers with radioactive initiators. As the C/A ratio is increased, the molecular weight distribution broadens as measured by the M̄v/M̄n ratio, the latter obtained by osmometry. There is also a significant effect of both C/A ratio and molecular weight on the sulfate group content per molecule, but there is no effect of C/A ratio on the number of basic dye sites per molecule, the number of sulfonate groups per molecule, or the weak acid groups per molecule. These effects can be explained by invoking a chain transfer to activator reaction in addition to the usual method of chain termination by recombination. The basic dyeability is found to correlate with the number‐average molecular weight and with the number of strong acid groups plus the nonchromophoric weak acid groups.
A valid method of calibration which includes correction for dispersion in gel permeation chromatography
Authors: Swartz T. D. , Bly D. D. , Edwards A. S.
Published: April 2003

Two independently derived distribution function methods validate both the calibration curve and the dispersion correction of the “effective linear calibration” method used in gel permeation chromatography (GPC). Experimental conditions are specified for making the method more useful by permitting linear extrapolation of the calibration line,

and for using a minimum number of standards. The independent methods quantitatively relate known differential of integral distribution functions for standard samples to their respective chromatograms. As such, they are useful calibration methods also, but are limited in scope and range.
Melt rheology of high‐density polyethylene
Authors: Fujiyama Mitsuyoshi , Kagiyama Yasuhiro
Published: April 2003

The melt rheology of high density polyethylene was investigated. Linear viscoelasticity, capillary flow properties, and molecular weight parameter were measured with a plate relaxometer, capillary rheometer, and gel permeation chromatography, respectively. Intimate correlations among the slope of relaxation modulus curve, non‐Newtonian flow behavior, Barus effect, and molecular weight parameter, Mz(Mz+1)/Mw, respectively, were found.
Difficulties associated with the measurement of the diffusion coefficient of solvating liquid or vapor in semicrystalline polymer. I. Permeation methods
Authors: Blackadder D. A. , Keniry J. S.
Published: April 2003

The diffusion coefficients D for solvating liquids and vapors in membranes can be measured in a number of ways. The effectiveness of permeation methods for systems involving semicrystalline polymers at near‐ambient temperatures has been assessed, and new experiments have been performed using p‐xylene and high‐density polyethylene. The conclusions are likely to apply to any semicrystalline polymer where the diffusant concentration is not zero. Stresses induced in the downstream side of the membrane by solvent sorption at the upstream surface during the nonsteady period are shown to lead to underestimation of D. The rate of attainment of a steady state is controlled primarily by the rate at which these stresses relax. The extremely slow rate of stress relaxation in polyethylene implies that, under many experimental conditions, a true steady state of permeation is not attained within an experimentally accessible time, a conclusion supported by experimental evidence. Diffusion coefficients calculated in the usual way from apparently steady‐state permeation rates may be grossly underestimated. In liquid permeation experiments, some of the polymer may dissolve in the upstream permeant, and this may lead to overestimation both of the time to reach an apparently steady state and of the steady‐state permeation rate itself.
Characterization of functionally terminated polybutadienes of low molecular weight
Authors: Ahad Elie
Published: April 2003

A difunctional hydroxyl‐terminated polybutadiene (sample A) was characterized by light scattering (LS), vapor pressure osmometry (VPO), and gel permeation chromatography (GPC). Sample A was then esterified, and the product (sample B) was also characterized. Light‐scattering measurements were carried out in different solvents (some were theta solvents for polybutadiene), and the results were corrected for anisotropy. Values of Mn (3100) and Mw (8000) determined respectively by VPO and LS for samples A and B were similar to those computed by GPC using two sets of columns of different resolution. The value of 2.3 found for the polydispersity index Mw/Mn is higher than the value which is usually reported by other workers (ca. 1.3 to 1.7) for functionally terminated polybutadienes.
Photolysis of poly(p‐methylstyrene)
Authors: Weir N. A.
Published: April 2003

Poly(p‐methylstyrene) films have been irradiated with 253.7‐nm radiation under high vacuum at 25°C. The main reaction product is hydrogen, but methane and traces of ethane and monomer were also detected. The quantum yield for H2 production (6 × 10‐2) is considerably greater than that for polystyrene photolysis indicating that both α‐CH bonds undergo fission. Solubility measurements also indicated the participation by the p‐methyl group. Main‐chain conjugation and coloration occur and are attributable to hydrogen abstraction from the β‐carbon atom. Cyclohexadienyl compounds are also formed and are presumably associated with crosslinking involving addition to the benzene ring. The mechanisms of photochemical and photophysical processes are discussed.
The graft copolymerization of styrene and lignin. III. Chain transfer reactions of lignin and lignin model compounds
Authors: Phillips R. B. , Brown W. , Stannett V.
Published: April 2003

The effect of addition of lignin model compounds on the polymerization rate and molecular weight of polymer in the radiation‐induced polymerization of styrene was studied. Guaiacol, a model for softwood lignin, reacted slowly with styrene radicals, while 2,6‐dimethoxyphenol, a hardwood lignin model, was a much more efficient chain transfer agent. Studies with isoeugenol indicate that allylic or phenoxy radical stability in a conjugated system may terminate polymerization quite effectively. The results are discussed in the light of new and previous data with isolated lignins; they are consistent with the previously presented grafting scheme.
Pyrolysis and combustion of polyester. I. Thermochemistry of poly(1,4‐cyclohexylene dimethylene terephthalate) treated with selected phosphorus‐ and halogen‐containing flame retardants
Authors: Bostic James E. , Yeh Kwan‐Nan , Barker Robert H.
Published: April 2003

A series of poly(1,4‐cyclohexylene dimethylene terephthalate) (PCHDT) fabrics treated with selected phosphorus‐ and halogen‐containing flame retardants has been studied by static oxygen bomb calorimetry. The amount of heat evolved when these fabrics are burned in the open atmosphere has been determined indirectly using calculations based on Hess' law of summation. This heat evolution when corrected for contributions due to burning of the flame retardant appeared to correlate with the efficiency of the flame retardant treatment and was interpretable in terms of mechanisms of flame retardant action. Also, this technique has been applied to blends containing polyester.
Grafting onto wool. III. Relationship between alpha‐ and beta‐forms in wool keratin of grafted fibers
Authors: Arai Kozo , Negishi Michiharu , Suda Tsutomu , Arai Shinji
Published: April 2003

A quantitative study of the change in the x‐ray intensity diffracted from the α‐ and β‐crystalline phases of grafted fibers was carried out. It was demonstrated that a part of the α‐helical sections is disrupted by the deposition of polymer and that during extension processes a marked stabilization for the remainder results from the interaction between the residues on the α‐helix and the rigid polymer chain. It was also considered that the disrupted sections are identical to the portions which would be easily deformed by stretching. The results on fibers containing hydrophilic polymer suggested little possibility that the β‐chain crystal is produced from the disrupted chains of α‐crystallites. The mechanism of the so‐called α–β transformation was proposed as ⇌ α M, M* ⇌ β.
Interpretation of the enhanced solubility of poly(vinylidene chloride) in certain solvent mixtures
Authors: Wessling R. A.
Published: April 2003

The 3‐component mixture poly(vinylidene chloride)—tetramethylene sulfoxide–tetrahydrophalene has been investigated by viscometric methods. This solvent pair shows an unusal affinity for the polymer. This can be attributed to the strong polar interaction between the acidic polymer and the basic sulfoxide which is enhanced by the presence of the nonpolar diluent.