bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polyelectrolytes. III. Viscosities of n‐butyl bromide addition compounds of 4‐vinylpyridine‐styrene copolymers in nitromethane‐dioxane mixtures
Authors: Fuoss Raymond M. , Cathers George I. 
Published: April 2003

AbstractA series of copolymers, of 4‐vinylpyridine and styrene, covering the range 1.5 to 100% vinylpyridine were prepared in 20% toluene solution at 80°. Strong electrolytes were then made by the addition of n‐butyl bromide in nitromethane solution. The salts with high vinylpyridine content were soluble in water, alcohols, nitromethane, and other polar solvents. Viscosities of the parent copolymers in methyl ethyl ketone were in the range 0.15–0.20; osmotic pressures gave molecular weights in the range 50,000‐80,000. The polyelectrolytes in nitromethane and nitromethane‐dioxane mixtures gave viscosity‐concentration curves which were strongly concave upwards: at 1 mg./100 cc., the reduced viscosity of the salt of polyvinylpyridine in nitromethane was 6.0. The salts of the different copolymers did not differ much in their viscosities at concentrations above a few tenths of a gram per 100 cc., a fact which shows a high degree of ionic association; only as zero concentration is approached, can the detailed polymer structure be seen. The extent of association at a given concentration is controlled by the amount of vinylpyridine in the copolymer and by the dielectric constant of the solvent. Addition of simple one‐one electrolytes, such as tetrabuty lammonium bromide, suppresses the electrostatic increase in viscosity which otherwise appears at low concentrations. The following empirical equation:

was found to fit the data for the different systems studied. The constant A depends on copolymerization ratio and probably on molecular weight; it is a measure of the extent to which the polymer coil can spread out at infinite dilution as a consequence of the intramolecular Coulomb repulsion between charges attached to the chain. It is roughly several orders of magnitude larger than the intrinsic viscosity of the parent polymer. The constant B is a measure of the electrostatic forces and increases with decreasing dielectric constant of the solvent.
X‐ray studies on the crystallinity of cellulose
Authors: Hermans P. H. , Weidinger A. 
Published: April 2003

AbstractThe method for the evaluation of the percentage crystallinity in cellulose preparations from x‐ray intensity measurements, previously described in detail (J. Appl. Phys., in press) is reviewed briefly and new material presented consisting of crystallinity percentages between 8% and 70%. Cotton, flax, and ramie possess equal crystallinity (70%) and so do the majority of rayons, independent of their degree of orientation and including cuprammonium and Lilienfeld rayons. Cellulose acetates saponified under varying conditions also yield almost the same value as rayon (40%). The New product Fiber G (du Pont) holds an exceptional position with 53% crystalline substance. In the series of native celluloses, wood pulp has about 65%, Valonia 65–70%, and bacterial cellulose about 40%. By dry grinding of rayon, a powder was obtained containing only slightly less than 10% crystalline substance, which on recrystallization in water, yields 2 product having the same crystallinity as rayon. The difference between the heats of wetting of the criginal and the recrystallized powder affords additional support of the results obtained.
Dependence of elastic properties of vulcanized rubber on the degree of cross linking
Authors: Flory Paul J. , Rabjohn Norman , Shaffer Marcia C. 
Published: April 2003

AbstractNatural rubber and GR‐S synthetic rubber have been vulcanized to varying degrees of cross linking through the use of disazodicarboxylates. These compounds react readily with the above unsaturated polymers in a manner which assures the formation of one cross linkage for each molecule of the disazo compound. Elastic properties of the vulcanizates so produced are similar to those of rubber specimens vulcanized in the conventional manner with sulfur and an accelerator. Their stress‐strain curves deviate from the form prescribed by the statistical theory of rubber elasticity in the same manner as observed by Gee for sulfur vulcanizates. The equilibrium force of retraction at 100% elongation has been measured over a 30‐fold range in the degree of cross linking; equilibrium swelling measurements extend over an 80‐fold range. The magnitude of the force of retraction over most of the range covered agrees remarkably well with the explicit predictions of the statistical theory. The significance of the deviations which are observed is discussed.
Preparation and vulcanization of liquid polyisoprene polymers
Authors: Conwell Y. , Roeser G. P. , Tobolsky A. V. 
Published: April 2003

AbstractBy means of chain transfer agents such as dodecyl mercaptan, polyisoprenes whose number‐average molecular weights range between 300‐1200 and which are liquid at room temperature have been prepared. The structure and physical properties of these substances have been investigated. Vulcanization of these liquids to rubberlike materials at room temperature and above is described.
Polymerization of isobutene catalyzed by boron trifluoride
Authors: Evans Alwyn G. , Meadows G. W. 
Published: April 2003

AbstractThe polymerization reaction which occurs when butene vapor is mixed with boron trifluoride gas has been studied under various conditions. It has been found that this polymerization occurs only if a third component, or cocatalyst, is present. The function of the cocatalyst has been investigated, and the mechanism of the polymerization reaction is discussed.
Some remarks on the first interaction coefficient of the viscosity‐concentration equation
Authors: Eirich F. , Riseman J. 
Published: April 2003

AbstractDuring recent years attempts have been made to formulate a viscosity‐concentration relationship. The method of Huggins, in introducing a factor k′ as a hydrodynamic correction factor is examined, and in particular the attempts to draw conclusions relating k′ to the thermodynamic properties of the solution. An explanation is offered to correlate the experimental viscosity‐concentration relationship and the change of solvent. A possible method for the actual calculation of concentration effects has been applied to the case of a suspension of spherical particles, for which, as a first approximation, a value of 10.6 for the coefficient of the c2 term has been obtained.
Light transmission and the formation and decay of spherulites in polythene
Authors: Hawkins S. W. , Richards R. B. 
Published: April 2003

AbstractThe effect of increasing and decreasing temperature on the light transmission of polythene has been measured. On raising the temperature of a sheet of polymer the light transmitted increases steadily at an increasing rate until the sample becomes glass clear at the melting point (ca. 112°C.). On cooling from the melt the specimen becomes very opaque a few degrees below the melting point, then becomes much more transparent and thereafter the light transmission decreases as temperature falls, the transmission‐temperature curve approximating to the curve for rising temperature. Changes in the spherulite structure of polythene film on heating and cooling have been observed under the microscope and recorded on a cinéfilm. Decay of spherulites on heating is seen not to occur by the reverse of the process by which they are formed from the melt, and the light transmission results are discussed in relation to the spherulitic structure of the polymer.
Emulsion polymerization of 2‐alkyl‐1,3‐butadienes.
Authors: Marvel C. S. , Williams Jack L. R. , Baumgarten Henry E. 
Published: April 2003

AbstractThe polymers of 2‐ethyl‐, 2‐isopropyl‐, and 2‐n‐amyl‐1,3‐butadiene alone, and their copolymers with styrene and with butadiene have been prepared and characterized. These monomers give the same ratio of 1,2 to 1,4 addition as has been noted for isoprene. Much less mercaptan must be used with these monomers than is required for butadiene to give soluble polymers. All these monomers copolymerize with styrene readily but have higher Wall α values than butadiene. The stress‐strain properties and Gehman low‐temperature properties of all of the new polymers have been determined by the Government Laboratories, University of Akron, and are included in this report. There appear to be no unusual properties to be noted.
Influence of molecular weight on the properties of polystyrene. I. Mechanical properties of polystyrene films cast from solvents
Authors: Merz E. , Nielsen L. , Buchdahl R. 
Published: April 2003

AbstractThe variables of casting polystyrene films from methyl ethyl ketone and from benzene are investigated. It is shown that stringent drying is necessary to remove the last traces of solvent. The differences in dry film structure, second‐order transition point, and temperature at which the dynamic modulus suddenly decreases are discussed.
Estimation of crystallinity of some polymers from x‐ray intensity measurements
Authors: Hermans P. H. , Weidinger A. 
Published: April 2003

AbstractThe paper deals with a tentative plan to extend quantitative x‐ray measurements for determining the degree of crystallinity of polymers (as used earlier in cellulose determinations), to the investigation of rubber, polythene, and a polyamide. Strictly monochromatized copper radiation was used. The results show that further work along these lines may be promising. The raw rubber sample used was identical with one of those investigated by Goppel and by Arlman. It yielded a crystallinity figure higher than that reported by Goppel, but conformed with that found by Arlman. The figures obtained for polythene at different temperatures are compared with those derived from density and heat capacity measurements by other workers. The degree of crystallinity of polythene at room temperature is found to be ∼ 55%, and in samples of polyhexamethylene sebacamide, previously treated in different ways, figures between ∼50 and 70% are obtained. It is shown that the possibility of using the background intensity as a measure of the disordered fraction is confined to not too high angles of diffraction. A method is described (and experimentally checked) allowing for reducing the curves of intensity distribution as a function of 2θ as observed in various polymers to a comparable scale. It is further emphasized that, in polymers where hydrogen bonds play a decisive role in intermolecular cohesion, the x‐ray results suggest that the “crystalline” or ordered fraction may to a considerable extent involve states of two‐dimensional order.
Influence of activated carbon on styrene polymerization
Authors: Breitenbach J. W. , Preussler H. 
Published: April 2003

AbstractDuring a definite polymerization time the rate of uncatalyzed polymerization of styrene may be decreased by the use of activated carbon. The intrinsic viscosities of the polymers formed may be either increased or decreased by the addition of active carbon, depending upon the activity of the carbon sample used.
Tetramethylthiuram disulfide vulcanization of extracted rubber. III. Short‐path distillation of TMTD and its reaction products from rubber
Authors: Craig David , Juve A. E. , Davidson W. L. 
Published: April 2003

Abstract(1) A technique has been described for the short‐path distillation of substances from rubber. It has been found that sulfur, TMTM, TMTD, ZnDMDC, phenyl‐beta‐naphthylamine, and palmitic acid are recoverable by this procedure. (2) The conversion of zinc compounds such as zinc oxide and zinc palmitate to ZnDMDC in rubber by treatment first with CS2 and then with dimethylamine has been studied. (3) The volatilization of zinc from vulcanizates after conversion to ZnDMDC has been shown to occur without devulcanization.
Modified osmotic balance
Authors: Masson C. R. , Melville H. W. 
Published: April 2003

AbstractThe construction of a modified form of osmotic balance has been described. By suspending a cell from each arm, the instrument has been made insensitive to temperature changes. In place of weighings, measurements are recorded by altering the buoyancy of one of the cells. By the use of an optical lever in conjunction with a divided photo‐ cell, a considerable increase in sensitivity has been obtained, the movements of the balance pointer being magnified about 300 times. A new method of matching the levels of solvent and solution has been described. Difficulties due to evaporation of solvent are discussed.
Hydroperoxides as initiators of emulsion polymerizations at low temperatures
Authors: Wicklatz J. E. , Kennedy T. J. , Reynolds W. B. 
Published: April 2003

AbstractThe results of emulsion polymerizations in which twenty‐eight different organic hydroperoxides were used as oxidizing agents in a standard redox recipe at 5°C. have been presented. Each hydroperoxide was tested at several different concentration levels. The hydroperoxides of chlorodiisopropylbenzene, di‐t‐butylisopropylbenzene, cyclohexylbenzene, 1,2,3,4,4a,9,10,10a‐octahydrophenanthrene, and t‐butylisopropylbenzene were found to be the most effective of the compounds tested. Oxidation mixtures, concentrates of oxidation mixtures, and purified samples of hydroperoxides served as sources of hydroperoxide for the polymerization experiments reported. Similar results were obtained with oxidation mixtures and concentrates, but purification of the hydroperoxide usually resulted in improved polymerization rates. The amount of hydroperoxide which gives the optimum results in a given polymerization recipe varies for structurally different hydroperoxides and appears to be related to the molecular weight.
Measurement of molecular weight of polyethylene by menzies‐wright boiling point elevation method
Authors: Morawetz H. 
Published: April 2003

AbstractThe Menzies‐Wright ebullioscopic method was used to evaluate unfractionated polyethylene resin, DYNH (Blend 1004). This material was found to have a number average molecular weight in the range 9000–9200. Results of good reproducibility were obtained with concentrations not exceeding 2.1 g. per 100 ml. tetrachlorethylene solvent. From the curvature of the boiling point elevation vs. concentration plot, the solvent–solute interaction constant μ was calculated and found to be slightly higher than the value predicted by Huggins for solvents with zero heat of mixing.
Oriented overgrowth on cold‐drawn polymers
Authors: Richards R. B. 
Published: April 2003

AbstractOriented overgrowth of paraffin wax crystals, grown from solution, has been observed on the surface of cold‐drawn strips of polyethylene and of polyethylene sebecate, but not on oriented gutta‐percha, rubber, polyethylene terephthalate, or nylon. The distribution of the angles at which the platelike paraffin crystals lie on polyethylene has been measured. This is found to be narrower than the angular distribution of the crystalline regions in the polymer as a whole, as calculated from the x‐ray diffraction pattern, suggesting that the crystallites in the polymer surface are more perfectly oriented than in the interior.
Solubility of crystallized polymers
Authors: Van Amerongen G. J. 
Published: April 2003

AbstractThe behavior in solution of three crystallized polymers, namely, gutta‐percha, rubber hydrochloride, and nylon, was investigated. In all three cases it was found that, at a low enough temperature, these materials exhibit a separation of phases in the solution owing to the formation of crystallites. The melting point of these crystallites is lower in the better solvents and also in solutions of a higher dilution.
Electrolytic initiation of polymerization
Authors: Kolthoff I. M. , Ferstandig Louis L. 
Published: April 2003

AbstractTwo new principles are discussed by which polymerization may be initiated electrolytically. One of these methods, the continuous electrolytic formation of the activator in a redox activation polymerization system, under various conditions, has been used successfully in the polymerization of acrylonitrile, but not of isoprene or styrene. The second method, based on the formation of free radicals in the electrolytic reduction of perdioxy compounds, has been tested under a limited number of conditions without significant success. Emulsion systems also have been employed in this research and the results are discussed.
Some improvements on the osmotic balance
Authors: Enoksson Bertil 
Published: April 2003

AbstractAn osmotic balance is described, whose principle is the same as that of an earlier one, but with the readings simplified by use of a chainomatic balance. A new cell has been constructed. Due to thin walls in the tube of the cell, this cell makes it possible to measure osmotic pressure without determining the reference point, the position at which the meniscus in the cell is at the same level as that in the container. A determination of osmotic pressure can be made in half the time by this new arrangement, compared with the older method. An example of the use of the balance has been given for a sample of cellulose nitrate and a fraction of polystyrene.
Influence of molecular weight distribution on the intrinsic viscosity‐molecular weight relationship
Authors: Frank H. P. , Breitenbach J. W. 
Published: April 2003

AbstractPolystyrene made by polymerization at 140° (polymer yield 18.9%) was fractionated successively into a number of fractions of increasing homogeneity. Intrinsic viscosity and osmotic molecular weight of the unfractionated polymer and of the fractions were determined. In the relation between them the constant K was found to decrease from K0 = 14.2 X 10−7 for the unfractionated polymer to K0 = 6.8 X 10−7 for the most homogeneous fractions. The distribution function of G. V. Schulz for the polymer and a Gaussian function for the most homogeneous fractions are discussed. From the ratio K0/K0K∞ = 2.09 (±0.15) we draw conclusion on the mechanism of polymerization under assumption of the validity of [η] = KMα instead of the simple Staudinger equation. A possible explanation for the deviation of the experimental value 2.09 from the theoretical 1.877 is given.
Polymerization of allyl compounds. V. Inhibition by nitro compounds
Authors: Hammond George S. , Bartlett Paul D. 
Published: April 2003

AbstractThe effect of various nitro compounds on the peroxide‐induced short‐chain polymerization of allyl acetate has been investigated. Of the compounds studied, sym‐trinitrobenzene is the most active as a retarder. Nitromethane and dinitrodurence were found to be less effective than aromatic nitro compounds which have replaceable nuclear hydrogen atoms but both exerted a measurable retarding influence on the polymerization reaction. It is found that trinitrobenzene reacts with a minimum of 5.9 radicals per molecule. This and other data are discussed in connection with the hypothesis that radicals react by an alkylation mechanism. An alternative mechanism involving attack on the nitro group itself is suggested.
Determination of the concentration of high polymer solutions
Authors: Grassie N. 
Published: April 2003

AbstractIt is shown that heating for several days at atmospheric pressure and 100°C. does not remove the volatile components from benzene solutions of polymethylmethacrylate and polystyrene solutions in benzene. Pirani gage measurements in a molecular still define the rather limited conditions under which all volatile components can be removed with out degradation and loss of polymer. Because of its low softening point, polyvinyl acetate can be dried to constant weight by overnight heating at 100°C.
Transition temperatures of plasticized material and copolymer systems
Authors: Nielsen Lawrence E. , Pollard Robert E. , McIntyre Elizabeth 
Published: April 2003

AbstractThe transition temperature, defined as the temperature where the log modulus temperature curve has an inflection point, is a linear function of the volume fraction of compatible plasticizer added to a high polymeric resin such as polyvinyl chloride. The transition temperature of plasticized compositions can be predicted from the transition temperatures of the pure polymer and plasticizer. The transition temperature of homogeneous copolymers can be predicted from the transition temperature of the individual polymerized monomers making up the copolymer. Data are presented on three copolymer systems containing vinyl chloride and on various plasticized materials.
Emulsion polymerization of styrene. II. Effect of agitation
Authors: Shunmukham S. R. , Hallenbeck V. L. , Guile R. L. 
Published: April 2003

AbstractEmploying a reproducible system for the emulsion polymerization of styrene it has been demonstrated that agitation (stirring or shaking) affects both the rate of polymerization and maximum average molecular weight of the polymer formed. Increasing the agitation increases the inhibition, decreases the polymerization rate, and lowers the average molecular weight of the polymer formed. Agitation affects both a peroxide and a persulfate catalyzed polymerization in a similar manner. Agitation effects have been observed in the presence of a redox system and in the presence of a chain modifier. Oxygen has been demonstrated to stop as well as inhibit the initiation of an emulsion polymerization.
Friedel‐Crafts polymerizations. III. Medium effects in the Friedel‐Crafts polymerization of styrene
Authors: George Joseph , Wechsler Harry 
Published: April 2003

AbstractIn polymerizing styrene at room temperature in the presence of tin tetrachloride, it is found that the rate of polymerization is greatly affected by the dielectric constant of the medium. It increases by a factor of approximately 1400 when the dielectric constant changes from 6.5 to 18.4. At the same time the degree of polymerization increases only slightly. The results are interpreted as supporting evidence for the mechanism of Friedel‐Crafts polymerizations as suggested by Polanyi and co‐workers. A unimolecular termination by proton‐splitting cannot be reconciled with these results.Quantitative equations are derived relating the rate and degree of polymerization to the dielectric constant. Traces of liquid water have no visible effect on the polymerization while larger amounts cause retardation. The degree of polymerization, which is of the order of 20, does not change with conversion and is unaffected by the catalyst present.
The degradation of long‐chain molecules by ultrasonic waves. III. Dependence of rate constant on chain length for polystyrene
Authors: Jellinek H. H. G. , White G. 
Published: April 2003

AbstractThe experimental variation of rate constant with chain length in the degradation of fractionated polystyrene samples by ultrasonic waves has been determined. The results are discussed in relation to a theory previously presented to account for molecular distributions obtained during degradation. It is shown that the experimental results cannot be explained satisfactorily by theories which assume that degradation is caused by frictional or impact forces.
Osmotic pressure measurements of ethyl acrylate polymers. I. Dependence of molecular weight on conversion
Authors: Hansen J. E. , McCarthy M. G. , Dietz T. J. 
Published: April 2003

AbstractBy employing the solution polymerization method, ethyl acrylate was readily polymerized, giving a product soluble in a number of organic solvents. By using benzene as the solvent, polymers of exceptionally high molecular weights were produced. The polymer samples were obtained by precipitation after the polymerization had proceeded for various periods of time. The slopes of the osmotic pressure curves were substantially constant for all the polymers. It is concluded that chain transfer to polymer during the polymerization process is insignificant and that the ethyl acrylate polymers do not contain any branched sites. It can be inferred from these data that the insolubility of ethyl polyacrylates frequently encountered is predominantly due to the extremely high molecular weights of the polymers.