bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tetramethylthiuram disulfide vulcanization of extracted rubber. IV. Behavior of rubber as an acid
Authors: Craig David , Juve A. E. , Davidson W. L. 
Published: April 2003

Abstract(1) The reaction of rubber with zinc palmitate was found to liberate palmitic acid at low pressures, thus revealing that rubber is acidic. (2) The reaction of zinc oxide with palmitic acid in toluene solution was enhanced by the presence of water. (3) The small increase in the nitrogen content of rubber caused by its reaction with TMTD was equivalent to the palmitic acid liberated by the zinc palmitate reaction. (4) The use of TMTD as a reagent for organic acids has been studied and found to convert carboxyl groups into dimethylamide groups. This result suggests that the acidic nature of rubber is due to carboxyl groups in the rubber molecule, a suggestion which is compatible with the nearly complete removal of zinc from the TMTD vulcanizate by the zinc removal technique.
Preparation of cyclized rubber from natural rubber latex
Authors: Van Veersen G. J. 
Published: April 2003

AbstractIn this paper a new method for the preparation of cyclized rubber from natural rubber latex is described. In this method, which follows logically from the new way of preparing rubber hydrochloride from natural rubber latex, latex stabilized with nonionic or cationic emulsifying agents is mixed with sulfuric acid. If a sufficient amount of sulfuric acid is added, cyclized rubber is formed after some heating. The influence of sulfuric acid concentration and the temperature on the rate of reaction have been investigated. Other cyclizing agents proved to be hydrogen fluoride and boron trifluoride. The advantage of the method described is that cyclized rubber can be obtained in the form of a latex.
Some aspects of depolymerization kinetics
Authors: Simha Robert , Wall L. A. 
Published: April 2003

AbstractA brief discussion of the importance of the transfer step and its effect in the pyrolysis of polyethylene is given. In this case the removal, by molecular distillation, of smaller species from the reacting mixture modifies the kinetics. The molecular weight decreases less rapidly and tends to a limiting value depending on the maximum size of the evaporating molecules. The number distribution of the latter is, in a first approximation, independent of their size. The pertinent expressions are presented and the general solution of the rate equations which can be used to obtain higher approximations is given.
New oxidants for initiation of emulsion polymerization in antifreeze recipes at −10°C.
Authors: Fryling Charles F. , Follett Archie E. 
Published: April 2003

AbstractThe introduction of the Dioxes as oxidants in emulsion polymerizations at subfreezing temperatures has opened up new horizons especially in the direction of the utilization of commercially available rosin acid soaps in formulations containing low iron concentrations. It is now possible to copolymerize butadiene and styrene to 60% conversion in 16 hours in an emulsion recipe containing only 0.3 millimole of iron per 100 g. of monomers with Diox* D, Dresinate 214, and potassium soap flakes; formerly it had been impossible to reach such a conversion within 24 hours. By the use of mixed potassium laurate‐ myristate emulsifier and Diox 7, a conversion of 60% with a fluid latex was achieved in 119 hours at −10°C. In order to attain these high rates of conversion, it is necessary that the redox components of the polymerization recipe be properly “balanced” with respect to the mole ratio of oxidant to iron, and that the potassium chloride concentration in the activator and the pH of the emulsifier solution be adjusted to their optimum values.
Studies on rate of emulsion polymerization of butadiene‐styrene (75:25) as a function of amount and kind of emulsifier used. III. Effect of amount of soap on rate of polymerization
Authors: Kolthoff I. M. , Meehan E. J. , Carr C. W. 
Published: April 2003

AbstractThe rate of emulsion copolymerization of butadiene‐styrene (75:25) has been studied at 50°C. as a function of the amount of soap. The following soaps were investigated: potassium myristate, potassium laurate, sodium caprate, sodium salt of dispropor‐ tionated rosin acids, and a commercial soap (largely sodium palmitate, oleate, and stearate). The initial rate of polymerization is decreased as the amount of soap is decreased, but the rate after about 25% conversion becomes almost independent of the amount of soap. If the concentration of soap in the aqueous phase is less than the critical concentration for micelle formation the initial rate is extremely small and becomes about equal to the rate in the absence of emulsifier. The initial rate with varying amounts of different detergents is approximately proportional to the amount of solu‐ bilization by the soap or other detergent solution. The data confirm Harkins' theory that solnbilization by soap micelles is a major factor in the initial stages of emulsion polymerization.
Denaturation of plant proteins. IV. Increase in reducing capacity, viscosity, and optical rotation upon denaturation with guanidine hydrochloride
Authors: Jirgensons B. 
Published: April 2003

AbstractLegumin of vetch and tuberin of potato have been denatured by guanidine hydrochloride. It was found that the reducing capacity (as estimated by titration with iodine in slightly acid solutions), the optical rotation, and the viscosity thereby increase. The specific rotation of legumin is increased from −42° for native legumin up to −90° for denatured legumin. The optical rotation and reducing capacity decrease with decreasing pH. According to the titration data, only about 12% of the sulfide can be detected by iodine; upon denaturation, the amount of detectable SH groups increases up to 40–80%.
Treatment of wood with ultrasonic waves
Authors: Gralén Nils , Berg Stig 
Published: April 2003

AbstractThe treatment of wood with ultrasonic waves causes a disintegrating of the biostructure of wood and splits the bonds between lignin and cellulose or other carbohydrates. It is possible that the bonds of the cellulose molecule are split at the same time, but certainly to a lesser degree or at a slower rate. After treatment with ultrasound, about 50% of the wood can be dissolved in cuprammonium. The dissolved material (carbohydrates) consists of two main components with different sedimentation constants. The two components are approximately classified as the cellulose and the hemicellulose of the wood.
Crystallinity of celluloses after treatment with sodium hydroxide (mercerization)
Authors: Hermans P. H. , Weidinger A. 
Published: April 2003

AbstractThe crystallinity of rayons measured with a standardized x‐ray method increases from 40 to 50% after previous treatment with 18% sodium hydroxide followed by removal of the alkali with boiling water. If the washing‐out of the alkali is carried out at room temperature, or if 4% sodium hydroxide is employed, the increase in crystallinity is smaller. Neither exclusion of oxygen during mercerization nor addition of hydrogen peroxide to the soaking lye has an influence on the final crystallinity. Native celluloses (ramie and wood pulp), after soaking in 18% sodium hydroxide and washing at the boil, yield the same figure of 50% crystallinity. A crystallinity figure of 50% is also obtained upon heterogeneous acid hydrolysis of rayon fibers at 100°C. and in cellulose precipitated from dilute viscose solution at 100°.
Viscosity‐molecular weight relationship for cellulose acetate in acetone
Authors: Philipp Howard J. , Bjork Carold F. 
Published: April 2003

AbstractCareful viscosity and osmotic pressure measurements with a membrane of known reliability are reported for 14 fractions of cellulose acetate prepared by repeated refractionation, For molecular weights up to 115,000 the following relation is obtained between intrinsic viscosity and absolute molecular weight:

the units of [η] being 100ml./g. An explanation is offered for the difference between this equation and other equations in the literature as well as for the discrepancies among the various literature equations.
Determination of Molecular Weight of High Polymers by Measurement of Osmotic Pressures at Low Concentrations
Authors: Gilbert G. A. , Graff‐Baker C. , Greenwood C. T. 
Published: April 2003

AbstractAn equilibrium osmometer for the measurement of very low osmotic pressures has been designed. It is constructed of metal and employs a large horizontal membrane. A rapid approach to equilibrium is obtained by the use of a fine capillary and a bacterial cellulose membrane (Masson and Melville) in conjunction with complete thermostatting. To avoid displacement, the membrane is stretched in a frame and held over a grooved domed support of the Carter‐Record type. Details of procedure, including concentration estimation and the preparation of membranes, are given.Measurements of the osmotic pressure of a fractionated sample of polystyrene, of molecular weight approximately one million, have served to determine the precision of the osmometer. At a pressure of 0.026 cm. of chloroform, the standard deviation was found to be 0.002 cm. The importance of correcting for the density of the solution, when measuring high molecular weights, is discussed.
Propriétés de dilatation thermique des polyamides
Authors: Ecochard F. 
Published: April 2003

AbstractA description is given for a simple method of measuring the expansion coefficient of plastic material, and other quantities, derived thereof (density of the liquid sample). A practical application is given in the case of some polyamides. This study makes it possible to show the presence of a maximum in the expansion curve; that maximum is probably related with the appearance, under thermal agitation, of a new degree of freedom of the molecules.
Sulfonation of natural rubber
Authors: Van Amerongen G. J. 
Published: April 2003

AbstractThe sulfonation reaction of rubber with SO2 is discussed. It proves to be a chain reaction which can be catalyzed by various compounds. Diazoamino compounds, hydroperoxides, some metal nitrates and nitrites, NO, and NO2 are found to be catalytically active. The activity of these substances varies considerably; the hydroperoxides NO and NO2 inducing immediate reaction; the diazoamino compounds within a few minutes; and the metal nitrates, such as LiNO3, in several hours.The reaction has a ceiling temperature at about 35 to 40°C., above which no reaction takes place. The properties of the reaction products are governed by the amount of SO2 bound and vary from rubbery to horny, and ultimately brittle and resinlike. Products of moderate SO2 content swell in organic solvents; products of high SO2 content dissolve only in concentrated H2SO4 of HNO3. The workability of the products is rather poor
Emulsion polymerization of styrene. I. A reproducible system
Authors: Yang P. T. , Guile R. L. 
Published: April 2003

AbstractExcellent reproducibility of an emulsion polymerization of styrene has been obtained in a nitrogen atmosphere and a technique and apparatus have been described to obtain this reproducibility. The rate of polymerization for this system has been shown to be proportional to the square root of the catalyst concentration and to increase with higher catalyst concentrations. Average molecular weights were higher with higher concentration of catalyst within the catalyst concentrations studied and polymerization occurred without significant pH changes.In contrast, reproducibility of the emulsion polymerization in air atmosphere was unsatisfactory. The presence of air (oxygen) increased the induction period, decreased the rate of polymerization and decreased the average molecular weight of the polymer. Since the time necessary for polymerization was increased, the decrease in pH was considerable during the polymerization.
Swelling of polyvinyl alcohol in water
Authors: Priest W. J. 
Published: April 2003

AbstractSwelling and solubility characteristics of polyvinyl alcohol and polyvinyl alcohol–acetate copolymers in liquid water have been examined. For a given species, swellings are found to be variable in a continuum of metastable states depending on the previous history of the polymer. Changes in swelling are induced in a predictable manner by treatments such as humidification. Changes are interpreted in terms of cumulative secondary bond cross‐linkages arising from the development of microcrystalline regions within the gel.
Polyalkylene sulfides. VIII. Polymers from 4‐vinylcyclohexene
Authors: Marvel C. S. , Roberts C. W. 
Published: April 2003

AbstractPure 4‐vinylcyclohexene and hexamethylenedithiol react under a variety of conditions to produce a polymer which has factice‐like properties. The polymers with the highest inherent viscosity were prepared in MP‐189‐EF emulsion at a pH of 4 with a persulfate–bisulfite–copper sulfate initiator. The polymers are readily cross‐linked, and if dried without careful removal of initiator solution, they show properties of vulcanized factice samples. Bisazoisobutyronitrile, a cumene hydroperoxide–ferrous pyrophosphate system, and a ceric sulfate–bisulfite copper system have also been used to initiate this polymerization reaction.
Copolymerization of butadiene and styrene in the oxygen–1‐alkanesulfinic acid system
Authors: Marvel C. S. , Meinhardt N. A. 
Published: April 2003

AbstractThe copolymerization of butadiene and styrene in an alkanesulfonic acid emulsion with air as the oxidizing agent and higher alkanesulfinic acids as oil‐soluble reducing agents has been studied. Dodecyl mercaptan and ferric salts are needed to make this recipe function well. The optimum pH for rapid polymerization was found to vary with the different alkanesulfinic acids (C8 to C18 in the even‐numbered straight‐chain series). Tetradecanesulfinic acid is the most active reducing activator in this series. The conversions with butadiene and styrene are about 75–80% at 30° in six hours and these copolymers have normal solubility and inherent viscosities.
The degradation of long‐chain molecules by ultrasonic waves. II. Degradation of polystyrene
Authors: Jellinek H. H. G. , White G. 
Published: April 2003

AbstractThe degradation by ultrasonic waves of a homogeneous polystyrene sample has been studied. The degradation does not proceed to the monomer but ceases at a definite intermediate chain length. A rate constant has been derived. The experimental size distributions of the polymer at various stages of the degradation have been determined and compared with size distributions derived from the theory of ultrasonic degradation. Satisfactory agreement has been found between experiment and theory for the main features of the degradation.
The degradation of long‐chain molecules by ultrasonic waves. IV. The dependence of rate constant on concentration for polystyrene
Authors: Jellinek H. H. G. , White G. 
Published: April 2003

AbstractThe dependence of the rate constant on concentration in the degradation by ultrasonic waves of polystyrene in benzene has been determined. At fairly high ultrasonic intensities the overall rate constant increases with decreasing concentration but appears to tend to a maximum. This maximum has been located at a reduced ultrasonic intensity for a particular sample of polystyrene and it is shown to occur at a concentration when the chains are highly entangled.
Studies in copolymerization. Kinetics of the copolymerization of styrene and p‐methoxystyrene
Authors: Bonsall E. P. , Valentine L. , Melville H. W. 
Published: April 2003

AbstractThe copolymerization of styrene and p‐methoxystyrene at 60°C., catalyzed by the thermal decomposition of 2‐azobisisobutyronitrile, has been studied. A combination of rate and molecular weight data has shown that δ = (kt1/2/kp) = 25, kf/kp = 1.1 X 10−4 for styrene and δ = 21, kf/kp = 0.74 X 10−4 for p‐methoxystyrene. The over‐all energy of activation for styrene is shown to be Ep − 1/2Et = 6.2 kcal. The rate of initiation (I) of these monomers does not correspond with the rate of production of free radicals from the catalyst, e.g., experimentally, I = 3.3 X 10−8 and I = 2.1 X 10−8 mole/liter/sec. for styrene and p‐methoxystyrene, respectively, at a catalyst concentration of 1 g./liter. The rate calculated from the rate of fission of the catalyst is 12.2 X 10−8 mole/liter/sec. The rates of copolymerization and initiation have been measured for various monomer mixtures; the former was practically independent of monomer composition but the latter varied directly with monomer composition. A value of ϕ = 1[ϕ = k/(kk)1/2] satisfies the experimental results, in agreement with the theory previously presented, i.e., that ϕ2 = (A212/A11A22)(1/r1r2). The validity and usefulness of this theory are discussed in the light of available data and criticisms, and it is shown that both entropy and polar effects play important roles in cross‐termination reactions.
Quantitative x‐ray studies of order in amorphous and crystalline polymers. Quantitative x‐ray determination of crystallinity in polyethylene
Authors: Krimm Samuel , Tobolsky Arthur V. 
Published: April 2003

AbstractVarious quantitative scattering relationships for polymers have been examined experimentally in order to test their validity as assumptions in the x‐ray determination of crystallinity. These are (a) the proportionality between the scattered intensity and the pt value of the specimen (p is the density and t the thickness of the material), (b) the relationship between equal pt values for two different specimens of the same material and the corresponding scattering masses in the beam, (c) the scattering from equal masses of a polymer in the amorphous or crystalline states, and (d) the values of the total scattered intensity from equal masses of different polymers. It has been demonstrated, at least in the case of polyethylene, that the percentage of crystalline material in a polycrystalline polymer can be determined quantitatively by means of x‐ray diffraction methods. The method used in this study, viz., a comparison of the amorphous scattering from the sample with that from a completely amorphous sample, has been applied to an investigation of the temperature variation of crystallinity in unstretched and stretched polyethylene. The comparison between the x‐ray and density results for the case of the unstretched material has been pointed out. The technique has also permitted a determination of the orientation of the crystallites. By means of these methods, it has been shown that the x‐ray diffraction results are in essential agreement with previous stress‐birefringence data on stretched polyethylene; and that the nature of the stretchng process is different at high and at low elongations.
On the dissociation equilibrium of high‐molecular weak electrolytes
Authors: Kagawa Ikumi , Katsuura Kakuji 
Published: April 2003

AbstractUsing the cellulose glycolic acid ethers of various etherification degrees as a sample of high‐molecular weak electrolytes, investigations were carried out on some problems on the dissociation equilibrium, such as the influence of sample concentration, distribution density of electrolyte radicals, the salt effect, and the effect of neutralization reagents. The experimental data were treated by means of the modified Kern's dissociation formula (1) and Kagawa's formula (2).

The results obtained were discussed with Kagawa's opinion on the fixation of counterions.
Some aspects of the motion of chain segments in plasticized polyvinyl chloride. II. Tensile creep of plasticized polyvinyl chloride
Authors: Dyson A. 
Published: April 2003

AbstractThe relations between stress, strain. and time in the tensile creep under constant load of polyvinyl chloride plasticized with dioctyl phthalate have been studied experimentally over a range of temperatures and compositions. It is concluded that existing theories are not adequate to deal with large strains, nonequilibrium conditions, and a distribution of relaxation times. The variables stress, strain, and time may be separated at low loads for “soft” compositions but not for “hard” compositions.
Elastoviscous properties of polyisobutylene. IV. Relaxation time spectrum and calculation of bulk viscosity
Authors: Andrews R. D. , Tobolsky A. V. 
Published: April 2003

AbstractThe elastoviscous behavior of polyisobutylene may be interpreted in terms of a mechanical model consisting of a distribution of Maxwell elements connected in parallel. The structure of this “generalized Maxwell model” is specified by the distribution of relaxation times of the component elements. The relaxation of stress curve of the material is directly related to the distribution of relaxation times, and general expressions for the bulk viscosities (tensile and shear) of such a system in terms of the distribution of relaxation times are readily obtained.A simple “box distribution” of relaxation times is described which can be used to approximate the relaxation behavior of polyisobutylene at the long‐time end of the relaxation time spectrum, and in terms of which the expressions for bulk viscosity reduce to very simple form. The parameters specifying this distribution may be determined from experimental relaxation curves by a simple graphical method. Values of these parameters as a functions of molecular weight and temperature are computed, by use of these data. It is shown that bulk viscosity values calculated from relaxation data by this method are in good agreement with experimental values for both tensile and shear deformations, and for both unfractionated and fractionated polymers. Measurements of viscosity and of relaxation of stress can thus be directly correlated, and could be used in combination to characterize elastoviscous properties over wide ranges of molecular weight and temperature.
A study of the oxidative degradation of polyvinyl formal
Authors: Beachell Harold C. , Fotis Peter , Hucks Janet 
Published: April 2003

AbstractThe oxidative degradation of polyvinyl formal at temperatures of 150°C. and above has been followed by changes in the infrared spectrum in conjunction with the loss in weight and color development. It is a complex process of cross‐linking and oxidation, rather than one of depolymerization. The infrared spectrum shows rapid development of carbonyl and ethylenic groups in the molecule, accompanied by loss of carbon‐hydrogen and formal groups.A free radical mechanism for the rupture of the formal ring is proposed, which explains the loss of formaldehyde and water from the polymeric molecule and the production of carbonyl and ethylenic groups in the chain that are capable of producing color.The stability of polyvinyl formals of various compositions is compared and the effects of residual acetate and alcohol groups on the rate of degradation are discussed.Several catalysts and inhibitors for the process are also presented.
Ripening reactions of viscose
Authors: Kagawa Ikumi , Kobayashi Haruo 
Published: April 2003

AbstractFrom the same standpoint as Kagawa and Katsuura's opinion on the hydrolysis of cellulose sulfate, the authors argue that the spontaneous decomposition of cellulose xanthate in the course of ripening is ripening is wholly due to the alkali saponification which arises at the unionized ester‐group:
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Taking the characteristic features of the electrolytic dissociation of polymeric electrolytes into consideration, the authors derive theoretically the fomula of saponification velocity:

The experimental results agree satisfactorily with this formula when n = 2. The authors also examine experimentally the variation in composition of viscose with especial reference to Na2S and Na2CS3 as the salt components, and explained the secondary reactions in ripening presumably as being caused by the successive decomposition of the primary decomposition product of xanthate, viz., dithiocarbonate, by the following mechanism, in which much stress is laid upon the ionization of reaction components:
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