bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polysoaps. I. Viscosity and solubilization studies on an n‐dodecyl bromide addition compound of poly‐2‐vinylpyridine
Authors: Strauss Ulrich P. , Jackson Earl G. 
Published: April 2003

AbstractPolysoaps are defined as polymers to whose chain soap molecules are attached. Through the reaction of poly‐2‐vinylpyridine with n‐dodecyl bromide such a polysoap was prepared in which 33.7% of the nitrogens were quarternized. This polysoap exhibited reduced viscosities in aqueous solution which were smaller than those of the parent polymer and of the polysoap in ethanol. The relatively compact structure of the polysoap molecule in water which this indicates is thought to be caused by micelle formation of the soap molecules attached to the polymer chain. This idea is substantiated by the fact that the polysoap acts as a solubilizer for isoöctane in water. Solubilization was measured utilizing the vapor pressure as an indicator for the attainment of saturation. Gram for gram, the polysoap solubilized more isoöctane in water than did the related monosoap, n‐dodecylpyridonium bromide. In contrast to the monosoap, no critical concentration of the polysoap was necessary before solubilization occurred. For polysoap concentrations ranging from 0 to 3%, the solubility of isoöctane was proportional to the polysoap concentration. The efficiency of solubilization over this concentration range was 0.066 gram of isoöctane per gram of polysoap.
Sedimentation and diffusion studies on a derivative of wool keratin
Authors: Mercer E. H. , Olofsson Bertil 
Published: April 2003

AbstractA derivative of wool keratin dissolved in a strong solution of urea was examined in the ultracentrifuge and by diffusion methods. The solution was polydisperse, yielding a single broad peak in the ultracentrifuge. Approximate molecular constants were calculated to be s 1.93, D20m = 1.9 × 107, M = 84,000, f/f0 = 3.8. The molecule is very asymmetrical, which is in accord with the fiber‐forming properties of the derivative. On further reduction the molecular weight falls to ca. 8000 and the molecule shortens. It is suggested that the fully reduced solution (M.W. = 8000) is that of the primary polypeptides of wool keratin and that the longer and larger molecules (M.W. = 80,000) are formed by the combination of the primary chains effected by disulfide bridges.
Polyalkylene sulfides. VI. New polymers capable of cross‐linking
Authors: Marvel C. S. , Markhart A. H. 
Published: April 2003

AbstractThe formation of polymers from diolefins and dimercaptans has been extended to some new monomer combinations to yield strong, slightly elastic fibrous polymers which contain groups that permit subsequent cross‐linking. Osmotic molecular weight data have been obtained on a variety of polymers with different inherent viscosities. Polymers with a molecular weight of 60,000 have been obtained from biallyl and hexamethylenedithiol.Diallyl sulfide has been found to be relatively unreactive toward the addition of a mercaptan under the conditions used. This indicates that a sulfur atom beta to the double bond interferes with the free radical‐catalyzed addition of a mercaptan. The basecatalyzed reaction of hexamethylenedithiol and the cross‐conjugated dienone, dibenzalacetone, has yielded a rubbery‐type polymer.
The degradation of long‐chain molecules by ultrasonic waves. I. Theoretical
Authors: Jellinek H. H. G. , White G. 
Published: April 2003

AbstractThe number and weight distribution functions, the number and weight average chain lengths, and the inhomogeneities of an initially homogeneous polymer sample have been calculated assuming a mechanism likely to be encountered during the ultrasonic degradation of long‐chain molecules. The evaluation of experimental results on the basis of this mechanism has been indicated and Schmid's theory of ultrasonic degradation has been briefly discussed.
Polyelectrolytes. IX. Light scattering from solutions of poly‐4‐vinyl‐N‐n‐butylpyridinium bromide
Authors: Fuoss Raymond M. , Edelson David 
Published: April 2003

AbstractThe turbidity and dissymmetry of polyvinylpyridine in ethanol containing 5% water are much greater than in anhydrous methanol. In both solvents, the dissymmetry decreases with dilution in the concentration range 0.1–0.6 g./100 cc. Quaternization with butyl bromide gives a polyelectrolyte whose scattering in aqueous solution is very low. Here, the dissymmetry goes through a minimum, as predicted by Doty and Steiner. By the addition of potassium bromide, turbidity is markedly increased, and the minimum in dissymmetry is eliminated. The latter effects may be explained as a consequence of association of excess counter ions with poly‐ions. Intermolecular forces are screened, thus increasing turbidity by suppression of long‐range order, and intramolecular forces are compensated, thus permitting the poly‐cations to revert to the statistical coil characteristic of ordinary polymers.
Polymerization in the system vinylidene chloride‐potassium laurate‐potassium persulfate
Authors: Wiener H. 
Published: April 2003

AbstractThe persulfate–initiated polymerization of vinylidene chloride in aqueous solutions of potassium laurate has been studied both with amounts of monomer small enough so as not to form a separate phase, and in emulsions of various compositions. In the first case, rates were determined by following the change in vapor pressure over the solution, and a method for obtaining the necessary vapor pressure‐concentration calibration curves was also developed; in the second, rates were determined by dilatometric and gravimetric methods. The rates were found to vary with the square root of the initiator concentration, and with the first power of the monomer concentration in solution, but to be independent of the amount of dispersed monomer in emulsion. They were found to increase with soap concentration, most markedly so in the region of low concentration. Approximate solubilities of monomer in polymer latices were also determined, and found to be about five times greater than solubilities in the original soap solutions; polymerization rates in emulsion and solution differed correspondingly. A high‐temperature viscometric technique has been developed for polyvinylidene chloride; intrinsic viscosity data indicate that chain transfer is appreciable in the reaction investigated.
Relation between stress relaxation and aging resistance of rubber vulcanizates—some preliminary investigations
Authors: Pedersen Holger Leth , Nielsen Bent 
Published: April 2003

AbstractIn this paper some details are given for the construction of a simple balance for the measurement of stress relaxation at constant elongation. A simple means of obtaining equal strain in the two parts of the strained specimen is provided. By means of four typical stocks covering the widest possible range of aging resistance it is shown that the stress relaxations give approximately the same estimate of stability as does the normal Geer test using 2 mm. dumbbell specimens. As a measure for stress relaxation the time is used that is required to obtain 50% of the value of the interpolated modulus at 200% elongation 6 seconds after the straining zero time at 110°C. The parameter for the aging test is the time in days at 70°C. for the 50% value of tensile strengths. The range for the stress relaxation parameter may be estimated to 8–1200 min. and the aging parameter from 10–600 days. Finally the concordance of temperature coefficient for relaxation and oxidation rates is shown.
Studies concerned with the structure of collagen. I. An x‐ray investigation of the denaturation of collagen
Authors: Wright Barbara A. , Wiederhorn Norman M. 
Published: April 2003

AbstractCollagen exhibits a low angle x‐ray diffraction pattern corresponding to a spacing of about 650 A. On denaturation (shrinking) this pattern disappears and does not return, regardless of how the material may be treated subsequently. It has been found that, when collagen tendons are stretched taut in a clamp, immersed in water, and then subjected to temperatures above the shrink temperature, the intensity of the low angle pattern diminishes appreciably. This has been interpreted as a decrease in the concentration of the structure which gives rise to the pattern and was assumed to be due to a melting of the crystalline structure of collagen. At constant temperature (above the shrink temperature), the low angle pattern continually decreases in intensity with increased shrinkage until it disappears completely. The extent to which the sample must be shrunk before the pattern disappears is dependent upon the temperature and increases with decreasing temperature.On analyzing the data quantitatively, using the theories of crystallization for linear polymers developed by Flory, it was possible to calculate a heat and entropy of shrinkage. The values obtained for these quantities indicate that the fusion is a stepwise process involving very few amino acid residues in each step (perhaps only one or two residues).Experiments were carried out on collagen shrunk in water and in formamide, as well as on formaldehyde tanned collagen shrunk in water. It was found that the heat and entropy of shrinkage apparently decrease with increasing tendency toward swelling. Thus the heat of shrinkage for formaldehyde tanned collagen is greater than for untanned, and the heat of shrinkage for native collagen is greater in water than in formamide.
Some aspects of the motion of chain segments in plasticized polyvinyl chloride. I. Dielectric relaxation of plasticized polyvinyl chloride
Authors: Dyson A. 
Published: April 2003

AbstractAnalysis of results of experiments on dielectric relaxation of polyvinyl chloride plasticized with tricresyl phosphate and with dioctyl phthalate gives values for heats and entropies of activation for dielectric relaxation rather lower than have been published in the literature for lower frequency ranges. The discrepancy may be due to a variation of heat of activation with temperature. A theoretical relation has been derived for the variation of heat and entropy of activation of dielectric relaxation with plasticizer content. The temperature dependence of the secondary high frequency loss factor maximum in unplasticized PVC has been ascertained, and some aspects of the relation between electrical and mechanical relaxation times and the second‐order transition point have been discussed.
Low‐temperature rubber: Emulsion polymerization in a salt antifreeze system
Authors: St. John W. M. , Uraneck C. A. , Fryling C. F. 
Published: April 2003

AbstractButadiene‐styrene copolymers have been prepared at subfreezing temperatures by means of redox recipes employing inorganic salts as freezing point depressants. Specific salt‐emulsifier combinations are required for optimum rates of polymerizations. With a sufficient amount of the inorganic salt to lower the freezing point of water 10°C., the sodium chloride–potassium caprylate combination resulted in a 60% conversion in 4.6 hours, the calcium chloride–sodium hexyl sulfate combination resulted in a 41% conversion in 24 hours, and the calcium chloride–alkyl aryl polyether alcohol combination resulted in a 58% conversion in 18.5 hours.Low molecular weight mercaptans such astert‐butyl mercaptan can be employed as practical modifiers for this recipe.Certain of the physical properties of the salt antifreeze copolymers prepared at −10°C. are superior to those of copolymers prepared at the same temperature by means of conventional recipes. The ease of processing and the heat‐aged properties are exceptional. One copolymer after 24 hours of aging at 100°C. withstood 118,000 flexures before a puncture increased to one inch in length at 99°C. The superiority of the product is attributed to the precipitation of the copolymer during the course of the polymerization.
Notes on the theory of high polymer solutions
Authors: Isihara Akira , Toda Morikazu 
Published: April 2003

AbstractWe have noted some correspondences in the theories of high polymer solutions. This article is divided in two independent sections: (I) Osmotic pressure. The second virial coefficients for polymers of the pearl‐necklace type are given and discussed in two limiting cases—the dumbbell and the infinitely polymerized molecule having a definite length. The variation of the coefficients against the polymerization is predictable from these limiting cases (Fig. 1). Attention must be paid to the manner of taking the (abscissa). The case of infinite polymerization can be considered as corresponding to polymers of a compact single‐body type such as globular proteins. Thus, an interesting correspondence in the second virial coefficients can be judged for the pearl‐necklace and the compact single‐body type of polymers. The general feature of the coefficient is also discussed. (II) Intrinsic viscosity. The relation between the two methods (Kirkwood‐Riseman and Debye‐Bueche) for intrinsic viscosity of high polymer solutions is discussed. Because the respective fundamental equations are equivalent to each other, we may choose whichever of these two methods we like.
Monomers containing large alkyl groups. IV. Polymerization and properties of the polymers of 2‐alkyl‐1,3‐butadienes
Authors: Overberger C. G. , Arond Lester H. , Wiley Richard H. , Garrett Robert R. 
Published: April 2003

AbstractThe polymerization and properties of the polymers of 2‐isopropyl, 2‐n‐heptyl, 2‐n‐decyl, and 2‐tert‐butyl‐1,3‐butadienes are described. Second‐order transition temperatures were obtained for the 2‐alkyl‐1,3‐butadiene polymers. Poly‐2‐n‐heptyl‐1,3‐butadiene has a transition temperature of −83°, near that of polybutadiene. Polymers of isopropyl, tert‐butyl, and n‐decylbutadiene have higher transition temperatures than polyisoprene. Branched side‐chains raise the second‐order transition temperatures markedly. This is especially true of the tert‐butylbutadiene polymer (Tm = +20°). Poly‐2‐n‐decylbutadiene has a transition temperature at −53° and is birefringent below −40°. From these results and those of previous workers it is apparent that sidechain branching raises the transition temperatures of poly‐2‐alkyl‐1,3‐butadienes and that low temperature flexibility cannot be materially improved over that exhibited by polybutadiene by the use of butadiene monomers containing 2‐substituted alkyl groups.
Polysoaps. II. Effect of added hydrocarbon on reduced viscosity of an n‐dodecyl bromide addition compound of poly‐2‐vinylpyridine
Authors: Jackson Earl G. , Strauss Ulrich P. 
Published: April 2003

AbstractThe effect of isooctane and n‐dodecane on the reduced viscosity of aqueous solutions of a polysoap, derived from poly‐2‐vinylpyridine (D.P. 2000) by partial quaternization with n‐dodecyl bromide, was determined. It was found that the reduced viscosity of polysoap solutions decreased linearly with added hydrocarbon, indicating that the polysoap molecule coils are contracted by the solubilizate. This contraction is ascribed to an increase in the van der Waals' attractive energy furnished by the solubilized hydrocarbon molecules.When the saturation limit of the hydrocarbon was reached, addition of more hydrocarbon caused no further decrease in the reduced viscosity. This phenomenon furnishes a new method for measuring solubilization of hydrocarbons by polysoaps. Solubilization values of isooctane obtained by this procedure were compared with those found previously by the vapor pressure method. The close agreement confirms the validity of both experimental methods.The efficiency of solubilization and the percentage depression of the reduced viscosity were not sensitive to changes in the polysoap concentration. The following differences in the solubilization behavior of the polysoap toward isooctane and dodecane were observed: (1) isooctane was solubilized to a greater extent than dodecane; (2) the maximum reduced viscosity depression obtainable with isooctane was greater than that obtainable with dodecane; (3) gram for gram, the dodecane was the more efficient at depressing the reduced viscosity.
Kinetics and mechanism of accelerated sulfur vulcanization
Authors: Gordon M. 
Published: April 2003

AbstractAs a step in the general development of a kinetic theory of sulfur vulcanization, rate data published by Zapp and co‐workers on the accelerated vulcanization of Butyl rubber are analyzed. Rate constants are calculated, some with remarkable accuracy, and these compare admirably with those previously calculated by the writer from data on unaccelerated Buna S vulcanization by Blake and co‐workers. In accordance with theory, acceleration is found to be due to a decrease in activation energy, which more than compensates for a considerable decrease in frequency factor predicted by theory. As in the case of unaccelerated cure, the reaction order is unity, at least initially, and reflects the disappearance of the sulfur during the reaction. The rate determining step is the reaction
magnified image
where Z· is a radical derived from the accelerator. Although the sulfur combines with the polymer and with zinc oxide, these two entities thus do not enter into the rate controlling step. The importance of classifying polymer reactions according to the participation or nonparticipation of the polymer in the rate control is stressed. Tentative arguments are advanced for kinetic and chemical details of the chain reaction between ZSSSSSSSS·. and rubbers. Some parallels are drawn between vulcanization, polymerization of sulfur, and the cyclization of rubber.
The problem of the heme interactions in hemoglobin and the basis of the bohr effect
Authors: Wyman Jeffries , Allen David W. 
Published: April 2003

AbstractIn this paper we have suggested that the interaction between the hemes of hemoglobin is due primarily to entropy effects associated with configurational changes in the molecule as a whole. In hemoglobin the four hemes appear to occur in paris, and the estimated interaction between members of the same pair would correspond to an entropy effect of 12 calories per degree or more, which is roughly the same as the entropy change which occurs when a mass of rubber equal to the half weight of hemoglobin is stretched to between twice and three times its initial length. Such an entropy change would account for the value of n = 1.9 observed in the oxygen and oxidation equilibria of hemoglobin split in halves by urea. The configurational hypothesis here proposed would at once explain the close similarity between the oxygen, carbon monoxide, and oxidation equilibria of intact hemoglobin, for x‐ray studies indicate that the same configurational changes accompany all three reactions. It would also account for the difference of solubility between hemoglobin and oxyhemoglobin, as well as a number of other matters. Some new data on the oxygenation of sickle‐cell anemia hemoglobin are presented and discussed in connection with the hypothesis.The further suggestion is made that the Bohr effect may be due, not to changes of bond type in the heme globin linkage as proposed by Coryell and Pauling, but to changes in the position and environment of certain acid groups resulting from changes in the configuration of the hemoglobin molecular as a whole. This would explain the essential identity of the Bohr effect for oxidation, oxygenation, and combination with carbon monoxide, as well as other things.It is finally suggested that the kind of entropy effect postulated in hemoglobin may play a role in the activation of substrates by enzymes more generally.As we have pointed out, the suggestions made in this paper are highly speculative and their value will depend largely on the extent to which they point to new experiments. Among many questions which arise are these: Is there any configurational change which occurs in myoglobin, with only a single layer of polypeptide chain, when it is oxygenated? What happens to the interaction and the Bohr effect when hemoglobin is caused to combine with a variety of reagents which react with specific groups in the molecule? Is there any significant change in the dipole moment of the hemoglobin molecule when it combines with oxygen and changes shape? These and other questions, if they were answered, would be highly pertinent to the suggestions presented in this paper.
Phthalyl peroxide as a polymerization initiator
Authors: Shah H. A. , Leonard F. , Tobolsky A. V. 
Published: April 2003

AbstractPolymeric phthalyl peroxide was used as an initiator for the polymerization of styrene at 60°C. The peroxide is initially partially insoluble in the monomer, but decomposes and becomes soluble during the course of the polymerization. The intrinsic viscosity of the polymer formed increases with increasing conversion and at about 65–70% conversion becomes higher than would arise from a monoradical‐initiated polymerization proceeding at the same rate.
Studies on rate of emulsion polymerization of butadiene‐styrene (75:25) as a function of amount and kind of emulsifier used with persulfate as activator. IV. Addition of emulsifier during reaction. Seeding effects
Authors: Kolthoff I. M. , Meehan E. J. , Carr C. W. 
Published: April 2003

AbstractThe effects of some factors on the rate of emulsion polymerization of butadiene‐styrene (75:25) in the GR‐S recipe at 50°C. are reported. The effects studied are the addition of soap during polymerization and the use of partially polymerized latex as seeder for the polymerization of the other ingredients of the recipe without further addition of soap.The addition of soap during the polymerization causes an acceleration of polymerization even if the amount added is less than that required for the formation of a monomolecular layer of soap on the surface of the polymer particles. This acceleration occurs even at conversions at which all the unreacted monomers are dissolved in the polymer particles.The seeding effect is accounted for on the assumption that after the disappearance of soap micelles, the particles are the only loci of reaction. The magnitude of the seeding effect is determined mainly by the amount of polymer that is added, the size of the polymer particles in the seeder being of secondary significance in determining the rate of polymerization.