bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of disappearance of bis‐isopropyl xanthogen (“dixie”) in synthetic rubber latex during polymerization
Authors: May D. R. , Kolthoff I. M.
Published: April 2003

Bis‐isopropyl xanthogen (“dixie”) is a poor promoter, but an effective modifier, in the GR‐S recipe, as was concluded from unreported intrinsic viscosity measurements. High molecular mercaptans are good promoters but very poor modifiers. In recipes containing mercaptans as promoters, dixie acts like a retarder until a conversion of 30% is attained. After this conversion the rate becomes normal. It is found that at a conversion of 30% most of the dixie has been dissipated. Bis‐isopropyl xanthogen can be determined polarographically. A procedure is given for the polarographic determination of dixie and the determination by amperometric titration of mercaptan when both dixie and mercaptan are present in a GR‐S latex. Disappearance curves of dixie and of mercaptans are given when both modifiers are present in the original charge.
Vitesse de polymérisation et de copolymérisation de l'acétate d'isopropényle
Authors: Hart R. , Smets G.
Published: April 2003

En présence de peroxyde de benzoyle, l'acétate d'isopropényle polymérise de la même facon que l'acétate d'allyle. Son comportement lors de la copolymérisation avec l'acétate de vinyle, le chlorure de vinyle et le méthacrylate de méthyle montre que ce monomère possède une réactivité générale semblable à celle de l'acétate de vinyle. Le caractère négatif de la double soudure est plus prononcé (−0.8). Ces copolymérisations sont caractérisées par un important transfert de chaîne, dû à la présence de l'acétate d'isopropényle. A l'égard du styrène, l'acétate d'isopropényle se comporte comme un solvant; il n'y a ni copolymérisation, ni transfert de chaîne.
Optische anisotropie und form von fadenmolekülen. II. Künstliche doppelbrechung
Authors: Stuart H. A. , Peterlin A.
Published: April 2003

Es werden die Beziehungen für die elektrjsche, magnetische und die Strömungsdoppelbrechung von Fadenmolekülen in Lösung in Abhägigkeit vom Polymerisationsgrade angegeben. Ferner werden einige Möglichkeiten die Makro‐ und die Mikroform eines hochpolymeren Moleküls zu bestimmen und Verzweigungen zu erkennen, besprochen. Schliesslich wird durch Messungen der elektrischen Doppelbrechung am Dampf nachgewiesen, dass Paraffinketten lose Knäuel bilden.
Tetramethylthiuram disulfide vulcanization of extracted rubber. II. Structure of radioactive tetramethylthiuram disulfide
Authors: Craig David , Davidson W. L. , Juve A. E. , Geib I. G.
Published: April 2003

(1) A study of the four sulfur atoms in tetramethylthiuram disulfide (TMTD) by radiosulfur techniques disclosed that these sulfur atoms are equivalent chemically. (2). The synthesis and reactions of radio‐TMTD were studied. (3) New reactions which were found for TMTD included those with the following substances: dimethylamine, n‐dodecyl mercaptan, ZnS, ZnO, zinc dust, S8*, and acetic acid. (4) Radiosulfur and the sulfur atoms in ZnDMDC do not undergo interchange, at least up to 150°.
Copolymerization of butadiene‐styrene by means of an oxygen, dodecyl mercaptan, and iron and cobalt pyrophosphates system
Authors: Marvel C. S. , Keplinger O.
Published: April 2003

Copolymerization of butadiene‐styrene in soap emulsion can be initiated by the interaction of oxygen and mercaptans catalyzed by traces of ferrous pyrophosphate and cobalt salts. A recipe is described which effects conversions of 53% within 36 hours at −1°. The resulting rubber is very soluble in benzene and has an intrinsic viscosity in the range of 3.5–4.36.
Redox recipes. III. Use of various sugars at 0° and 30°C. in a cumene hydroperoxide–iron–sugar recipe
Authors: Kolthoff I. M. , Medalia A. I. , Youse Madolyn
Published: April 2003

The cumene hydroperoxide–iron–sugar recipe which gave attractive rates of conversion at 30°C. has been studied with several variations at 0°, using several sugars or sugarlike products. Dihydroxyacetone appears to be the most suitable reducing agent at 0°.
Copolymerization of phenylacetylene with vinylpyridine
Authors: Price Charles C. , Greene Charles E.
Published: April 2003

Experiments on the copolymerization of phenylacetylene with 2‐vinylpyridine gave values for the copolymerization ratios, r1 = 4.0 ± 0.7 and r2 = 0.20 ± 0.05. Estimates of the copolymerization constants, Q = 0.3 and e = −0.6, from these experiments agree with those estimated from values of copolymerization constants recently reported by Doak from studies of copolymerization of phenylacetylene with methyl acrylate and acrylonitrile. The experiments reported herein support the report by Doak that phenylacetylene acts as a marked retarder, as well as a commoner.
Role of the semipermeable membrane in the osmotic molecular weight determination of cellulose acetate
Authors: Philipp Howard J. , Bjork Carold F.
Published: April 2003

Osmotic pressure measurements are reported for solutions of unfractionated and fractionated cellulose acetate in acetone, using denitrated collodion, gel‐cellophane, and caustic‐treated cellophane as semipermeable membranes. Although techniques are employed that are presumably correct for the effect of diffusion, different osmotic pres‐ sures and hence apparent molecular weights are obtained with the three types of membranes. No correlation is found between osmotic pressure and either the permeability constant or the average pore diameter of the membranes. Measurements with a very low molecular weight cellulose acetate, the molecular weight of which is known from independent measurements, show that the rate of diffusion of small solute molecules through various membranes is not related to the rate of transfer of solvent molecules.

It appears that the observed differences between membranes are caused by rapid diffusion of low molecular weight material at the beginning of the osmotic measurement, before even the first readings by a dynamic method can be taken. From measurements with the very low molecular weight cellulose acetate it is concluded that, in the case of cellulose acetate in acetone, correct osmotic molecular weights are obtained only with undried gel‐cellophane membranes, and that molecular weights determined with either the faster denitrated collodion or the slower caustic‐treated cellophane membranes are appreciably too high.
Rate of sorption of organic vapors by films of cellulose acetate
Authors: Mandelkern Leo , Long F. A.
Published: April 2003

A detailed study has been made of the rate of take‐up of vapors of methylene chloride and acetone by thin films of cellulose acetate (37.9% acetyl) as a function of vapor pressure, film thickness, and temperature. It was found that the method of film preparation and conditioning greatly influenced the kinetics of the take‐up. Films, which were not completely dry, exhibit a much faster rate of take‐up than dry films. Dry films could he obtained by either long treatment in a vacuum oven, or by water leaching followed by vacuum drying for five days. In either case, identical kinetic results are obtained. The mercury cast films used in this work give reproducible results and show a much slower rate of take‐up than a comparable glass cast film.

It was found that there was no fundamental difference in the rate of take‐up for the vapors of methylene chloride and acetone, although in the liquid state the former is a limited swelling agent, while the latter is a solvent. For both these yapors there is a characteristic pressure above which several anomalies appear, which make a complete quantitative explanation of the data rather difficult. The most important of these anomalies is that, if one plots the amount of vapor taken up as a function of time, an inversion of slope is observed. This inversian is very marked and is a function of film thickness. Another anomaly that appears is that the absolute amount of vapor sorbed for thinner films is greater than that for thicker films for an appreciable time interval. The effect of temperature is complex. Above the pressures where the inversion of a slope occurs, the rate is lower a t higher temperatures for a considerable range of the sorption. These effects cannot be explained on the basis of a generalized diffusion equation with the boundary conditions which have been considered so far, i.e., assuming that the outer film surface is always in equilibrium with the vapor.
Cationic polymerization of butadiene and copolymerization of butadiene and styrene
Authors: Marvel C. S. , Gilkey R. , Morgan C. R. , Noth J. F. , Rands R. D. , Young Charles H.
Published: April 2003

The cationic polymerization of butadiene with several Friedel‐Crafts catalysts has been described. Aluminum chloride and chlorosulfonic acid are active catalysts at −75°. The rate of polymerization at −75° is much faster than at the higher temperatures. Except for boron trifluoride etherate, which catalyzes the polymerization at −30°, the other catalysts (sulfuric acid, fuming sulfuric acid, stannic chloride, and boron trifluoride hydrate) produce appreciable amounts of polymer only at 0° or higher.

The effect of variables, such as catalyst concentration, catalyst solvent, dilution, reaction time, etc., differs with each individual catalyst. In some cases, results were not conclusive due to lack of reproducibility. It was found that the presence of moisture is mainly responsible for this lack of reproducibility. Traces of water promote the polymerization with stannic chloride or boron trifluoride etherate, but inhibit the polymerization when an ethyl bromide solution of aluminum chloride is used as catalyst.

Rubberlike polyhutadienes can be obtained with all catalysts except sulfuric and fuming sulfuric acids. However, the physical properties of these polymers show that the molecular weight is very low and that the polymer is not suitable as a rubber. Polymers ranging from viscous liquids to hard, brittle solids have also been obtained. In general, the solubility of the polymers is low. Approximately 60% of the butadiene enters the polymer chain by 1,4 addition.

The copolymerization of butadiene and styrene at −75° with an ethyl bromide solution of aluminum chloride has also been studied. At conversions between 20 and 30% a soluble, rubberlike copolymer having a low molecular weight is formed. An insoluble, brittle polymer is obtained a t higher conversions.

The soluble, cationic copolymer has a characteristic ultraviolet absorption curve which is different from that of GR‐S. It has a styrene content of approximately 50% by weight which demonstrates that the styrene is more active in cationic copolymerization than is butadiene.
Polyelectrolytes. VII. Viscosities of derivatives of poly‐2‐vinylpridine
Authors: Maclay William N. , Fuoss Raymond M.
Published: April 2003

Polyelectrolytes were prepared by partial quaternization of poly‐2‐vinylpyridine (M = 45,000) with methyl bromide and butyl bromide. Viscosities of the former salt were measured in water and methanol; of the latter in water, methanol, ethanol and nitrobenzene. A new method of calibrating viscometers is described. Shear constants of the salts in aqueous solution were determined. The viscosity data conform to the equation:

Correlations between both structure of salt and dielectric constant of solvent, and the constants of the equation were found. Quaternary derivatives of poly‐2‐vinylpyridine are more rodlike than corresponding derivatives of poly‐4‐vinylpyridine.
Azo‐bis nitriles. II. Use of 2,2′‐azo‐bis‐isobutyronitrile as a catalyst for the polymerization of styrene
Authors: Overberger C. G. , Fram Paul , Alfrey Turner
Published: April 2003

(1) The rate of polymerization catalyzed by 2,2′‐azo‐bis‐isobutyronitrile was found to be proportional to the square root of the catalyst concentration at 47.8° and 67.8° at a monomer concentration of 4 moles/liter. A square root dependence was also observed at 80.3° with 1‐azo‐bis‐cyclohexanecarbonitrile in pure monomer. At these temperatures, the number average degree of polymerization, assuming combination for the termination step, was inversely proportional to the square root of the catalyst concentration. These facts are additional evidence to support the unimolecular first‐order decomposition of the azo‐bis compound into radicals.

(2) The monomer dependence on the over‐all rate was found to be 1.2, again at 68.2° this result is consistent with first‐order initiation and bimolecular termination.

(3) The decomposition of 2,2′‐azo‐bis‐isobutyronitrile in pure styrene or in toluene and styrene is a unimolecular first‐order decomposition with a rate constant similar to that observed in pure toluene.
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

Polysoaps 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

A 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

The 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

The 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

The 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

The 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

In 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

Collagen 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

Analysis 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

Butadiene‐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

We 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.
A two‐constant equilibrium theory of linear association
Authors: Ginell Robert
Published: April 2003

A two‐constant equilibrium theory for linear association considering growth and degradation simultaneously is presented.

The choice of suitable rate constants is discussed.
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

The 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

The 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

As 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

In 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

Polymeric 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

The 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.
Preparation and properties of esters of polyorthotitanic acid
Authors: Boyd T.
Published: April 2003

In studies of the synthesis of alkyl titanates from anhydrous butyl alcohol and titanium tetrachloride employing ammonia or an amine to neutralize the hydrogen chloride formed, Speer has reported uniformly unsuccessful results in repeating the examples of Nelles' patents on this process. Kraitzer, Winter, and others followed Nelles' process successfully employing a large excess of anhydrous butyl alcohol. Repetition of Nelles' patent examples is awkward because the ammonium chloride formed in the reaction produces a thick slurry too inconvenient to handle. However, if this slurry was diluted or extracted with an anhydrous hydrocarbon solvent,i.e.,toluene, yields of 80% were achieved. Furthermore, since it is difficult to obtain rigorously anhydrous alcohols, it is more convenient to carry out the synthesis of alkyl titanates using an inert anhydrous solvent,i.e.,toluene or carbon tetrachloride, as a reaction medium along with the stoichiometric quantity of alcohol instead of using a large excess of the alcohol as the reaction medium. The formation of nonvolatile residues was avoided.

If the proper quantity of water dissolved in a low‐boiling alcohol is added slowly with stirring to a solution of the corresponding ester of orthotitanic acid, it is possible to obtain esters of polyorthotitanic acid of controlled average molecular weight. If less than 1 mole of water per mole of orthotitanate esters is employed, the amount of cross‐linked polymer derived is vanishingly little. When the butylorthotitanate was treated with 1.5–2.25 moles of water per mole of titanium, 1.4–1.5 moles of water were consumed per mole of titanium. Water was recovered from the system. Water in excess of 2.25‐3 moles of water per mole of titanium caused complete conversion of butylorthotitanate to titanium dioxide. The polyorthotitanates were soluble in benzene, toluene, and butyl alcohol. The uncross‐linked polymers vary in appearance from very viscous liquids to waxy solids. The polyorthotitanates enter into ester interchange reactions with alcohols in which one to all of the lower boiling alkyl groups may be replaced by the higher one. Long‐chain organic acids react with the alkyl polyorthotitanates or the alkyl titanates to replace one to all of the alkyl groups.
Light scattering studies on some muscle proteins
Authors: Steiner Robert Frank , Laki Koloman , Spicer Samuel
Published: April 2003

A light scattering investigation of actin and actomyosin gives the following information. The weight average molecular weight of 80,000 is found for G‐actin. The average molecular weight and length of F‐actin decrease upon increasing concentration of electrolyte, the effect being especially pronounced in the case of KI. The average molecular weight and length of F‐actin decrease with increasing of pH of polymerization. The average length and molecular weight of F‐actomyosin increase with decreasing ionic strength. The average length and molecular weight of F‐actomyosin decrease with decreasing size of the F‐actin component.
A new molecular weight distribution technique for polystyrene. I. Theory
Authors: Boyer Raymond F.
Published: April 2003

This paper is concerned with the description of a simple technique for determining the molecular weight distribution curve of polystyrene (and presumably any other soluble polymer consisting of a polymer‐homologous series). The general theory of the method as well as preliminary experimental results will be covered. The method is characterized by: (1) simple technique and equipment; (2) no need to isolate and measure fractions; and (3) a general basis in thermodynamic theory of polymer solutions, although a double calibration is needed to determine numerical parameters. The method consists in adding increasing quantities of nonsolvent to a dilute solution of polystyrene in a good solvent and observing the cumulative volume of precipitate as a function of nonsolvent content. The settled gel must re‐equilibrate (hence deswell) with the new solvent after each alcohol addition. The swelling ratio, S (cc. of swollen gel per gram of dry polymer), of the swollen precipitate is approximately independent of the molecular weight and depends mainly on the volume percent of nonsolvent, γ according to

where α, σ, and s are constants. Likewise, the molecular weight, M, of the species precipitated at any nonsolvent content is given by the Schulz precipitability equation:

where α, β, and m are constants. For the system polystyrene–benzene–methanol, we find s = 4/3 while Schulz had already noted that m = 2/3. Elimination of γ and α leads to the prediction of a linear relation between M and S2. A two‐fold calibration to obtain the constants in equations (1) and (2) is necessary to convert the observed data to an absolute cumulative weight versus molecular weight curve. However, even the simple plot of cc. of precipitate versus percent nonsolvent is informative. The relationship of these results to the thermodynamic theories of polymer solutions of Flory, Huggins, Gee, and Scott is outlined. The plot of cumulative volume of precipitate against percent nonsolvent has two characteristic features: an inflection point and a maximum. If the original polymer has a weight distribution function of the Schulz type, i.e., MkM × (1 − k)2, where k is related to the number‐average molecular weight, M̄n, through M̄n = M0(1 − k)−1, then it can be shown that the maximum occurs at M̄n while the inflection point occurs at 2.15 M̄n.
Cross‐linking in the polymerization of vinyl benzoate and related compounds
Authors: Ham George E. , Ringwald Eugene L.
Published: April 2003

Branching and cross‐linking are noted in emulsion and mass polymerizations involving vinyl benzoate and nuclearly substituted vinyl benzoates. A theory is proposed to account for this phenomenon based on free radical addition to the benzoate nucleus. Six new vinyl esters of substituted benzoic acids are described.
Étude sur les phénomènes de dissolution du chlorure de polyvinyle
Authors: Corbiere Jacques , Terra Pierre , Paris René
Published: April 2003

Après avoir rappelé quelques considérations générales concernant la mise en solution des hauts polymères dans les liquides organiques, les auteurs relatent les principaux résultats de leurs expériences sur la solubilisation des chlorures de polyvinyle industriels dans les liquides binaires. Ils montrent qu'en pastillant par compression le polymère il est possible d'examiner sur ces comprimés l'action de divers liquides et distinguent: (1) les liquides inertes; (2) les liquides désagrégeants; (3) les liquides gélatinisants. Les meilleurs solvants binaires se présentent généralement sous forme de mélange d'un liquide gélatinisant et d'un liquide désagrégeant ce qui revient à combiner l'action d'un liquide polaire et d'un liquide non polaire.

Ils montrent ensuite comment on peut apprécier le pouvoir solvant d'un solvant binaire en fonction de sa composition en mesurant la vitesse de pénétration de ce dernier dans une pastille de polymère. Les courbes obtenues ainsi accusent des maxima correspondant sensiblement à des rapports stoechiométriques simples entre les molécules des deux constituants.

Ils insistent ensuite sur la nécessité de considérer un phénomène de solvatation comme facteur de gélification et, par suite, comme premier stade de la dissolution. Ceci s'appuie sur leur détermination des degrés de solvatation du chlorure de polyvinyle au moyen de la méthode graphique des restes. Ces solvates font intervenir un seul ou deux des constituants du liquide binaire utilisé comme solvant. Mais dans le cas d'une fixation simultanée des deux constituants du solvant sur le polymère il y a lieu de considérer une action individuelle de ces deux constituants, les propriétés physiques des mélanges étudiés excluant en effet l'hypothèse de complexes d'addition dans le solvant binaire lui‐même.

Enfin les auteurs pensent que la solvatation des molécules du polymère persiste dans la solution colloïdale de ce dernier et annoncent qu'ils poursuivent actuellement leurs essais dans le but de mettre cette solvatation en évidence.
Mechanical properties of discrete polymer molecules
Authors: Baker W. O. , Mason W. P. , Heiss J. H.
Published: April 2003

A frequency‐dependent stiffness μB was found from the action of high frequency shear waves on dilute solutions of polyisobutylene, polypropylene, polyethylene, polystyrene, hevea rubber, and polybutadiene microgel. A dynamic viscosity associated with streaming of solvent through the molecular coil, ηB, dropped far more rapidly with rising temperature than solvent viscosity, denoting that it, too, reflected configurational changes. (The μB for polyisobutylene in solution declined moderately with rising temperature, corresponding to an exponential coefficient of 2.3 kcal.) This behavior suggested three chief mechanisms for deformation of isolated chains: (1) viscoelastic configuration changes (W. Kuhn's “macroconstellation changes”) with contribution to rigidity per average molecule per cubic centimeter of solution of 〈 μ2 〉 or force constant 〈 f2 〉; (2) temporary entanglements of interpenetrating segments in the chain coil (like the interchain entanglements in concentrated solutions of J. D. Ferry), with contribution to rigidity 〈 μ3 〉; and (3) restrictions to rotational flexibility around chain linkages, with rigidity contribution 〈 μ4 〉. Arrangement of these processes in parallel with solvent viscosity yielded frequency‐independent constants in agreement with the limited data so far obtained in the 103 to 108 cycle range.

Such a model gave molecular mechanical constants correlating roughly with chemical structures. For polyisobutylene, force constants per average molecule were 〈 f2 〉 = 17.1 × 10−13 dyne cm., 〈 f3 〉 = 6.3 × 10−12 and 〈 f4 〉 = 1.6 × 10−10. Lower molecular weight (1.2 × 106 vs. 3.9 × 106) gave slightly lower values. 〈 f4 〉 represents restrictions to rotation per isobutylene residue in the chain of 2.3 × 10−15, or about 104 less than valence bond infrared vibrational or twisting force constants for hydrocarbons. The combined average chain rigidities expressed by the force constant 〈 fB 〉, at 20 kc. and 25°C. were, for polyisobutylene of M̄V ∼ 106, 1.8 × 10−12; hevea rubber of M̄V = 2.3 × 105, 1.5 × 10−15; polystyrene of M̄V = 2.3 × 105, 4.5 × 10−16. Hence, single polystyrene chains are quite flexible, but polybutadiene microgel has 〈 fB 〉 = 5.2 × 10−11, for M̄W ∼ 18 × 106, showing effect of internal cross‐linking.

“Poor” solvents (“solvent power” μ > 0) caused chain rigidity of polyisobutylene and polystyrene to decrease, compared to good solvents (“solvent power” μ ∼ 0), and viscosity decreased also. Apparent decrease in 〈 fB 〉 apparently means external (solvent) “compression” of chain, and agrees with technological efficiency of poorly compatible plasticizers.

Complete theory of effects has been outlined by Kirkwood, for a rod model. Great range of rigidities shown even by hydrocarbon chains (intrinsic rigidity of polyethylene soln., [μ] = 906 dynes/cm.2, of polypropylene soln., [μ] = 92 dynes/cm.2) has not yet been treated, however.
Correlation between sensitivity to acid hydrolysis and skin‐core differentiation in viscose rayon
Authors: Hermans P. H. , Heikens D.
Published: April 2003

It is shown that the extent of hydrolysis in a given set of conditions is qualitatively related to the thickness of the rayon skin. This interpretation is preferable to that of relating extent of hydrolysis to crystalline amorphous ratio.
Absolute propagation rates in emulsion polymerization. II. Butadiene in hydroperoxide‐polyamine systems
Authors: Morton Maurice , Salatiello P. P. , Landfield H.
Published: April 2003

A study has been carried out on the emulsion polymerization of butadiene, using the “peroxamine” recipe at low temperatures in an attempt to evaluate the absolute propagation rate, according to the theory of Smith and Ewart, from a determination of the rate of polymerization per particle of latex. Unlike the persulfate‐mercaptan system previously reported, the hydroperoxide‐polyamine systems show a polymerization rate per particle which is independent of all variables other than temperature. Hence this system behaves according to case 2 of the Smith‐Ewart treatment, where the number of free radicals per particle is approximately 1/2. On this basis it is possible to calculate a value for the absolute propagation rate constant for butadiene, as follows: kp = 1.2 × 108 e−9300/RT l./mole/sec. This value in turn leads to an evaluation of the absolute rates of some other reactions involving the butadiene radical, such as cross‐linking, chain transfer, and copolymerization. It agrees with the current data on absolute rates for other monomers and with present‐day theories concerning the effect of conjugation on radical‐monomer interaction.