bluuebunny/crossref_metadata_2025 huggingface dataset:
Modern views on the chemistry of vulcanization changes. II. Role of hydrogen sulfide
Authors: Naylor Ralph F.
Published: April 2003

Hydrogen sulfide has often been thought to play an important role in the sulfur vulcanization of natural rubber. A study has therefore been made of the reaction of hydrogen sulfide with olefins, including polyisoprenes, with special reference to the capacity of the reagent to react with olefins in the presence of free sulfur. Comparison of the products so obtained with those derived (a) by light‐catalyzed reaction of hydrogen sulfide and (b) by reaction of free sulfur with polyisoprenes has greatly assisted the understanding of the course of sulfur reaction in vulcanization processes.
Elastic properties of textile yarns, represented with the aid of a mechanical model
Authors: Vreedenberg H. A.
Published: April 2003

A series of experiments on the elastic behavior of various textile materials was carried out. All results are described with the aid of a mechanical model. For this purpose it is necessary to introduce the possibility of a blockade of a part of the model. The elastic properties are characterized by the values of seven independent fundamental constants of the model. The value of one of these constants associated with the blockade can be determined experimentally in a direct way; it is found to be independent of the moisture content. The most important properties of the model correspond with the molecular image of Hermans.
Deformation mechanism of cellulose gels. I. Present status of the problem
Authors: Hermans P. H.
Published: April 2003

A brief outline is given of the present status of research on the problem of the deformation mechanism of cellulose gels. Emphasis is placed on the prevailing idea of a molecular network structure and recognition of the existence of an intimate relationship between the phenomena of deformation and those of swelling. In these respects the problems involved in cellulose research seem to show a marked convergence with those which emerge from recent developments in rubber research. The principle of Kratky's theory of “affined transformation” and the experiments carried out by this author in order to verify his theory are discussed briefly.
The reaction of benzoyl peroxide with cyclohexane and cyclohexene. Contribution to the mechanism of the catalyzing action of peroxides in the polymerization of vinyl derivatives
Authors: Hermans P. H. , Eyk J. Van
Published: April 2003

The course of the reactions of benzoyl peroxide with cyclohexane and cyclohexene may be accounted for by a mechanism involving free radicals and radical chain reactions. With cyclohexane, the average length of the chain hardly exceeds one step and one mole of hydrocarbon reacts with one mole of peroxide. With cyclohexene, chains of two and three steps also occur and about two and one‐half moles of hydrocarbon per mole of peroxide take part in the reaction. It is shown that this is due to the one‐sided addition of the primary radicals (originating from the peroxide) to the double bond, yielding a new radical without a double bond which can in turn react in the same way with another unsaturated molecule, thus giving rise to polycyclic compounds (chain formation). This polymerization reaction is, however, soon halted by a competitive side reaction involving substitution of the α‐ (or β)‐methylene group, which leaves the double bond intact. In polymerizable vinyl derivatives in which no reactive α‐methylene group is present, the competitive reaction cannot occur and the radical chain reaction continues to form a growing chain of interlinked monomeric molecules with annihilation of the double bonds. The two terminal groups of the macromolecules of the final polymerizate are radicals originating from the peroxide used as a catalyst. If a solvent is used, radicals of the latter may also appear occasionally as terminal groups of the polymer. The mechanism of the catalytic action of diacyl peroxides in the polymerization of vinyl derivatives is thus clarified. The molecule linking reaction induced by free radicals in unsaturated compounds also provides an explanation of the action of benzoyl peroxide as a rubber vulcanizer; the peroxide radicals are found as substituents in the rubber molecule.
Theory of rolling plastics. I. Calculation of roll pressure
Authors: Eley D. D.
Published: April 2003

An elementary theory is given for the rolling of polymeric materials, for the case in which the deformation is largely an irreversible flow of the viscous type. The theory treats the rolling process as the homogeneous deformation of volume elements over the arc of contact and neglects frictional forces that may exist at the roll surface. A numerical example is given of the calculation of roll pressure, which agrees with available data to a factor of two or better. A more complete test will require parallel measurements of viscosity and roll pressure on the same material.
Mercaptans as promoters and modifiers in emulsion copolymerization of butadiene and styrene using potassium persulfate as catalyst. II. Mercaptans as modifiers
Authors: Kolthoff I. M. , Harris W. E.
Published: April 2003

A close correlation exists between the modifying effect of mercaptans in emulsion copolymerization of butadiene (75 parts) and styrene (25 parts) and mercaptan consumption during the polymerization. A procedure is described for the rapid amperometric titration of mercaptans in latices. Mercaptan disappearance curves (i.e., mercaptan used at various conversions) are given for a series of primary and tertiary mercaptans of widely varying molecular weight and of two secondary mercaptans. The consumption of (and modification by) primary mercaptans is affected to a much greater extent by the molecular weight of the mercaptan than that of tertiary mercaptans. The consumption of pure and of commercial n‐dodecyl mercaptan is greatly affected by the mode and rate of agitation during the polymerization, manner of preparation of the charge (preformed soap and soap “in situ,” separate emulsification of the modifier), dilution of the monomers with inert organic solvents, excess of free caustic in the charge, amount and kind of emulsifier, and the presence of substances which from complexes with the mercaptan. The consumption of tertiary dodecyl mercaptan is not affected by these variables. The difference in behavior between the two mercaptans is interpreted as a faster rate of solubilization into the locus of the reaction of tertiary mercaptans than of primary mercaptans of the same molecular weight. The disappearance curve of a mercaptan from a mixture of two mercaptans remains unaffected by the presence of the other mercaptan. At the same conversion the consumption of a mercaptan increases with decreasing temperature. Disappearance of mercaptan during the polymerization as a result of nonmodifying reactions is discussed.
Relative reactivities in vinyl copolymerization
Authors: Alfrey Turner , Price Charles C.
Published: April 2003

From data in the literature on relative rates of copolymerization it has been possible to evaluate two constants, Q and e, characteristic of an individual monomer, which appear to account satisfactorily for its behavior in copolymerization. The constant Q describes the “general monomer reactivity” and is apparently related to possibilities for stabilization in a radical adduct. The constant e takes account of polar factors influencing copolymerization.
Survey of plasticizers for vinyl resins
Authors: Reed M. C.
Published: April 2003

For satisfactory performance in vinyl chloride‐acetate resins, plasticizer must be compatible with the resin in a wide range of concentration. Low volatility low rates of extraction by oil and water, and good chemical stability are necessary in most applications. In special applications good electrical properties, low flammability, preservation of compound flexibility at low temperatures, and freedom from odor and taste are also required. Physical test methods, suitable for the evaluation of plasticizers, are briefly described.
Application of a mechanistic theory of solvent action to plasticizers and plasticization
Authors: Doolittle Arthur K.
Published: April 2003

The conventional thermodynamic theory of solvent action is briefly reviewed. A mechanistic theory is advanced to supplement the thermodynamic theory. The mechanistic theory views a resin solution as an example of dynamic equilibrium between the tendency of the solvent molecules to solvate the resin and the tendency of the resin macromolecules to unite with each other in three‐dimensional aggregation. A plasticizer, being a nonvolatile solvent, remains in the resin film on evaporation of the solvent and thus opposes, to an extent depending on its concentration and solvent strength, the aggregation of the resin macromolecules. Although the permanence of plasticizers in resinous compositions does not correlate well with the author's measure of the relative solvent strengths of the plasticizers, very satisfactory correlation is obtained between the low‐temperature behavior of plasticized films and the temperature dependence of the solvent strength of the plasticizers. Data are presented in support of the contention that a necessary condition for good low‐temperature performance in plasticized resinous compositions requires that the plasticizer must show a considerable improvement in solvent strength on cooling.
Creep behavior of plasticized vinylite VYNW
Authors: Aiken William , Alfrey Turner , Janssen Arthur , Mark Hermann
Published: April 2003

The viscoelastic properties of plasticized Vinylite VYNW were studied over a wide range of time scale by means of the tensile creep test. A number of different plasticizers were compared as to their plasticizing effectiveness. It was found that different plasticizers imparted distinctly different shapes to the creep curve of the plasticized ferent plasticized resin. The flat creep curve, characteristic of trioctyl phosphate, is considered to be superior to the steep creep curve of tricresyl phosphate. Mixtures of plasticizers were also studied. A number of conjectures are advanced concerning the molecular mechanism of plasticizer action. One important characteristic of a plasticized formulation of the polyvinyl chloride types of resin is the existence of a three‐dimensional gel structure of great permanence which prevents the occurrence of irrecoverable viscous flow.
Use of perbenzoic acid in analysis of unsaturated compounds. II. Determination of external double bonds in synthetic rubbers
Authors: Kolthoff I. M. , Lee Thomas S.
Published: April 2003

A procedure is given for the determination of the external double bonds in synthetic rubbers. The method is based on the difference in the rates of reaction of perbenzoic acid with internal and with external double bonds. The principles of the interpretation of the analytical data are discussed. Calibration curves for use in the analysis of butadiene and isoprene polymers are given. The procedure is also applicable to the analysis of a mixture of two compounds, one of which contains an external double bond and the other an internal double bond. Data are given for the analysis of mixtures of oleic acid and undecylenic acid.
Advances in pectin chemistry. Part I
Authors: Speiser Rudolph
Published: April 2003

This paper is the first part of a review on some recent advances in pectin chemistry. Part I reviews recent work on the constitution and structure of pectin, the characterization of pectin, x‐ray diffraction studies on sodium pectate, and the acid dissociation of pectinic acids.
A magnetic rotation study of polymerization of styrene
Authors: Giguère Paul A.
Published: April 2003

The thermal polymerization of styrene in vacuo has been followed by measuring the change of its magnetic rotatory power. The degree of polymerization was determined from measurements of the refractive index, viscosity, and density. The Verdel constant of the monomer at 25 °C. was found to be 0.0338 minute per gauss per cm.; furthermore, it showed no appreciable change on polymerization. Because of experimental difficulties the measurements could not be made beyond 25% polymerization.
Diffusion of water vapor through high polymeric membranes
Authors: Korvezee A. E. , Mol E. A. J.
Published: April 2003

Practical, theoretical, and experimental aspects, including sources of error and methods of control, of the water and water vapor permeability of organic membranes are discussed. Determinations of the permeability have been made at two different temperatures. Data are given on: polyethylene (alkathene, Imperial Chemical Industries), polystyrene (Styroflex, D. Seekabelwerke), chlorinated polyvinyl chloride (Vinifol, I. G. farbenindustrie), cellulose acetates (Triacetat, Schering, and Triafol, I. G. Farbenindustrie), a plasticized polyvinyl chloride (Welvic, Imperial Chemical Industries), and a copolymer of vinylidene chloride and vinyl chloride (Saran, Dow).
Potentiometric titrations of polymethacrylic acid
Authors: Katchalsky Aharon , Spitnik Pnina
Published: April 2003

Potentiometric titrations of polymethacrylic acid were performed at different concentrations, different molecular weights, and in the presence of neutral salts, as well as in dioxane‐water mixtures. It was shown that the pH of the solutions fulfills the relation, pH = pK — n log [(1 — α)/α]. pK and n are independent of the molecular weight and concentration if a suitable activity factor is introduced. The equation is applicable to free acid solutions as well as acid mixtures. Copolymers of the type, polyallyl acetate‐maleic acid, show a more complicated curve. The curve is of the “polydibasic” type. Each branch of it fits equation (2) well. The formula is analyzed and is proposed to be the result of the action of the Maxwell‐Partington statistical factor, as well as of the decrease in entropy accompanying the stretch of the randomly kinked molecule. This stretch is caused by the repulsive forces between the ionized carboxyl groups. The distribution curves of the various degrees of ionization present, for any pH, are given. The activity correction implies small units of the size of one or two carboxyl groups. The behavior in salt solutions is dependent not only on the activity correction, but also on the salting‐out factor. This factor is high in polyvalent salts. The titration curves in dioxane‐water mixtures are satisfactorily accounted for by the change in the activity factor with the dielectric constant.
Some structural and chemical aspects of aging and degradation of vinyl and diene polymers
Authors: Mesrobian Robert B. , Tobolsky Arthur V.
Published: April 2003

The chemical reactivity of vinyl and diene polymers manifested during aging and degradation is similar to the reactivity manifested during polymerization; namely, the activated intermediates are radicals and the reaction proceeds by a chain mechanism. A discussion of the possible types of aggregative and disaggregative processes involved in aging is presented. On the basis that polymerization and degradation occur by means of the same radical mechanism, experimental evidence is given to indicate that under certain conditions both reactions may occur simultaneously. Viscosity changes of solutions of mono‐ and polystyrene and methyl methacrylate were studied under varying conditions of heat, oxygen, catalysts, light, and photosensitizers. An analysis of the concurrent aggregative and disaggregative reactions involved in aging may be obtained by isolating one reaction from the other, either by various physical methods, such as intermittent and continuous stress relaxation, or by such classical methods as sol‐gel determinations and aging in solution. A comparative study of the rate of oxygen absorption of a large number of polymer types was undertaken to evaluate the factors affecting oxidation. Evidence is presented to show that these factors may be specified by the following: (1) chemical structure of the polymeric material, (2) presence of antioxidants, and (3) compounding and vulcanization. The oxidizability of polymeric materials was also studied in a circulating oxygen absorption apparatus in order to determine the effect of evolved, gaseous oxidation products. A preliminary study of the effect of light on the aging of butyl and GR‐S rubber as measured by oxygen absorption and stress relaxation is presented.
Intrinsic viscosity‐molecular weight relationship for polystyrene
Authors: Goldberg A. I. , Hohenstein W. P. , Mark H.
Published: April 2003

The molecular weight‐viscosity relationships for polystyrene are reviewed and it is recommended that the Staudinger relationship be discarded in favor of the conventional modification of it, [η] = KMa. An emulsion‐prepared polystyrene was fractionated and the viscosities and osmotic molecular weight determined. The corresponding relationship between the viscosities in butanone and toluene is observed to follow the above equation. A table containing the molecular weight‐viscosity relationships for polymers is appended.
Atomic configuration of cellulose
Authors: Van Der Wyk A. J. A. , Meyer K. H.
Published: April 2003

Various problems related to the determination with x‐rays of the atomic configuration of organic fibers are discussed. Because of the approximate nature of the underlying theory, too far‐reaching conclusions should be avoided, especially since, in the case of organic fibers, the situation is much less simple than in the case of sodium chloride powder or metallic wires, for example. Because of these facts, and because of the relative poorness of fiber patterns, the atomic coordinates as well as the space group of the structure can be found only within certain limits. Though the use of macroscopic models is very helpful in visualizing the spatial arrangement, no conclusions of a quantitative nature can be reached with their aid because the assumptions embodied in these models are too numerous and too inexact to justify speculations on details of the structure. In the case of cellulose fibers, it is shown that the problem cannot yet be solved completely; the outlook for a really unique solution is not hopeful. The structure proposed by Meyer and Misch is still the best approximation available. More recent propositions are shown to be less well founded; the atomic configuration introduced by Peirce, being at variance with chemical, crystallographic and x‐ray evidence, is to be discarded.
Behavior of concentrated polymer solutions under periodic stresses
Authors: Ferry John D. , Sawyer W. M. , Ashworth J. N.
Published: April 2003

Experimental methods for measuring the mechanical properties of concentrated polymer solutions and other viscoelastic systems under periodically varying stresses are reviewed. These include direct measurements of stress and strain, measurements of response at resonance frequencies determined by the inertia of the apparatus, propagation of waves in extended media, and measurements of resonance vibrations. The conditions for the suitability of each method are discussed, and equations for the interrelation of the various quantities measured are given. Examples are shown to illustrate the fitting of experimental data to the calculated behavior of mechanical models, in order to obtain frequency‐independent mechanical constants which can be interpreted in terms of molecular behavior.
Determination of intrinsic viscosity of linear polymers in concentrated solution
Authors: Govaerts R. , Smets G.
Published: April 2003

Intrinsic viscosity, calculated in accordance with the empirical relation established by Schulz and Huggins, deviates considerably from its true value in the case of increasing viscosities. The introduction of a simple corrective, second degree term η/150, applicable to most of the polymers, permits the direct computation of intrinsic viscosity based upon polymer solutions of various concentrations. Specific viscosities may vary to a great extent and reach a value as high as 15; the use of high concentrations permits the reduction of experimental errors and the determination, to within an average of one per cent, of the intrinsic viscosity of the polymer sample, and thus of its molecular weight.
Precipitating power as a function of molecular weight
Authors: Dobry A.
Published: April 2003

A substance may have a precipitating action on other dissolved substances. The concentration at which this action becomes apparent depends not only on the chemical nature of the constituents, but also on their molecular weights. In a homologous series the precipitating power increases with increasing molecular weight until it attains a very high value, as in macromolecules. The incompatibility of high polymers, which is manifested at very great dilutions, is due to this increase in the precipitating power with an increase of the molecular weight.
Steric hindrance in macromolecular solutions
Authors: Duclaux J.
Published: April 2003

The same point in the space cannot be occupied simultaneously by two molecules. In a solution of rigid rodlike macromolecules, each molecule prevents its neighbors from occupying certain positions, the whole of which form the forbidden angle. Calculation shows that in the case of rigid, filiform molecules, this angle is large even at very low concentrations. Isotropy is not possible at moderate concentrations. The consideration of the forbidden angle is necessary in the study of viscosity, osmotic pressure, flow birefringence, sedimentation, and molecular light scattering. In the solid state, the substance can be put under great tension, and the return to the normal state is extremely slow. This tension accounts for the abnormal solubility of disordered high polymers.
Polymerization of methyl isopropenyl ketone in cyclohexane
Authors: Haward R. N.
Published: April 2003

Expreiments have been carried out on the benzoyl‐peroxide catalyzed polymerization of methyl isopropenyl ketone at 25 and 40°C. in cyclohexane, a solvent which dissolves the monomer but causes the polymer to be precipitated. It is shown that in solutions of suitable concentration (40–80%) the effect of the cyclohexane is to increase both the rate of polymerization and the intrinsic viscosity of the resulting polymer. The significance of these observations and of other recent experimental work is discussed.
Some thermodynamic properties of slightly cross‐linked styrene‐divinylbenzene gels
Authors: Boyer R. F. , Spencer R. S.
Published: April 2003

A study has been made of the swelling characteristics of Styrene‐divinylbenzene gels containing from 0.02 to 0.12% of the cross‐linking agent. Variation in swelling of samples containing the same amount of divinylbenzene was shown to increase with decreasing divinylbenzene concentration. The influence of amount of cross‐linking agent, type of solvent, and temperature, on equilibrium swelling is reported. By assuming that μg is 0.44 for polymer‐toluene, values of μg for over 50 different solvents have been obtained. No values of μg below 0.42 were found. A correlation of swelling values and of μg values with cohesive energy densities of the solvents is presented. The polymer appears to have a cohesive energy density of 82 cal. per cc. Equilibrium swelling decreases slightly in toluene and methyl ethyl ketone but increases markedly in cyclohexane with rising temperature. Efforts to calculate gel constants from the temperature coefficient of swelling failed completely in the case of cyclohexane, and were only moderately successful with toluene. These temperature studies, and the cohesive energy density correlations both appear to indicate a lack of complete understanding about the physical significance of μ, and why it depends so markedly on concentration.
Experimental study of copolymerization. II
Authors: Agron Paul , Alfrey Turner , Bohrer John , Haas Howard , Wechsler Harry
Published: April 2003

In order to study further the effect of structure on monomer reactivities in copolymerization the copolymer composition as a function of initial monomer mixture composition has been determined for the following monomer pairs: vinyl acetate–vinyl chloride, ethyl methacrylate–vinylidene chloride, butyl methacrylate–vinylidene chloride, vinyl acetate–tetrachloroethylene, allyl chloride–vinylidene chloride, vinyl acetate–vinylidenechloride, methyl methacrylate–vinyl chloride, pentene‐1–vinyl chloride, allyl chloride–vinyl acetate, methyl methacrylate–2,5‐di‐chlorostyrene, vinyl chloride–vinylidene chloride, and vinyl chloride–dioctyl maleate.
Polymeric amides from epsilon‐caprolactam
Authors: Hanford W. E. , Joyce R. M.
Published: April 2003

ε‐Caprolactam is converted to ε‐aminocaproic acid polymer by heating under pressure with water followed, by distillation of the water and heating at atmospheric pressure. The lactam is also polymerized directly to this polymer by a catalytic method in which sodiocaprolactam is the initiator.
Photochemistry of proteins. IV. Action of ultraviolet light on crystalline chymotrypsin
Authors: Finkelstein Paul , McLaren A. D.
Published: April 2003

Crystalline chymotrypsin has been inactivated by ultraviolet light (2537 Å.) with a quantum yield of 0.0032 based upon loss of ability to act upon casein as a substrate. The possible significance of this datum in terms of the duo‐specificity of chymotrypsin, the integrity of the molecule as a whole and the quantum efficiency of cleavage of CONH linkages is discussed. The ultraviolet light absorption spectrum of the pure enzyme has been determined.
Polyelectrolytes. II. Poly‐4‐vinylpyridonium chloride and poly‐4‐vinyl‐N‐n‐butylpyridonium bromide
Authors: Fuoss Raymond M. , Strauss Ulrich P.
Published: April 2003

Poly‐4‐vinylpyridine was precipitated from a toluene solution of the monomer after addition of benzoyl Peroxide. The sample used in these experiments had a molecular weight of 77,000, (DP 730) as determined by osmotic pressure in alcohol solution, and an intrinsic viscosity of 0.36 in this solvent. The hydrochloride is water soluble and behaves like the salt of an extremely weak base with an over‐all average base dissociation constant of 0.011 × 10−9, about one thousandth that of 4‐ethylpyridine. The decrease in apparent base strength is ascribed to the chain structure which produces high local concentrations of pyridine groups, independent of the total concentration. By addition of butyl bromide to the polymer in nitromethane, a long chain quaternary ammonium salt is formed which is also water soluble. Its conductance is not sensitive to concentration down to about 0.003 N, after which the conductance rises sharply with further dilution. Dissociation, calculated by the classical Arrhenius method, indicates that a minimum of about 20% of the bromide ions are free, the remainder being associated by Coulomb attraction to the chainlike positive ion. As the dielectric constant of the solvent is decreased by addition of ethanol, the relative amount of free bromide ions decreases. The viscosity of the polyelectrolyte in aqueous or alcoholic solution, when plotted in the conventional way (ηsp/c versus c), approaches infinity at zero concentration instead of approaching a limiting constant linearly. A plot of $ {{\eta _{sp} } \mathord{\left/ {\vphantom {{\eta _{sp} } {\sqrt c }}} \right. \kern‐\nulldelimiterspace} {\sqrt c }} $ versus $ \sqrt c $ is, however, linear; this behavior is characteristic of strong electrolytes. The coefficient of the square root term in concentration for the polymer is larger, by orders of magnitude, than that for ordinary electrolytes. The coefficient of the linear term in the square root function is about equal to the intrinsic viscosity of the parent polymer.
Vapor phase polymerization of 1,3‐butadiene with sodium
Authors: Eberly Kenneth C. , Johnson B. L.
Published: April 2003

Apparatus and technique have been described for the polymerization of 1,3‐butadiene in the vapor phase with sodium as catalyst. Research grade butadiene or that obtained from alcohol is necessary for production of high molecular weight polymers by this method. Unmodified polymerizations with increased sodium surface go faster and produce polymers of lower gel content and inherent viscosity. Increase in polymerization temperature reduces the rate, gel content, and inherent viscosity. The chemical structure of the modifier seems to be the predominant factor in its efficiency within a concentration range of 0.1 to 1.0 %. Ethyl chloride is the most powerful modifier of those examined, followed in order by dimethylamine, acetaldehyde, and acetoue. Gelfree polymers with average inherent viscosities of the whole sol between 0.4 and 4.6 were vulcanized and evaluated. The weight distribution was found to be rather narrow for the low viscosity polymers but to become broader as the average inherent viscosity of the polymer increased. Optimum processing and tensile properties were obtained on the polymers of medium viscosity. The dynamic properties of the vulcanizates improve with increase in average inherent viscosity of the raw polymer; the ethyl chloride modified polymer is exceptionally good. The physical properties of the vulcanizate of a blend of equal parts of five polymers of inherent viscosity 1.0 to 4.6 were near those of the lowest molecular weight polymer.
Beiträge zur kinetik der indenpolymerisation. II. Die verteilungsfunktion der thermischen polymeren des indens
Authors: Pass F.
Published: April 2003

Polyindenpräparate werden durch Ausfällung mit Butylalkohol aus Benzol oder mit Methylalkohol aus Äther in Fraktionen von Molekulargewichten von 200–1200 zerlegt. Diese Werte werden benutzt um die Verteilungsfunktion dieser Polymeren mit extrem niedrigen Molekulargewichten zu berechnen.
Beiträge zur kinetik der indenpolymerisation. III. Über den einfluss molekularen sauerstoffes auf die indenpolymerisation
Authors: Gutmann V.
Published: April 2003

Es wird die Polymerisation von Inden unter Sauerstoffeinfluss bei 30 und 40°C. untersucht. Sauerstoff wird absorbiert unter Bildung eines labilen “Oxydpolymers” oder “Polyindenperoxyds,” das vom normalen Polymer mittels einer Fällungsreaktion getrennt werden kann.
Surface tension of polyoxyethylene glycol solutions
Authors: Couper A. , Eley D. D.
Published: April 2003

The surface tension of polyoxyethylene glycol in water leads to a value for the area per molecule which shows that the polymer molecules lie approximately flat in the surface. Molecular weight determinations by end‐group analysis and freezing‐point depression are compared with values of the intrinsic viscosity and limiting area per molecule.
Hydrogen peroxide as catalyst for emulsion polymerization of butadiene and styrene
Authors: Marvel C. S. , Deanin Rudolph , Claus C. J. , Wyld Mary B. , Seitz Rachel L.
Published: April 2003

Evidence is presented to show that either sodium ferri‐ or ferropyrophosphate with hydrogen peroxide effectively initiates emulsion copolymerization of butadiene and styrene. The hydrogen peroxide appears to be destroyed as such before polymerization begins, thus indicating that it converts some other constituent of the recipe into the effective catalyst for polymerization.
Processes for modifying rosin
Authors: Rinse J.
Published: April 2003

Rosin can be modified by two fundamentally different methods. which usually are combined to get the best results. These methods are based on neutralization of the carboxyl group and reaction with the unsaturated part of the rosin molecule. The products are used as a filler to improve gloss and hardness of the paint or varnish film. They are easily soluble in the common solvents and the harder types promote drying. Depending upon the method of treatment, they are more or less liable to oxidation. The molecular weight increases most for the phenolic‐ and maleic‐modified ester gums and especially when esterified with penta‐erythritol.
Adiabatic reaction kinetics of buna S vulcanization
Authors: Gordon M.
Published: April 2003

The adiabatic technique of making kinetic measurements has been applied to published time‐–temperature data concerning the vulcanization of Buna S with 6% sulfur. The kinetic parameters of the rate‐determining step are calculated within stated limits of accuracy; the rate‐determining step is thereby identified as the reaction S8 (ring) → S8 (chain biradical) which has been speculatively advanced as the first step in vulcanization by some investigators.
Inhibiting effects of certain phenols on GR‐S polymerization
Authors: Marvel C. S. , Higgins N. A.
Published: April 2003

The inhibiting action of several phenols on the GR‐S 10 (rosin soap) recipe for synthetic 2,5‐Di‐t‐butylhydroquinone is shown to be a particularly powerful inhibitor rubber is reportor in this recipe.
Refractometric determination of second‐order transition temperatures in polymers. II. Some acrylic, vinyl halide, and styrene polymers
Authors: Wiley Richard H. , Brauer G. M.
Published: April 2003

A refractometric method for determination of second‐order transition temperatures of polymers has been extended to include a series of polymers for which the transition occurs between 0° and 75°C. Refractive index data within ±30° to 50°C. of the transition temperature are given for some acrylate, methacrylate, vinyl chloride, vinylidene chloride, and styrene polymers and copolymers. These data show discontinuities which locate the second‐order transition temperatures for these polymers. Deviation from the linear relation near Tm has been related to a time effect.
Beiträge zur kinetik der indenpolymerisation. IV. Über polyindenperoxyde
Authors: Gutmann V.
Published: April 2003

Polymeres Indol, das in Gegenwart von Sauerstoff dargestellt wurde, kann durch Fällen mit Methylalkohol in 2 Fraktionen getrennt werden. Polyindol ist unlöslich. Die methylalkohollösliche Fraktion kann aus Benzol mit Petroläther als ein weisses, pulveriges “Polyindolperoxyd” ausgefällt werden. Fraktionierung führte zu Substanzen mit Molekulargewichten zwischen 300 und 3000. Bromtitration deutete darauf hin, dass die niedrigmolekularen Proben ungefähr eine Doppelbindung pro Polymermolekül enthielten. Die qualitative Prüfung für Peroxyd war positiv, aber die jodometrische Titration einer Probe ergab nur 42.5% des berechneten aktiven Sauerstoffgehaltes.
Beiträge zur kinetik der indenpolymerisation. VI. Weiterpolymerisierung von indenfraktionen
Authors: Halla F. , Schützner W.
Published: April 2003

Eine Probe von Polyindol (mittleres Molekulargewicht 400) wird sorgfältig in 9 Fraktionen von steigendem Molekulargewicht von 300 bis 800 zerlegt. Die Beobachtung von Whitby und Katz, dass Bromtitrierung zu einer Doppelbindung pro Polymermolekül führt wird bestätigt. Diese Doppelbindung ist aber nicht länger zur Polymerisation fähig, da sich die Molekulargewichte verschiedener Fraktionen nicht mehr wesentlich änderten, wenn sie Polymerisationsbedingungen—Erhitzen für 500 Stunden bei 175° in Stickstoffatmosphäre—ausgesetzt wurden.
Transport and equilibrium phenomena in gas–elastomer systems. II. Equilibrium phenomena
Authors: Barrer R. M. , Skirrow G.
Published: April 2003

The solubility of nitrogen, ethylene, and the n‐paraffins from methane to pentane has been measured in a series of natural rubber vulcanizates in relation to chain length of paraffin, temperature, and degree of cross linking of vulcanizates which contained between 1.7 to 21.9% combined sulfur.

For smaller, less soluble paraffins the degree of vulcanization had little influence upon the solubility but for higher molecular paraffins such as pentane this influence became significant. A qualitative interpretation of the effects observed was given. The solubility data are in all cases represented by a statistical theory of one of the authors for a mean frequency of vibration of the solute in the medium corresponding to the infrared (0.5 to 1.0 × 1012 sec.−1). The solubility constants, σ, and critical temperature, Tc, are also empirically related by the equation:

Heats and standard free energies of solution for the earlier homologous paraffins show steady trends as the chain length increases. The heats are exothermal and are adequately interpreted as the sum of the heats of liquefaction together with a small heat‐of‐mixing term for liquid and rubber which was usually close to that given by Hildebrand's cohesive energy density equation:

As anticipated from statistical theory, entropies were usually several entropy units more negative than those for solutions of gases in monomeric solvents.
Physical properties of fractions of GR‐S and their vulcanizates
Authors: Yanko John A.
Published: April 2003

A large‐scale precise fractionation of GR‐S (X‐55) was performed using the fractional precipitation technique at 25°C. 9 fractions, each weighing approximately 150 g. and comprising approximately 11% by weight of the original unfractionated sample, were obtained and a detailed study was made showing the effect of number‐average molecular weight and related sol–gel properties on various physical and chemical properties of the crude and vulcanized fractions. Using a Santocure tread‐type recipe, preliminary compounding work indicated the sulfur ratios required to give vulcanizates with 300% modulus values of 1000 p.s.i. All fractions were recompounded using these indicated optimum sulfur values. Generally, as the number‐average molecular weight increased, better stress–strain and quality index data were obtained. These and other physical properties of the vulcanizates of these fractions are discussed in detail. As found in past fractionation studies pertaining to unsaturated high polymers, the higher molecular weight fractions, obtained from the unfractionated sample which was totally soluble in benzene, undergo considerable gelation when isolated and vacuum dried at 25°C. in the dark. As the indicated molecular weight of the fraction increased, higher per cent gel contents were obtained. Compared to unfractionated butadiene‐styrene copolymers of similar gel contents, the gel portions of the higher molecular weight fractions had unusually high swelling indices. indicating qualitatively that the average molecular weights between points of effective cross linking in the three‐dimensional gel structure were higher than those encountered in the past in unfractionated samples of similar gel contents. Other data are given pertaining to these fractions, such as the bound styrene content, per cent shrinkage of the compounded unvulcanized stocks, and the rate of gel breakdown with cold milling.
Polymer constitution and fiber properties
Authors: Hill R. , Walker E. E.
Published: April 2003

The chemical structure of a large number of linear condensation polymers is correlated with their ability to assume a polycrystalline form possessing the right degree of thermal stability, and with the possession of fiber‐forming properties. Certain structures lead to the absence of crystallinity and of fiber‐forming properties, while, under certain conditions, a low degree of crystallinity or its complete absence leads to polymers possessing rubberlike properties, which may form highly elastic threads. Some properties of fibers such as solubility, sensitivity to mositure, and certain dyeing characteristics, can be correlated to some extent with chemical structure. These effects are considered on the basis of the introduction of various polar links and ring structures, according to regular patterns, into the polymethylene chain (polythee). The ehter (RO) and ester (CO·O) links lower the crystallite melting point to such an extent that some polymers containing them are completely noncrystalline at normal room temperatures. Urethan (O·CONH), amide (CO·NH) and urea (NH·CO·NH) links raise the crystallite melting point to an extent which increases in the order named. Most other polar links raise the melting point. The introduction into the aliphatic chain of ring structures, particularly aromatic rings directly attached to polar groups, raises the crystallite melting point, but in this case symmetry exerts an over‐ruling effect. A low degree of symmetry may lower the melting point and even eliminate crystallinity entirely to the detriment of fiber‐forming properties. Inert side chains lower the melting point considerably, and in some cases render the polymer completely noncrystalline at normal room temperatures.
Concentration dependence of sedimentation constant for nitrocellulose
Authors: Jullander Ingvar
Published: April 2003

An empirical method of correcting the sedimentation constant of high polymers for its concentration dependence is proposed. It should be possible to determine the sedimentation constant at infinite dilution with reasonable accuracy from experiments at concentrations where reliable measurements can be made.
Polyvinyl chloroacetate
Authors: Wiley Richard H. , Brauer G. M.
Published: April 2003

Series of bulk and solution polymerizations of vinyl chloroacetate have shown that the properties of the polymer vary widely with variation in polymerization conditions. The highest viscosity polymer, intrinsic viscosity polymer, intrinsic viscosity of 1.32, is prepared by bulk polymerization with 0.028% benzoyl peroxide initiator at 70°C. At polymerization temperatures sdover 70°C. and at catalyst concentrations over 0.14%, the polymer is discolored, insoluble, or has relatively poor aging characteristics. Polymerization in an equal volume of methyl isobutyl ketone at 80°C. and with 0.013% benzoyl peroxide gave 93% yield of polymer of intrinsic viscosity 0.15. In nitrobenzene, toluence, trichloroethylene, or ethyl acetate, only traces of polymer are obtained. In carbon tetrachloride, unstable telomers are produced.
Interaction between cellulose nitrate in solution and inorganic salts
Authors: Campbell H. , Johnson P.
Published: April 2003

PartI. It was confirmed that certain cellulose nitrates in 1% solution in acetone become more viscous and finally gel on standing over CaO, PbO, the basic salts of weak acids and strong bases, and certain other materials. The gels, whose formation was facilitated by increased temperature, were broken by the addition of a small amount of acid. The rate of gelling increased with the nitrogen content of the cellulose nitrate, indicating that residual hydroxyl groups were not involved. Nor did gelling occur under the same conditions in 1% solutions of cellulose acetate and ethyl cellulose of comparable degree of substitution. The rate of gelling was enormously increased when COOH groups were artificially introduced into the cellulose before nitration. Gelation is most probably due, therefore, to the cross‐linking of different cellulose nitrate chains through COOH or possibly SO3H groups.

Part II. Dilute (< 0.2%) cellulose nitrate solutions on standing over CaO show a fall in viscosity with time (contrast 1). By ultracentrifuge examination this was shown to be due (for CaO and PbO treated solutions), not to degradation of the cellulose nitrate chains, but to association processes leading to the formation of aggregates of higher sedimentation constant and molecular weight. Sedimentation constants corresponding to molecular weights of several millions were observed from a cellulose nitrate of initial molecular weight ca. 100,000. Untreated control solutions showed no change in the state of aggregation. The association processes followed an approximately first‐order law at room temperature and were made more rapid by increase in temperature. After sedimentation, the association products could not be redispersed. Calcium introduced into cellulose nitrate before solution in acetone did not cause association or any other noticeable effect at low concentration.
Influence of structure on polymer–liquid interaction. III. Swelling and mechanical properties of some partly crystallized polymers
Authors: Salomon G.
Published: April 2003

Swelling and rate of crystallization from solution and gels of raw and vulcanized guttapercha have been studied. Sulfur vulcanization of gutta‐percha causes a reduction in the amount of crystalline phase that becomes evident from typical changes in mechanical and swelling properties. Liquid–polymer interaction of the crystalline phase in gutta‐percha, raw rubber, and “racked” rubber lead to different equilibria, which are probably due to differences in the free energy contents of the crystalline phases. A series of vulcanized rubber hydrochlorides with gradually increasing chlorine content show analogous changes in rate of elastic recovery and swelling equilibria that are also due to the gradual formation of a crystalline phase. Correlations between molecular structure and rate of crystallization in plastics and elastomers are discussed. Symmetry of the shape, as well as of inter molecular forces in the molecular units, size of substituents, and regularity of the polymer chain all have an essential influence on the rate and ease of crystallization.
X‐ray diffraction patterns of stretched low‐temperature polybutadiene using molybdenum, copper, and chromium radiations
Authors: Beu Karl E.
Published: April 2003

X‐ray diffraction patterns of stretched crystallized polybutadiene polymerized at −20°C were obtained using molybdenum, copper, and chromium characteristic x‐radiations on the same sample. The pattern obtained using molybdenum radiation showed diffraction effects in the 0, 1st, 2nd, 3rd, and 4th orders. The lack of detail in this pattern is partly due to the relatively intense background. By using the longer wavelength copper and chromium radiations the diffraction effects of the zero‐ and first‐order layer lines were brought out in considerable detail. The diffraction data obtainable from these layer line patterns may be useful in carrying out a structural analysis of crystalline polybutadiene.
Factors influencing the activation energies of reactions involving double bonds and radicals
Authors: Evans M. G. , Gergely J. , Seaman E. C.
Published: April 2003

By using the methods which have been developed to describe the activation energy of chemical reactions in terms of bond energies and the repulsing energies between reacting centers, the factors influencing the activation energies of reactions between radicals and monomers are discussed. Calculations are reported on a number of simple prototype reactions involving radicals and atoms and ethylenic bonds. It is found that the heat of reactions is a most important factor in determining the activation energies of such reactions and this result is extended to a wide variety of substituted radicals and monomers. The variation in the heat of reaction is expressed in terms of the resonance energies of the reacting radicals and molecules. Another important factor is the energy of repulsion between the reacting centers, and this energy is affected by (a) the charge distribution on the reacting centers and (b) the steric effect of substituent groups. The effect of substituents on the charge distribution is discussed in terms of the molecular orbital method, an attempt being made to distinguish between the influence on the π electrons of the inductive and mesomeric effect of substituents.
Thermal degradation of polystyrene. Part II
Authors: Jellinek H. H. G.
Published: April 2003

The production of monomer during degradation of polystyrene in vacuo below 310°C. has been investigated. A mechanism has been proposed which explains the dependence of monomer formation on the initial breaks in the chain. The degradation in presence of oxygen has been studied. A mechanism for this reaction has been proposed which accounts for the type of curves obtained experimentally. The role of antioxidants has been briefly indicated. The elementary steps for the degradation in vacuo and in the presence of oxygen have been discussed.
Adhesion. III. Adhesion of polymers to cellulose and alumina
Authors: McLaren A. D. , Seiler Charles J.
Published: April 2003

A relationship between tack temperature and molecular weight has been deduced and illustrated with polyvinyl acetate polymers. Provided the molecular weight is high enough to prevent cohesive failure, the adhesion of polyvinyl acetate to cellulose and aluminum is independent of molecular weight. The influence of humidity on adhesion of polymers to cellulose is shown. The influence of polymer composition on adhesion is illustrated with copolymers of vinyl acetate and methyl vinyl ketone and with styrene and methyl vinyl ketone. Above a mole fraction of ketone of 0.8, adhesion increases rapidly. The interdependence of tack temperature and composition on adhesion is exemplified with ethylene ‐ vinyl chloride copolymers. A temperature dependence of adhesion is cited for copolymers containing maleic acid.