bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractThe 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

AbstractAn 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

AbstractA 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

AbstractFrom 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

AbstractFor 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

AbstractThe 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

AbstractThe 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

AbstractA 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.
A magnetic rotation study of polymerization of styrene
Authors: Giguère Paul A. 
Published: April 2003

AbstractThe 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

AbstractPractical, 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

AbstractPotentiometric 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

AbstractThe 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

AbstractThe 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

AbstractVarious 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

AbstractExperimental 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

AbstractIntrinsic 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

AbstractA 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

AbstractThe 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

AbstractExpreiments 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

AbstractA 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

AbstractIn 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

Abstractε‐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

AbstractCrystalline 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.