bluuebunny/crossref_metadata_2025 huggingface dataset:
Photochemistry of phosphonitrilic chlorides. I. A photochemical reaction of low‐polymeric phosphonitrilic chlorides
Authors: Dishon B. R. , Hirshberg Y.
Published: April 2003

Photochemical reactions of trimeric and tetrameric phosphonitrilic chlorides with some hydrocarbons are described. Soluble and insoluble photoreaction products are formed. From the soluble fraction, distillable phenyl‐ and decahydronaphthyl‐phosphonitrilic chlorides were separated; the indistillable and deposit fractions were also found to contain high percentages of carbon and hydrogen. This shows that successive substitution of the chlorine atoms by radicals, R, of the solvents, RH, had taken place.
Polyelectrolytes. III. Viscosities of n‐butyl bromide addition compounds of 4‐vinylpyridine‐styrene copolymers in nitromethane‐dioxane mixtures
Authors: Fuoss Raymond M. , Cathers George I.
Published: April 2003

A series of copolymers, of 4‐vinylpyridine and styrene, covering the range 1.5 to 100% vinylpyridine were prepared in 20% toluene solution at 80°. Strong electrolytes were then made by the addition of n‐butyl bromide in nitromethane solution. The salts with high vinylpyridine content were soluble in water, alcohols, nitromethane, and other polar solvents. Viscosities of the parent copolymers in methyl ethyl ketone were in the range 0.15–0.20; osmotic pressures gave molecular weights in the range 50,000‐80,000. The polyelectrolytes in nitromethane and nitromethane‐dioxane mixtures gave viscosity‐concentration curves which were strongly concave upwards: at 1 mg./100 cc., the reduced viscosity of the salt of polyvinylpyridine in nitromethane was 6.0. The salts of the different copolymers did not differ much in their viscosities at concentrations above a few tenths of a gram per 100 cc., a fact which shows a high degree of ionic association; only as zero concentration is approached, can the detailed polymer structure be seen. The extent of association at a given concentration is controlled by the amount of vinylpyridine in the copolymer and by the dielectric constant of the solvent. Addition of simple one‐one electrolytes, such as tetrabuty lammonium bromide, suppresses the electrostatic increase in viscosity which otherwise appears at low concentrations. The following empirical equation:

was found to fit the data for the different systems studied. The constant A depends on copolymerization ratio and probably on molecular weight; it is a measure of the extent to which the polymer coil can spread out at infinite dilution as a consequence of the intramolecular Coulomb repulsion between charges attached to the chain. It is roughly several orders of magnitude larger than the intrinsic viscosity of the parent polymer. The constant B is a measure of the electrostatic forces and increases with decreasing dielectric constant of the solvent.
X‐ray studies on the crystallinity of cellulose
Authors: Hermans P. H. , Weidinger A.
Published: April 2003

The method for the evaluation of the percentage crystallinity in cellulose preparations from x‐ray intensity measurements, previously described in detail (J. Appl. Phys., in press) is reviewed briefly and new material presented consisting of crystallinity percentages between 8% and 70%. Cotton, flax, and ramie possess equal crystallinity (70%) and so do the majority of rayons, independent of their degree of orientation and including cuprammonium and Lilienfeld rayons. Cellulose acetates saponified under varying conditions also yield almost the same value as rayon (40%). The New product Fiber G (du Pont) holds an exceptional position with 53% crystalline substance. In the series of native celluloses, wood pulp has about 65%, Valonia 65–70%, and bacterial cellulose about 40%. By dry grinding of rayon, a powder was obtained containing only slightly less than 10% crystalline substance, which on recrystallization in water, yields 2 product having the same crystallinity as rayon. The difference between the heats of wetting of the criginal and the recrystallized powder affords additional support of the results obtained.
Dependence of elastic properties of vulcanized rubber on the degree of cross linking
Authors: Flory Paul J. , Rabjohn Norman , Shaffer Marcia C.
Published: April 2003

Natural rubber and GR‐S synthetic rubber have been vulcanized to varying degrees of cross linking through the use of disazodicarboxylates. These compounds react readily with the above unsaturated polymers in a manner which assures the formation of one cross linkage for each molecule of the disazo compound. Elastic properties of the vulcanizates so produced are similar to those of rubber specimens vulcanized in the conventional manner with sulfur and an accelerator. Their stress‐strain curves deviate from the form prescribed by the statistical theory of rubber elasticity in the same manner as observed by Gee for sulfur vulcanizates. The equilibrium force of retraction at 100% elongation has been measured over a 30‐fold range in the degree of cross linking; equilibrium swelling measurements extend over an 80‐fold range. The magnitude of the force of retraction over most of the range covered agrees remarkably well with the explicit predictions of the statistical theory. The significance of the deviations which are observed is discussed.
Preparation and vulcanization of liquid polyisoprene polymers
Authors: Conwell Y. , Roeser G. P. , Tobolsky A. V.
Published: April 2003

By means of chain transfer agents such as dodecyl mercaptan, polyisoprenes whose number‐average molecular weights range between 300‐1200 and which are liquid at room temperature have been prepared. The structure and physical properties of these substances have been investigated. Vulcanization of these liquids to rubberlike materials at room temperature and above is described.
Polymerization of isobutene catalyzed by boron trifluoride
Authors: Evans Alwyn G. , Meadows G. W.
Published: April 2003

The polymerization reaction which occurs when butene vapor is mixed with boron trifluoride gas has been studied under various conditions. It has been found that this polymerization occurs only if a third component, or cocatalyst, is present. The function of the cocatalyst has been investigated, and the mechanism of the polymerization reaction is discussed.
Some remarks on the first interaction coefficient of the viscosity‐concentration equation
Authors: Eirich F. , Riseman J.
Published: April 2003

During recent years attempts have been made to formulate a viscosity‐concentration relationship. The method of Huggins, in introducing a factor k′ as a hydrodynamic correction factor is examined, and in particular the attempts to draw conclusions relating k′ to the thermodynamic properties of the solution. An explanation is offered to correlate the experimental viscosity‐concentration relationship and the change of solvent. A possible method for the actual calculation of concentration effects has been applied to the case of a suspension of spherical particles, for which, as a first approximation, a value of 10.6 for the coefficient of the c2 term has been obtained.
Light transmission and the formation and decay of spherulites in polythene
Authors: Hawkins S. W. , Richards R. B.
Published: April 2003

The effect of increasing and decreasing temperature on the light transmission of polythene has been measured. On raising the temperature of a sheet of polymer the light transmitted increases steadily at an increasing rate until the sample becomes glass clear at the melting point (ca. 112°C.). On cooling from the melt the specimen becomes very opaque a few degrees below the melting point, then becomes much more transparent and thereafter the light transmission decreases as temperature falls, the transmission‐temperature curve approximating to the curve for rising temperature. Changes in the spherulite structure of polythene film on heating and cooling have been observed under the microscope and recorded on a cinéfilm. Decay of spherulites on heating is seen not to occur by the reverse of the process by which they are formed from the melt, and the light transmission results are discussed in relation to the spherulitic structure of the polymer.
Emulsion polymerization of 2‐alkyl‐1,3‐butadienes.
Authors: Marvel C. S. , Williams Jack L. R. , Baumgarten Henry E.
Published: April 2003

The polymers of 2‐ethyl‐, 2‐isopropyl‐, and 2‐n‐amyl‐1,3‐butadiene alone, and their copolymers with styrene and with butadiene have been prepared and characterized. These monomers give the same ratio of 1,2 to 1,4 addition as has been noted for isoprene. Much less mercaptan must be used with these monomers than is required for butadiene to give soluble polymers. All these monomers copolymerize with styrene readily but have higher Wall α values than butadiene. The stress‐strain properties and Gehman low‐temperature properties of all of the new polymers have been determined by the Government Laboratories, University of Akron, and are included in this report. There appear to be no unusual properties to be noted.
Influence of molecular weight on the properties of polystyrene. I. Mechanical properties of polystyrene films cast from solvents
Authors: Merz E. , Nielsen L. , Buchdahl R.
Published: April 2003

The variables of casting polystyrene films from methyl ethyl ketone and from benzene are investigated. It is shown that stringent drying is necessary to remove the last traces of solvent. The differences in dry film structure, second‐order transition point, and temperature at which the dynamic modulus suddenly decreases are discussed.
Copolymerization. II. Molecular weight distribution and mean molecular weights in copolymerization systems
Authors: Melville H. W. , Noble B. , Watson W. F.
Published: April 2003

An extension of the kinetic analysis of the generalized reaction mechanism for copolymerization given in Part I has been carried out to obtain the functions for molecular weight distribution and number and weight‐average molecular weights.
Estimation of crystallinity of some polymers from x‐ray intensity measurements
Authors: Hermans P. H. , Weidinger A.
Published: April 2003

The paper deals with a tentative plan to extend quantitative x‐ray measurements for determining the degree of crystallinity of polymers (as used earlier in cellulose determinations), to the investigation of rubber, polythene, and a polyamide. Strictly monochromatized copper radiation was used. The results show that further work along these lines may be promising. The raw rubber sample used was identical with one of those investigated by Goppel and by Arlman. It yielded a crystallinity figure higher than that reported by Goppel, but conformed with that found by Arlman. The figures obtained for polythene at different temperatures are compared with those derived from density and heat capacity measurements by other workers. The degree of crystallinity of polythene at room temperature is found to be ∼ 55%, and in samples of polyhexamethylene sebacamide, previously treated in different ways, figures between ∼50 and 70% are obtained. It is shown that the possibility of using the background intensity as a measure of the disordered fraction is confined to not too high angles of diffraction. A method is described (and experimentally checked) allowing for reducing the curves of intensity distribution as a function of 2θ as observed in various polymers to a comparable scale. It is further emphasized that, in polymers where hydrogen bonds play a decisive role in intermolecular cohesion, the x‐ray results suggest that the “crystalline” or ordered fraction may to a considerable extent involve states of two‐dimensional order.
Influence of activated carbon on styrene polymerization
Authors: Breitenbach J. W. , Preussler H.
Published: April 2003

During a definite polymerization time the rate of uncatalyzed polymerization of styrene may be decreased by the use of activated carbon. The intrinsic viscosities of the polymers formed may be either increased or decreased by the addition of active carbon, depending upon the activity of the carbon sample used.
Tetramethylthiuram disulfide vulcanization of extracted rubber. III. Short‐path distillation of TMTD and its reaction products from rubber
Authors: Craig David , Juve A. E. , Davidson W. L.
Published: April 2003

(1) A technique has been described for the short‐path distillation of substances from rubber. It has been found that sulfur, TMTM, TMTD, ZnDMDC, phenyl‐beta‐naphthylamine, and palmitic acid are recoverable by this procedure. (2) The conversion of zinc compounds such as zinc oxide and zinc palmitate to ZnDMDC in rubber by treatment first with CS2 and then with dimethylamine has been studied. (3) The volatilization of zinc from vulcanizates after conversion to ZnDMDC has been shown to occur without devulcanization.
Modified osmotic balance
Authors: Masson C. R. , Melville H. W.
Published: April 2003

The construction of a modified form of osmotic balance has been described. By suspending a cell from each arm, the instrument has been made insensitive to temperature changes. In place of weighings, measurements are recorded by altering the buoyancy of one of the cells. By the use of an optical lever in conjunction with a divided photo‐ cell, a considerable increase in sensitivity has been obtained, the movements of the balance pointer being magnified about 300 times. A new method of matching the levels of solvent and solution has been described. Difficulties due to evaporation of solvent are discussed.
Hydroperoxides as initiators of emulsion polymerizations at low temperatures
Authors: Wicklatz J. E. , Kennedy T. J. , Reynolds W. B.
Published: April 2003

The results of emulsion polymerizations in which twenty‐eight different organic hydroperoxides were used as oxidizing agents in a standard redox recipe at 5°C. have been presented. Each hydroperoxide was tested at several different concentration levels. The hydroperoxides of chlorodiisopropylbenzene, di‐t‐butylisopropylbenzene, cyclohexylbenzene, 1,2,3,4,4a,9,10,10a‐octahydrophenanthrene, and t‐butylisopropylbenzene were found to be the most effective of the compounds tested. Oxidation mixtures, concentrates of oxidation mixtures, and purified samples of hydroperoxides served as sources of hydroperoxide for the polymerization experiments reported. Similar results were obtained with oxidation mixtures and concentrates, but purification of the hydroperoxide usually resulted in improved polymerization rates. The amount of hydroperoxide which gives the optimum results in a given polymerization recipe varies for structurally different hydroperoxides and appears to be related to the molecular weight.
Measurement of molecular weight of polyethylene by menzies‐wright boiling point elevation method
Authors: Morawetz H.
Published: April 2003

The Menzies‐Wright ebullioscopic method was used to evaluate unfractionated polyethylene resin, DYNH (Blend 1004). This material was found to have a number average molecular weight in the range 9000–9200. Results of good reproducibility were obtained with concentrations not exceeding 2.1 g. per 100 ml. tetrachlorethylene solvent. From the curvature of the boiling point elevation vs. concentration plot, the solvent–solute interaction constant μ was calculated and found to be slightly higher than the value predicted by Huggins for solvents with zero heat of mixing.
Oriented overgrowth on cold‐drawn polymers
Authors: Richards R. B.
Published: April 2003

Oriented overgrowth of paraffin wax crystals, grown from solution, has been observed on the surface of cold‐drawn strips of polyethylene and of polyethylene sebecate, but not on oriented gutta‐percha, rubber, polyethylene terephthalate, or nylon. The distribution of the angles at which the platelike paraffin crystals lie on polyethylene has been measured. This is found to be narrower than the angular distribution of the crystalline regions in the polymer as a whole, as calculated from the x‐ray diffraction pattern, suggesting that the crystallites in the polymer surface are more perfectly oriented than in the interior.
Solubility of crystallized polymers
Authors: Van Amerongen G. J.
Published: April 2003

The behavior in solution of three crystallized polymers, namely, gutta‐percha, rubber hydrochloride, and nylon, was investigated. In all three cases it was found that, at a low enough temperature, these materials exhibit a separation of phases in the solution owing to the formation of crystallites. The melting point of these crystallites is lower in the better solvents and also in solutions of a higher dilution.
Electrolytic initiation of polymerization
Authors: Kolthoff I. M. , Ferstandig Louis L.
Published: April 2003

Two new principles are discussed by which polymerization may be initiated electrolytically. One of these methods, the continuous electrolytic formation of the activator in a redox activation polymerization system, under various conditions, has been used successfully in the polymerization of acrylonitrile, but not of isoprene or styrene. The second method, based on the formation of free radicals in the electrolytic reduction of perdioxy compounds, has been tested under a limited number of conditions without significant success. Emulsion systems also have been employed in this research and the results are discussed.
Some improvements on the osmotic balance
Authors: Enoksson Bertil
Published: April 2003

An osmotic balance is described, whose principle is the same as that of an earlier one, but with the readings simplified by use of a chainomatic balance. A new cell has been constructed. Due to thin walls in the tube of the cell, this cell makes it possible to measure osmotic pressure without determining the reference point, the position at which the meniscus in the cell is at the same level as that in the container. A determination of osmotic pressure can be made in half the time by this new arrangement, compared with the older method. An example of the use of the balance has been given for a sample of cellulose nitrate and a fraction of polystyrene.
Influence of molecular weight distribution on the intrinsic viscosity‐molecular weight relationship
Authors: Frank H. P. , Breitenbach J. W.
Published: April 2003

Polystyrene made by polymerization at 140° (polymer yield 18.9%) was fractionated successively into a number of fractions of increasing homogeneity. Intrinsic viscosity and osmotic molecular weight of the unfractionated polymer and of the fractions were determined. In the relation between them the constant K was found to decrease from K0 = 14.2 X 10−7 for the unfractionated polymer to K0 = 6.8 X 10−7 for the most homogeneous fractions. The distribution function of G. V. Schulz for the polymer and a Gaussian function for the most homogeneous fractions are discussed. From the ratio K0/K0K∞ = 2.09 (±0.15) we draw conclusion on the mechanism of polymerization under assumption of the validity of [η] = KMα instead of the simple Staudinger equation. A possible explanation for the deviation of the experimental value 2.09 from the theoretical 1.877 is given.
Polymerization of allyl compounds. V. Inhibition by nitro compounds
Authors: Hammond George S. , Bartlett Paul D.
Published: April 2003

The effect of various nitro compounds on the peroxide‐induced short‐chain polymerization of allyl acetate has been investigated. Of the compounds studied, sym‐trinitrobenzene is the most active as a retarder. Nitromethane and dinitrodurence were found to be less effective than aromatic nitro compounds which have replaceable nuclear hydrogen atoms but both exerted a measurable retarding influence on the polymerization reaction. It is found that trinitrobenzene reacts with a minimum of 5.9 radicals per molecule. This and other data are discussed in connection with the hypothesis that radicals react by an alkylation mechanism. An alternative mechanism involving attack on the nitro group itself is suggested.
Determination of the concentration of high polymer solutions
Authors: Grassie N.
Published: April 2003

It is shown that heating for several days at atmospheric pressure and 100°C. does not remove the volatile components from benzene solutions of polymethylmethacrylate and polystyrene solutions in benzene. Pirani gage measurements in a molecular still define the rather limited conditions under which all volatile components can be removed with out degradation and loss of polymer. Because of its low softening point, polyvinyl acetate can be dried to constant weight by overnight heating at 100°C.
Transition temperatures of plasticized material and copolymer systems
Authors: Nielsen Lawrence E. , Pollard Robert E. , McIntyre Elizabeth
Published: April 2003

The transition temperature, defined as the temperature where the log modulus temperature curve has an inflection point, is a linear function of the volume fraction of compatible plasticizer added to a high polymeric resin such as polyvinyl chloride. The transition temperature of plasticized compositions can be predicted from the transition temperatures of the pure polymer and plasticizer. The transition temperature of homogeneous copolymers can be predicted from the transition temperature of the individual polymerized monomers making up the copolymer. Data are presented on three copolymer systems containing vinyl chloride and on various plasticized materials.
Emulsion polymerization of styrene. II. Effect of agitation
Authors: Shunmukham S. R. , Hallenbeck V. L. , Guile R. L.
Published: April 2003

Employing a reproducible system for the emulsion polymerization of styrene it has been demonstrated that agitation (stirring or shaking) affects both the rate of polymerization and maximum average molecular weight of the polymer formed. Increasing the agitation increases the inhibition, decreases the polymerization rate, and lowers the average molecular weight of the polymer formed. Agitation affects both a peroxide and a persulfate catalyzed polymerization in a similar manner. Agitation effects have been observed in the presence of a redox system and in the presence of a chain modifier. Oxygen has been demonstrated to stop as well as inhibit the initiation of an emulsion polymerization.
Friedel‐Crafts polymerizations. III. Medium effects in the Friedel‐Crafts polymerization of styrene
Authors: George Joseph , Wechsler Harry
Published: April 2003

In polymerizing styrene at room temperature in the presence of tin tetrachloride, it is found that the rate of polymerization is greatly affected by the dielectric constant of the medium. It increases by a factor of approximately 1400 when the dielectric constant changes from 6.5 to 18.4. At the same time the degree of polymerization increases only slightly. The results are interpreted as supporting evidence for the mechanism of Friedel‐Crafts polymerizations as suggested by Polanyi and co‐workers. A unimolecular termination by proton‐splitting cannot be reconciled with these results.

Quantitative equations are derived relating the rate and degree of polymerization to the dielectric constant. Traces of liquid water have no visible effect on the polymerization while larger amounts cause retardation. The degree of polymerization, which is of the order of 20, does not change with conversion and is unaffected by the catalyst present.
The degradation of long‐chain molecules by ultrasonic waves. III. Dependence of rate constant on chain length for polystyrene
Authors: Jellinek H. H. G. , White G.
Published: April 2003

The experimental variation of rate constant with chain length in the degradation of fractionated polystyrene samples by ultrasonic waves has been determined. The results are discussed in relation to a theory previously presented to account for molecular distributions obtained during degradation. It is shown that the experimental results cannot be explained satisfactorily by theories which assume that degradation is caused by frictional or impact forces.
Osmotic pressure measurements of ethyl acrylate polymers. I. Dependence of molecular weight on conversion
Authors: Hansen J. E. , McCarthy M. G. , Dietz T. J.
Published: April 2003

By employing the solution polymerization method, ethyl acrylate was readily polymerized, giving a product soluble in a number of organic solvents. By using benzene as the solvent, polymers of exceptionally high molecular weights were produced. The polymer samples were obtained by precipitation after the polymerization had proceeded for various periods of time. The slopes of the osmotic pressure curves were substantially constant for all the polymers. It is concluded that chain transfer to polymer during the polymerization process is insignificant and that the ethyl acrylate polymers do not contain any branched sites. It can be inferred from these data that the insolubility of ethyl polyacrylates frequently encountered is predominantly due to the extremely high molecular weights of the polymers.
Gelation of polyacrylic acid by divalent cations
Authors: Wall F. T. , Drenan J. W.
Published: April 2003

“Gel point” studies involving polyacrylic acid and certain divalent ions have been carried out. As a gelation agent, barium hydroxide was found to be more effective than strontium hydroxide, which in turn was better than calcium hydroxide. This indicates that the association between inorganic cation and polyacrylate ion is not entirely a matter of coulombic charge. However, experiments involving partial replacement of barium hydroxide by barium chloride suggest that charge is still the most important factor in the bonding. The data cannot be explained upon the basis of simple ionic equilibria.
Spectrometric determination of refractive index at low temperatures
Authors: Wiley Richard H. , Garrett Robert R.
Published: April 2003

A spectrometric technique for the determination of refractive indices of liquids and polymers over a temperature range of −70 to +70°C. has been developed and used to establish the absolute accuracy, within =0.0004 refractive index units, of a more convenient refractometric method previously described. Refractive index values are reported for dimethyl phthalate from + 70 to +15°C.; polyvinyl acetate from + 65 to −70°C.; and tricresyl phosphate from +30 to −80°C. The refractometric values are within =0.0004 or less units of the spectrometric values over this range. The data for tricresyl phosphate locate two apparent second order transitions at −47 and at −62°C. The higher value (−47°C.) is observed with thoroughly dried tricresyl phosphate.
The viscosities of dilute solutions of nitrocellulose
Authors: Moore W. R.
Published: April 2003

The viscosities of dilute solutions (0.05, 0.1, and 0.2 g. per 100 ml.) of relatively high nitrogen content nitrocelluloses, weight‐average molecular weights ca. 100,000, have been studied using homologous series of methyl ketones, alkyl acetates, and dialkyl phthalates as solvents. The simple form of the Huggins equation,

does not appear to hold, plots of ηsp/c against c being generally curved. The results are capable of expression by

where A equals [η] and B the initial slope. Values of B and A appear to be related to solvent power as determined by the volume of hexane required to cause initial phase separation from solution, good solvents giving higher values of B and A than poor. The variation of B with solvent is more marked than that of [η] and may reflect differences in degree of coiling of chains in different solvents. Values of B/[η]2 (Huggins k′) do not generally decrease with solvent power increase. The slopes of Martin plots divided by intrinsic viscosities are not generally related to solvent power in the manner observed by Spurlin with solutions of ethyl cellulose.
General theory of deformation of viscoelastic substances
Authors: Sips R.
Published: April 2003

The general theory of the deformation of viscoelastic substances developed in two previous papers for the one‐dimensional case is now extended to three dimensions. The integro‐differential equations obtained are generalizations of the well‐known Navier‐Cauchy equations and, like these, only apply to small deformations.

Some special cases are considered in detail and lead to interesting conclusions. In particular, the theory predicts that for incompressible high polymers, one should obtain the same creep and relaxation functions when the material is subjected to extension, torsion, or bending.
Polymerizable derivatives of long‐chain fatty acids. IV. Vinyl esters
Authors: Port William S. , Hansen John E. , Jordan E. F. , Dietz T. J. , Swern Daniel
Published: April 2003

Contrary to some published reports, the vinyl esters of saturated fatty acids polymerize readily and rapidly. Vinyl oleate, when present in excess of 5%, and oxygen exert marked retarding effects.

Techniques are described for the free‐radical‐initiated polymerization of the vinyl esters of caprylic, capric, lauric, myristic, palmitic, and stearic acids in bulk, dispersion, solution, and emulsion. Some data are given for polymerization in the presence of chain‐transfer agents, such as carbon tetrachloride, dodecylmercaptan, and ethylbenzene. Conditions are reported for obtaining degrees of polymerization from about 2 (when chain‐transfer agents are employed) to 10,000 (weight average). The weight average degree of polymerization increases markedly as the conversion increases, particularly above 80%. Even up to extremely high conversions, soluble polymers are obtained in most cases.

Solubility characteristics, transition point data, molecular weights (osmometric and light‐scattering), and isolation and purification techniques are also reported.
Photoinitiated free radical polymerization of vinyl compounds in aqueous solution
Authors: Evans M. G. , Santappa M. , Uri N.
Published: April 2003

A new method for the photochemical initiation of polymerization of vinyl compounds in aqueous solution is described. The photochemically active species is an ion pair complex of the formula Fe3+X−(X− = OH−, CI−, N−3, etc.). The light absorption by the ion pair leads to an electron transfer causing reduction of the cation and oxidation of the anion to an atom or free radical X. The latter leads to the initiation of polymerization in accordance with X + CH2CHR→XCH2CHR. The kinetics of the reaction were studied by the measurement of: (a) ferrous ion formed (colorimetrically), (b) monomer disappearance (by titration and by weighting the polymer), (c) the chain length of the polymer (in the case of methyl methacrylate). The dependence of the quantum yield on the light intensity, light absorption fraction, and the concentration of vinyl monomer and ferrous ion added initially was investigated. A complete mechanism, both with regard to the formation of free radicals and the polymerization reaction, was put forward involving: (1) light absorption, (2) a primary dark back reaction, (3) dissociation of the primary product, (4) a secondary dark back reaction, (5) initiation of polymerization by free radicals, (6) propagation of polymerization, and (7) termination by recombination of active polymer endings. The mechanism was verified by the experimental results and some constant ratios were estimated quantitatively.
Spreading properties of high polymers
Authors: Saraswat H. C. , Kalyanasundaram A.
Published: April 2003

Many linear polymers containing water‐attracting groups spread uniformly at the airwater interface. The spreading property of polymethyl methacrylate is due to the ester groups which serve as anchors and promote spreading. The spreading of polystyrene, although it is a pure hydrocarbon, appears probably to be due to the end groups in each polymer molecule, introduced at the termination of the chains which act as anchors and facilitate spreading.

The surface pressure extended by the films of the high polymers is a sort of two‐dimensional swelling pressure. The distinguishing feature of these films is their high compressibility in the rectilinear portion of the F–A curve.

The limiting areas for F–A curves are not independent of the concentrations of spreading solutions as might be expected. The primary cause of this phenomenon in the case of high polymers appears to be a more or less coherent sponge‐ or felt‐like structure which develops at high concentration. The linear polymers, like polystyrene, become coiled up statistically and at higher concentration the coils become interlocked and produce an imperfectly spread film.
Recherches sur la cellulose III régénérée de l'ammoniac‐cellulose
Authors: Legrand Ch.
Published: April 2003

L'étude de la cellulose régénérée des composés de gonflement que fournissent avec NH3 liquide la cellulose native et la cellulose mercerisée conduit à la définition de deux formes correspondantes aux matières de départ: les celluloses IIIα et IIIβ. L'action de l'eau fournit avec le réseau IIIα un réseau élargi et avec IIIβ conduit à la cellulose II. Les mailles des celluloses IIIα et IIIβ toutes les deux monocliniques, présentent une petite difference.
Molecular weight distribution in polymethyl methacrylate
Authors: Harris Ivan , Miller R. G. J.
Published: April 2003

The Morey‐Tamblyn turbidity method has been used to investigate the molecular weight distribution in a series of polymethyl methacrylates including commercial and experimental injection moulding powders. Evidence has been obtained that the increase in rate of polymerization occuring in the polymerization of methyl methacrylate (Norrish‐Smith effect) causes widening of the distribution in high conversion polymers, but the separation into multiple peaks reported by other authors has not been observed. From an examination of specially prepared polymers, e.g., at small degrees of conversion, it is concluded that chain combination is a more likely termination process than disproportionation.
Dielectric dispersion in cellulose nitrate solutions
Authors: Scherer Philip C. , Testerman M. K.
Published: April 2003

The dielectric dispersion of cellulose nitrate solutions in acetone was studied over a frequency range of 100‐500 KC by a resonance method using substitution techniques to measure the capacitance. An abnormally narrow region of dispersion was found which could not be reconciled with the Debye type of absorption. By assuming the solvated chain molecule to have the form of a loosely held random coil it was possible to explain the experimental, dispersion curve on the basis of resonance absorption.

Speculation on the similarity of the shape of the dispersion curves to those found for distribution by fractional precipitation suggested a possible correlation between them. In the case of at least one polymer the derived correlation proved satisfactory.
The relative reactivities of initiating radicals in vinyl polymerizations
Authors: Herbst Ralph L.
Published: April 2003

As a possible approach to the problem of correlating the relative reactivities of initiating radicals in vinyl polymerizations, theoretical considerations are presented for the extension of the Alfrey and Price Q and e treatment of copolymerization to the initiation process.
Polymerization of acetaldehyde and crotonaldehyde catalyzed by aliphatic tertiary amines
Authors: Degering Ed. F. , Stoudt T.
Published: April 2003

Acetaldehyde was condensed with acetaldol using triethylamine as the catalyst. The reaction products of the branch‐chained type were found to predominate. Acetaldehyde was polymerized by trimethylamine, triethylamine, tri‐n‐propylamine, and tri‐n‐amylamine to resinous materials possessing desirable film‐forming properties. Crotonaldehyde was polymerized by triethylamine to a resin similar in all respects to the product of acetaldehyde produced under similar conditions.
Propriétés comparées des polyamides n‐n′ et des polyamides 1‐n
Authors: Cannepin A. , Champetier G. , Parisot A.
Published: April 2003

D'autres travaux sont encore à effectuer pour permettre un choix certain entre ces trois hypothèses. Les faits expérimentaux montrent cependant que, s'il existe une grande ressemblance entre les polyamides n‐n′ et 1‐n′, ces derniers presentent des particularités qui permettent de supposer que leur structure spatiale peut differer de celle des polyamides n‐n′. Plus précisément, il est possible d'admettre l'existance dans ces composés, de forces d'interactions hydrogène d'ordre bifurque, que la proximité des groupements CONH amplifie. Cela se traduit par une élévation anormale du point de fusion de ces composes qui les met à part dans la hiérarchie des polyamides normaux.

Il faut signaler cependant que ces conclusions ne peuvent, en l'état de la question, ětre absolues, et qu'il y a lieu de ne pas négliger la possibilité de l'existence de ponts de covalence interchaînes qui rapprocheraient alors les polyamides 1‐n des résines uréeformol plutôt que des Nylons.
Statistical thermodynamics of solutions of low molecular weight polystyrenes
Authors: Tompa H.
Published: April 2003

The lowering of the vapor pressure of the solvent in solutions of low molecular weight polystyrenes in benzene and in toluene was measured by a differential manometer. Heats of dilution of the same solutions were measured in a small calorimeter. The calorimeter had been designed in such a way that there was no vapor space above the solution and above the solvent. The activity of the solvent as a function of concentration can be represented either by Orr and by Guggenheim's formulas, using site fractions, or by Huggins' and by Flory's formula, using volume fractions, but only in the latter case is the interaction constant μ independent of the solvent, and only slightly dependent on chain length. Heat is always evolved on dilution and can be represented by a van Laar type of expression. The partial molar entropy of mixing of the solvent comes out very near to its value in an ideal solution. No satisfactory explanation can be given in terms of current statistical theories based on the lattice model.
On ionic copolymerization
Authors: Landler Yvan
Published: April 2003

The reactivity of monomers in an ionic copolymerization is shown to be a function of the polarity of the substituent on the ethylenic double bond.

The nonalternating tendency is explained by the absence of an alternating polar effect during the propagation step.

The results seem to indicate in the case of the monomers studied here the absence of any other selective effects (e.g., steric) and furthermore that the reactivity of the carbonium ions derived from these different monomers is the same. Therefore it is suggested that:

The original Wall equation, dM1/dM2 = α(M1/M2) may be applied.
Absolute propagation rates in emulsion polymerization I. Butadiene in mutual system
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 Mutual Recipe, 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. It was found, as expected, that the number of particles formed is a function of the temperature of initiation, almost doubling in number for a 10°C. rise in temperature. This number is also a function of the soap charge, being approximately proportional to the square root of the soap concentration. Unlike the case of styrene polymerization, the rate of polymerization per particle was found to be affected by the amount of soap adsorbed on the particle, hence it cannot be considered as representing the true propagation rate for butadiene. However, the rate of polymerization, when calculated per mole of soap present, was found to be a function of temperature only, yielding an activation energy value of ca. 14 kcal.
Statistics of linear macromolecules with a relatively short chain. IV. Molecular dimensions from viscosity and sedimentation
Authors: Peterlin A.
Published: April 2003

In the usual model of linear macromolecules the number of chain links, Z, is so assumed that in the calculation only the highest term in Z need be considered. This is correct if Z is infinite, and holds fairly well in the soft, flexible molecules, but fails completely in the stiffer ones—like cellulose—even for molecular weights of some hundred thousands. With the exact values for the effective distance of the chain elements the theory of the sedimentation constant and of the intrinsic viscosity yield results which fit the experiments much better than could be achieved by the simple theory of the infinite chain. In plotting log (M/[η]) and log [s] versus log M, a pair of the characteristic parameters α and a/b can be determined from the experiments. Since α = cos β is the mean cosine between two consecutive links, it measures the stiffness of the macromolecule. In the second parameter a is the hydrodynamic radius and b the length of the chain unit. The values for cellulose acetate in acetone are in good agreement with our knowledge about the cellulose.
The hofmann reaction with polymethacrylamide
Authors: Arcus C. L.
Published: April 2003

The reaction of polymethacrylamide, [‐CH2C(CH3)(CONH2)‐]n, in aqueous solution with hypobromite and hypochlorite has been investigated. Different reaction procedures yielded polymers which were similar, and which contained a small number of primary amino groups, considerable carboxyl and unreacted amide groups and, probably, alkylacylurea groups formed by interaction between adjacent isocyanate and halogenoamide groups. Analytical data supporting these conclusions are presented. The polymer from the Hofmann reaction is soluble in dilute alkali and also in strongly acid media, precipitating on dilution. Methacrylamide monomer reacts with hypochlorite to give N‐α‐methylvinyl‐N′‐methacrylurea and acetone.
Amide interchange reactions
Authors: Beste L. F. , Houtz R. C.
Published: April 2003

(1) Sebacamide and N,N′‐diacetylhexamethylenediamine interchange to produce acetamide and polyhexamethylene sebacamide. (2) The rate is proportional to the concentrations of the two reacting species and to the square root of carboxyl group concentration. (3) The rate increases with increasing concentration of water. Reagents which had been held in the molten state under high vacuum were still capable of reaction. (4) N‐Substitution decreases the rate constant; the isobutyl group is more effective than methyl in this respect. (5) As an indication of the amount of interchange occurring during a typical polymerization, it is computed that at least 42% of the amide links interchange during the 66 nylon synthesis. This means that it is not feasible to make nonrandom copolyamides by polymerizing together low molecular weight homopolyamides. Interchange does provide for the production of nonrandom copolymers from two or more high molecular weight homopolyamides.
Molecular weight degradation of polyvinyl acetate on hydrolysis
Authors: Wheeler O. L. , Ernst S. L. , Crozier R. N.
Published: April 2003

When the acetate groups of polyvinyl acetate are removed and subsequently restored, the viscosity of the polymer is usually decreased. It is found that after such processing, vinyl acetate polymers prepared at a given temperature approach a maximum viscosity regardless of the viscosity of the original resins. This maximum is increased by lowering the temperature of polymerization and is different for other vinyl esters. The extent of degradation is negligible at low conversions. It is concluded that this phenomenon is characteristic of the monomer. The chemical bond responsible for the degradation has many of the properties of ester linkages. The resins degrade with both bases and acids although the latter catalyst sometimes requires the presence of water. They also degrade when heated in a solution of pyridine, acetic acid and acetic anhydride. The extent of degradation closely parallels the degree of hydrolysis. It is suggested that these ester linkages are formed during polymerization as a result of transfer with the carbon‐hydrogen bonds of the acetate groups of both monomer and polymer. Evidence of another transfer reaction involving the vinyl group, but having no bearing on the degradation, is also advanced. If polyvinyl acetate is alcoholized with an acid catalyst, in the absence of water, the processed resin may have a higher viscosity than would be the case with an alkaline catalyst. How much higher is governed by the type of initiator used in the polymerization. This suggests that polymer molecules may be united under these conditions, but the nature of the reaction is obscure.
The fibrillate structure of natural cellulose
Authors: Hock Charles W.
Published: April 2003

Interpretations of the small‐scale structure of natural cellulose have been greatly influenced by information obtained from x‐ray diffraction studies. This work has given rise to a structural model, according to which there are some regions of cellulose in which the molecules are highly ordered (crystalline) and other regions in which there is considerable disorder (amorphous). This interpretation does not, however, adequately emphasize the fibrillate character of natural cellulose‐a structure which, as the result of light and electron microscope investigations, is well established. Since many reactions proceed more readily in the interfibrillar regions than in the fibrils themselves, it seems that the cellulose molecules in the fibrils, in contrast to those in the interfibrillar regions, are more highly ordered. Intensive treatments, such as acid hydrolysis, may cause a further breakdown whereby the fibrils are split transversely into small rodshaped particles, but the comparatively greater ease with which fibrillation occurs following a variety of degradative reactions suggests that the ordered character of the fibrils along the long axis is not interrupted by regions of the same magnitude and extent of disorder as those which occur between the fibrils. Although x‐ray diffraction diagrams of cellulose have generally been considered to indicate the presence of small elongated regions of highly crystalline cellulose, i.e., micelles, it would be equally consistent to suppose that the diffuse diffraction patterns were caused by larger essentially homogeneous regions in which the arrangement of the molecules only approximates crystalline regularity. These regions which, except for occasional grosser irregularities, have a more or less uniform intermediate molecular order, may be identified with the fine electron microscopically visible fibrils. According to this viewpoint highly ordered micelles, unlike fibrils, are to be regarded more as incidental rather than as fundamental units of cellulose structure.
Polymerization of iodinated fibrinogen
Authors: Laki K. , Steiner R.
Published: April 2003

Light scattering and ultracentrifuge experiments were made on iodinated fibrinogen. The molecular weight was found to be 560,000 and the length 900 A. The experiments on polymerized iodo‐fibrinogen indicated that the lateral and end‐to‐end associations have different pH optima.
Size and shape of the molecules in artificially branched polystyrene
Authors: Thurmond Carl D. , Zimm Bruno H.
Published: April 2003

A sample of copolymer of divinylbenzene and styrene has been prepared and fractionated. Using the techniques of light scattering and viscometry the relations between the molecular size, intrinsic viscosity, and weight‐average molecular weight have been determined. The results may be interpreted in terms of the already existing theory of branched polymers. The curve of logarithm of intrinsic viscosity plotted against logarithm of molecular weight shows clearly the effect of branching in the polymer chains, the intrinsic viscosities of the higher molecular weight fractions being low compared to those of pure polystyrene. The mean square radius of the molecules as determined by light scattering shows similar effects, though complications obscure the picture. Some of the other solution properties of the branched materials also are peculiar. The results show that the semiquantitative determination of branching is possible in this way.
Vinyl‐type polymers containing phosphorus
Authors: Marvel C. S. , Wright John C.
Published: April 2003

Some copolymers which contain either aldehyde or ketone carbonyl groups have been treated with phosphorus trichloride and then in sequence with acetic acid and water. On the basis of phosphorus analyses of the resulting products, α‐hydroxyphosphonic acid groups have been introduced in amounts ranging from zero to 100% of the theoretical amount. These phosphorus containing polymers with 2% or more of phosphorus are somewhat flame resistant.