bluuebunny/crossref_metadata_2025 huggingface dataset:
Inhibition of the copper‐catalyzed oxidation of polypropylene
Authors: Hansen R. H. , Russell C. A. , De Benedictis T. , Martin W. M. , Pascale J. V.
Published: April 2003

Thermal oxidation and copper‐catalyzed thermal oxidation of polypropylene were studied over a range of elevated temperatures. The apparent activation energy for both of these processes, based on t10 induction periods, was 27 kcal./mole. Measurement of the time (t10) required for interaction of 1 g. of polymer with 10 cc. of oxygen was found to be a convenient and expedient technique for estimating the induction period, since this amount of oxygen is sufficient to cause deterioration of physical and dielectric properties of the polymer. In the absence of copper, stabilization of polypropylene comparable to that achieved with polyethylene was observed when antioxidant concentration was increased proportionately to compensate for the larger number of oxidation‐susceptible tertiary carbon atoms in polypropylene. However, it was found that thermal antioxidants, even in high concentration, were ineffective protectants for polypropylene when copper was present. Conventional copper chelators and metal deactivators were, at best, only slightly effective in suppressing oxidation catalyzed by copper and usually were unsatisfactory for a variety of other reasons. Oxamide, however, and particularly its less volatile, high melting, disubstituted derivatives, functioned cooperatively with a wide variety of antioxidant systems and were found to comprise a highly effective and useful family of inhibitors of the copper‐catalyzed oxidation of polypropylene.
An evaluation of column thermal diffusion as a means of polymer characterization
Authors: Taylor David L.
Published: April 2003

The mechanism of polymer fractionation in a Clusius‐Dickel thermal diffusion column was elucidated by a systematic study of the effects of important experimental factors on the separations attainable combined with an analytical description of column operation and recent theories of polymer thermal diffusion. Several polystyrene samples of known molecular weight distribution were studied in toluene and methyl ethyl ketone solvents at varying conditions of temperature gradient (up to 1050°C./cm.), mean temperature (20–45°C.), and concentration (up to 2.4 wt.‐%). The thermal diffusion column was of the concentric cylinder type, equipped with thirty sample ports. The degree of separation of polymer from solvent increased with temperature gradients below 40°C./cm., increased slightly with decreased mean temperature, increased markedly with starting concentration, and was greater in toluene at a given concentration. The degree of fractionation was found to increase rapidly with temperature gradient, and was largely independent of concentration in methyl ethyl ketone but increased strongly with concentration in toluene solutions. These effects were interpreted by means of a theoretical calculation of the influence of both ordinary and thermal diffusion on column behavior in conjunction with an evaluation of the radical concentration gradients. The experimental results are in accord with a recent theory of polymer thermal diffusion which predicts that the thermal diffusion coefficient should not be a strong function of molecular weight. The fractionation effect is apparently governed by differences in ordinary diffusion coefficients. The fractionation was greater for higher molecular weights.
Crystallographic study of xylan from wood
Authors: Horio Masao , Imamura Rikizo
Published: April 2003

Some preparations of xylan in the form of transparent membrance or amorphous powder prepared from deciduous woods such as beech and birch show a number of Debye‐Scherrer rings at the irradiation with x‐ray. Of special interest from the crystallographic standpoint is the diffraction pattern of the membrane, which shows an indication of a fiber diagram with the beam parallel to the surface, and this is more obvious when the membrane is stretched to an appropriate extent by rolling. The diagram can be neatly interpreted on the basis of an end surface‐centered rhombic cell whose two axes of the base plane have exactly the ratio of \documentclass{article}\pagestyle{empty}\begin{document}$ \sqrt 3 :1\ $\end{document}, within the limit of experimental error. It is assumed that the cell has a trigonal or hexagonal symmetry. The observed reflections are indexed on the base of orthohexagonal unit cell, whose postulated three axes are a = 9.16 A., b = \documentclass{article}\pagestyle{empty}\begin{document}$ \sqrt 3 a\ $\end{document}., and c = 15.5 A. (fiber axis). The crystalline lattice of xylan is susceptible to mechanical treatment, heat, and moisture. The crystallinity depends greatly upon the uronic acid content. The diffraction pattern becomes less distinct and the interplanar spacings are enlarged with increasing uronic acid content, until at last the pattern diffuses into a single halo.
Emulsion polymerization of styrene in coacervating and noncoacervating soap–electrolyte systems
Authors: Mateo J. L. , Cohen Irving
Published: April 2003

An attempt is made here to delineate some of the consequences of the special properties of coacervating soaps when the soaps are used in the emulsion polymerization of styrene. In dilute solutions an essential difference between a coacervating soap and a noncoacervating soap is the critical suppression of the micellar ionization in coacervating systems when relatively small amounts of simple electrolytes are added to the systems. A direct correlation between the polymerization rates and polymer molecular weights with the state of micellar ionization has been demonstrated. The highest polymerization rates and highest polymer molecular weights occur in solutions in which the coacervating soaps show a maximum ionization. In soap solutions in which the micellar ionization is critically suppressed there is evidence of soap desorption from polymer particles, resulting in the generation of an increasing number of particles during the course of the polymerization. Two coacervating systems and two noncoacervating systems were used in this investigation. For the anionic noncoacervating K laurate–KCl system, where the micellarsize remains practically constant with the addition of electrolyte, the following relationship between the polymerization rate and KCl concentration, up to 1M KCI, has been found: R = R0 + B√C. The effects of the charge properties of soap micelles on the course of the polymerization of styrene have been associated with two effects. (a) For highly ionized micellar systems the micelle periphery presents an open structure due to the coulombic repulsion of the charged polar hydrophilic groups of the soap molecules. This open structure facilitates the diffusion of monomer to the loci of polymerization. (b) Where the micellar ionization is suppressed, monomer diffusion to the loci of polymerization is impeded. Extensive suppression of micellar ionization results in micelles of enhanced stability. In the highly stabilized systems when the loci of polymerization are polymer particles there is competition for soap molecules between the adsorption sites on the polymer particle and soap micelles. The influence of soap concentration on the emulsion polymerization for different soaps and electrolyte concentrations has been investigated. For the coacervating Hyamine 1622 soap at zero electrolyte concentration, the rate of polymerization has been found to be proportional to the 0.5 power of the soap concentration. This relationship is not maintained when electrolyte is added to the polymerization system.
Rheological properties of polybutadienes prepared by n‐butyllithium initiation
Authors: Gruver J. T. , Kraus Gerard
Published: April 2003

The flow behavior of n‐butyllithium‐polymerized polybutadienes was investigated as a function of molecular weight, temperature, and shear rate. At low shear rates these polymers exhibit Newtonian flow up to molecular weights of several hundred thousand so that “zero shear” Newtonian viscosities can readily be determined without the risk of long extrapolation. Above 10,000 molecular weight the Newtonian viscosities obey the well‐known 3.4 power dependence on weight‐average molecular weight. The entanglement spacing molecular weight is estimated at 5600. The temperature dependence of viscosity is substantially independent of molecular weight and shear stress and can be represented analytically by functions proposed in the literature. The apparent activation energy for viscous flow is not constant, but decreases with rising temperature. The flow of the polymers becomes increasingly non‐Newtonian with the product of shear rate, molecular weight and Newtonian viscosity. However, the departure from Newtonian behavior is apparently less than for any polymer system whose flow behavior has been described in the literature. The indications are, therefore, that sharp molecular weight distribution and freedom from long chain branching favor Newtonian flow and that the n‐butyllithium initiated polybutadienes represent some of the most perfectly linear, narrow distribution polymers known.
Some reactions of p‐vinylacetophenone–styrene copolymers
Authors: Beckerbauer Richard , Baumgarten Henry E.
Published: April 2003

A new synthesis of p‐vinylacetophenone was developed. Copolymers of p‐vinylacetophenone and styrene were prepared by copolymerization and by partial Friedel‐Crafts acetylation of polystyrene. The copolymers were converted into the oximes, but subsequent reduction was unsuccessful. Beckman rearrangement of the oximes led to insoluble resins. The acetyl copolymers were partially brominated to give an α‐bromo‐p‐vinylacetophenone/p‐vinylacetophenone/styrene terpolymers. Nucleophilic displacement of the bromine of these terpolymers with secondary amines yielded α‐piperidino‐ and α‐morpholino‐p‐vinylacetophenone terpolymers. The Delepine reaction of the brominated copolymer produced an α‐amino‐p‐vinylacetophenone terpolymer. The piperidino and amino ketone terpolymers were reduced to the corresponding alcohol derivatives with lithium‐aluminum hydride. The amino ketone and amino alcohol terpolymers had moderate solubility characteristics in acidic alcohols and water. The α‐amino ketone terpolymer was very sensitive to base and afforded a facile crosslinking of the acetyl copolymer.
Instrument for the studies of differential flow dichroism of polymer solutions
Authors: Wada Akiyoshi , Kozawa Shichibei
Published: April 2003

A concentric cylinder apparatus for the studies of flow dichroism in polymer solutions is described in detail. The outer and inner cylinders are both made of fused quartz which is transparent in visible and ultraviolet region down to 220 mμ. The velocity gradient is produced in solution in the gap between the cylinders by rotating the inner one. The light path is designed to be perpendicular to the axis of rotation of the quartz cylinder. A differential device makes it possible to measure the difference in absorption coefficients, ε‖ and ε⊥, which are the absorption coefficients measured by plane‐polarized light having parallel and perpendicular electric vector with the stream line. The apparatus is found to be useful for studying the regularity of orientation of chromophores in both synthetic and biological polymer chains.
High resolution NMR study of vinylidene chloride–vinyl chloride copolymer
Authors: Chûjô Richiro , Satoh Shiroh , Nagai Eiichi
Published: April 2003

The presence of head‐to‐head structure in vinylidene chloride sequence in copolymer of vinylidene chloride and vinyl chloride with various feed ratios was demonstrated by the high resolution NMR study. The ratio of head‐to‐head structure in vinylidene chloride sequence was evaluated from measurement of the intensities of NMR spectra. The quantities of local regularity of copolymer were used in the theoretical treatment based on the virtual boundary energy and combinatory method. The experimental results were compared with the theoretical calculations.
Anisotropic elasticity of composite molecular networks formed from non‐gaussian chains
Authors: Smith K. J. , Ciferri A. , Hermans J. J.
Published: April 2003

The theory of composite networks by Berry, Scanlan, and Watson was generalized so as to include the case in which the elasticity of the chains is described by non‐Gaussian statistics. For this purpose, existing theories of non‐Gaussian networks had to be critically reviewed and a new simple treatment is presented here. This new treatment yields substantially the same results as that obtained from the more complex theory of Wang and Guth. Results obtained from the simple three‐chain model for the network, as described by Treloar, were also shown to be in satisfactory agreement with both the new treatment and that of Wang and Guth. The generalized theory of composite networks predicts anisotropic elastic behavior; the tensile force at a given strain should be generally higher for elongation in the direction parallel to orientation than in the direction perpendicular to it. However, depending upon details pertaining to the preparation of the networks (ratio of first and second stage crosslinks and elongation at which the latter are introduced), the tensile force required for elongation in the direction perpendicular to orientation may be higher. It appears that the isotropic elastic behavior, predicted by previous theories of composite networks, is merely a consequence of the use of the Gaussian approximation.
Aromatic polysulfonates: Preparation and properties
Authors: Thomson David W. , Ehlers Gerhard F. L.
Published: April 2003

Aromatic polysulfonates of high molecular weight and purity can easily be prepared by interfacial polycondensation of the disulfonyl chlorides with diphenols. The polymers were found to have a low degree of crystallinity, softening ranges in the region 200–250°C, molecular weights up to 50,000 and a thermal stability under nitrogen to above 300°C.
Free volumes in polystyrene and polyisobutylene
Authors: Miller A. A.
Published: April 2003

The melt viscosities of polystyrene and polyisobutylene fractions are expressed by a modified Arrhenius (M.A.) temperature equation, η = A exp {B/(T − T0)}, and by a free volume equation, η = A exp 1/{f}, in which f = vf/v, the free volume fraction. Thus, it is assumed that f, as defined, is a linear function of temperature, since f = (T − T0)/B. By this method, the derived “occupied” volume, vs = v −vf, has a temperature dependence which is determined by the temperature coefficients of f and v (i.e., 1/B and αl) and is not related to the experimental αg value for the glass. For polyisobutylene, the temperature coefficient of vs is positive, while for polystyrene it is slightly negative. Possible effects of liquid structure in determining the temperature behavior of vs are suggested. Calculated viscosities and free volume fractions at the glass point, Tg, over a wide range of molecular weight, M, in both polymers lead to the conclusion that the glass transition is primarily an “iso‐viscosity” (ηg ≃ 1013 poise), rather than an “iso‐free volume”, state. However, in the two polymers, both conditions can exist simultaneously for similar values of M. Thus at equal M,fg = (Tg = T0/B) is about the same for both polymers. For M ≃ 100,000, fg ≃ 0.031. These observations support the view that the glass transition is primarily a kinetic, rather than a thermodynamic, phenomenon. The estimated time dependence of Tg is found to differ in the two polymers at equal M and to vary with M in each case.
Multicomponent non‐fickian diffusion through inhomogeneous polymer membranes
Authors: Frisch H. L.
Published: April 2003

We point out explicitly the dependence of the non‐Fickian diffusive flows of low molecular weight penetrants through a polymer membrane possessing a gradient in internal composition or a local property, such as a stress, on the gradient of the chemical potential of the polymeric substance. The possibility of maintaining for sufficiently long times a gradient in internal composition or property in these substances is a consequence of the long relaxation times encountered in these substances. A number of ways are suggested for preparing such membranes. Certain consequences for the diffusive separation of penetrants by such membranes are noted.
Poly(1,3,4‐oxadiazoles): A new class of polymers by cyclodehydration of polyhydrazides
Authors: Frazer A. H. , Sweeny W. , Wallenberger F. T.
Published: April 2003

Thirteen aliphatic and aromatic polyhydrazides have been converted as bulk polymer by a unique polymer by a unique polymer post reaction into high molecular weight poly(1,3,4‐oxadiazoles). This reaction proceeds by thermal cyclodehydration at 170–280°C. with elimination of water. The resulting poly(1,3,4‐oxadiazoles) have been characterized by microanalysis, inherent viscosity, x‐ray diffraction patterns, and by infrared and ultraviolet absorption spectra. Films could be pressed from the melt of polyoxadiazoles melting below 350°C., while very high melting or infusible aromatic polyoxadiazoles could not be manufactures into films and fibers by conventional means. Such polymers are extremely thermally and oxidatively stable and decompose between 450 and 500°C.
Poly(1,3,4‐oxadiazolidine)
Authors: Frazer A. H. , Wallenberger F. T.
Published: April 2003

Poly(3,4‐isophthaloyl‐1,3,4‐oxadiazolidine) was prepared from poly(isophthalic dihydrazide) by treatment by reaction with formic acid in dimethylsulfoxide as high‐molecular weight film‐forming polymer. Under thermal treatment with the evolution of formaldehyde and water, high yields of chemically pure poly[1,3‐phenylene‐2,5‐(1,3,4‐oxadiazole)] were obtained.
Molecular weight dependence of the second virial coefficient. Solutions of styrene dimers up to high polymers and other systems
Authors: Sotobayashi H. , Ueberreiter K.
Published: April 2003

The second virial coefficient B or A2 has been calculated from cryoscopic measurements in naphthalene of polymers of styrene from dimers up of high polymers. The B‐degree of polymerization curve has a maximum in the range of the tetramer. The portion of the curve showing the increase to a maximum is explained as a “macromolecule effect” of rigid rods according to the theory of Flory and Huggins. The A2–P (or B–P) curves investigated so far are described by the equation, A2 = (a/M1/2) + b. It is assumed that the shape of a macromolecular coil in solution depends upon the fact whether the main chain skeleton and its sidegroups have the same or opposite affinity to the solvent. In the case of polystyrene in naphthalene it is assumed that the CC chain behaves as a lyophobe and the benzene groups as a lyophil. This leads to an increased density of the benzene sidegroups in the surface of the macromolecular coil. The interaction potential between the coils as a whole is therefore different from that in the interior. This effect is realized by splitting the excluded volume into two parts and leads to the reciprocal square root dependence of A2. This equation has been tested for many endothermal and exothermal systems. The constants a and b are zero at the θ‐temperature and can be determined therefrom.
Product distribution of consecutive competitive second‐order reactions
Authors: Maget Henri J. R.
Published: April 2003

Product distribution of consecutive competitive second‐order reactions can be calculated from a general distribution equation independently of the number of reaction steps.
An elementary theory of nonlinear viscoelasticity
Authors: Davis Julian L.
Published: April 2003

A first‐order, nonlinear, one‐dimensional theory of viscoelasticity is constructed by use of an elementary perturbation technique. It is based on applying some simple hypotheses of nonlinearity to single nonlinear Maxwell and Voigt models. The response of the Maxwell model to a sinusoidally applied strain is governed by a nonlinear complex modulus whose nonlinear part is given as a function of applied strain and strain rate as well as external frequency and internal or model parameters. This is a nonlinear relaxation effect. A nonlinear creep effect is obtained by describing the nonlinear response of the Voigt model to a sinusoidally applied stress in terms of a nonlinear complex compliance.
Polymerization studies on allylic compounds. Part II
Authors: Reed Samuel F. , Baldwin M. G.
Published: April 2003

The free radical polymerization of a series of compounds having the general formula
magnified image
in which Y was F, Cl, Br, I, NO2, and CN has been studied. The compounds were found to vary markedly in polymerizability. An explanation is advanced in which it is postulated that chain transfer involving a substituent in the allylic position of the monomers is the controlling factor in determining their polymerization behavior.
Determination of halogen in copolymers by dye‐partition technique and calculation of r1 therefrom
Authors: Saha Mihir Kumar , Ghosh Premamoy , Palit Santi R.
Published: April 2003

Halogen‐bearing polymers have been prepared by copolymerization of monomers (M1) such as styrene, methyl methacrylate, methyl acrylate, and vinyl acetate with traces of chlorine‐bearing monomers (M2) such as allyl chloride and tetrachloroethylene at varying M1:M2 ratios in the 100:1 composition range. The halogen atoms in the copolymers were transformed to quaternary pyridinium halide groups by quaternization with pyridine. The copolymer compositions and the monomer reactivity ratio r1 were determined by the estimation of the quaternary halide groups in the copolymers by the dye‐partition technique, with aqueous disulfine blue VN150 in 0.01M hydrochloric acid as the dye reagent.
Branching in high conversion poly(methyl methacrylate)
Authors: Krause Sonja , Cohn‐Ginsberg Elizabeth
Published: April 2003

The dilute solution properties (intrinsic viscosity, weight‐average molecular weight, and mean square radius of gyration) of fractions of high conversion, free‐radically initiated poly(methyl methacrylate) samples indicate a slight amount of branching in these samples, consistent with the chain transfer constant with polymer (exclusive of endgroups), Cp = 2.2 ± 0.7 × 10−5, found by Schulz and co‐workers. The dilute solution properties of these fractions are compared with those of fractions of low conversion poly(methyl methacrylate) of comparable molecular weight and with the dilute solution properties of fractions of deliberately branched sample, also of comparable molecular weight. Some evidence was obtained which indicated that impurities in the monomer used for polymerization can lead to additional branching sites in the polymer chains.
Preparation of poly(arylene sulfides)
Authors: Tsunawaki Shigemitsu , Price Charles C.
Published: April 2003

The attempted polymerization of thiyl radicals from 4‐bromothiophenol (I), 2,6‐dimethyl‐4‐bromothiophenol (II), 2,6‐dimethylthiophenol, and bis(2,6‐dimethylphenyl) disulfide gave no polymer. The polymerization of lithium and sodium salts of I, II, and 2‐methyl‐4‐bromophenol and of sodium 4‐chlorothiophenoxide by refluxing in various solvents with or without copper catalyst, gave the corresponding poly(arylene sulfides). Poly(phenylene sulfide), m.p. 270–290°C. was stable at 500°C. for 2 hr. under nitrogen and showed high crystallinity by x‐ray. Poly(2,6‐dimethylphenylene sulfide), m.p. 160–180°C., showed little if any crystallinity by X‐ray diffraction. Poly(2‐methylphenylene sulfide) melted at 60–100°C.
Fractionation of chemically heterogeneous latex particles by centrifugation
Authors: Yannas J. B.
Published: April 2003

A simple centrifugation method for the clean separation of chemically heterogeneous latex particles is described in some detail. It exploits density differences among particles that could be due to differences in composition, degree of crosslinking, crystallinity or other structural features. Particles differing in density by as little as 0.005 g./ml. have been cleanly separated. The fractionation of particles differing in density by less than the above should be feasible with this method which is applicable to concentrated as well as dilute latices.
α‐Trifluoromethyl vinyl acetate
Authors: Haas Howard C. , Schuler Norman W.
Published: April 2003

α‐Trifluoromethyl vinyl acetate has been synthesized. Although the homopolymer has not been obtained, this new monomer readily copolymerizes with a variety of vinyl monomers including styrene. Alcoholysis of vinyl acetate/α‐trifluoromethyl vinyl acetate copolymers leads to trifluoromethyl‐substituted polyvinyl alcohols having new and unusual properties. These polyvinyl alcohol derivatives, containing about 30 wt.‐% of fluorine, are completely insoluble in water but dissolve in the lower alcohols. Because of the increased acidity of fluorosubstituted alcohols, they are also soluble in dilute aqueous alkalies to yield polyalkoxide‐type solutions.
Nitrogen adsorption isotherms on polyolefins
Authors: Hightower Joe W. , Emmett P. H.
Published: April 2003

Nitrogen adsorption isotherms were determined for a number of polyolefinic compounds. B.E.T. calculations showed that most of the samples possess surface areas averaging about 0.5 m.2/g., although a few very high molecular weight polyolefins precipitated during polymerization have areas of about 8 m.2/g. On most of the polyolefins, the C values from the B.E.T. equation are unusually small, indicating a relatively low heat of nitrogen adsorption. Adsorption isotherms were determined with krypton on two of the high polymers and were found to yield areas in satisfactory agreement with those obtained from the nitrogen adsorption experiments.
Effect of temperature on molecular weight measurements in polyethylene
Authors: Schreiber H. P. , Waldman M. H.
Published: April 2003

Light‐scattering evaluations of molecular weight and gyration radii have been carried out over a range of temperatures for linear and branched polyethylenes in α‐chloronaphthalene solutions. In a number of cases the molecular size parameters have been found to depend on the solution temperature. When observed, the temperature dependence can change molecular weight values by as much as 50%. The temperature dependence tends to be more pronounced at higher molecular weights, in linear than in branched polyethylenes, and is particularly noticeable at solution temperatures below that of the normal crystalline melting temperature of the polymer. It is suggested that the temperature dependence of molecular weight parameters may be due to a gradual dissociation in solution of polymer aggregates arising from persisting interchain entanglements. A relationship was established between intrinsic viscosity and molecular weight for selected fractionated polyethylenes by using molecular weight data obtained under conditions unfavorable to the persistence of polymer aggregates. A number of published viscosity–molecular weight functions for polyethylenes was compared with the calibrated relationship. Some of the published equations gave results in good agreement with the present function, but a number of others resulted in gross overestimates of molecular weight. Polymer aggregation problems may have been encountered in the derivation of some of these viscosity–molecular weight functions. The comparison indicates the danger of indiscriminate choice of viscosity–molecular weight functions for use in rapid estimates of polymer molecular weight.
Radiolysis of polyisobutene. Part III. Effect of additives
Authors: Turner D. T.
Published: April 2003

The effect of various liquid additives on the degradation of polyisobutene exposed to 4 M.e.v. electrons has been studied by solution viscometry and by measurement of gas volatile at −196°C. At a concentration of about 10−4 mole/g. some additives result in an increased yield of fractures, the maximum observed being about 20% with nitrobenzene, presumably due to the scavenging of polymer radicals which otherwise would combine. At higher concentrations most additives result in a decrease in the yield of fractures. Thus, 2 × 10−3 mole/g. thiophenol decreases the yield by about two‐thirds and itself suffers sensitized decomposition as evidenced by an increase in the yield of gas from the irradiated mixture. In the simplest case, di‐n‐butyl disulfide has a symmetrical effect in suppressing part of the yield of fractures and gas. This is consistent with the view that a proportion of the fractures is associated with gas formation.
Stereochemical configurations of polypropenes by high resolution nuclear magnetic resonance
Authors: Stehling Ferdinand C.
Published: April 2003

High resolution hydrogen NMR spectra of amorphous, stereoblock, and isotactic fractions of polypropylene show distinct differences. The spectra are complex but those of polypropene‐2‐d1 and polypropene‐2,3,3,3‐d4 are simple and easily interpreted. The differences in the spectra of the amorphous, stereoblock and isotactic fractions of the polymers is the result of a difference in the chemical shifts of isotactic and syndiotactic type methylenes. The ratio of the types of methylenes can be estimated from the spectra of polypropene‐2,3,3,3‐d4. In isotactic polymer the concentration of syndiotactic type methylenes is below the limit of detection. Assuming that the inversions in stereochemical configuration are randomly distributed along the polymer chain, the average length of sterically identical segments in stereoblock polymer is about fifteen monomer units. In amorphous polymer the ratio of isotactic to syndiotactic type sequences is approximately one. The spectra of the deuterated polymers show no detectable rearrangement of hydrogen and deuterium atoms in the polymerization.
Metal chelates of polyhydrazides
Authors: Frazer A. H. , Wallenberger F. T.
Published: April 2003

Two all‐aromatic polyhydrazides have been investigated with respect to their propensity to form metal‐chelate bulk polymer, films, and fibers. The aromatic polyhydrazide derived from isophthalic acid was found to give chelate bulk polymer with Ni+2, Ca+2, Ag+1, Hg+2, Pb+2, Zn+2, Cd+2, and Cu+2 which analyze for a 1:1 ratio of hydrazide link:metal ion. Films of the polyhydrazide–metal chelate were prepared by soaking polyhydrazide films in dimethylformamide solutions of metal salts. Tough fibers of the polyhydrazide–metal chelates with such metal ions as Cr+3, Co+2, and Ag+1 were prepared by passing polyhydrazide fiber through dimethylformamide solutions of these metal salts.
Bis(imidazolato)–metal polymers
Authors: Brown G. P. , Aftergut S.
Published: April 2003

The reaction of imidazole and the sulfates of Cu(II), Zn(II), and Co(II) in aqueous NaHCO3 gave products whose analysis corresponded to two imidazole residues per metal atom. The products were insoluble in common organic solvents and had very high melting points. Thermogravimetric analyses revealed that the Co‐ and Zn‐containing materials had unusually high thermal stability, as no loss in weight could be detected below 500–575°C. when heated in nitrogen. The properties led to their formulation as metal coordinate polymers. The electrical resistivity of the products was in excess of 1015 ohm‐cm. at 140°C.
Solubility of nonpolar gases in polymers: Some new considerations
Authors: Kwei T. K. , Arnheim W. M.
Published: April 2003

A model is proposed for the solution of gases in polymers. Gas molecules are assumed to reside in the “free” volume without net disruption of polymer–polymer contacts. A number of conclusions result from this model, which are in excellent agreement with experimental results.
Reactivities of esters of methacrylic acid. Part I. Relative reactivities of esters toward the benzoyloxy radical
Authors: Bevington J. C. , Malpass B. W.
Published: April 2003

Tracer methods have been used to compare the reactivities of methyl, ethyl, phenyl, benzyl, and cyclohexyl methacrylates toward the benzoyloxy radical at 60°C. Certain of the characteristics of the polymerizations of these monomers are recorded.
Proton resonance spectra and tacticities of some poly(methyl vinyl ethers)
Authors: Brownstein S. , Wiles D. M.
Published: April 2003

Methyl vinyl ether has been polymerized by BF3 etherate catalyst under a variety of conditions to obtain polymers of different molecular weights and tacticities. Some properties of these polymers have been compared with those of a sample prepared with a special stereoregulating catalyst at the Hercules Powder Company. The proton magnetic resonance spectra of poly(methyl vinyl ether) in several solvents have been investigated and it has been possible to assign the absorptions by the methoxyl protons to particular steric configurations of the polymer chain. These data have been used to compare the tacticities of the different polymer samples and to establish that good steric control in the propagation reaction is possible with a soluble BF3 etherate catalyst.
Polymer formation through diazonium coupling
Authors: Ravve A. , Fitko C.
Published: April 2003

Polymers were prepared through coupling of bisdiazonium salts to polyphenols. Three different polyphenols were employed for this condensation with four aromatic diamines. Products were obtained with molecular weights ranging from below 2,000 to over 20,000. In three of the four condensations carried out, no loss of nitrogen was detected through the coupling reactions, but some nitrogen appeared to have been lost in the fourth case. All polymers obtained were dark in color. The polymers possessing p‐hydroxy azo groups in their makeup occluded water which was held strongly.
ω‐Cyanothiaalkyl polyacrylates: A new class of synthetic rubbers
Authors: Prager Julianne H. , McCurdy Richard M. , Rathmann George B.
Published: April 2003

The synthesis and polymerization of a series of ω‐cyanothiaalkyl acrylates, CH2CHCO2(CH2)mS(CH2)nCN, are described. The length of the side chain and the position of the sulfur atom are varied. Microgelation is found to occur during polymerization, as indicated by viscosity and molecular weight measurements (for 5‐cyano‐3‐thiapentyl polyacrylate at 90% conversion: [η], 0.37 in acetone; M̄w, 600 million). Possible mechanisms of gelation are considered. Glass transition temperatures and solvent swellings are reported as follows: 4‐cyano‐3‐thiabutyl polyacrylate, Tg −24°C., 14% volume swell in benzene; 5‐cyano‐3‐thiapentyl polyacrylate, −50°C., 20% 6‐cyano‐3‐thiahexyl polyacrylate, −58°C., 38% 6‐cyano‐4‐thiahexyl polyacrylate, −58°C., 42% 8‐cyano‐7‐thiaoctyl polyacrylate, −59°C., 120%. The relation between these properties and the structure of the polymers is discussed. The swelling of 5‐cyano‐3‐thiapentyl polyacrylate in eighteen other fluids is given; an estimate (between 10 and 12.5) is made of the solubility parameter of this polymer. Bulk properties are reported for the vulcanizate of 5‐cyano‐3‐thiapentyl polyacrylate.
Copolymerization of tetrafluoroethylene with ethylene induced by ionizing radiation
Authors: Tabata Yoneho , Shibano Hiroshi , Sobue Hiroshi
Published: April 2003

Radiation‐induced copolymerization of tetrafluoroethylene with ethylene was carried out. It was found from this investigation that the composition of copolymers varied continuously in a wide range of molar concentrations of one component. The melting point of the copolymers obtained varied continuously with the molar concentration of one component in monomer mixture between the melting points of both homopolymers. The x‐ray diffraction measurements showed that the copolymer obtained was crystalline. The copolymerization proceeds by a radical mechanism. It was concluded that both the energy transfer to ethylene from tetrafluoroethylene during irradiation and great affinity of hydrogen atom for fluorine atom would play an important role in the copolymerization.
Elemental sulfur as a plasticizer for polysulfide polymers and other polymers
Authors: Tobolsky A. V. , Takahashi N.
Published: April 2003

In a recent publication from this laboratory it has been shown that the so‐called elastic sulfur obtained by quick quenching molten sulfur from a temperature of 250°C. to a temperature of about −10°C. is really a mixture of polymeric sulfur and monomeric S8 sulfur, the latter in a metastable condition. The reason why quick quenched sulfur is elastic is because of the plasticizing effect of the liquid S8 sulfur on the polymeric sulfur. In this publication we show that large concentrations of S8 can exist dissolved in a liquid condition in other polymers where it also acts as a plasticizer. In many cases these compositions appear completely stable, i.e., there is no tendency for the dissolved sulfur to crystallize out. The best example is crosslinked polyethylene tetrasulfide polymers. We show that these polymers can retain 40% of dissolved sulfur in the form of liquid S8 over indefinitely long periods of time. We prove that the sulfur is in its elemental form by quantitative extraction with CS2. The specific volume of the dissolved sulfur shows it is in a liquid condition. The mechanical properties of the sulfur plasticized crosslinked polymers are just what would be expected from this type of structure. Preliminary information concerning sulfur in other polymers is presented.
Transformation of mechanical model representations of viscoelasticity to operator equations
Authors: Wessling R. A.
Published: April 2003

A general method has been developed with which mechanical model representations of viscoelasticity can be transformed into the corresponding operator equation. The method is restricted to linear systems but is equally applicable to any type of model within these limits.
The use of syton 2X colloidal silica as a calibration medium for light‐scattering photometers
Authors: Jennings B. R. , Jerrard H. G.
Published: April 2003

Details are given of studies made on a colloidal silica suspension known as Syton 2X. The studies were carried out to investigate the possibilities of Syton as a calibration medium for light‐scattering photometers. The requisites of a suitable calibration medium are discussed. The same studies were made on another silica suspension, Ludox, which has been much used by others for calibration and the results obtained for the two substances compared. Transmission and angular scattering properties were studied using a spectrophotometer and a light scattering photometer respectively. The calibration constant J of the latter instrument was determined using Syton and Ludox. The values obtained for J were almost identical. The instrument was used to determine the Rayleigh ratios R90 of benzene, toluene, and carbon disulfide for two wavelengths (4358 and 5641 A.). The values compare favorably with those of other workers and are considered very reliable. Weight‐average particle sizes were found with the use of an electron microscope, an analytical ultracentrifuge, and the light‐scattering and transmission data. The electron micrographs showed Ludox and Syton particles to be almost spherical. The particle diameters of Ludox were found to be 199 A. by the electron microscope, 174 A. by the ultracentrifuge, and 195 A. by light‐scattering and transmission measurements. For Syton the corresponding values were 145 A., 142 A., and 142 A., respectively. Depolarization ratios were also determined; in both cases they were small. It is concluded that provided oil‐free samples are used, Syton is a good substitute for Ludox. Its particles are smaller and the solutions are less polydisperse. It is thought that the ultracentrifuge gives low values for particle diameters and that this is possibly due to an incorrect assumption for the frictional coefficient of the sedimenting particles.
Kinetic study of the autoxidation of cellulose suspended in sodium hydroxide solution
Authors: Michie R. I. C. , Neale S. M.
Published: April 2003

An apparatus has been designed to measure small extents of gas absorption by a relatively large volume of liquid under conditions of vigorous agitation. With this apparatus a study has been made of the absorption of oxygen by finely divided cotton cellulose suspended in sodium hydroxide solution at 40°C. over a range of alkali concentration, cellulose content, and oxygen pressure. In one series of experiments cellulose depolymerization was also determined and in another experiment the alkaline autoxidation of β‐methyl cellobioside was followed. During the early stages the reaction is autocatalytic with alkali concentrations above 8N. In the absence of diffusion effects, that is with alkali concentrations below approximately 10N, the steady rate of oxygen absorption is given by the equation,

where [Cell] refers to the weight of cellulose immersed in the solution, [O2] the partial pressure of oxygen, aNaOH the molal activity of the sodium hydroxide, θ[M] a function of the metal ion content and K and K′ are constants. The known characteristics of the autoxidation are consistent with a modified Gee‐Bolland mechanism. Thus a cellulose radical formed as a result of peroxide decomposition reacts with oxygen to form a radical of the type \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm RO}_2^{.} $\end{document}. The last named is likely to be unstable and split off the \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm O}_2^{\bar .} $\end{document} radical ion which is comparatively unreactive but must nevertheless be capable of attacking an ionized cellulose molecule, thus completing one oxidation cycle. In principle a chain reaction could follow but the evidence indicates that a long chain mechanism is not involved, particularly at the stage of attainment of the steady rate.
Intramolecular hydride shift polymerization by cationic mechanism. II. Spectroscopic analysis of poly‐3‐methylbutene‐1
Authors: Kennedy J. P. , Minckler L. S. , Wanless G. , Thomas R. M.
Published: April 2003

The structures of cationically obtained poly‐3‐methylbutene‐1, isotactic poly‐3‐methylbutene‐, and hydrogenated 3,4‐polyisoprene have been investigated by nuclear magnetic resonance and infrared spectroscopy. These studies corroborate the previously proposed structure of an α,α′‐dimethylpropane repeating unit for the cationic polymer and they confirm the conventional 1,2 head‐to‐tail enchainment for the isotactic polymer and for the hydrogenated 3,4‐polyisoprene. The NMR spectra of cationic poly‐3‐methylbutene‐1 and polyisoprene are very similar and show only two peaks. They are quite different from the spectra of isotactic poly‐3‐methylbutene‐1 and hydrogenated 3,4‐polyisoprene. The isotactic product was solubilized by careful pyrolysis to render it amenable to spectroscopic studies. Unfortunately, present‐day NMR spectroscopy does not possess high enough resolution to be useful in the quantitative investigation of mixtures of 1,3 and 1,2 enchainments. The NMR spectrum of polyisobutylene oxide can be used to distinguish cationic poly‐3‐methylbutene‐1 from the isotactic modification and from the hydrogenated 3,4‐polyisoprene. The more important bands have been analyzed and assigned. Isotactic poly‐3‐methylbutene‐1 and hydrogenated 3,4‐polyisoprene both have a conventional 1,2 structure, and their infrared spectra are essentially identical.
Electron spin resonance studies of irradiated single crystals of methacrylamide
Authors: Ueda Hisashi
Published: April 2003

Irradiated single crystals of methacrylamide were studied by electron spin resonance. Irradiations were made at 77 and 288°K. and measurements were made at 77, 193, and 293°K. Only chemical changes explain these spectra. The original scission is CC breakage between (CONH2) and CH2C(CH3), and CH breakage between CH2C‐(CONH2)CH2 and H; these small fragments react with methacrylamide and finally produce two free radicals at room temperature. These two free radicals are the ones which propagate or terminate the polymerization. The free radical transformation at the last period of polymerization is concluded to be:
Thermal degradation of poly(m‐diethynylene benzene)
Authors: Newkirk A. E. , Hay A. S. , McDonald R. S.
Published: April 2003

Powdered poly(m‐diethnylene benzene) can be dissolved in hot nitrobenzene, and thin clear sheets having a yellow color and a tensile strength approaching 9000 psi can be cast from this solution. When the polymer powder is heated rapidly in vacuo, it explodes gently at about 180°C. to yield carbon, but it can be annealed at 150°C. and then heated to form carbon without the explosive reaction. The major gaseous decomposition products of the explosive reaction are methane and hydrogen. The polymer film can be crystallized in tetrahydrofuran and shows excellent spherulitic growth. The crystalline film as well as aged noncrystalline film degrades when heated rapidly, but without explosive decomposition. Some indication of the mechanism of decomposition is provided by infrared studies of the film pyrolyzed at 100°C. intervals to 600°C. X‐ray diffraction studies show that the polymer may exist in amorphous and crystalline forms In the amorphous form, the diffraction maximum indicates an average interchain separation of 4.28 A., substantially less than for other polymers. Chars prepared by heating the polymer give diffraction patterns similar to those for amorphous carbon blacks. A related substance, poly(p‐diethynylene benzene), is an intractable crystalline powder having a hexagonal unit cell, a0 = 7.74 A., c0 = 8.97 A., containing three monomer units.
Radiation‐induced copolymerization of tetrafluoroethylene with propylene at low temperature
Authors: Tabata Yoneho , Ishigure Kenkichi , Sobue Hiroshi
Published: April 2003

Radiation‐induced copolymerization of tetrafluoroethylene with propylene was carried out at low temperature in the liquid phase. The resulting copolymers were found to range from viscous oils to rubberlike materials, depending on the polymerization conditions. It was observed that there are induction periods in these copolymerizations, and that the rate of copolymerization is proportional to the square root of the dose rate. Fluorine contents of the copolymers were determined, and the monomer reactivity ratios in the copolymerization were found to be rC3H6 = 1.0 and rC2F4 = 0.06. The viscosity of the copolymer was measured in tetrahydrofuran at 30°C. Infrared spectra of the copolymers were also measured. It was concluded from these experimental results that the copolymerization proceeds by a radical mechanism.