bluuebunny/crossref_metadata_2025_split huggingface dataset:
Water cocatalysis in the polymerization of benzene by ferric chloride
Authors: Kovacic Peter , Koch Fred W. , Stephan Charles E. 
Published: April 2003

AbstractThe influence of change in water cocatalyst concentration on polymer yield and composition, and on reaction rate was investigated in the benzene‐ferric chloride system. For short reaction times, polymer yield passes through a maximum at a H2O/FeCl3 molar ratio of 1. The most rapid rate of hydrogen chloride evolution was observed at this same ratio. The data suggest that ferric chloride monohydrate constitutes the active catalyst‐cocatalyst complex. With more prolonged reaction times, the yield maximum shifted to lower values of H2O/FeCl3, accompanied by a progressive increase in polymer yield. As evidenced by the C/(H + Cl) atomic ratio, p‐polyphenyl formation is favored by short reaction times at H2O/FeCl3 ratios of 0, 1, and 2. Longer reaction times, gave C/(H + Cl) ratios greater than 1.5 for the polymer, indicating the presence of polynuclear structures. An increase in chlorine content attended the rise in C/(H + Cl) ratio. Interpretations of the data are presented.
Light‐scattering study of the oxidative degradation of polystyrene
Authors: Spitsbergen James C. , Beachell Harold C. 
Published: April 2003

AbstractAn investigation into the nature of the structural and molecular changes during the bulk oxidation of polystyrene has been conducted by light‐scattering and viscometric methods. Oxidations were conducted on films in an air oven at 0, 2, 4, and 5 hr. at 200°C. The oxidized films were dissolved and various parameters obtained on the resulting solutions. Fractionation of unoxidized and oxidized thermally polymerized polystyrene showed a narrowing of the molecular weight distribution during oxidation. The weight‐average molecular weight decreased from 1,090,000 to 33,000. That of an unfractionated commercial polystyrene, Styron 683K, decreased from 281,000 to 16,000. These results show that random chain scission of oxidize polymer occurs along with the formation of carbonyl groups giving polymer molecules of shorter chain length most of which probably retain the initial linear random coil structure. In addition to the chain scission, branching and crosslinking are indicated by the distortion of Zimm plots by microgel.
Polysulfones of norbornene and derivatives
Authors: Hill Edward H. , Caldwell John R. 
Published: April 2003

AbstractNorbornene and some of its monosubstituted and disubstituted derivatives reacted with sulfur dioxide to give polysulfones. These polysulfones are very stable thermally, compared to those of 1‐butene and cyclohexene. Their stability can be further improved by using tin(II) oxide or thioacetamide as stabilizers. The polysulfones of norbornene and its derivatives have very high polymer melt temperatures.
Electron spin resonance studies of irradiated polypropylene
Authors: Forrestal Lloyd J. , Hodgson William G. 
Published: April 2003

AbstractPolypropylene has been irradiated at −196°C. and its electron spin resonance spectra studied at temperatures between −196°C. and room temperature. The intensity of the eight‐line spectrum observed at −196°C. corresponded to a G for radical production of 3.3. The spectrum could be reconstructed from theoretical curves assuming equal concentrations of radicals with four‐ and eight‐line spectra. On warming to room temperature the radical concentration was reduced to 30% of the initial concentration. In experiments in which the sample was warmed to −100°C. no change in radical concentration was observed. Annealing experiments at temperatures between −100°C. and the glass transition temperature showed that at each temperature there was a rapid decay of radicals after which no further change in radical concentration took place. Above the glass transition temperature a continuous decay occurred. The onset of decay above −100°C. may be associated with the onset of segmental motion in the amorphous regions of the polymer. The rapid decay of the radicals suggests that they are formed near each other as the results of hot hydrogen atom reactions.
Nature of the price‐alfrey q and ε parameters
Authors: Charton Marvin , Capato Anthony J. 
Published: April 2003

AbstractThe equation, εX = mεX + c, has been derived from the Price‐Alfrey and Hammett equations. The σp constants give the best correlation. With multiple substituted monomers, the equation εX,Z = m (σX + σZ) + c has been found to be applicable. Thus the ε parameter is found to be a function of both inductive and resonance effects. The equation qX = nσX + d has been derived from the Price‐Alfrey and Hammett equations. Correlations of qx have been attempted with a number of substituent constants. The correlation, though generally best with σp and related constants, remains poor, even in series in which steric effects should be constant.
Rapid characterization of ion‐exchange resins by NMR
Authors: de Villiers J. P. , Parrish J. R. 
Published: April 2003

AbstractThe proton magnetic resonance spectrum of an ion‐exchange resin is often characteristic of that type of resin. It has been shown that the internal molality of a strongly acidic or strongly basic polystyrene resin can be determined from its NMR spectrum.
Intramolecular hydride shift polymerization by cationic mechanism. I. Introduction and structure analysis of poly‐3‐methylbutene‐1
Authors: Kennedy J. P. , Minckler L. S. , Wanless G. G. , Thomas R. M. 
Published: April 2003

AbstractThe low temperature cationic polymerization of 3‐methylbutene‐1 proceeds by intramolecular hydride shift mechanism. The secondary carbonium ion
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rearranges to a tertiary one
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prior to propagation. Thus the repeat unit of cationically obtained poly‐3‐methylbutene‐1 is not the expected
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or 1,2 structure but an α,α′‐dimethylpropane‐type 1,3 unit, e.g.,
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A novel diels‐alder polymerization
Authors: Stille J. K. , Anyos T. 
Published: April 2003

AbstractThe double dienophilesN,N′‐hexamethylene‐bismaleimide and theo‐,m‐, andp‐phenylene‐bismaleimides were prepared and copolymerized with benzalazine by the Diels‐Alder reaction. Melt polymerization afforded these polymers in high yields with inherent viscosities in the range 0.13 to 0.30 and softening temperatures from 238 to 325°. Solution polymerization gave no polymers and only starting materials were isolated. Benzalazine in this reaction behaves as a double diene and undergoes a 1,3‐addition with the bismaleimides to form these polymers. That this 1,3‐addition occurs in the polymer formation is further verified by the basic hydrolysis of the model compounds, 4,8‐diphenyl‐1,5‐diazabicyclo[3.3.0]octane‐2,3,6,7‐tetracarboxylic acid bisanhydride (I) and 4,8‐diphenyl‐1,5‐diazabicyclo[3.3.0]octane‐2,3,6,7‐bis‐n‐butylamide (II) and one of the polymers to give 4,8‐diphenyl‐1,5‐diazabicyclo[3.3.0]octane‐2,3,6,7‐tetracarboxylic acid in each case.
Catalytic polymerization of glycine ethyl ester
Authors: Carter Mary E. , Carlson O. K. 
Published: April 2003

AbstractPolyglycines have been prepared in good yields from glgcine ethyl ester with a new catalyst system, aluminurn isopropoxide and/or diisopropoxide aluminum chloride. A random sttitisticsl experiment was pcrfornied to optimize the bulk stage polymerization conditions. The reaction mechanism proposed hegins as in the Meerwein‐Ponn‐dorf‐Verley reduction with an attack by the aluminum on the carbonyl oxygen and is dependent on an arnintrcsrbonyl entity which allows the romplexcd aluminurn to approach a eeeond carbonyl.
Determination of molecular weights of polymers by procedure X in stress relaxation
Authors: Sobue Hiroshi , Murakami Kenkichi , Hoshino Hiroyuki 
Published: April 2003

Abstractτm, defined as the maximum relaxation time, was shown in previous papers to be one of the elements characterizing the “box” type curve in the rubbery region of a linear amorphous polymer, and a new procedure called procedure X was proposed to obtain τm. The relation among τm, weight‐average chain length nw, temperature T, and characterized temperature Ti (glass transition temperature Tg, WLF temperature Ts, or Tobolsky's temperature Td) was indicated by an equation, with which constant values of log A depending on the kind of polymer were obtained for several polymers in the regions of M ≫ Mc. For polymers in the vicinity of Mc, another set of constant values of log A′ was obtained. Finally, the effect of τm on temperatures for a polymer was studied.
Rubber elasticity in highly crosslinked polyethyl acrylate
Authors: Katz Dov , Tobolsky Arthur V. 
Published: April 2003

AbstractCopolymers of ethyl acrylate with three different dimethacrylates were prepared over the complete range of copolymer composition. Modulus temperature curves of these polymers were constructed and contrasted with the modulus temperature curves of phenol–formaldehyde type polymers. The ethyl acrylate–dimethacrylate polymers appeared to have rubbery plateau regions at high temperatures, even for very high mole percentages of dimethacrylate. This was especially true if the dimethacrylate molecule had a long flexible chain within it, as in tetraethylene glycol dimethacrylate. On the other hand the phenol–formaldehyde type polymers and polyethylene glycol dimethacrylate did not appear to have rubbery plateau regions. Up to 12 mole‐% of dimethacrylate the shear moduli of the ethyl acrylate copolymers in the rubbery plateau region were independent of the structure of the dimethacrylate at equivalent crosslink concentrations. Furthermore these polymers appear to obey the laws of ideal rubber elasticity with a front factor of unity.
Structures of vinylidene chloride–vinyl chloride copolymers
Authors: Okuda Kensuke 
Published: April 2003

AbstractThe relationships between composition and structure of vinylidene chloride (VDC)–vinyl chloride (VC) copolymer were investigated by various methods such as x‐ray wide‐angle and small‐angle scattering, electron diffraction and microscopy, thermal analysis, and high resolution nuclear magnetic resonance. The copolymers used were made by suspension copolymerization below 5% conversion. The crystalline regions are fundamentally ismorphous to polyvinylidene chloride (PVDC) for the VDC–VC copolymers in the composition range from 1 to 0.560 in terms of the molar fraction of VDC (0.560 VDC). In the composition range below 0.145 VDC, the copolymers form crystallites isomorphous to polyvinyl chloride. The copolymers having the intermediate compositions are amorphous. In the composition range above 0.560 VDC, the average crystallite sizes of the uniaxially oriented specimens are almost constant; on the contrary, the long periods increase with decrease of the molar fraction of VDC. The intensities of the long‐period diffraction peaks show a maximum for the copolymer in which the molar fraction of VDC is 0.685. The crystallinities, which were estimated from the x‐ray method, decrease with decrease of the VDC fraction. The melting point depression is so small that it cannot be explained by Flory's equation. The results of NMR indicate that a large percentage of VC monomer units exists as sequences even in VDC‐rich copolymers. PVDC and the VDC–VC copolymers higher than 0.745 VDC crystallize in the form of layer crystal aggregates from monochlorobenzene solutions. The molecules are sharply folded within these layers. The average crystallite sizes and long periods of the solution growth crystals are almost constant. These experimental facts cannot be interpreted in the terms of the structure which is expected by the copolymerization theory, but may be explained only on the basis of the molecular structure model which means the copolymer has a kind of block‐type structure.
The chemistry of poly(vinyl chloride) stabilization. III. Organotin stabilizers having radioactively tagged alkyl groups
Authors: Frye Alfred H. , Horst Raymond W. , Paliobagis Marko A. 
Published: April 2003

AbstractThe stabilizing action of a representative group of organotin compounds of the formula Bu2Sn Y2 has been studied by a radioactive tracer technique, the tags (14C) being located in the butyl group's C1‐position. The Y groups of the chosen organotin compounds were: monomethyl maleate, oxoöctyl thioglycolate, β‐mercaptopropanoate, and 2‐ethylhexanoate. It was found that after a sequence of two dissolution and precipitation cycles (using tetrahydrofuran and methanol) an appreciable portion of radioactivity is retained by the resin, the resins having been previously admixed with the tagged stabilizer, milled into films and then subjected to carefully controlled heat treatments. Under these conditions it was found that the amount of radioactivity retained by the resin was determined by the nature of the Y group and the duration of the heat treatment. Further, it was found that for a given Y group, the amount of retention first increases with increase in the duration of the heat treatment, reaches a maximum, and then drops off. However, the amount of radioactivity retained by such a resin was not found to be constant when the sample was subjected to further dissolution–precipitation cycles, but, within the limits of the present experiments, to decrease markedly with each successive cycle. It is suggested that the major portion of this retention is due to the formation of an associative link between the polymer and the organotin compound and that this linkage is partially ruptured by the tetrahydrofuran–methanol treatment. It is also shown that only a very minor portion of the radioactivity retained by the precipitated resin can be due to actual butylation of the resin as preposed by Kenyon, and that it is unlikely that it could contribute appreciably to the resin's stabilization. It is suggested that the formation of an associative complex between the resin and the organotin compound functions as a precursor wherein certain relatively labile centers in the polymer chain can be altered, possibly by a displacement reaction involving the organotin compound's Y group, and int his way retard or inhibit the zipperlike elimination of hydrogen chloride which is the initial phase of the polymer's degradation.
Viscoelastic behavior of plasticized polyvinyl chloride at large deformations. III. The effect of filler
Authors: Sabia Raffaele , Eirich F. R. 
Published: April 2003

AbstractThe behavior of filled and plasticized samples is similar in many ways (such as creep, critical strain for the onset of a permanent deformation, etc.) to plasticized polyvinyl chloride. The presence of small amounts of CaCO3 as filler was found to result in improved mechanical response, while high amounts produced stiffening effects of the nature of an inert filler. At larger deformations, the polymer ceases to wet the filler and the volume of the filled resin increases with strain by crazing, the more so the more highly filled. Filler wetting by the resin is influenced by plasticizer content. In stress relaxation, the dewetting time, very short for the highly filled samples, increases appreciably with decreasing filler content while depending at the same time on plasticizer content. Because of this, equilibrium and delayed moduli increase with filler content at low strain and decrease variously at higher strain.
Molecular weight of poly(vinyl chloride)
Authors: Freeman M. , Manning P. P. 
Published: April 2003

AbstractA number of fractionated and unfractionated poly(vinyl chlorides) have been characterized by light scattering, osmometry, and solution viscometry. From the results on fractions it is concluded that the larger molecules contain long branches. For linear fractions the relation between intrinsic viscosity in tetrahydrofuran at 25°C. and weightaverage molecular weight measured by light scattering is: [η] = 1.63 × 10−4Mw0.766 dl./g.
Absolute propagation rate constants for the radical polymerization of substituted styrenes
Authors: Paoletti K. P. , Billmeyer F. W. 
Published: April 2003

AbstractAbsolute propagation rate constants were determined by application of the Smith‐Ewart kinetic theory to the emulsion polymerization of styrene, o‐methylstyrene, p‐methylstyrene, and “vinyltoluene” (Dow, 60:40 m‐:p‐methylstyrene). Conversion during polymerization was followed by dilatometry, and weight‐average molecular weights of the latex particles were determined by light scattering. The monomer–polymer equilibrium ratio was determined both dynamically as the inflection point of the rate curve and statically by equilibrating monomer with polymer. For styrene, the propagation rate constant (300 l./mole sec. at 50°C.) and its activation energy (17.6 kcal./mole) are in good agreement with literature values. Both rates and activation energies are lower for the other monomers (o‐methylstyrene, 60 l./mole sec. and 13.9 kcal./mole; p‐methylstyrene, 140 l./mole sec. and 7.7 kcal./mole; vinyltoluene, 220 l./mole sec. and 13.4 kcal./mol, all at 50°C.). The differences are attributed to increased radical stability from methyl group contributions to resonance structures and to steric hindrance of the ortho‐methyl group.
Photodegradation of poly(methyl acrylate)
Authors: Fox R. B. , Isaacs L. G. , Stokes S. , Kagarise R. E. 
Published: April 2003

AbstractThin films of poly(methyl acrylate) at room temperature have been photodegraded in air and in vacuum by radiation from a low‐pressure mercury source. Changes in intrinsic viscosities, ultraviolet absorption, and volatile products were followed as a function of the energy absorbed. Crosslinking occurs in both air and vacuum, but at a slower rate in air. The apparent quantum yield for random scission in air was 0.013 scissions per quantum absorbed. In air, carbonyl groups are formed along the backbone chain. Most of the volatile products studied appear to orginate from the ester groups in the polymer; formaldehyde, methanol, and methyl formate evolved at a constant rate for doses up to at least 2 × 1020 quanta/g.; quantum yields for each were determined. Carbon dioxide forms in amounts increasing exponentially with dose. Small amounts of carbon monoxide, methane, and hydrogen were detected qualitatively, but monomer was not observed. A mechanism compatible with these findings is suggested.
Polyesters of 1,4‐cyclohexanedimethanol1
Authors: Kibler Charles J. , Bell Alan , Smith James G. 
Published: April 2003

AbstractA series of polyesters of trans‐1,4‐cyclohexanedimethanol was prepared and the melting points compared with those of the analogous series of polyesters prepared from p‐xylylene glycol. Only slight differences in melting points were noted between the corresponding pairs of polyesters prepared from a single aliphatic dicarboxylic acid and from the two glycols. However, polyesters derived from aromatic dibasic acids and trans‐1,4‐cyclohexanedimethanol melt at a higher temperature than the corresponding polymer from p‐xylylene glycol. The probable molecular configuration of polyesters based on trans‐1,4‐cyclohexanedimethanol is discussed. It is suggested that the diol moiety in the polyester can adopt a slightly contracted conformation so that the oxygen‐oxygen distance is less than in polyesters derived from p‐xylylene glycol. This, together with the similar degree of rigidity and symmetry of the trans‐1,4‐cyclohexylene and p‐phenylene ring systems, is employed to explain the observed melting points. Polyesters prepared from cis‐1,4‐cyclohexanedimethanol are also described. As expected from the lower degree of symmetry of the diol, these polyesters have lower melting points than the analogous compositions prepared from trans‐1,4‐cyclohexanedimethanol. Polyesters of cis‐1,4‐cyclohexanedimethanol and trimethylene glycol have similar melting points. It is suggested that a cis‐1,4‐cyclohexylene ring and a methylene group have a similar effect on the melting point of a polyester. Copolyesters of cis‐ and trans‐1,4‐cyclohexanedimethanol with terephthalic acid do not form a minimum melting composition. Instead, they show a continuous change of melting point from that of the polyester prepared from one stereoisomer to that of the polymer prepared from the other isomer.
On the relation between long spacings, molecular length, and orientation in long chain compounds with reference to the possibility of chain folding. Part I. Oligomeric amides
Authors: Calleja F. J. Baltá , Keller A. 
Published: April 2003

AbstractIn this set of two papers the possibility of chain folding occurring in chain molecules not much longer than the presumed fold length was examined. The present paper deals with oligomeric amides. Following up the preceding work on the relation between long spacing and chain length by Zahn and Pieper on the same compounds, the relation between long spacings and chain orientation was examined in order to assess how far oblique structures could present alternatives to chain folding. It could be concluded that they cannot, the chains remaining straight up to a certain length only (80 A.), beyond which chain folding offers the most probable explanation. The preparation and examination of oriented aggregates required for this conclusion to be reached are discussed. In addition the dependence of the long spacings on the crystallization temperature, and relation between melting point and long spacing are demonstrated, and examples of annealing behavior are given all of which have their corresponding counterpart in the chain‐folded high polymers.
On the relation between long spacings, molecular length, and orientation in long chain compounds with reference to the possibility of chain folding. Part II. Poly(ethylene oxide)s
Authors: Calleja F. J. Baltá , Keller A. 
Published: April 2003

AbstractPoly(ethylene oxide)s, including low molecular weight Carbowaxes and high molecular weight Polyox resins were examined as regards their long period chain length relationship with reference also to chain inclination with respect to the long spacings. The results show that the chains can only be straight up to a certain length (100–150 A.), beyond which chain folding needs to be invoked. Reference is made to single crystals required for these experiments. The long spacings (fold length) depend on the solvents, presumably by their effect on the crystallization temperature and on the heat treatment (annealing) of the samples, this providing the continuity between the behavior of the waxy low molecular weight compounds and that of typical high polymers. The general conclusion (based on Part I and II) is reached that in the light of present concepts there seems to be no acceptable alternative to chain folding beyond a certain critical length (dependent on physical factors) to account for the observations.
Fractionation of polymers of higher α‐olefins
Authors: Flowers D. L. , Hewett W. A. , Mullineaux R. D. 
Published: April 2003

AbstractFractionation of 1–10 g. samples of a series of poly‐α‐olefins in a glass bead column has been studied. A thermal gradient was found to decrease fractionation efficiency relative to that obtained at constant (ambient) temperatures. A “stepwise‐continuous” solvent gradient technique was developed to improve fractionation of the high molecular weight material. Fractionation efficiency decreased with increasing bead loading but was still good at polymer to bead ratios of 0.1 compared to the ratio of 0.01 usually used; efficiency is poorer in the absence of a column, even when the latter is operated at constant temperature. The Kuhn‐Mark‐Houwink equation was used to correlate intrinsic viscosities to light‐scattering molecular weights. Values of the constants were K = 2.1 × 10−4 and α = 0.61. Molecular weight distribution correlations show these polymers to have very high Mw/Mn.