bluuebunny/crossref_metadata_2025 huggingface dataset:
Stress relaxation of γ‐irradiated fluorocarbon elastomers
Authors: Yoshida T. , Florin R. E. , Wall L. A.
Published: April 2003

Poly(vinylidene fluoride), polytrifluoroethylene, and two rubbery copolymers with vinylidene fluoride were crosslinked by γ‐irradiation in vacuum. Radiation‐induced chain scissions in the copolymers were studied by observing the relaxation of stress at constant extension during further irradiation at 27°C., at 0.31–2.7 Mr./hr. in nitrogen and in air. From gel content, swelling, and elasticity, the values of Gc (crosslinking) and Gd (scission) were respectively; for CF2CFH, Gc = 2.2 and Gd = 0.4; for CF2CH2, 2.0 and 0.3; for CF2CH2 + C3F6, 3.4 and 1.3; for CF2CH2 + CF2CFCl, 1.8 and 1.4. The Gd values from stress relaxation were variable; the lowest were: for CF2CH2 + C3F6, 4.6 in nitrogen and 8.4 in air; for CF2CH2 + CF2CFCl, 1.9 in nitrogen and 3.6 in air.
Mechanism of fracture in glassy polymers. I. Fracture surfaces in polymethyl methacrylate
Authors: Kambour R. P.
Published: April 2003

The interference colors on poly(methyl methacrylate) fracture surfaces have been shown to arise from a layer of craze material. The order of interference can be determined in various ways for most areas on the fracture surface and craze layer thicknesses determined. Layer thickness is a function of fracture velocity; at zero velocity where the Griffith criterion may be applied with the least error an average surface layer thickness of 6800 A. is calculated. The plastic work of this amount of craze formation corresponds to 13–20% of the nominal Griffith energy.
Etude de la polymérisation des oléfines catalysée par les oxydes métalliques. II. Influence des impuretés sur la cinétique de polymérisation du propylène par le système catalytique phillips
Authors: Guyot Alain , Daniel Jean‐Claude , Durrieu Marc , Ptack Marius
Published: April 2003

A study was made of the influence of oxygenated impurities probably present in propylene on the polymerization kinetics and on the paramagnetic properties of the Phillips catalysts which contain about 2.5% chromium. Only a fraction of chromium atoms are active centers, which could be the pentavalent atoms.
Macroreticular redox polymers. I. Hydroquinone–quinone redox polymers
Authors: Kun Kenneth A.
Published: April 2003

Redox polymers based upon the hydroquinone–quinone redox system are prepared by the addition of hydroquinone and hydroquinone derivatives to preformed polystyrene matrices. Conventional gel and macroreticular styrene–divinylbenzene copolymers were chloromethylated with chloromethyl ether by using a Friedel‐Crafts catalyst and the reaction products were treated, by a second Friedel‐Crafts reaction, with hydroquinone, benzoquinone, or alkyl homologs of these materials or with the dimethyl ether or the diacetoxy derivatives of hydroquinone to give polymeric vinylbenzylhydroquinones. Macroreticular redox polymers show greater reactivity and better stability than resins having redox systems on conventional gel‐type matrices. These redox polymers convert iron III to iron II, cerium IV to cerium III, iodine to iodide, and remove dissolved oxygen and peroxides from aqueous and organic liquids when the resins are in the reduced form. When in the oxidized form, the resins are reduced with titanium III, sodium sulfite, sodium bisulfite, sodium dithionite, sulfur dioxide, and sodium borohydride.
Use of a capillary extrusion rheometer to measure curing of thermosetting plastics and rubbers
Authors: Salyer I. O. , Heyd J. W. , Brodbeck R. M. , Hartzel L. W. , Brown L. E.
Published: April 2003

By use of a modified, small‐bore, capillary extrusion rheometer (MCER) with an Instron tensile testing machine, the flow and set‐up properties of thermosetting plastics and rubbers were characterized. The majority of the experiments were performed with diallyl phthalate, where the rate of curing was also followed by infrared determination of the reduction in unsaturation as the polymerization‐curing proceeded. Phenol–formaldehyde was also characterized. Finally, the curing of ethylene–propylene and ethylene–vinyl acetate copolymer rubbers with peroxide was studied and correlated with the type of peroxide used. The MCER data are shown to be of practical use for predicting the time–temperature–pressure relationships for processing thermosetting plastics and rubbers. Moreover, the history of the curing, as obtained by analysis of the continuously extruded strand, is also of theoretical interest for studying reaction kinetics and for evaluating the effectiveness of various curing systems. It is predicted the MCER will be widely used for studying the curing of thermosetting plastics and rubbers.
Kinetics of the polymerization and styrene copolymerization of m‐ and p‐divinylbenzene
Authors: Wiley Richard H. , Devenuto Giovanni
Published: April 2003

The rate of polymerization and copolymerization with styrene of m‐, 2:1/m : p‐, commercial, and p‐divinylbenzene in tert‐butylbenzene decreases in the order listed at 65 and 80°C. The copolymerization of the para isomer at 80°C. accelerates more rapidly than does that of the other isomers. The overall activation energies increase from 14.9–20.8 kcal./mole to 23.5–26.9 kcal./mole in the polymerizations and from 9.0–12.1 to 13.0–17.6 kcal./mole in the copolymerizations over the time interval involved. The differences in rates and autocatalytic effects are attributed to differences in relative reactivities of the m‐ and p‐vinylstyrene‐derived radicals, the m‐ and p‐alkyl styrene structures, and to the different distribution of divinyl units in the copolymers.
Deformation mechanism of polyethylene spherulite
Authors: Oda Takashi , Nomura Shunji , Kawai Hiromichi
Published: April 2003

A deformation mechanism for polyethylene spherulites has been proposed which is based on the affine transformation method. Individual crystal lamellae are taken as the orientation units within the spherulites and are allowed to rotate around the a‐ and b‐ axes of the crystal. Deductions based on this model and on previous models are compared with experimental results obtained with four kinds of polyethylene film. These results agree fairly well with the predictions of the present model and suggest that the plastic deformation of crystal lamellae by gliding along the (110) plane predominates over the untwisting of crystal lamellae at the initial stage of deformation.
Solvent effects in anionic copolymerization. II. Molecular orbital treatment for the pair: Styrene–methylstyrene
Authors: O'Driscoll K. F. , Yonezawa T. , Higashimura T.
Published: April 2003

A model is proposed for the transition state of the anionic copolymerization of styrene and p‐methylstyrene in hydrocarbon solvent with lithium counterion. An LCAO‐MO treatment which considers the effect of the positive counterion on the negative chain end is used to calculate the electrostatic and the π electron resonance contributions to the activation energies of the four propagation reactions. The electron contributions to the activation energies are also calculated for the propagation reactions of free ions, i.e., in the absence of a counterion. The previously determined rate constants in benzene and tetrahydrofuran are then compared with the results of these calculations.
Synthesis and structure of polyglyoxal
Authors: Brady William T. , O'Neal Hubert R.
Published: April 2003

The polymerization of glyoxal has been carried out in the presence of sodium naphthalene in THF at −78°C. The polyglyoxal decomposed at 150°C. and was slightly soluble in water and alcohol. The polymer was readily acetylated with acetic anhydride to yield a material that decomposed at about 290°C. Structure elucidation of the glyoxal polymer indicated that it had a polyacetal type of structure containing pendant enol groups and also a cyclic chelated structure involving hydrogen bonding between an enolic hydroxy group and a pendant carbonyl group.
Thermochemistry of polymerization. Part II. Thermochemical aspects of equilibrium copolymerization
Authors: Sawada Hideo
Published: April 2003

A new theory of equilibrium copolymerization is presented. The theory is based upon statistical thermodynamics and yields useful information about the sequence distribution along the chain. The effect of temperature on the sequence distribution of copolymerization is discussed.
Copolymerization of α‐olefins with ω‐halo‐α‐olefins by use of Ziegler catalysts
Authors: Bacskai R.
Published: April 2003

The copolymerization of α‐olefins with ω‐halo‐α‐olefins by use of Ziegler catalysts has been investigated. It was found that ω‐halo‐α‐olefins deactivate the catalyst, thus resulting in low copolymer yield and reduced molecular weight. The deactivation is caused by hydrogen halide formation which is greatly facilitated in the case of the allyl halides and 6‐halo‐1‐hexenes. The different degrees of deactivation were interpreted by considering the ease of carbonium ion formation from the various ω‐halo‐α‐olefins. The copolymer yields were considerably improved when a catalytic amount of a Lewis base was added to the polymerization system. It is proposed that the added Lewis base, by decreasing the Lewis acid character of the catalyst, suppresses the decomposition of the ω‐halo‐α‐olefin leading to hydrogen halide formation. Depending on the Ziegler catalyst employed, the copolymers of α‐olefins and ω‐halo‐α‐olefins can be either crystalline or amorphous solids. The halogen, especially the bromine in the copolymers, is reactive in nucleophilic substitution reactions. Reaction with amines gave polymers which could be dyed by acid dyes.
Semiquantitative aspect of short branch detection by using polyelectrolyte expansive effects
Authors: Pasika W. M. , Cragg L. H.
Published: April 2003

Linear and branched dextran polyelectrolyte reduced viscosity–concentration curves, obtained by employing a solvent which contained a low concentration of simple electrolyte, were characterized by means of a set of relative expansion ratios, \documentclass{article}\pagestyle{empty}\begin{document}$ R_{nc_m } $\end {document} . The sets of \documentclass{article}\pagestyle{empty}\begin{document}$ R_{nc_m } $\end {document} for branched and linear dextran polyelectrolyte samples of identical degree of substitution, whose reduced viscosity–concentration curves were determined in the same solvent, did not differ. This is interpreted as indicating that the same expansive mechanism operated in the linear and branched polyelectrolyte systems when they were diluted. Plots of \documentclass{article}\pagestyle{empty}\begin{document}$ R_{nc_m } $\end {document} versus absolute concentration for linear and branched polyelectrolyte samples (of identical degrees of substitution, of different degrees of substitution and whose reduced viscosities were determined in solvents of different simple electrolyte concentrations) gave straight lines with a common intercept on the ordinate axis but with different slopes. It is suggested that the slope factor or p values of these lines might be employed as a means of detecting and measuring short branching in polymers convertible to polyelectrolytes.
Studies in condensed phosphates. Part VIII. Complex potassium polymetaphosphates of calcium, zinc, and cadmium
Authors: Mehrotra R. C. , Vyas P. C.
Published: April 2003

Derivatives with the formulas [K4Ca(PO3)6]n, and [K4Cd(PO3)6]n have been prepared by heating together mixtures of KH2PO4, CaO, (or ZnO or CdO), and (NH4)2HPO4 in the mole ratio of 4 : 1 : 2 at 800°C. for 1 hr. The number‐average molecular weights of these derivatives have been measured by endgroup titration. Their conductance has been measured in aqueous solution of varying concentration, and their properties compared with those of Graham's salt and its complex derivatives prepared under similar conditions.
Thermodynamic stability of polymer crystals. III. Torsional and longitudinal chain vibrations
Authors: Peterlin A. , Reinhold Chr.
Published: April 2003

The free energy density of a folded‐chain crystal varies with the length of the straightchain section between consecutive folds. It is always minimum at infinite length. Another minimum at finite length L appears below a critical temperature T0 which among other things depends on the surface energy of the fold‐containing planes. This minimum is a result of the smearing out of the nonharmonic lattice potential energy field by the incoherent vibrations of adjacent chains. In the present paper the simultaneous influence of both longitudinal and torsional vibrations of polyethylene chains in the orthorhombic lattice is considered. Due to the relative smallness of the amplitude of the potential energy for chain translation in comparison to that for chain rotation the calculated equilibrium length L at any temperature does not appreciably differ from the value obtained formerly for the torsional vibrations only. L increases with temperature and is maximum at the critical temperature. With increasing surface energy the equilibrium long period at constant temperature increases, and the critical temperature decreases. The calculated values fit fairly well the experimental data of polyethylene crystals grown from dilute solution if one admits that the surface energy varies slightly from solvent to solvent.
Electron traps in polyethylene
Authors: Partridge R. H.
Published: April 2003

Qualitative and quantitative results from previous studies of the thermoluminescence induced in polyethylene by irradiation are used in an attempt to deduce the main polyethylene electron traps. It is concluded that the most probable traps are the molecular chains themselves, the different degrees of molecular motion in different structural regions of polyethylene being responsible for the untrapping of the trapped electrons at different rates and hence the appearance of multiple glow peaks in the glow curve. An explanation is given for the correspondence between the activation energies of thermoluminescence, radiation induced electrical conductivity, and molecular chain motion (as measured by NMR) in polyethylene.
Melting of homopolymers under pressure
Authors: Baer Eric , Kardos John L.
Published: April 2003

The effect of pressure on the melting of polyethylene, polypropylene, poly(ethylene oxide), and poly‐3,3‐bischloromethyloxacyclobutane (Penton), has been studied up to 3000 atm. The melting temperature–pressure curves for all polymers studied rose indefinitely with pressure, thus behaving in a manner similar to that previously reported for long‐chain hydrocarbons. For polyethylene, analysis of the total entropy change on melting, in terms of changes in configurational and volume entropies showed that the percentage of the total entropy change due to change in configurational entropy increased rapidly with pressure, attaining a value of 90% at 3000 atm. The changes in the configurational entropies of melting for polypropylene, poly(ethylene oxide), and Penton were subsequently shown to be lower than that of polyethylene suggesting more melt order. This could arise from helical conformations in the melt for polypropylene and polyethylene oxide and from a stabilized planar zigzag conformation in the Penton melt. A pronounced broadening of the melting range with pressure was attributed to pressuresensitive transitions which are known to occur near the melting temperature and also to the effect of molecular weight distribution.
Integral and differential binary copolymerization equations
Authors: Meyer Victor E. , Lowry George G.
Published: April 2003

An analytic solution to Skeist's copolymerization equation has been obtained for the case of binary copolymerization. From this solution, a differential copolymer composition equation is also derived. For given values of the reactivity ratios, these equations then permit the convenient calculation of expected binary copolymerization behavior as a function of conversion. Critical conditions leading to incompatible copolymerizations are also discussed.
Homogeneous ionic copolymerization. A study of solvent effects in the styrene systems
Authors: Overberger C. G. , Chapman T. M. , Wojnarowski T.
Published: April 2003

The effect of solvent in the homogeneous anionic copolymerization of styrene with p‐methylstyrene, p‐tert‐butylstyrene, and m‐methylstyrene has been determined. In nonpolar media where the gegenion is lithium, a nonhomogeneous distribution exists with the more basic monomer in higher concentration at the growing chain end which shows as an enhanced relative reactivity. This is depressed by the addition of a small amount of more polar solvent. The influence of temperature as a function of solvent has been determined for selected anionic systems. In nonpolar media, an increase of temperature favors incorporation of the less basic monomer whereas a more polar solvent has only a small effect and favors a more ideal copolymerization. In cationic copolymerization the effect of hyperconjugation has been demonstrated. This effect of hyperconjugation appears to be enhanced in polar media. The cationic copolymerizations of styrene with p‐tert‐butylstyrene in nitrobenzene shows a steric hindrance of the bulkier monomer on its incorporation into the copolymer. Determination of reactivity ratios as defined for radical systems does not fully characterize ionic copolymerizations.
Existence of long‐lived radicals in the γ‐radiation induced polymerization of ethylene
Authors: Machi Sueo , Hagiwara Miyuki , Gotoda Masao , Kagiya Tsutomu
Published: April 2003

In the γ‐radiation‐induced bulk polymerization of ethylene under high pressure, the growing polymer radical is shown to have a long lifetime at low temperatures (30°C.). Separation of the propagation reaction from other elementary reactions is possible. During the propagation reaction the molecular weight of the polymer increases with polymer yield when irradiated with an extremely low dose rate. At elevated temperatures (100°C.), the lifetime of the growing polymer radical is not prolonged.
Preparation and polymerization of vinyl esters of chloro‐ and hydroxystearic and eicosanoic acids
Authors: Marvel C. S. , Griffith J. H. , Comp J. L. , Applewhite T. H. , Goldblatt L. A.
Published: April 2003

Homopolymers and copolymers with vinyl acetate and vinyl chloride have been prepared from the vinyl esters of 9‐chlorostearic acid, 12‐chlorostearic acid, 14‐chloroeicosanoic acid, 9‐hydroxystearic acid, 9,10‐dihydroxystearic acid, 14‐hydroxyeicosanoic acid, and 8‐(1,3‐dioxylone‐2‐yl) octanoic acid.
Molecular motions of polymers having helical conformation. I. Poly(ethylene glycol) and polyoxymethylene
Authors: Hikichi Kunio , Furuichi Jiro
Published: April 2003

In order to study molecular motion characteristic of a helical polymer, proton magnetic resonance spectra and the complex dielectric constants ε* for a wide frequency range have been measured in the temperature region between 90°K. and the melting point for poly(ethylene glycol), which is thought to be helical in the solid state. The molecular weights of the samples are 4000, 1000, and 400. These results suggest that a molecular motion such as rotation or oscillation is able to occur even in crystalline regions well below the melting point. The temperature at which this type of molecular motion begins seems to be independent of the molecular weight of the samples, although the melting point is found to depend markedly on molecular weight. X‐ray and dilatometric measurements were carried out for the same samples and indicate the absence of a crystalline phase transition (first‐order transformation) at the temperature region where the narrowing of the NMR line width of PEG is observed. The results for another helical polymer, polyoxymethylene, are also presented.
Dye‐sensitized polymerization of vinyl monomers in aqueous solution
Authors: Sheriff A. I. , Santappa M.
Published: April 2003

The kinetics of the polymerization of the vinyl monomers methyl methacrylate, methyl acrylate, and acrylonitrile sensitized by dye‐reducing agent systems have been studied systematically. The systems were irradiated with light of 350–450 mμ wavelength. The induction period before the onset of polymerization was kept to a minimum by suitable experimental conditions. All the experiments were conducted in the presence of oxygen. The redox system sodium fluorescein (Uranine)–ascorbic acid was used for polymerization. The systems were buffered with phosphate buffer. The effects of temperature, viscosity, etc., on the reaction system were studied. The course of the reactions was followed by the measurements of rate of monomer disappearance (gravimetrically), rate of dye disappearance (spectrophotometrically) and the chain length of the polymer formed (viscometrically). Light intensity, wavelength, monomer concentration, dye concentration, reducing agent concentration, temperature, etc., were variable. The tentative kinetic scheme proposed is examined in the light of the experimental results. The values for the specific rate constants for the various steps have been evaluated.
Kinetics of the initiation of styrene polymerization by n‐butyllithium
Authors: O'driscoll K. F. , Ricchezza E. N. , Clark J. E.
Published: April 2003

The reaction between styrene and n‐butyllithium in benzene has been studied by spectrophotometry and calorimetry at 25°C. It was observed that the initiation of polymerization was first‐order in styrene and one‐third‐order in butyllithium at styrene concentrations of 0.5 mole/l.. and that addition of butyllithium to styrene solutions caused an evolution of 1.7 kcal./mole of butyllithium. It was also noted that the rate of initiation was approximately an order of magnitude larger than that previously reported in very dilute styrene solutions (0.03 mole/l.) and comparable butyllithium concentrations. It is concluded that styrene stabilizes trimeric butyllithium relative to its hexamer by a nonstoichiometric, exothermic solvation process.
Anionic polymerization of ω‐lactam. Part I. Polymerization of ε‐caprolactam by alkaline catalysts and ketenimines
Authors: Yasumoto Takaya
Published: April 2003

Ketenimines have been found to be useful cocatalysts for the alkaline polymerization of ε‐caprolactam. The induction period preceding the start of the reaction is shortened by addition of a ketenimine, and the polymerization rapidly proceeds at low temperature below the melting point of the polymer. A reaction mechanism is proposed for the polymerization of ε‐caprolactam with alkaline catalyst and ketenimine, which involves a formation of a reactive N‐imidoyl lactam from ketenimine and lactam, and chain propagation by the stepwise addition of anionic lactam at the end of the molecule leading to the polymer. This mechanism is supported by the experimental fact that imino chloride has the same effect as ketenimine on the alkaline polymerization of ε‐caprolactam. The conditions for the polymerization have been carefully investigated. Both conversion and relative viscosity of polymer diminish with increasing concentration of ketenimine and also with increasing reaction temperature.
Vinyl polymerization. XCI. Polymerization of styrene initiated by nickel peroxide
Authors: Nakata Tadashi , Otsu Takayuki , Imoto Minoru
Published: April 2003

A study of the radical polymerization of styrene initiated by nickel peroxide (Ni‐PO) as a solid initiator has been made. The rate of polymerization (Rp) was found to be expressed by the equation: Rp = k[Ni‐PO]1/2[Styrene]3/2. This equation could be understood by considering that the radical polymerization by Ni‐PO is initiated through the interaction between the monomer and the Ni‐PO initiator and terminated by the ordinary bimolecular termination mechanism. By extracting the resulting polystyrene with methyl ethyl ketone (MEK), the MEK‐insoluble polymer, which was confirmed by infrared spectra and x‐ray diffraction analyses to be isotactic polystyrene, was isolated. The amount of the isotactic polymer increased as the polymerization temperature decreased. The results obtained in the present study indicate that the stereospecific absorption (π‐complex formation) of the monomer on the solid Ni‐PO initiator might be important for producing an isotactic polystyrene.
Preparation and polymerization of addition compounds of unsaturated tertiary phosphine oxides
Authors: Welch F. J. , Paxton H. J.
Published: April 2003

Complexes of vinyldiphenylphosphine oxide, vinyldi‐n‐butylphosphine oxide, and trans‐1‐propenyldiphenylphosphine oxide have been prepared with salts of Zn(II), Hg(I), Sb(III), Sn(IV), Ti(IV), Fe(III), and U(VI). The observed shifts in the phosphoryl stretching frequency on complex formation were similar to the values reported for corresponding complexes with triphenylphosphine oxide. The polymerization behavior of these compounds in the presence of free‐radical and ionic intiators is similar to that of the unsaturated phosphine oxides themselves. In spite of high salt content, the polymers form clear plaques on molding, and they are completely soluble in appropriate organic solvents.
Crosslinking of copolymers containing N,N‐dimethylacrylamide
Authors: Needles H. L. , Whitfield R. E.
Published: April 2003

Aqueous solutions of N,N‐dimethylacrylamide–acrylic copolymers crosslink in the presence of peroxydisulfates at elevated temperature. It is shown that effectiveness of crosslinking depends on the amount of N,N‐dimethylacrylamide present in the copolymer, being quite effective with as little as one unit of N,N‐dimethylacrylamide in each eleven units of copolymer. Dilute solutions of these copolymers are slowly degraded initially by peroxydisulfate, and then begin to crosslink after a few minutes. Crosslinking is believed to proceed via sulfate‐ and hydroxyl‐radical attack of N‐methyl in the polymers to yield N‐methylol derivatives capable of crosslinking with other reactive sites.
Glass temperatures of some acrylic polymers
Authors: Krause Sonja , Gormley James J. , Roman Nicholas , Shetter John A. , Watanabe Warren H.
Published: April 2003

Dilatometrically determined glass transition temperatures and thermal expansion coefficients of 47 different polymers, most of them acrylics, are reported. The experimental values are discussed in terms of the effect of side‐chain flexibility, bulkiness, and polarity on the glass transition temperature and are compared with the isofree‐volume theory of the glass transition temperature, as recently set forth by Simha and Boyer. Possible reasons for the poor agreement with this theoretical treatment are discussed. The effect of equilibrium time at each temperature during a dilatometric run was determined for one sample, polystyrene, which was measured both in the usual way and with long equilibrium times (over a week) at each temperature, yielding glass temperatures of 97 and 89°C. for the usual and for the long equilibrium times, respectively.
Terpolymerization of olefins and cis, cis‐1,5‐cyclo‐octadiene with sulfur dioxide and carbon monoxide
Authors: Frazer A. H.
Published: April 2003

The terpolymerization of propylene, 1‐butene, isobutene, and cis, cis‐1,5‐cyclooctadiene with sulfur dioxide and carbon monoxide at elevated temperatures and pressures has been studied. With the α‐olefins, at carbon monoxide pressures of 1000 and 3000 atm. and temperatures above the ceiling temperature of the particular olefin‐sulfur dioxide system, terpolymers of the olefin, sulfur dioxide, and carbon monoxide were obtained. With the diene, at these carbon monoxide pressures over a broad temperature range, similar terpolymers were obtained. All of these systems exhibited a ceiling temperature. The properties of these terpolymers were determined, and the structures and mechanism for the preparation of such structures postulated.
Studies on alcohol‐modified transition metal polymerization catalysts. I. Infrared studies
Authors: Marchessault R. H. , Chanzy H. , Hider S. , Bilgor W. , Hermans J. J.
Published: April 2003

The interaction of titanium tetrachloride and alcohols in benzene and carbon tetrachloride has been studied by means of infrared spectroscopy. A “continuous variation” study of various absorption bands has allowed establishment of two different interactions: one involving a 1:1 alcohol‐titanium tetrachloride ratio and another at 3:1. High‐resolution spectroscopy in the 3 μ region for the latter indicates well‐defined hydrogen bonding of the intramolecular kind. This has been interpreted in terms of the alcohols being both reacted and coordinated in a titanium complex. Significantly, polymerization activity of the titanium compound decreases sharply when alcohol is in molar excess and goes to zero at a 3:1 ratio. The effect of added aluminum triethyl on the infrared spectrum of the propanol–titanium tetrachloride 3:1 complex in the 3 μ region was observed. Significant changes in the OH stretching modes were noted. Interaction spectra of propanol–methyl titanium trichloride were also recorded.
Radiation grafting of vinyl monomers to wool. Part I
Authors: Stannett V. , Araki K. , Gervasi J. A. , McLeskey S. W.
Published: April 2003

A number of vinyl monomers have been grafted to wool by using the mutual radiation technique. Styrene has been studied in considerable detail in dioxane solution; water or methanol was found to be necessary for successful grafting. It is believed that these function as swelling agents, enabling the monomer to diffuse to the active centers created in the wool by the radiation. The rate of grafting always went through a maximum and then leveled off to a slower rate. This is believed to be due to the slow build‐up of the radical population, leading eventually to a diffusion‐controlled rate of grafting. Considerable post‐polymerization grafting was found to take place. Acrylonitrile and a number of allyl monomers were also successfully grafted to wool by the mutual radiation method in dimethylformamide solution. Again water or methanol was found to be necessary; the grafting rate leveled off close to zero at a degree of grafting depending on the amount of swelling agent present.
Crystal and molecular structure of optically active poly‐D(–)‐β‐methyl‐ε‐caproamide
Authors: Coiro V. M. , De Santis P. , Mazzarella L. , Picozzi L.
Published: April 2003

The investigation of the crystal and molecular structure of optically active poly‐D(–)‐β‐methyl‐ε‐caproamide was carried out in two stages. The molecular conformation was first studied by means of Fourier transform methods and the crystal packing was later deduced by detailed structure factor calculations. The structure thus established bears some close resemblance to that characteristic of the γ modification of unsubstituted nylon 6. A marked shortening of the chain along its axis is produced by the presence of a methyl group in the β position. This causes the rotation about the skeleton bonds adjacent to the amide bonds, whereas the rest of the chain retains its trans planar stable conformation. The hydrogen bonds of normal length (2.85 A.) crosslink the molecules in parallel sheets in planes parallel to the (100) plane which are translated with respect to each other by 5/14 of the b axis in the P monoclinic space group.
Polymers of fluorocarbon ethers and sulfides. I. Trifluoromethyl trifluorovinyl ether and sulfide
Authors: Durrell William S. , Stump Eugene C. , Westmoreland Geraldine , Padgett Calvind D.
Published: April 2003

Trifluoromethyl trifluorovinyl ether (I) and sulfide (II) were prepared by dehalogenation of the corresponding 1,2‐dichlorotrifluoroethyl compounds. These were prepared from the reactions of trifluoromethyl hypofluorite with 1,2‐dichlorodifluoroethylene and trifluoromethane sulfenyl chloride with chlorotrifluoroethylene, respectively. The polymerization behavior of these, along with the known trifluoroethyl trifluorovinyl ether (III) was examined. Only III gave a high molecular weight homopolymer, and, along with I, copolymers. II was quite unreactive in all polymerization reactions. High molecular weight copolymers of I and III were obtained with tetrafluoroethylene, vinylidene fluoride, vinylene fluoride, ethylene, and chlorotrifluoroethylene. Those with vinylidene fluoride and ethylene were elastomers in both cases as was the copolymer of III with tetrafluoroethylene, I and II were reacted with CF3NO slowly to give low polymers and volatile products, the corresponding 1,3‐disubstituted oxazetidines. III was reacted with nitrosyl chloride to give a nitroso compound.
Relaxation phenomena of polyoxymethylene obtained from solid‐state polymerization
Authors: Yamada Nobuo , Orito Zenich , Minami Shunsuke
Published: April 2003

A highly oriented crystal of polyoxymethylene was prepared by solid‐state polymerization of trioxane single crystals. The relaxation phenomena of this sample were investigated by the dynamic viscoelastic and nuclear magnetic resonance methods from −180°C. to the melting point and were compared with those of single crystals obtained from a dilute solution in cyclohexanol and a bulk‐crystallized sample. The β absorption at about −70°C. completely disappeared, and a new absorption peak with a low intensity appeared at about −100°C. at a frequency of 138 cycles/sec. The crystalline absorption at about 150°C. also remarkably decreased in intensity. This viscoelastic behavior was confirmed by the results of a broad line NMR measurement.
Polymerization of aromatic nuclei. VIII. Molecular weight control in benzene polymerization
Authors: Kovacic Peter , Hsu Li‐Chen
Published: April 2003

The molecular weight of p‐polyphenyl prepared from benzene—aluminum chloride—cupric chloride, was affected by solvent, concentration, and temperature. Relative molecular weights were measured by polymer solubility in chloroform, and positions of the infrared para band and ultraviolet reflectance λmax. The order of effectiveness of the solvents in reducing molecular weight was: o‐C6H4Cl2 > 1,2,4‐C6H3Cl3 > SnCl4 ∼ CS2 > [C6H6]. Degradative oxidation revealed that o‐dichlorobenzene solvent was incorporated as an endgroup to only a minor extent. In general, the molecular weight of p‐polyphenyl decreased with increasing temperature and with decreasing concentration. The theoretical aspects are treated.
Kinetics of styrene homogeneous polymerization to atactic polypropylene
Authors: Wallace R. A. , Hadley K. L.
Published: April 2003

The rate of polymerization of styrene initiated by hydroperoxidized atactic polypropylene in a homogeneous toluene solution has been measured at 60 and 70°C. The reaction is first‐order with respect to styrene concentration and independent of the polymeric hydroperoxide concentration above 2 × 10−5N hydroperoxide. The individual rate constants, length and frequency of the grafted polystyrene chains along the polypropylene backbone have been calculated and their significance discussed. The initiation rate constant compares closely with values reported for the analogous tert‐butyl hydroperoxide‐initiated polymerization. The rate constant for the chain transfer termination elementary step at 70°C., however, is 18 times the value reported for the tert‐butyl hydroperoxide‐initiated polymerization of styrene. This high constant accounts for the relatively low rates of polymerization observed and high termination rates. Chain deactivation is presumably accelerated by increased collisions between growing styrene chains and inactive propylene hydroperoxide and polystyrene molecules. Distribution of polystyrene grafts on polypropylene is estimated from knowledge of effects of styrene concentration, polymeric hydroperoxide concentration, and temperature upon the rate of polymerization.
Polymers and telomers of perfluoro‐1,4‐pentadiene
Authors: Fearn James E. , Brown Daniel W. , Wall Leo A.
Published: April 2003

Perfluoro‐1,4‐pentadiene was prepared by pyrolysis of sodium 3,5,6‐trichloroperfluorohexanoate and subsequent dehalogenation. The monomer was polymerized under a number of conditions of temperature and pressure using various periods and various dose rates of γ‐ray initiation. The compound was found to undergo doublebond migration producing perfluoro‐1,3‐pentadiene. The polymer samples, some of them rubbery, others grainy, are assumed to be copolymers of the 1,4‐pentadiene and the 1,3 pentadiene, the 1,4‐diene polymerizing according to a cyclic mechanism and the 1,3‐diene undergoing the 1,4‐addition that is characteristic of butadienes under certain conditions. Infrared and nuclear magnetic resonance studies tend to support these assumptions. Under polymerization conditions the monomer also produced four distinct dimers and traces of two monomeric substances.
Relationship between the ionic nature of some organoaluminum—transition metal catalysts and the rate of polymerization
Authors: Bushick R. D. , Stearns R. S.
Published: April 2003

The electrical conductivity of several trialkylaluminum and alkyl‐aluminum halides was investigated in dry benzene at 25°C. within the concentration range of 10−1–10−3M. The equivalent conductance of the trialkylaluminum systems decreased in the following order: Al(n‐C6H13)3 > Al(n‐C10H19)3 > Al(n‐C4H9)3 > Al(i‐C4H9)3 > Al(n‐C3H7)3 > Al(C2H5)3. The conductance (1/R) of a given series was also examined and found to decrease as each alkyl group was successively replaced by a chlorine atom, thus: Al(C2H5)3 > Al(C2H5)2Cl > Al(C2H5)1.5Cl1.5 > Al(C2H5)Cl2 and Al(i‐C4H9)3 > Al(i‐C4H9)2Cl > Al(i‐C4H9)Cl2. The ion pair dissociation constants K were calculated and show in a qualitative manner the difference between various organoaluminum systems. The relative rate of olefin polymerization was related to the conductivity of various organoaluminum–transition metal catalyst systems used. The effect of Lewis bases such as monoglyme, diglyme, triglyme, and tetraglyme on triethylaluminum indicated that the first‐mentioned base forms a 1:1 type of complex as ordinary ethers do, whereas the remaining three bases utilize only two of their available oxygen atoms to coordinate with triethylaluminum. The effect of TiCl3 (in the presence of an ether) on the conductance was also determined.
Investigation by infrared absorption of the by‐products of the cyanoethylation of cotton cellulose
Authors: Chatterjee Pronoy K. , Conrad Carl M.
Published: April 2003

The soluble cyanoethyl ether of cellulose, prepared by reaction in the presence of NaOH catalyst to high degrees of substitution (DS = 2.95), can be precipitated by various organic media and contains more nitrogen than can be accounted for by simple addition of acrylonitrile at each cellulose hydroxyl group. Infrared absorption spectra of such samples and of the reacted residues show various types of vibrational absorption bands, characteristic of amino groups. At advanced stages of the reaction the characteristic broad unresolved band of cellulose extending from 1200–950 cm.−1 largely disappears, leaving only a few weaker bands which likely overlap those due to C–N stretching. Comparison is made of the spectra of the partially cyanoethylated cellulose and the polyacrylonitrile which forms in the stock acrylonitrile, to characterize the products. It is inferred that the highly cyanoethylated cellulose, partly dissolved in the acrylonitrile, further degrades and changes under a complex mechanism to various forms of amines. The yellow to orange color of the samples is assumed to be due to these by‐products. The thermogravimetric analysis reveals that these products are more heat‐resistant than the cyanoethylated cellulose.
Short‐chain branching in γ‐radiation‐induced polymerization of ethylene
Authors: Machi Sueo , Tamura Takashi , Hagiwara Miyuki , Gotoda Masao , Kagiya Tsutomu
Published: April 2003

In an attempt to elucidate the mechanism of chain‐branch formation in the polymerization of ethylene, the effect of reaction conditions on short‐chain branching in γ‐radiationinduced polymerization of ethylene was investigated by using infrared spectroscopy. The concentration of methyl groups, i.e., the frequency of short‐chain branching, increases with temperature and pressure and is independent of ethylene conversion to polymer and radiation intensity. The number of methyl groups per polymer molecule increases almost proportionally with the degree of polymerization. These facts indicate that short‐chain branching occurs mainly by the mechanism of intramolecular hydrogen transfer. The effect of pressure on the rate of chain branching can be postulated by considering the transition state to be six‐membered rings in hydrogen transfer reactions. The activation energy of chain branching is found to exceed that of propagation by 6 kcal./mole.
Solution properties of cellulose triacetate. I. Fractional precipitation
Authors: Howard P. , Parikh R. S.
Published: April 2003

Using petroleum ether as a precipitant and chloroform–acetone mixture as solvent, six fractions of cellulose triacetate were obtained by fractional precipitation. The molecular weight of each fraction was obtained from osmotic pressure measurements carried out on chloroform solutions. It was shown that virtual nonfractionability of cellulose triacetate with regard to molecular weight occurred in this system. This behavior was also observed in attempts to fractionate it from tetrachloroethane or acetic acid solutions. These results are explained by the hypothesis that specific polymer–solvent interaction takes place due to hydrogen bonding.
Degradation of polymers in high speed rotary homogenizers: A hydrodynamic interpretation
Authors: Harrington Rodney E.
Published: April 2003

Dilute solutions of DNA in neutral phosphate buffer and of polystyrene in toluene are degraded to limiting molecular weights by high speed stirring in a Virtis homogenizer equipped with special thin, highly sharpened blades. Results are interpreted and justified in terms of the hydrodynamic theory of laminar boundary layers. Estimates of critical stress values for chain scission are obtained at various limiting molecular weights for the two polymer systems, and the treatment is used to rationalize the dependence of degradation upon homogenizer speed. The agreement between the hydrodynamic theory and experimental data implies that limiting molecular degradation occurs entirely in the boundary layer region extending a distance equal to approximately the molecular contour length from the leading edge of the blade tip and that laminar flow conditions prevail in this region. It therefore seems likely that polymer molecules subjected to a critical shearing stress are essentially completely extended in the streamlines of flow. The hydrodynamic theory is finally used to explain the peculiar kinetics of molecular degradation in high speed rotary homogenizers.
Interfacial anodic polymers from benzene in hydrogen fluoride
Authors: Shepard A. F. , Dannels B. F.
Published: April 2003

Benzene–HF mixtures containing two liquid phases exhibit unusual electrical conductivity characteristics on the addition of small amounts of H2O or KF. Maximum conductivity is obtained with the anode contacting the interface between the phases and the cathode either contacting the interface or situated in the HF layer. On electrolysis, with the anode contacting the interface, polymer forms as a flat horizontal plate extending out from the anode at interface level; hydrogen is evolved at the cathode. The polymer is swollen by the cell liquid, and this composite appears to conduct electricity by a nonionic mechanism, and shows directional variation of conductivity. After removal of cell liquid from the polymer deposit, the remaining polymer is infusible, insoluble, and possesses excellent heat and chemical and electrical resistance. Elementary analyses of dry polymers from water bearing systems show loss of more than 2H per C6H6 molecule and introduction of variable amounts of F and O. Organic anionic complexes appear to be involved in the polymerization.
Triad distributions of 1,1‐diphenylethylene–methyl acrylate copolymer determined from NMR study
Authors: Ito Koichi , Yamashita Yuya
Published: April 2003

The triad distributions of 1,1‐diphenylethylene (D)–methyl acrylate (M) copolymers have been determined from NMR measurements and examined according to the terminal and penultimate models of copolymerization theory. As expected from the diamagnetic shielding by the phenyl rings of the nearest D units, the methoxy proton resonances were found to appear as three resolved peaks at 6.4–6.6 τ, 6.7–7.0 τ, and 7.2 τ, and have been assigned to the central M units of the triads MMM, MMD or DMM and DMD, respectively. The copolymer composition and the triad distributions observed are shown to agree better with the terminal model with the methyl acrylate reactivity ratio of 0.092 ± 0.010 than with the penultimate model.
Fluorine NMR spectra of poly(vinyl trifluoroacetate)
Authors: Pritchard J. G. , Vollmer R. L. , Lawrence W. C. , Black W. B.
Published: April 2003

Samples of poly(vinyl trifluoroacetate) with differing stereosequences have been prepared. The NMR signals at 56.4 Mc./sec. corresponding to the three types of triadstereosequences of the trifluoroacetate groups (isotactic, heterotactic, and syndiotactic) can be resolved. The results for specific polymers are discussed.
Diffusion of water vapor through a hydrophilic polymer film
Authors: Gillespie Thomas , Williams Bill M.
Published: April 2003

Multifilm techniques have been used to measure the diffusion coefficient of water vapor in cellophane, and the data have been compared with the integral diffusion coefficient obtained in previous work with single films. The multifilm techniques lead to a much sharper resolution of the effect of concentration on diffusion, and the maximum integral diffusion coefficient. The diffusion coefficient for water vapor in cellophane peaks at a moisture content corresponding to about 70% R. H., which is presumably the “critical concentration” discussed in previous work on the thermodynamics of water sorption by cellophane.
Grafting vinyl monomers to starch by ceric ion. I. Acrylonitrile and acrylamide
Authors: Reyes Zoila , Rist C. E. , Russell C. R.
Published: April 2003

Studies were carried out on the grafting of acrylonitrile (AN) and acrylamide (AA) to starch by ceric ion. The variables affecting the grafting of AN and AA were investigated with granular wheat starch dispersed in aqueous N,N‐dimethylformamide and ceric ammonium nitrate as catalyst. Results showed that the concentrations of monomer and catalyst are the major factors influencing the grafting of AN; thus the monomer content of the grafts can be regulated by these variables. The grafting of AA is also influenced by these variables, but to a much less degree. Increasing concentrations of monomer promote homopolymerization and increasing concentration of catalyst inhibit grafting. The extent of grafting of this monomer can best be controlled by reaction time. Under the most favorable conditions, maximum grafting efficiency (ratio of amount of grafted monomer to total amount of monomer converted to polymer) was 87% for AN and 43.8% for AA. Although the monomer content of the AN grafts was higher than that of AA grafts prepared under identical conditions, the number of branches in the grafts was almost the same; only the length of the branches was different. The AN‐starch grafts have branches of higher molecular weight.
Anionic heterogeneous polymerization of methacrylonitrile by n‐butyllithium
Authors: Feit Ben‐Ami , Heller Eri , Zilkha Albert
Published: April 2003

The anionic heterogeneous polymerization of methacrylonitrile by butyllithium in petroleum ether was investigated. The polymerization was of the “living” type, as seen from the linear dependence of the molecular weights on [MAN]/[BuLi]. This behavior was further supported by block polymerization experiments in which the monomer was added in two portions and the molecular weights obtained were directly proportional to the total monomer concentration. The initiator efficiency was low, and initiator consumption was only about 2%. This fact, together with the results of the block polymerizations showed that there was preferential addition of monomer to the growing chain ends rather than to the initiator. The molecular weights were independent of the rate of monomer addition. This as well as the “living” behavior of the polymerization of methacrylonitrile on a wide range of monomer and catalyst concentrations and the absence of chain transfer to monomer was essentially different from that of the similar heterogeneous polymerization of acrylonitrile by butyllithium previously investigated. This is due to the absence of an α‐acidic hydrogen in methacrylonitrile.