bluuebunny/crossref_metadata_2025_split huggingface dataset:
Branching in poly(butadiene‐co‐styrene). II. Radiation‐induced branching examined by viscometry
Authors: Blachford J. , Robertson R. F. 
Published: April 2003

AbstractThe dependence of intrinsic viscosity on radiation dose has been examined for poly(butadiene‐co‐styrene) irradiated in vacuo and for mixtures of this polymer and N‐phenyl‐β‐naphthylamine irradiated in air and in vacuo. If no correction is made for crosslinking in the unirradiated polymer, theories examined appear to overestimate the increase in intrinsic viscosity. However, if it is assumed that in the unirradiated polymer the number of crosslinked units per weight‐average primary molecule δ0 is 0.65, the results agree with the theory of Spiro which uses the Stockmayer‐Fixman relation between intrinsic viscosity and branching. The dose required for incipient gelation, Rg, was determined for the various samples. These results were used together with the number‐average molecular weight of the unirradiated polymer and with assumed values of δ0 to calculated values of Gx, the number of crosslinks formed per 100 e.v. of radiation energy absorbed by the sample. Good agreement with solubility and swelling results, reported elsewhere, was obtained if δ0 = 0.9.
Branching in poly(butadiene‐co‐styrene). III. Radiation‐induced branching examined by solubility and swelling
Authors: Blachford J. , Robertson R. F. 
Published: April 2003

AbstractThe dependence of solubility and swelling on radiation dose has been examined for pure polymer and polymer containing varying amounts of the antioxidant N‐phenyl‐β‐naphthylamine. Degradation did not occur when samples were irradiated in vacuo but in the presence of air degradation was initiated and crosslinking was retarded. During irradiation in vacuo the antioxidant interacted with the polymer and prevented the formation of a large number of crosslinks. An analysis of the solubility data indicated that there were 0.9 crosslinked units per weight‐average primary molecule in the unirradiated polymer, and that 1.59 crosslinks were formed in the pure polymer on the absorption of 100 e.v. of radiation energy (i.e., Gx = 1.59). These values are consistent with the swelling data but not with the experimentally determined molecular weight distribution.
Kinetics of polymerization of styrene initiated by substituted benzoyl peroxides. III. Induced decomposition
Authors: O'Driscoll K. F. , Lyons P. F. , Patsiga R. 
Published: April 2003

AbstractThe polymerization of styrene has been initiated by redox systems consisting of diethylaniline and symmetrically substituted benzoyl peroxides. Decomposition rate constants and efficiencies of initiation were determined by the dead‐end technique. Hammett plots of these rate constants and of those previously determined for polystyryl‐radical induced decomposition of substituted benzoyl peroxides have the same slope, suggesting that an SH2 mechanism is involved in the radical attack on peroxides just as in the radical attack on disulfides. The predictive ability of a combined Hammett‐type equation was shown to be excellent for the decomposition rate constants of initiating systems consisting of both substituted diethylaniline and substituted benzoyl peroxide. The effect of substituents on the efficiency of initiation remains unexplained.
Synthesis and polymerization of N[2‐(2‐methyl‐4‐oxopentyl)]‐acrylamide–A new reactive vinyl monomer
Authors: Coleman L. E. , Bork J. F. , Wyman D. P. , Hoke D. I. 
Published: April 2003

AbstractThe synthesis and polymerization reactivity of N[2‐(2‐methyl‐4‐oxopentyl)]‐acrylamide (diacetone acrylamide) is described. This reactive vinyl monomer is prepared in good yield from acetone, acrylonitrile and sulfuric acid. Diacetone acrylamide is a white crystalline solid with the water solubility characteristics of acrylamide and the organic solvent solubility of N‐alkyl acrylamides. Diacetone acrylamide readily homopolymerizes and forms copolymers with a wide variety of comonomers. Reactivity ratios in the copolymerization of diacetone acrylamide with styrene and methyl methacrylate are reported and the Alfrey‐Price Q and e values calculated. These results, along with data from the copolymerization of diacetone acrylamide with a group of typical vinyl monomers, are presented to indicate the high reactivity of this new monomer.
Glass temperatures of mixtures of compatible polymers
Authors: Krause Sonja , Roman Nicholas 
Published: April 2003

AbstractDilatometric glass transition temperatures were measured on mixtures of isotactic and syndiotactic poly(methyl methacrylate) and on mixtures of poly(isopropyl acrylate) with poly(isopropyl methacrylate). The glass temperatures of copolymers of isopropyl acrylate with isopropyl methacrylate fall on the same glass temperature versus composition curve as those of the homopolymer mixtures. The data are compared with theoretical predictions of Fox, Gordon and Taylor, and Kanig. None of these treatments can adequately explain the results.
Analysis of relaxation constants in polyurethanes
Authors: Singh Ajaib , Weissbein Leonard 
Published: April 2003

AbstractA simple Maxwell model is shown to be inadequate in describing stress‐relaxation behavior of polyurethanes at 120°C. These data fit better to a multi‐Maxwell model. Various relaxation parameters contributing to the thermal degradation of polyurethanes have been resolved, and their significance is discussed.
A dye partition method for the determination of hydroxyl endgroups in polymers
Authors: Ghosh Premamoy , Sengupta Pranab K. , Pramanik Ananda 
Published: April 2003

AbstractA dye partition method for the determination of hydroxyl endgroups in poly(methyl methacrylate) samples prepared in aqueous media with the use of hydrogen peroxide as the photoinitiator has been described. The dried polymers were treated with chlorosulfonic acid under suitable conditions whereby the hydroxyl endgroups present in them were transformed to sulfate endgroups. Spectrophotometric analysis of sulfate endgroups in the treated polymers was carried out by the application of the dye‐partition technique developed for the purpose, and thus a measure of hydroxyl endgroups in the original polymers was obtained. H2O2, in the concentration range of 0.004–0.1M, was found to incorporate an average of nearly 1 OH endgroup per polymer chain.
Free radical chain transfer to allyl monomers at low polymerization temperatures
Authors: Dawson T. L. , Lundberg R. D. 
Published: April 2003

AbstractAlkylboron–oxygen, an active, low‐temperature free radical initiator, has been employed to investigate the effects of very low polymerization temperatures on the free radical homopolymerization and copolymerization of allyl monomers. Unlike some polymerizations which have been reported to undergo dramatic changes in polymerization rates at very low polymerization temperatures, the allyl systems behaved in a like manner at high and low temperatures. Similar, low values of reduced viscosities were obtained for homopolymers of allyl monomers prepared over a 300°C. temperature range. An almost identical effect of allyl chloride concentration on the molecular weight of ethyl acrylate/allyl chloride copolymers was also observed for copolymerizations performed over a 100°C. temperature range. For solution homopolymerizations and copolymerizations the activation energy for free radical abstraction from the allyl monomer is, therefore, nearly equal to the activation energy for addition of that radical to the allyl double bond, even at temperatures down to the melting points of the monomers.
Hydrodynamic behavior of fully acetylated guaran. Test of the Eizner‐Ptitsyn theory for the semirigid macromolecule
Authors: Kurath Sheldon F. , Schmitt Charles A. , Bachhuber John J. 
Published: April 2003

AbstractPrevious results on the hydrodynamic and configurational properties of fully acetylated guaran in acetonitrile have been reexamined in light of the recent Eizner‐Ptitsyn theory for the intrinsic viscosity of the semirigid macromolecule. Numerical values for the hydrodynamic function arising in the theory were calculated by numerical summation on an electronic computer and are tabulated. The theory is found to remove some of the inconsistencies inherent in earlier hydrodynamic theories and leads to reasonable values of the persistence length and monomeric friction coefficient of guaran acetate. The persistence length calculated from viscosity data was 57.8 A., only slightly lower than the limiting value of 64 A. obtained from light scattering. The ratio of monomeric friction coefficient to solvent viscosity was ζ/η0 = 6πr0 = 57.3 A., from which a value of r0 = 3.04 A. was obtained for the hydrodynamic radius of the monomer unit.
Investigation of the elastic properties of the particle network in gelled solutions of hydrocolloids. I. Carboxymethyl cellulose
Authors: Hermans Jan 
Published: April 2003

AbstractIn order to obtain information on the structure of the particle network existing in gelled solutions of carboxymethyl cellulose, the elastic modulus was determined of series of dilutions of three samples of different molecular weight. It was found that these results could be accounted for reasonably well with the assumptions (1) that the crosslinking of molecules can be described as a reversible bimolecular aggregation between surface sites, (2) that the network formed may be described by Flory's theory of gelation and (3) that the network is deformed according to the theory of rubber elasticity.
Proton magnetic resonance spectra of variously treated nylon 66
Authors: Glick R. E. , Phillips R. C. 
Published: April 2003

AbstractA proton NMR study on variously treated nylon 66 has been made to gain additional information on hydrogen bonding in solids. The nylon sample was found to be 48% amorphous based on the deuterium exchange of amide protons. The broad line NMR spectra of all samples consisted of a superposition of a broad and narrow component at all temperatures studied. Dried nylon and dried deuterated nylon afforded identical NMR spectra. This identity was interpreted as indicating a possible electrostatic rather than overlap description of hydrogen bonds in amorphous regions. Additives, such as water, deuterium oxide, methanol, and deuterium methoxide, lowered the temperature at which the narrow‐component line width was further reduced. Such effect was consistent with other studies that indicated such additives were associated with hydrogen bonds in amorphous regions of the polymer. This effect appeared to saturate at a concentration of additive equal to that for the amide functions in the amorphous regions. Contrary to our previous studies, little difference in spectra were found for proteo and the corresponding deutero additives.
Characterization of emulsion polyethylene
Authors: Kurz James E. 
Published: April 2003

AbstractPolyethylene which was made by emulsion polymerization was characterized by means of osmometry, light scattering, and viscometry. The samples have unusually high weight‐ and number‐average molecular weights. Low molecular weight polymer which is usually present in commercial polyethylenes was not detected. The data indicate a compact, highly ramified molecular structure. The light‐scattering data suggest each latex particle is made up of essentially one giant molecule which swells but does not dissolve in organic solvents at 100°C. Swelling factors calculated from viscosity and lightscattering data indicate low degrees of crosslinking. A clear distinction cannot be made between a highly long‐chain branched structure and the crosslinked structure of microgels. Of the low‐density polyethylene, 1–2 wt.‐% is made up of molecules which have a comparable structure. In contrast, the greatest portion of the experimental samples is composed of the high molecular weight, highly ramified molecules.
Copolymerization of 2,6‐dimethyl‐4‐bromophenol with 2‐methyl‐4‐bromo‐6‐allylphenol and other p‐bromophenols
Authors: Tsou K. C. , Hoyt H. E. , Halpern B. D. 
Published: April 2003

AbstractA series of poly(phenylene oxide) copolymers was prepared from 2,6‐dimethyl‐4‐bromophenol and 2‐methyl‐4‐bromo‐6‐allylphenol by the Price method of interfacial oxidative coupling. The physical and chemical properties of the copolymers were correlated with the molar proportions of the bromophenols. The thermosetting rates were proportional to the concentration of the allyl function and were of interest in the development of high‐temperature thermosetting resins and adhesives. The preparation and copolymerization of 2‐methyl‐6‐(α‐methallyl)‐4‐bromophenol were also investigated. Homopolymerization of 2‐methyl‐4‐bromophenol or 2,2′‐methylenebis‐(4‐bromo‐6‐methylphenol) under the same conditions did not occur to any significant degree. When these bromophenols were used in attempted copolymerizations with 2,6‐dimethyl‐4‐bromophenol, only low molecular weight homopolymers of the latter were obtained. The effect of these nonpolymerizing bromophenols as chain stoppers is discussed in connection with the mechanism for this type of polymerization.
Dissolution and crystallization temperatures of high polymers. II. New method of characterization of polyacrylonitrile
Authors: Chiang R. 
Published: April 2003

AbstractPolyacrylonitriles prepared under different conditions have similar infrared spectra, x‐ray diffraction patterns, and densities, but they show marked differences in dissolution and crystallization behavior. On the basis of the dissolution and crystallization behavior, a characterization method, sensitive enough to show a small difference in chain regularity in the polymer, yet independent of the physical state and previous history of the sample, has been developed. With this method, polyacrylonitriles with different chain regularities can be conveniently differentiated.
Polymerization of vinylphosphonium compounds
Authors: Rabinowitz Robert , Marcus Ruth 
Published: April 2003

AbstractThe mechanism of the ionizing radiation‐initiated polymerization of aqueous solutions of tributylvinylphosphonium bromide (TBVPB) to high molecular weight polymers was established to be free radical. Similar polymerization was observed in acetone, acetonitrile, and acetic acid. The failure of even high radiation doses to induce the polymerization of TBVPB when in chlorobenzene solution was explained on the basis of the interaction of chlorine atoms with bromide ions. Triethylvinylphosphonium bromide, tricyclohexylvinylphosphonium bromide, and dimethylphenylvinylphosphonium bromide gave little or no polymer using conditions which polymerized TBVPB almost completely. Conventional oxidizing peroxidic free radical catalysts failed to initiate the polymerization of TBVPB. Nonoxidizing materials like di‐tert‐butyl peroxide and azo compounds did catalyze the polymerization to give high molecular weight polymers. Apparently the oxidizing peroxides are quickly reduced by the bromide ion before any homolytic cleavage can occur. Tributylvinylphosphonium chloride was polymerized in aqueous solution using potassium persulfate, the homolytic cleavage of persulfate competing favorably with redox processes involving the chloride ion. Copolymerization of TBVPB with a series of common monomers resulted in copolymers containing varying amounts of phosphorus in the expected order.
Cyclo‐ and cyclized diene polymers. IV. Infrared spectra of cyclopolyisoprenes and cyclized polyisoprenes
Authors: Kössler I. , Vodehnal J. , Štolka M. 
Published: April 2003

AbstractThe infrared absorption bands which appear in cyclized polyisoprenes (cis‐1,4‐,trans‐1,4‐, and 3,4‐) and in ladder cyclopolyisoprenes have been divided into three groups: (1) absorption bands typical of six‐membered saturated rings, (2) bands characteristic of endgroups, and (3) absorption bands which have their origins in chemically bound solvent from transfer reactions. The assignment of these bands to probable modes of vibration has been made.
Aromatic polybenzoxazoles
Authors: Moyer W. W. , Cole Carl , Anyos T. 
Published: April 2003

AbstractThe polymerization of 3,3′‐dihydroxybenzidine with the phenyl esters of phthalic, isophthalic, terephthalic, and 5‐chloroisophthalic acids yielded a series of aromatic polybenzoxazoles exhibiting high thermal stability. Melt polymerization afforded these polymers in quantitative yield with inherent viscosities in the range of 0.20–1.04 and thermal stability very similar to those obtained with the aromatic polybenzimidazoles. Homopolymerization of 3‐amino‐4‐hydroxybenzoic acid and 4‐amino‐3‐hydroxybenzoic acid was achieved through the preparation of an intermediate poly(ester‐amide) followed by thermal cyclization (at 250–300°C.) to the benzoxazole unit. Six model compounds containing the benzoxazole unit were prepared for use as standards of reference. These were 2‐phenylbenzoxazole, 2,2′‐p‐phenylene‐bisbenzoxazole, 2,2′‐m‐phenylene‐bisbenzoxazole, 2,2′‐o‐phenylene‐bisbenzoxazole, 2,2′‐(5‐chloro‐1,2‐phenylene)‐bisbenzoxazole, and 2,2′‐(diphenyl)‐6,6′‐bibenzoxazole.
Interaction of ethylaluminum dichloride with organic nitrogen and phosphorus compounds in three‐component polyolefin catalysts
Authors: McConnell Richard L. , McCall Marvin A. , Cash G. O. , Joyner F. B. , Coover H. W. 
Published: April 2003

AbstractThe chemistry of three‐component coordination catalysts for the polymerization of α‐olefins is very complex. The present investigation was initiated to elucidate the chemistry involved in the interaction of third‐component compounds such as hexamethylphosphoric triamide, tributylamine, triphenylphosphine, or dimethylformamide with ethylaluminum dichloride. The present chemical and spectral data demonstrate that ethylaluminum dichloride and third‐component compounds form stable complexes even at temperatures up to 100°C. in the absence of solvents or in homogeneous solutions. These data are in agreement with the fact that organoaluminum compounds form stable complexes with a variety of electron‐donor compounds. The ethylaluminum dichloride third‐component complexes in combination with titanium(III) chloride produce highly stereospecific catalysts for the polymerization of α‐olefins.
Block copolymers based on 2,2‐bis(4‐hydroxyphenyl)propane polycarbonate. II. Effect of block length and composition on physical properties
Authors: Merrill Stewart H. , Petrie S. E. 
Published: April 2003

AbstractBlock copolymers of 2,2‐bis(4‐hydroxyphenyl)propane (BPA) polycarbonate and poly(ethylene oxide) (PEG) were used in a study of the influence of composition and block size on the thermal and mechanical properties of block copolymers. By copolymerizing polycarbonates of controlled molecular weight with similarly characterized poly(ethylene oxide) glycols, it was found feasible to alter the size of each type of block independently of the other. To complement this investigation, the effect of varying the concentration of a compatible plasticizer on the physical properties of the BPA polycarbonate was also studied. The BPA polycarbonate was rendered thermally crystallizable and flexible either by the copolymerization with PEG or by the addition of low molecular weight plasticizer. Degradation of tensile modulus and strength was observed with increased PEG content but was less for the copolymers with the longer blocks.
Alkyl‐free cobalt catalyst for the stereospecific polymerization of butadiene
Authors: Balas J. G. , De La Mare H. E. , Schissler D. O. 
Published: April 2003

AbstractThe stereoselective polymerization of butadiene to a predominantly cis polymer has been carried out with complex cobaltous halide catalysts, e.g., CoCl2·AlCl3. The unique features of such polymerizations are the homogeneous nature of the catalysis and the activity of such catalysts in the absence of any added reducing agent. The composition and spectroscopy of some of these catalyst solutions have been studied and possible structures proposed. The present status of the work does not permit a conclusive report on the mechanism of this polymerization, but some results of termination with tritiated methanol (CH3OH3) are described. Unfortunately, these experiments do not define the nature of the propagating end of the polymer chain.
Raman spectra of polyethers
Authors: Matsui Yoshiki , Kubota Tanekazu , Tadokoro Hiroyuki , Yoshihara Toshio 
Published: April 2003

AbstractExperimental techniques for the measurements of the Raman spectra of crystalline high polymers have been developed. The preparation of samples and a procedure for the measurements are described in some detail. The Raman spectra of polyoxymethylene (CH2O)n, deuterated polyoxymethylene (CD2O)n, poly(ethylene oxide) (CH2CH2O)n, and polytetrahydrofuran (CH2CH2CH2CH2O)n have been obtained. These results as well as the infrared data are interpreted on the basis of the factor group analyses and the normal coordinate treatments. The experimental results are in fairly good agreement with the results of the theoretical treatments for these polyethers.
Electron spin resonance studies on oriented polyoxymethylene
Authors: Yoshida Hiroshi , Rånby Bengt 
Published: April 2003

AbstractElectron spin resonance spectra of stretched polyoxymethylene irradiated with γ‐rays from a Co60 source were studied. With suitable treatment three kinds of spectra were selectively observed: doublet with irradiation and measurement at room temperature; singlet with irradiation and measurement at about −180°C.; triplet with the irradiation at about −180°C. and the measurement at −102°C. The doublet and the triplet spectra showed anisotropy, while the singlet did not. These observations confirm the assignment of the spectra so far reported with unoriented polyoxymethylene, i.e., CH2O, OĊHO, OĊH2 for the singlet, doublet, and triplet, respectively. The doublet spectrum is treated as related to the anisotropic hyperfine coupling tensor, the anisotropic g value and the chain conformation in crystalline polyoxymethylene. A rather small value, p≈0.45, was obtained for the spin density at the central carbon atom.
1‐Fluorovinyl methyl ketone: Preparation and polymerization
Authors: Sedlak John A. , Matsuda Ken 
Published: April 2003

Abstract1‐Fluorovinyl methyl ketone, a new vinyl monomer, was prepared by dehydration of 1‐fluoro‐2‐hydroxyethyl methyl ketone with phosphoric acid or boric anhydride. The monomer was stabilized with anhydrous ammonia during preparation and storage. Homopolymers of 1‐fluorovinyl methyl ketone were prepared with free‐radical initiators in bulk, in solution, and in buffered emulsions.
A generalization of the debye light‐scattering equation
Authors: Heller Wilfried 
Published: April 2003

AbstractThe Debye light‐scattering equation is generalized by making allowance for the variation of (dn/dc)and therefore of Hwith the concentration of the solute. This should allow one to use it with more concentrated solutions provided light scattering is weak enough (oligomer solutions) so that multiple scattering does not exclude such a procedure.
Radiation polymerization of crystalline trithiane
Authors: Lando J. B. , Stannett V. 
Published: April 2003

AbstractThe polymerization of single crystals and finely powdered samples of trithiane (m.p. 215–216°C.) was accomplished by irradiation of the samples at room temperature with Co60 γ‐radiation to doses of 1–10 Mrad. Polymerization occurred during subsequent heating of the samples at 180°C. The conversion to polythiomethylene after a given time of heating at 180°C. is dependent on radiation dose, the G values for conversion being higher at lower doses. Purified polymer samples were studied by means of differential thermal analysis. Polymerized single crystals of trithiane were found to retain their orientation in three dimensions, although the polymer samples were systematically twinned. The directions of greatest chain growth were along the diagonals in the (ab) plane of the monomer. This reaction can be classified as topotactic; that is, the molecular orientations of the product are correlated with the molecular orientation in the reactant crystal. The relationship between the polymer structure and that of the monomer is evaluated.