bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heteroaromatic polymers. The polybithiazoles
Authors: Longone Daniel T. , Un Howard H. 
Published: April 2003

AbstractThe polycondensation of dithioöxamide with bifunctional aromatic bromomethyl ketones affords a series of poly‐4,4′‐diaryl‐2,2′‐bithiazoles. These polymers exhibit outstanding thermal stability. They are characteristically insoluble, infusible, highly crystalline, and of high molecular weight. Controlled structural variations within the polymer recurring unit allow for modifications of gross polymer properties. Structural characterization and thermal stability measurements are discussed.
Polymers containing the 3,3,3′,3′‐tetramethyl‐1,1′‐spirobiindane residue
Authors: Stueben K. C. 
Published: April 2003

AbstractA variety of condensation polymers were prepared from the 6,6′‐dihydroxy‐3,3,3′,3′‐tetramethyl‐1,1′‐spirobiindanes including polyesters, polyurethanes, and a polyhydroxyether. The polycarbonate displayed good oxidative resistance at 200°C. but was found to lack toughness despite the presence of a low temperature transition at −100°C. A tendency toward brittleness was also evident in the other polymers and copolymers prepared. The contribution of the spiroindane structure to polymer properties is discussed. All of the polymers studied were amorphous and displayed high glass transition temperatures.
Polymer–filler interaction. Thermodynamic calculations and a proposed model
Authors: Kwei T. K. 
Published: April 2003

AbstractFrom a study of the sorption of water vapor by epoxy polymers filled with titanium dioxide, the differences in enthalpy and entropy of the filled and the unfilled polymers are calculated. The enthalpy and the entropy of the filled polymer are smaller than those of the unfilled polymer by about 2 cal./g. and 6 × 10−3 e.u., respectively. These differences may be explained by the existence of a higher degree of local ordering of the polymer segments. A model is proposed to describe the interaction between the polymer and the filler as a function of the distance from the interface. It appears that polymer segments at a distance less than 1500 A. from the surface of the filler particle are within the sphere of influence of the filler. The effects of filler incorporation of the thermal expansion coefficient, heat capacity, and partial molar heat of solution of the polymer are discussed in terms of the model.
Oxonium ion‐initiated polymerization of tetrahydrofuran
Authors: Vofsi David , Tobolsky Arthur V. 
Published: April 2003

AbstractThe kinetics of polymerization of tetrahydrofuran was studied, with the use of triethyloxonium tetrafluoroborate as initiator and dichloroethane as solvent. Conversion versus time and degree of polymerization versus time were measured at 0°C. at various monomer and initiator concentrations. The data were systematized by means of a kinetic equation, and the absolute rate constants for initiation and propagation were determined.
Range of practical validity of the debye and the rayleigh equations for determining molecular weights from light scattering and methods allowing a limited extension of this range
Authors: Heller Wilfried 
Published: April 2003

AbstractUsing the equivalence of the Rayleigh and the Debye equations on light scattering as a basis, the per cent error in molecular weight committed on using the latter is evaluated by comparing results with those derived from the exact Mie scattering functions. The variable is, by necessity, the quantity M V/λ3 as long as the radiation diagram is symmetrical, where M is the molecular weight, V the partial specific volume of the solute, and λ the wave length in the medium. The errors committed are consequential only if the dissymmetry is finite. A possible method is outlined for correcting M values obtained from the Debye equation outside of its range of practical validity. It may be applied as long as the dissymmetry does not exceed about 30%. The possibility of determining from light scattering the approximate degree of swelling of latex particles and the size of clusters of spheres is discussed briefly.
A unified approach to failure and its application to highly filled polymers
Authors: Majerus J. N. 
Published: April 2003

AbstractTwo interrelated general approaches to the study of structural failure of highly filled polymeric materials, e.g., a solid propellant, are described. These consist of the macroscopic (thermodynamics and continuum mechanics) and microscopic (molecular model) methods of analysis in conjunction with solid propellant experimental data. The thermodynamic investigation indicates that propellant material under loading goes through stages of stable and unstable behavior which depend upon the rate at which work is absorbed and dissipated by the material. The instability point seems to correlate with results from subscale motors. The thermodynamic investigation is then extended by a functional analysis of failure treated from a viewpoint of continuum mechanics. Since fracture, per se, is a physical observable, it is represented by a “state vector” in n‐dimensional space. The number of dimensions of this space depends upon the basic variables involved in fracture. Since the correct failure criteria must be tensorally consistent with the tensor rank of fracture, distinct sets of functions can be applied to experimental data. The data are compared to the classical scalar functions of failure. They were obtained from uniaxial and biaxial creep and relaxation tests to failure, uniaxial and biaxial tension tests conducted under constant rates of loading and of strain, with and without superimposed hydrostatic pressure, and pure shear tests to failure. The correlation between the different types of induced failure is demonstrated through the microscopic approach by use of molecular models and the application of statistical mechanics.
Radiation‐induced polymerization of 1,2‐cyclohexene oxide
Authors: Cordischi D. , Lenzi M. , Mele A. 
Published: April 2003

AbstractRadiation‐induced polymerization of 1,2‐cyclohexene oxide was investigated in the liquid and in the solid state. Addition of water drastically reduces the rate of polymerization and the molecular weight of the obtained polymer. The results have been interpreted according to an ionic mechanism.
Preparation and polymerization of propenyldiphenylphosphine oxide isomers
Authors: Welch F. J. , Paxton H. J. 
Published: April 2003

AbstractIsopropenyldiphenylphosphine oxide (I) and both cis‐ and trans‐n‐propenyldiphenylphosphine oxides (II) have been prepared and their structures assigned primarily on the basis of infrared and NMR analyses. Like vinyldiphenylphosphine oxide, these monomers are polymerized sluggishly by free radical catalysts although copolymers with may common vinyl monomers can be prepared. Grignard reagents polymerize (I) very rapidly to low molecular weight products, but the polymerization of II by these catalysts is slower and requires larger amounts of catalyst. Evidence is presented which indicates that in the polymerization of vinyldiphenylphosphine oxide by Grignard reagents molecular weight may be limited by a chain transfer to monomer process.
Reactions of high molecular weight polyacrolein
Authors: Bergman Elliot , Tsatsos W. T. , Fischer R. F. 
Published: April 2003

AbstractHigh molecular weight polyacrolein reacts readily with a variety of aldehyde reagents to form soluble derivatives. The reactions proceed at a measureable rate at room temperature when suitably catalyzed by acid or base. Gentle warming is occasionally required to attain useful reaction rates. The reactions of polyacrolein are conveniently divided into those involving (a) the aldehyde function alone or (b) the active hydrogen alpha to the carbonyl. The first class includes reactions with HCN, NaHSO3 (SO2), Na2S2O4, primary and secondary amines, alcohols, thiols, and aqueous based. The second type reaction includes additions to the α‐carbanion and oxidations involving chain scission. Depending on the reagent employed and conditions, reaction of polyacrolein gives open‐chain derivatives or the 2,6‐disubstituted tetrahydropyran structure which is present to a large extent in hydrated polyacrolein.
Base‐catalyzed disproportionation of polyacrolein yields a polymethylol polycarboxylic acid via internal Cannizzaro reaction. In the presence of formaldehyde, α‐methylol groups are introduced during the disproportionation.
cis‐trans isomerization in polyisoprenes. Part VII. Double bond movement during the isomerization of natural rubber and related olefins
Authors: Cunneen J. I. , Higgins G. M. C. , Wilkes R. A. 
Published: April 2003

AbstractWhen trans‐3‐methylpent‐2‐ene or trans‐3‐methylhex‐3‐ene is treated with butadiene sulfone, thiolbenzoic acid, and dibenzoyl disulfide under anaerobic conditions, the olefin undergoes only cis—trans isomerization. However, similar reactions in the presence of oxygen or peroxides also cause changes in the position of the double bond. The latter structural modification is probably caused by acidic compounds formed by oxidation of the isomerization reagents. With natural rubber the nonrubber substances prevent movement of the double bond, and cis–trans isomerization is the sole change, even when the reaction with sulfur dioxide is carried out under aerobic conditions.
Benzaldehyde polymerization and copolymerization studies
Authors: Raff R. , Cook J. L. , Ettling B. V. 
Published: April 2003

AbstractIn attempts to homopolymerize benzaldehyde with various ionic and coordination catalysts, or by γ‐radiation, only the ionic catalyst BF3 etherate formed a polymeric product. This product was identified as polybenzyl with a degree of polymerization (DP) of 133. Mixtures of benzaldehyde and styrene did not copolymerize under γ‐irradiation, but yielded only polystyrene. With a BF3 etherate catalyst, however, mixtures of styrene and benzaldehyde were found to have copolymerized through the carbonyl group of the latter, and a 50 : 50 styrene–benzaldehyde monomer mixture yielded an 80:20 styrene–benzaldehyde copolymer with a DP of 139.
Divinyl copolymerization initiated by high intensity, low energy electrons
Authors: Burlant W. , Hinsch J. 
Published: April 2003

AbstractSolutions of unsaturated esters in styrene were copolymerized by 0.04 M.e.v. electrons at dose rates of 0.44–85.8 Mrad/min. Disappearance of each monomer and gel fractions were measured as a function of dose rate. Rates noted under these conditions of high linear energy transfer exhibited linear dependence on intensity, followed by a region independent of intensity. The data suggest that polymerization occurs in discrete volume elements, and that chain growth is initiated by hot radicals. For 65% ester solutions, the polymerization rate of the bulk sample, dαt/dt, is given by dαt/dt = {(kp*2/kt,)[M20]}V, where kp* is an activated propagation rate constant tenfold greater than that for more conventional polymerizations, kt is the termination rate constant, [M20] is the starting ester concentration, and V, proportional to the radiation intensity, is the volume fraction of the sample occupied by the reacting elements. The volume of the element in which polymerization is occurring, estimated from experimental data and using reasonable values for the life of a growing radical, is 3 × 109 A.3, a value consistent with what is known of electron impact processes in liquids.
Phase separation, viscosity, and thermodynamic parameters for poly‐2‐methyl‐5‐vinylpyridine–diluent systems
Authors: Gechele G. B. , Crescentini L. 
Published: April 2003

AbstractLiquid–liquid phase separation has been investigated for several poly‐2‐methyl‐5‐vinylpyridine fractions in eleven solvents. The plots of precipitation temperatures against polymer volume fractions are shown for a few systems. The agreement between two curves calculated according to Flory and the experimental ones is only qualitative, and the calculated critical concentrations are much smaller than the experimental ones. Plots of reciprocal critical precipitation temperature against reciprocal square root molecular weight of the polymer are straight lines. From the intercepts and slopes the values of the thermodynamic paramerers θ and ψ were calculated. Intrinsic viscosities were determined for a fraction of 990,000 molecular weight in five solvents at various temperatures. Theta measurements yielded for Flory's constant K the value 8.4 × 10−4, which can be assumed to be constant with the temperature and the solvent. Moreover the parameter θ and ψ were calculated according to Flory and Fox, Kurata, Stockmayer, and Roig, and Kurata and Stockmayer. The viscometric ψ are different from each other and all much smaller than the ones from phase separation. An attempt is made to compare the above theories by utilizing intrinsic viscosity results on fractions of various molecular weights in n‐propyl acetate and methyl isobutyl ketone. The results show nearly the same behavior for all the three theories.
Thioureas and isothiuronium salts. Polymeric derivatives
Authors: Overberger C. G. , Friedman Herbert A. 
Published: April 2003

AbstractA series of derivatives of N‐(p‐vinylphenyl)thiourea were found to be capable of free radical polymerization. N‐(p‐Vinylphenyl)‐N'‐methylthiourea was copolymerized with p‐aminostyrene, p‐N,N‐dimethylaminostyrene, and N‐vinyl‐phthalimide. S,N‐Dimethyl‐N‐(p‐vinylphenyl) isothiuronium iodide was also polymerized in a similar fashion. p‐Vinylphenyl isothiocyanate was found to undergo polymerization with difficulty. The latter polymer was reacted with dimethylamine to yield the polymeric thiourea.
Gel permeation chromatograms: Approximate relation of line shape to polymer polydispersity
Authors: Berger H. L. , Shultz A. R. 
Published: April 2003

AbstractCharacteristics of gel permeation chromatograms are investigated for three molecular distribution functions assuming a linear relation between elution volume and the logarithm of solute molecular weight. The average molecular weight, Mgpc, determined by the peak position of a chromatogram lies between the Mw and Mn for a polydisperse polymer.
Penultimate effect in stereospecific polymerization by ionic mechanism
Authors: Ohsumi Y. , Higashimura T. , Okamura S. 
Published: April 2003

AbstractTo clarify the penultimate effect in the stereospecific polymerization by ionic catalysts, the relationship between the steric structure of the polymer and polymerization conditions was studied for α‐methylstyrene (αMS), methyl vinyl ether (MVE), and methyl methacrylate (MMA) from our result and literature results. Two possible probabilities of an isotactic addition considering the penultimate effect, Pii and Psi, are compared. We define the α value as Psi = αPii. The greater the deviation of the α‐value is from unity, the greater the penultimate effect. It is shown that the α value in a given monomer is constant for a wide range of tacticity in the various conditions. In αMS, the α value is unity and there is no penultimate effect. Otherwise, in the MVE‐BF3.‐O(C2H5)2 system, α is 0.7 and the penultimate effect is present. When MMA is polymerized by alkali alkyl, the α value is changed by the kind of alkali metal, that is, α values in toluene solution are 0.45, 0.65, and 0.75 for Li, Na, and K, respectively.
Poly(chloroaldehydes). III. Poly(dichloroacetaldehyde)
Authors: Rosen Irving , Sturm C. L. 
Published: April 2003

AbstractAlthough dichloroacetaldehyde has only one chlorine less than chloral, the polymerization and polymer characteristics are quite different. Dichloroacetaldehyde is readily polymerized by Lewis acid catalysts to polymer with terminal hydroxyl groups. The catalyst BF3·Et2O, at 0°C., produces very high molecular weight polymer, in bulk polymerization. A DPn of about 400 is readily attainable. The characteristics of the polymerization indicate a cationic type, with greater dependence of DP upon chain termination rather than chain transfer. The polymer is readily end‐capped by acetic anhydride, with a pyridine catalyst, to increase its thermal stability. Melting point, infrared spectra, and x‐ray diffraction measurements confirm that the polymer produced under these conditions is amorphous. Cast films of the polymer could be only partially oriented The polymer is soluble in many common organic solvents.
Polymerization and telomerization reaction of olefins with a tertiary amine‐coordinated lithiumalkyl catalyst
Authors: Eberhardt G. G. , Davis W. R. 
Published: April 2003

AbstractTertiary amine‐chelated alkyllithium compounds were investigated as catalyst systems for the reactions of olefinic hydrocarbons. Ethylene is polymerized in paraffinic hydrocarbon solution to a high‐melting, low molecular weight polyethylene wax having terminal olefinic unsaturation. A chain‐transfer reaction is interpreted in terms of an olefin displacement reaction. Other olefins with available allylic hydrogen are metallized in this position. The C4 olefins in conjunction with ethylene were found to undergo a telomerization reaction, involving the olefin as telogen and ethylene as taxogen. The structure and the mechanism of formation of these telomeric olefins are discussed.
Phase separation of some acrylonitrile—butadiene—styrene resins
Authors: Gesner B. D. 
Published: April 2003

AbstractOne model and two commercial ABS (acrylonitrile–butadiene–styrene) resins have been separated into three polymeric phases: polybutadiene, styrene–acrylonitrile copolymer, and styrene–acrylonitrile copolymer grafted onto polybutadiene. A third commercial ABS resin has been separated into two polymeric phases: styrene–acrylonitrile copolymer and butadiene–acrylonitrile copolymer.
Base‐catalyzed polymerization of p‐styrenesulfonamides. II. N‐methyl and N‐phenyl derivatives
Authors: Konishi A. , Yoda N. , Marvel C. S. 
Published: April 2003

AbstractN‐Methyl‐ and N‐phenyl‐p‐styrenesulfonamides have been prepared, and they have been polymerized by basic and radical initiators. The polymers prepared by base catalysis contain units resulting from proton‐transfer polymerization and units of the vinyl type. The ratio of the two recurring units has been established by determining the NH absorption in the infrared. The polymers are completely soluble in strong alkali, which shows that they contain substantial numbers (60–80%) of vinyl‐type units, since a proton‐transfer unit would not have an acidic sulfonamide group to produce solubility.
Gas permeability of three isomeric polyhydroxyethers
Authors: Stenstrom J. A. , Hale W. F. 
Published: April 2003

AbstractThe gas permeation behavior of three isomeric polyhydroxyethers has been studied with the use of hydrogen, helium, oxygen, and carbon dioxide as the test gases. Amorphous polymers were prepared from epichlorohydrin and 1,8‐, 2,8‐, and 1,2‐bis(4‐hydroxyphenyl)menthane at equivalent molecular weight levels and therefore differed only in the position of substitution on the menthane unit. The permeabilities of the 1,8‐, 2,8‐, and 1,2‐isomers were in the approximate ratio of 1:2:4 for each gas at 23°C. Also, this ratio was observed to hold from 23 to 80°C. for carbon dioxide. Since the diffusion constants were found to be in the same ratio, the gas solubilities were essentially identical for the three isomeric polymers. Therefore, the permeability data could be related directly to the steric configurations of the polymers and were consistent with the hypothesis that the permeation process is controlled primarily by the degree of chain packing. Activation energy data were interpreted as an indication that the diffusion mechanism is similar for each of the isomers. In addition, the relationship of permeability, density, and glass transition temperature to steric configuration of the isomeric polymers was discussed.
Inorganic polymers. Part II. The thermal bulk condensation polymerization of P‐phenylphosphonic diamide
Authors: Shaw R. A. , Ogawa Takeshi 
Published: April 2003

AbstractThe thermal bulk condensation polymerization of P‐phenylphosphonic diamide under a variety of conditions is described. Polymerization and degradation processes were observed. The maximum molecular weights attained were about 3000. These polymers, soluble in most organic solvents, are hydrolytically unstable, giving low molecular weight products soluble only in hydroxylic solvents.
Anionic polymerization of ω‐lactam. Part II. Polymerization of ε‐caprolactam by alkali metal and imino chlorides
Authors: Yasumoto Takaya 
Published: April 2003

AbstractIt has been found that imino chlorides may be used as cocatalysts for the alkaline polymerization of ε‐caprolactam. Addition of an imino chloride shortens the induction period before polymerization, and the polymerization proceeds rapidly at a low temperature below the melting point of the polymer. A mechanism is proposed for the anionic polymerization of ε‐caprolactam with alkali metal and an imino chloride. It involves the formation of a reactive N‐imidoyl lactam and chain propagation by the stepwise addition of anionic lactams at the end of a molecule. The conditions for the polymerization have been carefully investigated. As the concentration of imino chloride increases, the conversion and relative viscosity increase slightly, but ε‐caprolactam is unpolymerizable when equimolar quantities of imino chloride and alkali metal are present, or when there is a higher concentration of imino chloride than of alkali metal.
Determination of degree of crosslinking in natural rubber vulcanizates. Part VII. Crosslinking efficiencies of di‐tert‐butyl and dicumyl peroxides in the vulcanization of natural rubber and their dependence on the type of natural rubber
Authors: Bristow G. M. , Moore C. G. , Russell R. M. 
Published: April 2003

AbstractThe efficiency with which di‐tert‐butyl peroxide and dicumyl peroxide vulcanize (crosslink) natural rubber depends on the type of natural rubber. Crosslinking efficiencies of the peroxides are increased by acetone extraction of the rubber and by increasing the concentration of peroxide but in no case studied was either peroxide 100% efficient. These findings indicate that the natural rubber samples contain non rubber compounds which compete with the rubber hydrocarbon for reaction with the peroxide. The implications of these findings are: (1) that the values of chemical crosslinks determined by Moore and Watson from the yields of tert‐butyl alcohol and methane formed when an unextracted deproteinized pale crêpe is crosslinked with di‐tert‐butyl peroxide may be overestimated; and, thus, (2) the calibration of Mullins which relates the number of chemical crosslinks in a natural rubber–peroxide vulcanizate to the number of physically manifested crosslinks may require revision.
Aromatic poly(phenylene)4‐phenyl‐1,2,4‐triazoles
Authors: Holsten J. R. , Lilyquist M. R. 
Published: April 2003

AbstractHigh molecular weight poly(m‐,p‐phenylene)4‐phenyl‐1,2,4‐triazole has been prepared by the cyclocondensation reaction of aniline with high molecular weight poly(m‐,p‐phenylene) hydrazide in polyphosphoric acid (PPA). It is proposed that the cyclocondensation reaction proceeds through the attack of “free” aniline on either or both of two intermediate substrate polymers (a polyhydrazide phosphate and/or a protonated polyoxadiazole) to provide the desired polytriazole composition. The nature of the intermediate substrate polymer is determined primarily by the reaction temperature. Known model compounds containing the 4‐phenyl‐1,2,4‐triazole ring were prepared from model hydrazide compounds under cyclocondensation reaction conditions to demonstrate the validity of this synthesis approach to the polytriazoles. Thermally stable fibers and films having maximum zero strength temperatures of 465 and 490°C., respectively, have been prepared from formic acid solutions of poly(m‐,p‐phenylene)4‐phenyl‐1,2,4‐triazole. Thermogravimetric and differential thermal analyses of this polymer showed that the polymer was stable in nitrogen up to 512°C.