bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of crosslink density on the creep behavior of natural rubber vulcanizates
Authors: Plazek Donald J. 
Published: April 2003

AbstractTorsional creep measurements on four natural rubber vulcanizates, crosslinked to different degrees, were carried out in the temperature range from −50 to 90°C. This investigation complements the studies on identical samples of the stress relaxation behavior by Chasset and Thirion and of the dynamic mechanical response by Ferry, Mancke, Maekawa, Ōyanagi, and Dickie. The creep measurements reported are shown to be in agreement with the stress relaxation results. In addition to the usual temperature reduction, a superposed curve was obtained for the long time response using the apparent molecular weight between crosslinks, Mc, as a reduction variable. The variation in viscoelastic response with crosslink density is interpreted as a restrictive action of the chemical crosslinks on the transient entanglement network.
Group motions in the glassy state of some substituted polystyrenes and poly(vinyl benzoates)
Authors: Baccaredda Mario , Butta Enzo , Frosini Vittorio , Magagnini Pier Luigi 
Published: April 2003

AbstractMechanical damping measurements were carried out in the range of 103–105 cps and between 60°K. and the softening point on some substituted Polystyrenes and poly(vinyl benzoates) containing different substituents (methyl groups, methoxy groups, and halogen atoms) either in the ring or in the main chain. The ortho and meta ring‐substituted polystyrenes do not show any secondary mechanical relaxation in the glassy state, although all the other substituted polystyrenes, exhibit a low‐temperature damping peak (δ process) (which is in some way connected with ring motions) whose height and temperature location depend on nature, position, and number of substituents. Substituents in the para position of the ring or in the α position in the backbone chain shift the δ peak of the unsubstituted polystyrene towards higher temperatures; this shift is accompanied by an increase of the apparent activation energy E*. Substitution in the β position, on the contrary, does not affect the δ peak. Analogous results are obtained for substituted poly(vinyl benzoates), which exhibit, in addition, a β relaxation effect, associated with carboxyl group motions. A very good correlation is found between the values of E* and the limiting relaxation time τ for the δ relaxation of polystyrenes and poly(vinyl benzoates), similarly substituted in the ring, indicating that the δ relaxation leads to absorption curves in the mechanical relaxation spectrum which are characteristic of the structure of the aromatic side chain.
X‐ray determination of crystallinity and orientation in poly(ethylene terephthalate)
Authors: Dumbleton J. H. , Bowles B. B. 
Published: April 2003

AbstractThe measurement of crystallinity and orientation in poly(ethylene terephthalate) is discussed. A simple procedure is given for the estimation of orientation from the (105) plane, and it is shown that methods which use the equatorial planes are subject to certain disadvantages. In addition a method is given for the measurement of x‐ray crystallinity. The technique is applied to fibers and films of various treatments and a linear relation is found between density and x‐ray crystallinity.
Crystal structure of poly(m‐xylylene adipamide)
Authors: Ōta T. , Yamashita M. , Yoshizaki O. , Nagai E. 
Published: April 2003

AbstractThe crystal structure of poly(m‐xylylene adipamide) was reinvestigated by x‐ray diffraction. It is found that the helical chain model proposed by Yoda et al. needs to be corrected to a large extent. The unit cell obtained is triclinic with dimensions a = 12.01 A., b = 4.83 A., c = 29.8 A. (fiber axis), α = 75.0° = 26.0°, and γ = 65.0°, in which one molecular chain with two chemical repeating units is involved. The space group is C1i–P1. An almost planar zigzag chain conformation with a small degree of contraction from the original planar arrangement is given. The CH2 planar zigzag chain and the aromatic rings are so oriented that their planes are inclined to the c axis at an angle of a few degrees. The hydrogen‐bonded sheets nearly coincide with the (100) plane and the aromatic rings are close to the (120) plane, which is nearly perpendicular to the direction of hydrogen bonding.
Infrared characterization of polymorphism in polybutene‐1
Authors: Luongo J. P. , Salovey R. 
Published: April 2003

AbstractThe transformations of the polymorphic forms of polybutene‐1 (I,II,III) were studied by infrared spectroscopy. Attenuated total reflectance spectra demonstrate that the II → I transformation occurs initially and most rapidly on the film surfaces. Electron irradiation experiments showed the II → I conversion can be suppressed by irradiation. The degree of suppression was dependent on the irradiation dose. Comparison of spectra on irradiation in air and vacuum indicate that radiation‐produced radicals are scavenged by oxygen, preventing intermolecular crosslinking and allowing normal expansion of the helix during transformation. In addition, remolding an irradiated sample of II caused immediate conversion to I rather than its return to II as was noted when unirradiated samples are remolded. These observations are related to certain conformational changes in the molecular structure.
Block copolymerization of methyl methacrylate with poly(ethylene oxide) radicals formed by high‐speed stirring
Authors: Minoura Yuji , Kasuya Tanekazu , Kawamura Shinji , Nakano Akihiko 
Published: April 2003

AbstractA block copolymer of methyl methacrylate with poly(ethylene oxide) was synthesized by initiation with poly(ethylene oxide) radicals formed by high‐speed stirring. The effects of the concentration of the monomer, the concentration of the polymer, the degree of polymerization, the rotation speed, and the solvent on the rate of copolymerization were studied. It was found that the rate of copolymerization was proportional to the concentration of the monomer and to the square root of the rate of scission of the polymer chain. The block copolymerization of methyl methacrylate monomer and styrene monomer (1 : 1 mole ratio) with poly(ethylene oxide) radicals was also carried out by the same method and it was found that the block copolymerization was a radical one.
α,ω‐Disubstituted polymethylpolyphosphonates and polyphenylpolyphosphonates from condensation polymerization
Authors: Grant David , Van Wazer John R. , Dungan Claude H. 
Published: April 2003

AbstractCondensation polymerization of phosphonates through formation of POP linkages has been achieved by (1) volatilization of methyl chloride from mixtures of CH3P(O)Cl2 with CH3P(O)(OCH3)2; (2) volatilization or chemical removal of water from CH3P(O)(OH)2; and (3) volatilization of HCl from mixtures of CH3P(O)Cl2 with CH3P(O)(OH)2 or C6H5P(O)Cl2 with C6H5P(O)(OH)2. Depending on the proportions of the reagents, the polymerization products consist of various mixtures of chain molecules of the type \documentclass{article}\pagestyle{empty}\begin{document}${\rm X \hbox{--} P}({\rm O})({\rm R})\rlap{--}[{\rm O \hbox{--} P}({\rm O})({\rm R})\rlap{--}]_n {\rm X}$\end{document} for R = CH3 and X = OCH3, Cl, or OH, or for R = C6H5, x = Cl or OH. 31P nuclear magnetic resonance (NMR) was used to investigate both the polymethylpolyphosphonates and the polyphenylpolyphosphonates; and 1H NMR of the CH3P and CH3O moieties was also used to study the polymethylpolyphosphonates. In the methoxyl‐terminated polymethylpolyphosphonates, which was the system studied most extensively, no detectable amounts of cyclic molecules were found at equilibrium, but a crystalline methylphosphonic anhydride, CH3PO2, exhibited some ring structures. The equilibrium size distributions gave evidence that the sorting of the mono‐ and difunctional phosphorus‐based units making up the oligomeric chains is affected by neighboring units. Kinetic measurements demonstrated that the condensation polymerization is a complicated process involving considerable scrambling of terminal groups with bridging oxygen atoms.
Copolymerization parameters of acrolein and acidic vinyl monomers
Authors: D'Alelio G. F. , Huemmer T. F. 
Published: April 2003

AbstractAcrolein was copolymerized by radical initiation in aqueous solutions with sodiump‐styrenesulfonate and acrylic acid, respectively, in the pH range of 3–7. The reactivities were shown to be pH‐dependent. For the acrolein (M1)–sodiump‐styrenesulfonate (M2) pair,r1= 0.33 ± 0.15 andr2= 0.32 ± 0.05 at pH 3;r1= 0.23 ± 0.12 andr2= 0.05 ± 0.03 at pH 5;r1= 0.26 ± 0.03 andr2= 0.025 ± 0.025 at pH 7. For the acrolein (M1)–acrylic acid (M2) pair,r1= 0.50 ± 0.30 andr2= 1.15 ± 0.2 at pH 3;r1= 2.40 ± 0.50 andr2= 0.05 ± 0.05 at pH 5;r1= 6.70 ± 3.00 andr2= 0.00 at pH 7. For acrolein, the new values ofQ= 1.6 ande= 1.2 have been calculated. For sodiump‐styrenesulfonate, the valuesQ= 0.76 ande= −0.26 at pH 3,Q= 0.51 ande= −0.87 at pH 5,Q= 0.39 ande= −1.00 at pH 7 were obtained; and for acrylic acid, the valuesQ= 1.27 ande= 0.50 at pH 3,Q= 0.11 ande= −0.22 at pH 5 were derived. The changes in reactivity are explained on the basis of inductive and resonance effects.
Polymerization of thietane
Authors: Price Charles C. , Blair E. Allan 
Published: April 2003

AbstractGrignard reagent‐initiated polymerization of thietane gave a soluble crystalline polymer melting at 59°C. Oxidation of the polymer with one or two equivalents of hydrogen peroxide gave the sulfoxide and sulfone, respectively. The sulfoxide was noncrystalline and insoluble in all common solvents at room temperature and softened at 185–200°C. The sulfone was partially crystalline and insoluble.
Polymerization of cyclic sulfides
Authors: Stille J. K. , Empen J. A. 
Published: April 2003

AbstractThe ring‐opening polymerizations of cyclic sulfides containing three‐, four‐, and fivemembered rings were studied. In conjunction with these polymerizations, the relative basicities of the cyclic sulfides employed were also investigated. Polymerizations were effected by the use of phosphorus pentafluoride, boron trifluoride ethyl ether, triethylaluminum, and trimethyloxonium tetrafluoroborate. The resulting polymers were oxidized to the sulfones and differential thermal analyses were obtained on the sulfide polymers as well as the sulfone analogs.
Cationic graft copolymerization of styrene onto natural rubber
Authors: Ueno Yukio , Kasabo Toshiyuki , Hanada Takeshi , Minoura Yuji 
Published: April 2003

AbstractThe polymerization of styrene was carried out in a cyclohexane solution of natural rubber with stannic chloride. It was found that the grafting copolymerizations of styrene took place as well as the cyclization of rubber. The rate of polymerization of styrene was proportional to the second power of the concentration of styrene and to the concentrations of stannic chloride and natural rubber, respectively. The overall activation energy was about 6 kcal./mole. The percentage grafting increased with increasing concentration of rubber. On the other hand, the grafting efficiency showed the reverse tendency. The percentage grafting could be increased to 150% by the addition of nitrobenzene, a polar solvent.
Carborane polymers. IV. Polysiloxanes
Authors: Mayes N. , Green J. , Cohen M. S. 
Published: April 2003

AbstractCarboranes attached to silicon through straight‐chain alkyl groups were prepared and characterized for thermal stability by TGA and molecular weight change on heating. The monomers for these polymers were prepared generally by platinum‐catalyzed addition of a silylhydride to an alkenyl or dialkenyl carborane. Polymerization was effected by hydrolysis‐condensation of chlorosilanes, ring opening of cyclosiloxanes, and condensation of alkoxy and chlorosilanes. Two types of polymer structures were prepared, one contained m‐carborane in the chain backbone, the other contained o‐carborane as pendant alkylcarborane groups. Both types were obtained as elastomers; however, higher proportions of carborane in the polymers reduced elasticity and finally resulted in nonelastomers. TGA of the backbone carborane siloxane polymer indicated degradation at 370°C. in nitrogen and at 235°C. in air. Chain scission, as determined by molecular weight decrease, was observed on heating in nitrogen at 350°C. TGA of the pendant carborane siloxane polymer indicated that degradation in nitrogen and in air occurred at greater than 400°C. However, chain scission, as determined by molecular weight decrease, was observed upon heating at 300°C. in nitrogen.
Computer program for calculations and automatic data plotting in binary copolymerization
Authors: Molau G. E. 
Published: April 2003

AbstractThe copolymer composition equation as well as the composition‐drift equation recently published by Meyer and Lowry have been transformed into a weight fraction–weight conversion form. The resulting weight‐notation equations contain the original molenotation equations as a special case. Based on the weight‐notation equations, a computer program has been written which allows calculations and automatic data plotting of composition and composition‐drift data in binary copolymer systems in either weight or mole notation.
Polymerization of 1,3‐butadiene on cobalt and nickel halides
Authors: Anderson W. S. 
Published: April 2003

AbstractButadiene polymerizes to cis‐1,4 polymer on irregularly stacked, halogen‐deficient crystals of cobalt(II) or nickel(II) halides. Halogen is removed from the halides by heating the salts under high vacuum or by photolyzing them in the presence of butadiene. Intrinsic viscosity and solubility of the polymer reach a steady state during polymerization. Cobalt chloride produces polymer of higher intrinsic viscosity than nickel chloride, but polymerization on nickel chloride is faster. Catalytic activity is attributed to the presence of ≤0.1% of nickel and cobalt monohalides in the catalyst.
New synthetic route to α‐alkylacrylonitriles and a study of their homopolymerization and copolymerization reactions
Authors: Kovács J. , Marvel C. S. 
Published: April 2003

AbstractAliphatic aldehydes have been condensed with cyanoacetic acid and the resulting olefin intermediates hydrogenated and then submitted to a Mannich‐type reaction to produce α‐alkylacrylonitriles with the alkyl groups ranging from C1 to C12. It was not necessary to isolate the intermediates when the reactions were carried out in acetonitrile solutions. The α‐alkylacrylonitriles with C7 or higher alkyl groups in the chains would polymerize by radical initiation in emulsion to give polymers which were sticky, rubbery products and showed adhesive characteristics. Anionic initiation did not yield polymers with the α‐alkylacrylonitriles containing high alkyl groups but did convert the C2 to C4 alkyl‐substituted acrylonitriles to low molecular weight colored products. Some copolymers of α‐alkylacrylonitriles with acrylonitrile were prepared in emulsion by radical initiation. The monomer ratios in these copolymers were determined by nuclear magnetic resonance spectra.
Stereospecific polymerization of methacrylonitrile. II. Influence of polymerization conditions on polymerization and on properties of polymers
Authors: Joh Yasushi , Kotake Yahide , Yoshihara Toshio , Ide Fumio , Nakatsuka Kazuo 
Published: April 2003

AbstractStereospecific polymerization of methacrylonitrile with diethylmagnesium has been studied. Polymerization temperature has an important effect on polymerization. The conversion, stereoregularity, and intrinsic viscosity of the polymer increased significantly with increasing polymerization temperature. Stereoregularity of the polymer improved with increasing the polymerization time and the monomer concentration, but it is independent of the catalyst concentration. Intrinsic viscosity of the crystalline polymer increased with increasing monomer concentration but is independent of the polymerization time and the catalyst concentration. It is suggested that two mechanisms are involved in this polymerization: coordinated anionic polymerization to from the crystalline polymer, and probably conventional anionic polymerization to form the amorphous polymer. It is found that crystalline polymer can also be obtained in homogeneous phase such as in tetrahydrofuran solvent.
Cationic and free‐radical polymerization of optically active 1‐olefins
Authors: Bacskai R. 
Published: April 2003

AbstractThe AlCl3‐initiated cationic polymerization of optically active 1‐olefins yields polymers of varying optical rotatory power. Polymers of (+)‐3‐methyl‐1‐pentene and (−)‐4‐methyl‐1‐hexene prepared between −78 and −55°C. in CH2Cl2 or n‐heptane are almost completely optically inactive. Under identical reaction conditions (+)‐5‐methyl‐1‐heptene gives polymers of significant optical rotatory power. Alternating SO2copolymers of the same olefins, formed in reactions which proceed through free‐radical intermediates, yield optically active products with specific rotations similar to those of low molecular weight analogs. These results are consistent with a cationic polymerization mechanism in which the growing chain undergoes intramolecular hydride shift and the asymmetric carbon atoms are converted into carbonium ions. The data also provide evidence for the lack of rearrangement in free‐radical polymerization. By comparing the specific rotations of the cationic and free‐radical polymers, the extent of rearrangement during cationic polymerization can be estimated. The calculations show that the 1,2‐polymer in cationic poly‐3‐methyl‐1‐pentene is less than 2%, the sum of 1,2‐ and 1,3‐polymer in cationic poly‐4‐methyl‐1‐hexene is less than 4%, and the sum of 1,2‐, 1,3‐, and 1,4‐polymer in cationic poly‐5‐methyl‐1‐heptene is 14–20%.
Polymerization of styrene with the VOCL3–AlEt2Br catalyst system
Authors: Anand L. C. , Deshpande A. B. , Kapur S. L. 
Published: April 2003

AbstractThe rate of polymerization with the VOCl3–AlEt2Br catalyst system at 30°C. in n‐hexane reached a maximum at an Al/V molar ratio of 1.5. At this ratio, the rate of polymerization was first‐order with respect to catalyst and second‐order with respect to monomer concentrations. The apparent activation energy calculated was 6.4 kcal./mole. Diethylzine was found to act as a chain transfer agent. However, the molecular weights of polymers obtained were low. The possibility of bromide‐containing catalyst sites acting in the termination reaction has been investigated. The average valence of vanadium is discussed in relation to molecular weights.
Polymerization of itaconic acid derivatives
Authors: Ishida Shin'ichi , Saito Shizuko 
Published: April 2003

AbstractThe γ‐ray‐initiated polymerization of dimethyl itaconate was studied. Dimethyl itaconate was polymerized by γ‐irradiation at temperatures where the monomer does not polymerize thermally; so long as the monomer is kept in a liquid state, even at temperatures below the melting point, the polymerization takes place. Itaconic anhydride was polymerized in the solid state with γ‐irradiation or benzoyl peroxide. The molecular weight of the polymer increases with time or yield and is greater than that of polymer obtained by other methods. The kinetic study and crystallographic study indicate that the γ‐ray‐initiated solid‐phase polymerization is a first‐order reaction with respect to monomer and the rate‐determining step changes as the polymerization proceeds.
Identification of volatile products produced during the peroxide vulcanization of poly(vinyl alkyl ethers)
Authors: Lal Joginder , McGrath James E. 
Published: April 2003

AbstractVolatile products are produced during vulcanization of the polymers of vinyl methyl, ethyl, isopropyl and n‐butyl ethers with dicumyl peroxide, both in the presence and, absence of added sulfur. They were identified and estimated by gas‐liquid chroma tography and mass spectrometry. The principal products formed during the vulcanization of poly(viny1 ethyl ether) with dicumyl peroxide were ethane and acetaldehyde and to a lesser extent methane. The addition of sulfur in the curing recipe resulted in a sharp increase in the proportion of ethyl alcohol, a large increase in methane, and a large decrease in ethane. The formation of these volatile products and the observed changes due to the presence of sulfur in the curing recipe can be accounted for on the basis of side‐chain scission of the polymer radicals produced during vulcanization. The length and/or shape of the alkyl group in poly(viny1 alkyl ether) determine the composition of the volatile products. The data are in harmony with the postulated chemistry of vulcanization of these polymers.
Effect of temperature and polymer type on gel permeation chromatography
Authors: Cantow Manfred J. R. , Porter Roger S. , Johnson Julian F. 
Published: April 2003

AbstractA series of polyisobutene and polystyrene fractions was subjected to gel‐permeation chromatography at 150°C. The two types resulted in distinctly different calibration curves in a plot of projected, extended chain length versus elution volume. The average end‐to‐end distances of the samples were determined by intrinsic viscosity measurements. It was found that these data plotted versus elution volume could be represented by a common curve for both polymer types. The elution volumes of the polyisobutene series were determined at three additional temperatures, 35, 70, and 110°C. It could be shown that elution volume is again determined by polymer coil size at the temperature of measurement.
Electron‐transfer polymers. XXVIII. Synthesis of vinyl hydroquinone derivatives by means of the wittig reaction
Authors: Hashimoto Mutsuko , Uno Keikichi , Cassidy Harold G. 
Published: April 2003

AbstractThe Wittig reaction has been applied to unsubstituted, monomethyl‐, 3,6‐dimethyl‐, and trimethyl‐2,5‐dimethoxybenzyl chlorides to produce in quantitative to good yields the corresponding vinyl monomers, unsubstituted, monomethyl‐, 3,6‐dimethyl‐, and trimethyl‐2,5‐dimethoxystyrenes. The reaction is applicable also to 2,5‐dimethoxy‐4‐methylbenzaldehyde, and to O,O′‐bis‐(methoxymethyl)resorcinol‐4‐aldehyde to yield the corresponding vinyl monomers. The reaction is particularly suitable with all these compounds because it is run at room temperature or below and gives good to quantitative yields.
Studies of the micro‐brownian motion of a polymer chain by the fluorescence polarization method. III. Fluorescent conjugates of polyethyleneimine
Authors: Teramoto Akio , Morimoto Masayoshi , Nishijima Yasunori 
Published: April 2003

AbstractFluorescent conjugates of polyethyleneimine (PEI) were prepared by conjugation of fluorescent dyes, fluorescein isocyanate (FIC), and 1‐dimethylaminonaphthalene‐5‐sulfonyl chloride (DNS), to PEI. The degree of polarization of the fluorescence was measured as a function of temperature and solvent viscosity on aqueous solutions of the conjugates and the data thus obtained were analyzed in terms of an equation of the Perrin type to calculate the mean relaxation time of the conjugate. The mean relaxation times obtained for the two types of the conjugates, which differ in the excited lifetime by a factor of about three, practically agree with one another and are about 2.5 X 10−8 sec. The relaxation time of the DNS conjugate increases with increasing molecular weight of the conjugate from 2 X 10−8 to 4 X 10−8 sec. These values are much larger than those of the PAA conjugates reported in Part I of this series. The relaxation time of this order may correspond to that for the cooperative rotary motion of about ten monomeric residues on the PEI chain, that is, for the motion of an intermediate segment of the PEI molecule in solution. Finally, relaxation time–molecular weight relationships for various types of fluorescent conjugates are compared. It is suggested that these data may serve as a basis for elucidating the mode of motion of a given molecule in solution from the polarization data.