bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the photooxidation mechanism of polymers. V. Oxidation of polybutadienes by singlet oxygen from microwave discharge and in dye‐photosensitized reactions
Authors: Rabek J. F. , Rånby B. 
Published: April 2003

AbstractThe singlet oxygen oxidation of cis‐ and trans‐ 1,4‐polybutadienes was studied by using singlet oxygen generated in a microwave generator and in dye‐photosensitized reactions of these polymers in the solid state and in solution. It was shown that the reactions of singlet oxygen result in formation of hydroperoxide groups, whereas ultraviolet oxidation by molecular oxygen in addition leads to formation of carbonyl groups. During dye‐photosensitized oxidation of polydienes in benzene solution, a very rapid decrease in the molecular weight was observed.
Polyimidines, a new class of polymers. I. Phenylated polypyromellitimidines
Authors: Cassidy Patrick E. , Syrinek Allen 
Published: April 2003

AbstractModel compounds and polymers containing the imidine functional group have been synthesized from diphenylphthalide and tetraphenylpyromellitide by condensation with mono‐ and diamines. The diamine monomers included: 1,6‐diaminohexane, p‐phenylenediamine, and 4,4′‐diaminodiphenyl ether. Reactions were run either in biphenyl or with no solvent at 250–300°C to yield up to 57% product with molecular weights up to approximately 16,000 and inherent viscosities to 0.15. All polymers were soluble in chloroform and dimethylformamide and showed thermal stabilities by TGA to range from 225°C (for aliphatic backbones) to 400°C (for aromatic systems).
Anionic polymerization initiated by lithium diethylamide in organic solvents. III. Investigation of the polymerization of styrene
Authors: Hurley S. A. , Tait P. J. T. 
Published: April 2003

AbstractThe polymerization of styrene, initiated by lithium diethylamide in mixtures of benzene and THF, has been investigated. Kinetic and molecular weight measurements are interpreted on the basis of simultaneous initiation and propagation steps, and the effect of solvation and coordination processes on these reactions is discussed. Initiation of polymerization is thought to involve addition of solvated lithium diethylamide ion‐airs to styrene, giving species with diethylamide end groups. The possible influence of these end groups on the initiation is considered in terms of an intramolecular cyclization process. Propagation of polymerization is believed to involve polystyryllithium ion‐pairs, solvated to varying extents by THF. No evidence has been found to suggest that chain transfer, or termination, reactions are an integral part of the polymerization process. The polymerization has a number of similarities to the alkyllithium‐initiated polymerization of styrene, but also exhibits some interesting differences.
Effect of chemical structure and thermal history on the β transition of polystyrene and some substituted polystyrenes
Authors: Bach Van Nguyen , Noel C. 
Published: April 2003

AbstractDTA (differential thermal analysis) traces for various kinds of polystyrene and substituted polystyrenes, including bulk‐polymerized, monodisperse, and isotactic samples, have been recorded below the glass temperature. It has been shown that the β transition is dependent upon polymer structural modification, traces of water or solvent, and sample thermal history. The experimental data presented here support the conclusion that the β transition is due to conformational changes involving backbone motions and phenyl ring reorientation.
Aromatic polyethers, polysulfones, and polyketones as laminating resins. VIII. Aryl disulfide units as crosslinking agents
Authors: Wong Daniel Ting‐Man , Marvel C. S. 
Published: April 2003

AbstractOxidation of 1,4‐phenylenedimercaptan has given a cyclic trimeric disulfide. Oxidation of 1,3‐phenylenedimercaptan has yielded a similar product. These monomers have been incorporated in the chains of aromatic polyether, sulfone, ketone polymers and serve as crosslinking sites on heating these polymers.
Mechanisms of inhibition against the copper‐catalyzed oxidation of polyethylene: Structures and catalytic reactivities of copper–inhibitor complexes
Authors: Allara D. L. , Chan M. G. 
Published: April 2003

AbstractA series of compounds, mostly derivatives of N,N′‐diphenyloxamide, used as inhibitors of copper‐catalyzed oxidation in polyolefins has been reacted with cupric salts. The resultant copper–inhibitor complexes have been characterized as insoluble, polymeric solids, and their catalytic reactivities in the oxidation of low‐density polyethylene were measured at 100°C. The maximum rates of oxidation are first‐order in surface area, and some very general trends in structure and reactivity can be drawn from these data. Reasons for the relative effectiveness of various copper deactivators in polyolefin oxidation are briefly discussed.
Interaction of poly(vinylpyrrolidone) with p‐substituted phenols in aqueous solution
Authors: Inoue Masami , Otsu Takayuki 
Published: April 2003

AbstractThe interaction of poly(vinylpyrrolidone) (PVP) with various p‐X‐substituted phenols (X = CH3O, CH3, C2H5, H, Cl, Br, and NO2) in aqueous solution was investigated by means of equilibrium dialysis at 30°C. By applying the Klotz equation for the results obtained, the bonding constants K between PVP and p‐substituted phenols were determined. It was found that the K values were approximately correlated with the Hammett σ values of p‐substituents in phenols, indicating that the bonding forces due to electrostatic and hydrogen‐bonding interactions were significant, and they increased with increasing electron‐withdrawing nature of the substituents. Therefore, in addition to the hydrophobic interaction which has been accepted, it was assumed that the above interaction forces also played an important role in the interactions between PVP and p‐substituted phenols in aqueous solution.
Molecular weight analysis of pitches and polymeric pitches by gel‐permeation chromatography
Authors: Lewis I. C. , Petro B. A. 
Published: April 2003

AbstractThe technique of gel‐permeation chromatography (GPC) has been developed as a method for measuring molecular weight distribution in pitch materials. Molecular weight calibration data were obtained from measurements made on GPC fractions collected from a standard pitch. By solubilization of the polymeric portion of pitch through a reduction with lithium in ethylenediamine, the molecular weight range for analysis was extended to in excess of 3000. Mass spectroscopy has been used to further analyze some of the GPC fractions. The GPC calibration data can be employed, with the aid of computer analysis, to determine quantitatively number‐average molecular weights M̄n weight‐average molecular weights M̄w, and molecular weight distribution D (= M̄w/M̄n) in pitch materials.
Conductance studies of salt solutions in the presence of poly(vinylbenzo crown ethers)
Authors: Shah S. C. , Kopolow S. , Smid J. 
Published: April 2003

AbstractThe conductance of acetone and methyl ethyl ketone solutions of tetraphenylborate salts in the presence of homopolymers and styrene copolymers of vinylbenzo‐15‐crown‐5 and vinylbenzo‐18‐crown‐6 was studied, and the results compared with data obtained for crown ethers. Polycations are formed on binding cations to the poly(crown ethers), and the conductance behavior of the polyelectrolytes depends on the nature of the cation‐crown complex and the spacing between crown moieties which in turn determines the charge density on the polymer chain. The compositions of the crown‐cation complexes were determined for crown ethers. The complex formation constants of sodium and potassium cations to poly(vinylbenzo‐18‐crown‐6) were found to change as more cations bind to the chain. This is not the case for the copolymers where the crown ligands are spaced farther apart. A mixture of poly(vinylbenzo‐15‐crown‐5) and 10−3M potassium tetraphenylborate in methyl ethyl ketone or acetone has a minimum conductance at a crown to cation ratio of 3.0, but the conductance rapidly increases on addition of crown ether. This was used to qualitatively determine the binding efficiency of a series of crown ethers since the rate of increase in the conductance is a measure of the binding ability of the crown ether to the cation.
Emulsifier‐free emulsion polymerization with ionic comonomer
Authors: Juang Mike Shi‐Der , Krieger Irvin M. 
Published: April 2003

AbstractEmulsion polymerization of styrene in the absence of emulsifier with K2S2O8 as initiator produced uniform latices. Incorporation of ca. 0.5% ionic comonomer (sodium styrenesulfonate) reduced the particle size from the range 0.5–1.0 μm achieved in prior emulsifier free formulations to a range of 0.15–0.40 μm. Some advantages achieved by incorporation of ionic comonomer were higher polymer content and independently controllable surface charge density. Particle diameter varied as the 0.64 power of the ratio of ionic strength to comonomer, as the −0.20 power of initiator concentration, and as the 0.46 power of monomer content. Kinetic data suggest that copolymerization takes place in the aqueous phase, and that nuclei for particle growth are formed by precipitation of the initially water‐soluble copolymer. The latex is stabilized by sulfonic acid groups of the comonomer, as well as by sulfate end groups from the initiator.
Hydroxamic acid polymers. II. Design of a polymeric chelating agent for iron
Authors: Winston Anthony , McLaughlin Glenn R. 
Published: April 2003

AbstractThe iron chelating ability of hydroxamic acid polymers was studied as a function of the atomic chain spacing separating neighboring hydroxamic acid units. Two polymers were prepared, one having the hydroxamic acid group separated by 11 atoms and the other by three atoms. The iron binding of these polymers was compared with the model compound desferrioxamine B (DFO) and with a previously prepared polymer having a nine‐atom spacing. Mole ratio plots indicated the following order of stability: DFO ≈ 11 atom > 9 atom > 3 atom. These results are in accordance with the picture derived from molecular models which shows that with a spacing of 11 atoms, three neighboring hydroxamic acids can fit the octahedral arrangement of the iron (III) complex without appreciable strain. Some strain is introduced when the spacing becomes only nine atoms, and with three atoms, complex formation between three neighboring groups becomes virtually impossible.
Study of radiation‐induced polymerization of vinyl monomers adsorbed on inorganic substances. VIII. Polymerization of styrene and methyl methacrylate adsorbed on aerosil
Authors: Fukano Kazuyuki , Kageyama Eiichi 
Published: April 2003

AbstractAerosil is silica having a purity which is very high compared with that of silica gel and having, unlike silica gel, no micropores. To investigate the effects of impurities and micropores on the radiation‐induced polymerization of styrene and methyl methacrylate adsorbed on silica gel, the radiation‐induced polymerization of styrene and methyl methacrylate adsorbed on Aerosil was carried out. The results of both the styrene–Aerosil 300 system and the methyl methacrylate–Aerosil 300 system were similar to those of the styrene–silica gel and methyl methacrylate–silica gel systems, respectively. This suggests that in the radiation‐induced polymerization of both styrene–silica gel and methyl methacrylate–silica gel systems the impurity and the presence of micropores have almost no effects on the reaction mechanism. The effect of aluminum as an impurity was investigated on the styrene–Aerosil MOX 170 system. It was found that aluminum accelerated the cationic polymerization.
Study of radiation‐induced polymerization of vinyl monomers adsorbed on inorganic substances. IX. Preirradiation polymerization of styrene–silica gel system
Authors: Fukano Kazuyuki , Kageyama Eiichi 
Published: April 2003

AbstractPreirradiation polymerization of the styrene–silica gel system was studied in detail. Both graft polymers and homopolymers have bimodal GPC spectra. High molecular weight peaks were formed in a radical mechanism and the low molecular weight peaks were formed in a cationic mechanism as same as those in the simultaneous irradiation polymerization. The rate of formation of the low molecular weight peaks was very high compared with that of the high molecular weight peaks. Monomer conversion and percent grafting leveled off at about 1–2 Mrad. Radiation dose dependence of the four peaks were different from each other. Monomer conversion and percent grafting decreased as the preheating temperature of silica gel increased. The amount of the low molecular weight peaks of graft polymers depended on the number of silanol groups, as in the case of the simultaneous irradiation polymerization. A reaction mechanism for the preirradiation polymerization is proposed based on the results obtained.
Radiation‐induced emulsion copolymerization of tetrafluoroethylene with propylene. VI. Effects of pressure and temperature
Authors: Matsuda Osamu , Okamoto Jiro , Tabata Yoneho , Machi Sueo 
Published: April 2003

AbstractIn a radiation‐induced emulsion copolymerization of tetrafluoroethylene with propylene, the effects of pressure and temperature were investigated in the range of 0–40 kg/cm2 and 7–53°C at emulsifier concentration of 0.5 and 2.0%. Both the polymerization rate and the molecular weight of copolymer increase with increasing pressure and decreasing temperature. These facts are mainly due to an increase of the monomer concentration in the polymer particles. The rate of polymer chain formation was found to be independent of pressure and temperature. The initiation reaction is due mainly to the entry of radicals generated in the aqueous phase into the polymer particles. The apparent activation energy is −2.0 to −3.8 kcal/mole for the polymerization in the presence of 0.5% emulsifier, but is nearly zero at an emulsifier concentration of 2.0%. This difference in apparent activation energies at emulsifier concentrations of 0.5 and 2.0% is explained in terms of the termination mechanisms.
Formation of crystalline polyelectrolytic complexes on matrix polymerization
Authors: Kabanov V. A. , Kargina O. V. , Ulyanova M. V. 
Published: April 2003

AbstractZwitterionic matrix stepwise polymerization of 4‐vinylpyridine (VP) using isotactic poly(acrylic acid) (i‐PAA) as a template results in formation of crystalline polycomplexes consisting of i‐PAA and of ionene (I):
magnified image
Depending on the concentration of VP and i‐PAA, the two types of crystalline polycomplexes can be prepared. The complex containing long ionene sequences with n ≫ 2 is formed when [VP]0 = [i‐PAA]0 ≥ 0.05M. At [VP]0 = [i‐PAA]0 ⩽ 0.01M, the complex formed evidently contains the ionene dimer (n = 2). The x‐ray structures of the crystalline complexes are identical with those obtained by mixing of i‐PAA and the corresponding dimer and polymer presynthesized in the absence of the template. The matrix polymerization of VP in the presence of syndiotactic and atactic PAA at the same conditions results in formation of amorphous polycomplexes.
Preparation and heat of polymerization of 3‐methyl‐3‐butyl‐2‐azetidinone
Authors: Šebenda J. , Hauer J. , Biroš J. 
Published: April 2003

AbstractThe synthesis of 3‐methyl‐3‐butyl‐2‐azetidinone, which forms a polymer which is soluble in a number of common solvents including toluene, chloroform, and carbon tetrachloride, is described. Anionic polymerization, carried out in toluene solution in a calorimetric vessel, yielded for the heat of polymerization of a four‐membered lactam −19.1 kcal/mole at 25°C.
Kinetics of radiation‐induced grafting reactions. III. Poly(isobutylene oxide)—styrene systems
Authors: Omichi Hideki , Araki Kunio , Takahashi Thoru , Yasukawa Tamio , Murakami Kenkichi 
Published: April 2003

AbstractGraft polymerization of styrene onto preirradiated poly(isobutylene oxide) was carried out at 25°C. The concentration of active sites for grafting was estimated by means of ESR and by the activation analysis of bromine atoms bound to the chain ends. Kinetic data such as differential amount of active sites (DACT), growth rate (GR), and average lifetime (τ) were obtained to calculate the molecular weight distribution of graft chains by the Monte Carlo simulation method. The number‐average molecular weight of the graft chain was calculated from the equation, Mn = 2GRτ (mw), which agreed well with the observed value.
Direct synthesis and properties of polybenzodipyrrolediones from dibenzylidenebenzodifurandiones and various diamines
Authors: Imai Yoshio , Ueda Mitsuru , Takahashi Takeyoshi 
Published: April 2003

AbstractAromatic and aliphatic polybenzodipyrrolediones have been synthesized directly by the solution cyclopolycondensation of two dibenzylidenebenzodifurandiones with four different diamines in refluxing m‐cresol or o‐phenylphenol in the presence of boric acid. The polymerizations proceeded smoothly in a homogeneous solution and afforded the heterocyclic polymers having inherent viscosities as high as 1.0 almost quantitatively. All the polymers were readily soluble in a wide range of solvents, including N‐methyl‐2‐pyrrolidone (NMP), hot m‐cresol, and hot pyridine. Tough, transparent, yellow films could be cast from NMP solutions of the polymers. Thermogravimetric analysis of the aromatic polybenzodipyrrolediones showed a 10% weight loss temperature of 460–500°C under nitrogen. The results also indicated that the aromatic polymers were somewhat less thermally stable than wholly aromatic polypyromellitimides.
Crystalline copolyamides of β‐(4‐aminophenyl)‐propionic acid and caprolactam
Authors: Shalaby S. W. , Turi E. A. , Harget P. J. 
Published: April 2003

AbstractMethyl β‐(4‐aminophenyl)propionate was prepared and converted to a crystalline polyamide. The copolymerization of β‐(4‐aminophenyl)propionic acid or its methyl esters with caprolactam resulted in polyamides having wide ranges of crystallinity and thermal stability, depending on the chemical composition. Copolymers with 10, 50, 85, 90, and 95 mole‐% of caproamide sequences were shown by x‐ray and differential scanning calorimetry to be semicrystalline. The composition and thermal stability of the polyamides were studied by infrared spectroscopy and thermogravimetric analysis, respectively.
Functionality and structure of polymers. I. Photoreaction and fluorescence of polyesters having pendant anthryl groups
Authors: Tazuke Shigeo , Banba Fumio 
Published: April 2003

AbstractVarious polyesters having pendant (9‐anthryl)methyl groups were prepared from 2‐(9‐anthryl)methylpropane‐1,3‐diol and the esters or chlorides of dicarboxylic acids. These polyesters are poly[2‐(9‐anthryl)‐methylpropane‐1,3‐diyl‐oxy‐(9‐anthryl)methylmalonyl‐oxy](PA‐1A), poly‐[2‐9‐anthrylmethylpropane‐1,3‐diyl‐oxysuccinyloxy](PA‐2), poly‐[2‐9‐anthrylmethylpropane‐1,3‐diyl‐oxyadipyloxy](PA‐4), poly[2‐(9‐anthryl)methylpropane‐1,3‐diyl‐oxysebacyloxy] (PA‐8), poly[2‐(9‐anthryl)methylpropane‐1,3‐diyl‐oxy‐(1‐naphthyl)methylmalonyloxy](PA‐1N), and poly[2‐(9‐anthryl)methylpropane‐1,3‐diyl‐oxyterephthaloyloxy](PA‐Ph). Although the absorption spectrum of the anthryl group is not influenced by the change in the environment in which the anthryl group is located, the fluorescence spectra show characteristic change reflecting the environment around the chromophore. Dimer, aggregates, or excimer fluorescence of anthryl groups and energy transfer from naphthyl to anthryl groups for PA‐1N were discussed. The rates of photodimerization of anthryl groups determined spectroscopically in dilute solutions for these polyesters and their monomer model compound(1,3‐diacetoxy‐2(9‐anthryl)methylpropane) (MA), were in the following order; PA‐8 > PA‐4 > PA‐1A > PA‐2 > PA‐Ph > MA. The effects of polymer structure on the photoreaction were discussed on the basis of information on molecular interactions obtained by fluorescence spectroscopy. The fraction of intramolecular cyclization was estimated from dependence of the rate of photoreaction on the concentration of the polyesters. When anthryl groups are linked by a long, flexible polymethylene chain (PA‐8), intramolecular process predominates whereas intermolecular dimerization proceeds almost exclusively for a rodlike molecule(PA‐Ph). These results are discussed from the viewpoint of the structure–functionality relationship in polymeric systems.
Investigation of structural changes in wool fibers due to annealing
Authors: Shishoo Roshan , Lundell Malte 
Published: April 2003

AbstractStructural changes in wool fibers after annealing, i.e., storage at 45°C and 80% RH, have been investigated by using the method of laser Raman spectroscopy and by measuring birefringence and density of wool. The results show that CH2 groups in wool give parallel Raman dichroism which increases very significantly after annealing. No increase in birefringence and density occurred after annealing. A hypothesis has been put forward which states that for minimum energy considerations in wool fibers the existence of intrahelix crosslinks other than hydrogen bonds is important. It is highly probable that a large number of electrovalent intrahelix crosslinkages exist between the suitable side groups on the main polypeptide chain in the α‐helix of annealed wool.
Polymerization of propylene with TiCl3–AlEt2Cl–polymeric electron donor catalyst
Authors: Shikata Kazuo , Osawa Hisakazu , Kida Yasuji 
Published: April 2003

AbstractPolymeric donors having ether or carbonyl groups were added to the TiCI3–AlEt2CI catalyst system as the third component, and the effects on the polymerization of propylene were investigated in comparison with the effect of the electron donors with low molecular weight. The polymeric donors were effective in making the catalyst more active, but the donors of low molecular weight depressed the catalyst activity. In the case of poly(propylene glycol dimethyl ether) (PPG‐DME), PPG–DME with a number of propylene oxide units (n) of more than 6.7 was effective in enhancing the catalyst activity. These effects were considered to be due to the different reactivities between TiCI3 and AlEt2CI‐polymeric donor complexes having various chain lengths.
Synthesis of oligoesters from oxalic acid and glycerol
Authors: Alksnis A. F. , Gruziń I. V. , Surna Ya. A. 
Published: April 2003

AbstractA new synthesis for the polycondensation of oxalic acid and glycerol was used. Polycondensation was carried out in the presence of compounds that do not dissolve oxalic acid and glycerol, but form an azeotropic mixture with water below 100°C. Anhydrous oxalic acid and oxalic acid dihydrate was used for the synthesis of oligoesters. The decarboxylation proceeds parallel with polycondensation of oxalic acid and glycerol was investigated. Decarboxylation of carboxyl groups of glycerol monooxalate was found to be accelerated by the arrangement of primary and secondary hydroxyl groups in the glycerol molecule in the 1,2 position.
Chloroaromatic ether amines
Authors: Kwiatkowski G. T. , Brode G. L. , Bedwin A. W. 
Published: April 2003

AbstractA new and useful class of aromatic amines, based on multichlorinated benzenes and polyphenyls, has been developed. The amines are prepared by reacting the alkali metal salt of p‐aminophenol with the chloroaromatics under nucleophilic substitution reaction conditions. Oligomeric amines can be obtained by condensing, e.g., the dialkali salt of bisphenol A and the alkali metal salt of p‐aminophenol with the chloroaromatics. The products are mixtures of mono‐, di‐, and triamines, as a result of the complex functionalities of the chloroaromatics employed. Unique features of the amines include: (1) flame‐retarding characteristics; (2) markedly reduced amine reactivity (compared with aniline); (3) thermal stability; (4) good solubility in the usual organic solvents.