bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal decomposition of poly(vinylidene chloride) prepared in presence of oxygen
Authors: Roberts D. R. , Gatzke A. L. 
Published: April 2003

AbstractThe thermal decomposition of poly(vinylidene chloride) was studied for samples prepared in the presence of oxygen. The products from both mass and aqueous suspension polymerizations show two modes of thermal decomposition. A rapid initial mode varies in rate and extent with the amount of oxygen present. A slower mode is unaffected by oxygen and in similar in rate to the polymer made in the absence of oxygen. The chief volatile products are phosgene and formaldehyde for the rapid decomposition and hydrogen chloride for the slow decomposition. The rapid decomposition is interpreted to be an unzipping reaction of a vinylidene chloride–oxygen alternating copolymer initiated by homolysis of a peroxide bond. The absence of significant amounts of hydrogen chloride during this stage of decomposition shows that none of the free radicals generated are capable of initiating a chain reaction that would unzip hydrogen chloride from the poly(vinylidene chloride) backbone. The presence of oxygen during the aqueous suspension polymerization correlates with the generation of hydrochloric acid in the aqueous phase. By analogy with the high temperature decomposition, the hydrochloric acid is believed to result primarily from the hydrolysis of phosgene produced by partial decomposition of the polyperoxide. Initiation of the decomposition is believed due to a reaction of the chain propagating radical.
Anionic polymerization with alkaline‐earth counterion. II. Polymerization of styrene initiated by dicarbanionic oligostyrylbarium in THF
Authors: Mathis Claude , François Bernard 
Published: April 2003

AbstractThe propagation kinetics of anionic polymerization of styrene initiated by dicarbanionic oligostyrylbarium (PS=Ba++) in THF are described. The apparent propagation rate constant kp increases drastically with the degree of polymerization (DP) of living chains and tends at 20°C, for the highest molecular weight (DP ≃ 5000), to the value determined for monocarbanionic polystyrylbarium(PS−)2Ba++. At given DP, the propagation step follows usual first‐order kinetics with respect to monomer, and kp is inversely proportional to carbanion concentration; as observed for (PS−)2Ba++. Similar behavior is observed in the temperature range from −60 to +20°C. The activation energy of the propagation is 4–5 kcal/mole (16.7–21 kJ/mole). It is shown that kp may be considered as directly proportional to the dissociation constant Kd of ion pairs (∼S−Ba++−S∼ is considered as an ion pair ∼(SBa)+S−∼). The striking variation of kp with the DP living chains is interpreted in terms of cyclic living chains, in which both carbanionic ends are bound to the same cation. Values of the intramolecular dissociation constant Kd of ion pairs included in such a model are computed as a function of DP, and their variation is found to fit rather well with experimental data.
Synthesis and exchange reactions of some polymeric benzotriazolides
Authors: Ferruti Paolo , Vaccaroni Franco , Tanzi Maria Cristina 
Published: April 2003

AbstractThe benzotriazolides of N‐methacryloylglycine, N‐methacrylolyl‐ε‐aminocaproic acid, and 4‐methacryloxybenzoic acid, have been prepared and polymerized. The exchange reactions of the resulting polymers with amines, alcohols, and phenol have been studied.
Cationic polymerization of dimethyl‐1,3‐butadienes
Authors: Hasegawa Kan‐Ichi , Asami Ryuzo 
Published: April 2003

AbstractThe cationic polymerizations of dimethyl‐1,3‐butadienes with various catalysts in methylene chloride and toluene have been investigated. The activity of catalysts decreased in the order WCl6 > AcClO4 > SnCl4·TCA > BF3OEt2. The homopolymerization rate of dimethyl‐1,3‐butadienes with WCl6, AcClO4, and SnCl4·TCA decreased in the order 1,3‐dimethyl‐1,3‐butadiene > 2,3‐dimethyl‐1,3‐butadiene > 1,2‐dimethyl‐1,3‐butadiene > 2,4‐hexadiene. The polymers prepared with WCl6, SnCl4.TCA, and BF3OEt2 were rubberlike polymers or white powders, whereas those prepared with AcClO4 were oily oligomers. The 1,4‐propagation increased in the order 1,2‐dimethyl‐1,3‐butadiene < 1,3‐dimethyl‐1,3‐butadiene < 2,3‐dimethyl‐1,3‐butadiene < 2,4‐hexadiene. This order may indicate that the steric effect of methyl group determine primarily the microstructure of the polymer. The relative reactivity of dimethyl‐1,3‐butadienes toward a styryl cation decreased in the order 1,3‐dimethyl‐1,3‐butadiene > 1,2‐dimethyl‐1,3‐butadiene > 2,3‐dimethyl‐1,3‐butadiene > 2,4‐hexadiene. This order may be explained in terms of the stability of the resulting allylic cation.
Alkaline hydrolysis of cured phenol–formaldehyde resins at high temperatures
Authors: Summers R. M. 
Published: April 2003

AbstractHydrolysis of cured phenolic resin, either straight or oil‐ or epoxy‐modified, in dilute caustic at 280–320°C, gives novolac resins in 70–80% recovery. Infrared analysis indicates these novolacs have the same composition as conventional novolacs made by the acid‐catalyzed phenol–formaldehyde condensation. Like the conventional novolacs, these recovered resins are soluble in oxygen‐containing solvents and form crosslinked infusible thermoset materials when heated with 10% hexamethylenetetramine. Molecular weights of the recovered novolacs, determined by high‐pressure liquid chromatography, are dependent on both time and temperature of the hydrolysis. The weight‐average molecular weight varied from 270 to 770. The Lowry index values indicate that the molecular weight distribution is narrower for the recovered novolacs than that normally obtained for conventional novolacs. The recovered novolacs have higher melting temperatures than the corresponding commercial novolacs. This is believed to be due to the lower free phenol content of the recovered novolacs.
Estimation of monomer reactivity ratios by nonlinear least‐squares procedure with consideration of the weight of experimental data
Authors: Yamada Bunichiro , Itahashi Masaki , Otsu Takayuki 
Published: April 2003

AbstractTo obtain the optimum values of the monomer reactivity ratios for the copolymerization systems with largely different reactivities between both monomers, a nonlinear least‐squares procedure which took into account the weights of experimental data, was proposed and discussed. The weights of the data were treated for the errors arisen from the amounts of monomers charged, the densities of monomers, the weights of copolymer formed, and the composition of copolymer. The least‐squares procedure with the consideration of the weights was applicable to both differentiated equation and integrated equation derived by Lewis and Mayo. This procedure was applied to radical copolymerizations of α‐substituted crotonic esters with styrene, and reasonable monomer reactivity ratios were obtained. It was noted that errors from the copolymer composition were more important than those from the other factors and that the use of the integrated equation was recommended even when the copolymers were isolated at low conversions.
Preparation of (AB)n‐type block copolymers by use of polyazoesters
Authors: Walz R. , Heitz W. 
Published: April 2003

AbstractPolyesters of the formula, [(OR)nOCOC(CH3)2NNC(CH3)2CO]m, where (OR)n are poly(ethylene oxide), Poly(propylene oxide), or PTHF units, were used to prepare block copolymers with styrene. Ester and ether groups were cleaved with HI, NaOCH3, and diisobutylaluminum hydride. The resulting polystyrene is telechelic with two COOH and OH groups, respectively. The number of styrene blocks per polymer molecule is 3–4.
Bisorthoesters as polymer intermediates. I. Synthesis of bisorthoesters
Authors: Dudgeon C. D. , Vogl O. 
Published: April 2003

AbstractDerivatives of three types of bisorthoesters, hexaalkyl orthoisophthalates, hexaalkyl orthoterephthalates, and hexaethyl orthooxalate, were synthesized. The orthoesters of isophthalic and terephthalic acid were prepared from α, α, α, α′, α′, α′ ‐hexachloro‐m‐xylene or hexachloro‐p‐xylene, respectively. It was found more advantageous to prepare initially the hexamethyl orthoesters by reacting the hexachloro compounds with sodium methoxide in methanol either at the boiling point of methanol or under pressure at temperatures up to 200°C. Transesterification with higher alcohols, for example, ethanol or propanol, with the aid of molecular sieves gave the higher bisorthoesters in high yield and high purity. Attempts to synthesize orthoisophthalates and orthoterephthalates of higher alcohols directly from the hexachloroxylenes and alkoxides of higher alcohols gave only low yields of impure products. The Pinner synthesis of the bisorthoesters from the corresponding dinitriles was also ineffective. The ease of purification of hexa‐n‐propyl orthoisophthalate and orthoterephthalate makes these orthoesters the favored candidates for use in polymer syntheses. Hexaethyl orthooxalate was prepared in a three‐step synthesis from triethyl orthoformate by a convenient, but low yield reaction. All bisorthoesters were purified to give compounds which were monomer grade materials free of normal esters.
Synthesis and properties of polymeric azine and thiazine dyes
Authors: Shigehara Kiyotaka , Matsunaga Haruo , Tsuchida Eishun 
Published: April 2003

AbstractSome polymeric azine or thiazine dyes were prepared by radical polymerization of dye monomers or by polymer reactions between dyes and suitable prepolymers, and their photoredox reactivities were studied. The thionine polymers containing labile OH groups exhibited photochromism and thermochromism, which were extremely sensitive to the moisture content of the polymer film. The reversibility of the photochromism and thermochromism increased with the water content in the film. The water‐soluble polymeric dyes were photobleached under the influence of suitable reducing agents. The degree of photobleaching was smaller than for the monomeric systems except for the dye polymers containing OH groups, probably because of the large steric hindrance of the polymers.
Catalysis by polymer complexes. VIII. Enhanced nucleophilic reactivity of hydroxamate anions bound to quaternized polyethylenimines and related compounds
Authors: Okahata Yoshio , Kunitake Toyoki 
Published: April 2003

AbstractWater‐soluble polyethylenimine derivatives composed only of the tertiary amine and quaternary ammonium groups were prepared by methylation and quaternization of commercial polyethylenimine. The reaction of the hydrophobic hydroxamate anion and p‐nitrophenyl acetate (aqueous solution, 30°C) was more than 100 times accelerated by the polyethylenimine partly quaternized by stearyl bromide. The polymers quaternized by less hydrophobic groups or by the stearyl and methyl groups were much less effective. The former polymer also accelerated decomposition of the acetyl hydroxamate up to 25 times. The rate‐enhancing effect of these polyethylenimine derivatives appeared to be produced by the general, hydrophobic microenvironment without regard to the peculiar structural characteristics of polyethylenimine. The effect of fully quaternized triethylenetetramine was similarly studied.
Catalysis of hydrolysis of a schiff base by a carboxyl‐containing poly(ethylenimine) derivative
Authors: Suh Junghun , Klotz Irving M. 
Published: April 2003

AbstractHydrolysis of 3‐methyl‐2‐cyclohexenylidene laurylamine (I) in the presence and absence of laurylsuccinoylpoly(ethylenimine) has been studied. Water attack on the conjugate acid of I in the polymer environment is about 102 times faster than in bulk medium. To achieve the same rate in bulk media by general base catalysis, about 70 M acetate or cacodylate would be needed. This indicates that the reactivity of the carboxylate attached to the polymer is substantially enhanced by the polymer environment.
Synthesis and properties of polymers containing sprio(indoline‐isoxazoline)
Authors: Watarai Syu , Katsuyama Harumi , Umehara Akira , Sato Hideo 
Published: April 2003

AbstractPolymers containing spiro(indoline‐isoxazoline) nuclei were prepared by 1,3‐dipolar cycloaddition reactions of N,N′‐alkylene‐bis‐3,3‐dimethyl‐2‐methyleneindolines with bis‐hydroxamic chlorides. Irradiation of the polymers with UV in solution resulted in novel skeletal rearrangements and resulted in polymers containing benzo‐1,5‐diazocine‐2‐one nuclei. Photoconductivities of the polymers were also studied.
Preparation and properties of carboxyl‐functional mixed esters of hydrolyzed starch
Authors: Rudolph Stephen E. , Glowaky Raymond C. 
Published: April 2003

AbstractMixed esters of hydrolyzed starch represent a new class of chemically modified natural polymers demonstrating a broad range of properties. Members of this class of polymers have both neutral aliphatic ester side chains and carboxyl‐functional half‐ester side chains. Use of hydrolyzed starch as the backbone polymer results in products that are considerably lower in molecular weight than whole starch derivatives, but which are still polymeric in character. Synthesis proceeds smoothly in pyridine using anhydrides as acylating agents and the pure solid mixed ester products are isolated by precipitation in water. Measurement of degree of substitution (D.S.) by NMR or hydrolysis characterizes the chemical composition of the polymers. The actual D.S. achieved in the synthesis depends upon the competition between starch and residual water for anhydrides, which can be quantitatively evaluated by monitoring the acid content of the reaction mixture. The Tg and Ts of starch mixed esters vary with both D. S. and length of the aliphatic ester side chain. As the composition changes from acetate—phthalate to butyrate—phthalate a Tg range of greater than 100°C is observed. Hydrolyzed starch mixed esters are hydrophobic and organic‐soluble, but may be readily solubilized in aqueous base through the half‐ester groups. Solutions show surface activity which varies according to the type and extent of substitution.
Cationic polymerization with boron halides. VI. Polymerization of styrene with BF3, BCl3, and BBr3
Authors: Kennedy J. P. , Feinberg S. C. 
Published: April 2003

AbstractThe polymerization of styrene with BF3, BCI3, and BBr3 coinitiators and CH2Cl2 solvent has been investigated. The effects of temperature, monomer concentration, and the nature of the boron halide on molecular weights, molecular weight distribution, and conversion were determined. Molecular weights were found to decrease in the order BCl3 >BF3 >BBr3. This sequence was discussed in terms of system ionicity and counterion stability. The overall energies of activation for polymerization (ΔE) were −1.6 ± 0.3, −1.9 ± 0.8, and −0.9 ± 0.5 kcal/mole for BF3, BCI3, and BBr3, respectively, which indicated similar overall polymerization mechanisms in the range of −20 to −80°C. The predominant molecular‐weight‐governing event in polymerizations with BCl3, and BBr3 was chain transfer to monomer, whereas with BF3 chain transfer and termination were nearly equal. Chain termination in BCl3‐coinitiated polymerizations involves chlorination of the growing polystyryl cation by BCl3OH⊖ and leads to benzylic chlorine termini.
An analytical evaluation of anhydrosugar polymerizations
Authors: Ito Hiroshi , Schuerch Conrad 
Published: April 2003

Abstract1,6‐Anhydro‐2,3,4‐tri‐O‐(p‐methylbenzyl)‐β‐D‐glucopyranose (TXGL, M1) has been copolymerized with 1,6‐anhydro‐2,3,4‐tri‐O‐benzyl‐β‐D‐glucopyranose (TBGL, M2). Reactivity ratios, calculated by the Mayo and Lewis procedure, are r1 = r2 = 1.25 ± 0.25. Within experimental error these values represent azeotropic copolymerization. Therefore preceding interpretations of the relative reactivity of TXGL and other benzylated anhydrosugars are not incorrect because the possible effect of p‐methyl substitution was ignored. Analysis of this copolymerization system and the reported copolymerizations of TXGL with 1,6‐anhydro‐2,3,4‐tri‐O‐benzyl‐β‐D‐manno‐(TBMN) and galactopyranoses (TBGA) by the linear method recently proposed by Kelen and Tudos has confirmed that true copolymerization takes place in all the systems mentioned above and that the classical copolymerization theory adequately describes the copolymerization mechanism. Physical properties of the copolymers of TXGL and TBGL indicate the usual high stereoregularity of structure.
Polyepiiodohydrin
Authors: Schacht E. , Bailey D. , Vogl O. 
Published: April 2003

AbstractPolyepiiodohydrin was prepared from polyepichlorohydrin by the Finkelstein reaction with sodium iodide in butanone. An 88% degree of replacement of chlorine by iodine was obtained. The reaction of iodides with polyepichlorohydrin was accompanied by a substantial drop in molecular weight. The copolymer, which contains eight epiiodohydrin units per epichlorohydrin unit, has a glass transition temperature of 1°C and a density of 2.2 g/cm3. Properties of epiiodohydrin homopolymer were estimated by extrapolation of copolymer data.
Photodegradation of aramids. II. Irradiation in air
Authors: Carlsson D. J. , Gan L. H. , Wiles D. M. 
Published: April 2003

AbstractA series of isomeric fully aromatic polyamides (aramids) were photodegraded in the presence of oxygen. Films and fibers of these aramids gave carboxylic acids as the major products when measured by infrared spectroscopy and potentiometric titration. These acids probably resulted from the oxygen interception of the radicals generated by photocleavage of the amide bonds. In contrast to results found upon irradiation in the absence of oxygen, carboxylic acid formation was accompanied by a rapid loss in molecular weight, and a decrease in useful mechanical properties. Quantum yields for carboxylic acid formation were ≤5.5 × 10−5 mole/einstein and decreased along the aramid series roughly in agreement with increases in Tg. The photo‐Fries rearrangement product was observed in aramid fibers irradiated in air, whereas no rearrangement product was seen in films irradiated in air.
Olefin polymerization in liquid sulfur dioxide initiated by m‐chloroperbenzoic acid. I. Homopolymerization of styrene and α‐methylstyrene
Authors: Akcelrud L. , Gomes A. S. 
Published: April 2003

AbstractHomopolymerizations of styrene (Sty) and α‐methylstyrene (AMS) in liquid sulfur dioxide were carried out in the temperature range from −10°C to −78°C, using m‐chloroperbenzoic acid as initiator. It is shown, through the effect of initiator concentration, temperature, and times of reaction on the conversion and molecular weight of the polymers, that AMS is more reactive than Sty because it requires a smaller amount of initiator for the same conversion to be reached, although the molecular weight of the resulting polymer is lower. A linear relationship has been observed for Sty between the degree of polymerization and the initiator concentration. Within the experimental conditions employed, the presence of polysulfones has been discarded by elemental analysis. The polymerization reactions are considered to be cationic in mechanism.
Olefin polymerization in liquid sulfur dioxide initiated by m‐chloroperbenzoic acid. II. Copolymerization of styrene and α‐methylstyrene
Authors: Akcelrud L. , Gomes A. S. 
Published: April 2003

AbstractCopolymerizations of styrene (Sty) and α‐methlstyrene (AMS) were carried out in liquid sulfur dioxide at −10°C and at −40°C with m‐chloroperbenzoic acid (MCPBA) as initiator. Reactivity ratios were determined by the methods of Fineman–Ross and Kelen–Tüdös, from polymer composition obtained by nuclear magnetic spectroscopy. As indicated by thermogravimetric analysis, a block copolymer was obtained at −40°C.
Copolymerization of styrene with vinyl acetate in presence of tributyl amine (TBA)
Authors: Bataille P. , Charifi‐Sandjani N. 
Published: April 2003

AbstractThis work presents the results of solution and emulsion copolymerization of vinyl acetate and styrene in the presence of a tertiary amine such as tributyl amine. This amine increases the stability of the vinyl acetate free radicals and favors copolymerization reaction. Emulsion polymerizations in the presence of TBA resulted in a terpolymer of styrene‐vinyl acetate‐vinyl alcohol. Vinyl alcohol is due to hydrolysis in the basis aqueous medium.The homo‐and copolymers obtained by precipitation from the reacting mixtures were fractionated according to procedures devised from solubility trials and from the work of Soen et al.13Fractions were characterized by nuclear magnetic resonance (NMR), infrared (IR), gel permeation chromatography (GPC), and thermal analysis.Heteropolymers were obtained with both techniques, and a terpolymer was obtained by emulsion polymerization, due to ester hydrolysis. The monomer conversion was more than 26%; 15% of the motives in the polymer were alcohols and 4%, acetates. With solution polymerization the conversion was more than 11%; 14% of the motives, as indicated by NMR, were acetates and the rest styrene.
Polymerization of α,α‐disubstituted‐β‐propiolactones and lactams. 10. Crystalline structure, thermal and mechanical studies of statistical and block copolymers of pivalolactone and α‐methyl‐α‐propyl‐β‐propiolactone
Authors: Allegrezza A. E. , Lenz R. W. , Cornibert J. , Marchessault R. H. 
Published: April 2003

AbstractAB and ABA block copolyesters based on racemic poly(α‐methyl‐α‐n propyl‐α‐propiolactone) (PMPPL) as a “soft” or elastomeric segment and polypivalolactone (PPL) as a “hard” or crystallizable segment have been synthesized and compared with random copolymers of the same composition. X‐ray studies show the coexistence of polymorphic crystal forms for a given polymer in a given sample. Thermal and dynamic mechanical properties give clear evidence of heterophase structure corresponding to segregation of PPL and PMPPL. The crystalline phase clearly provides thermally reversible crosslinking in the ABA block copolymers. On stretching, the planar zigzag form of PMPPL is observed. Because of the domain structure, moduli of ABA samples are higher than those of PMPPL and their tensile strengths are similar to those of comparable styrene‐butadiene block copolymers.The polymer synthesis was achieved by sequential monomer addition with tetrahexyl ammonium benzoate as initiator. For the ABA polymers the diammonium salt of sebacic acid provided a di‐functional initiator. The agreement between calculated and observed molecular weights testify to the “living” character of this polymerization reaction.
ESR study of γ‐irradiated 1,3,5‐trithiane and its derivatives
Authors: Andrzejewska E. , Żuk A. , Pietrzak J. , Krzyminiewski R. 
Published: April 2003

AbstractRadicals formed in γ‐irradiated 1,3,5‐trithiane and its derivatives at room temperature have been studied by ESR spectroscopy. ESR evidence establishes that 1,3,5‐trithiane as well as α‐ and β‐2,4,6‐trimethyl‐1,3,5‐trithiane yield radicals mainly by loss of the hydrogen atom, whereas α‐ and β‐2,4,6‐triphenyl‐1,3,5‐trithiane and 2,4,6‐trimethyl‐2,4,6‐triphenyl‐1,3,5‐trithiane produce radicals that are parent radical cations, which are also present in small amounts in aliphatic trithianes. Furthermore, in all the spectra examined R–S.‐type radicals are observed. The probable initiation process of radiation‐induced 1,3,5‐trithiane polymerization is discussed briefly.