bluuebunny/crossref_metadata_2025_split huggingface dataset:
New elastomers derived from copolymers of tetrahydrofuran and propylene oxide
Authors: Dickinson L. A. 
Published: April 2003

AbstractThe homopolymers of tetrahydrofuran, polytetramethylene glycols, may be chain‐extended to form polyurethane elastomers. These materials, while possessing a low glass point temperature, suffer from cold hardening, and it was decided to investigate copolymers of tetrahydrofuran and propylene oxide as elastomer ingredients. The preparation of these copolymers has been achieved by use of a boron trifluoride etherate polymerization catalyst. Details are given of the properties of both the copolymer and derived elastomers at nominal compositions in the range 50–85 wt.‐% of tetrahydrofuran. The copolymers described were synthesized as ingredients for castable elastomers, and in consequence viscosity effects are important. It has been found that no significant increase in viscosity occurs until the tetrahydrofuran content exceeds 75 wt.‐%. This indicates that each side methyl group exerts a screening effect over an average of 13 atoms of the polymer backbones. The mechanical testing of the derived elastomers indicates that the copolymerization of tetrahydrofuran and propylene oxide leads to material possessing a low glass point temperature and much better physical properties than the homopolymer of propylene oxide. The elastic properties of a chain‐extended diol are dependent on the degree of crosslinking and on the incidence of network deficiencies. Network deficiencies are caused by the presence of monofunctional species in the copolymeric diols, and a novel technique for determining diol monofunctionality based on analysis of physical test data was evolved for these studies.
Polymerization of ethylene with a preactivated aluminum‐titanium(IV) chloride catalyst and a statistical study of the polymerization variables
Authors: Joyner F. B. , Shearer N. H. , Coover H. W. 
Published: April 2003

AbstractConversion of ethylene to a high‐density polymer was readily effected at low pressures and temperatures with the use of a catalyst consisting initially of a mixture of aluminum and titanium(IV) chloride. The principal factors influencing the polymerization and properties of the resulting polyethylene were investigated. These reactions at preferred catalyst concentrations were always preceded by a prolonged induction period; consequently, a means of reducing this period was developed. Factors influencing the polymerization included the nature of the aluminum in the catalyst, type of solvent, and molecular weight regulators. The effects of pressure, temperature, aluminum concentration, and Al/TiCl4 mole ratio on induction period, reaction rate, and polymer properties were determined from a factorial experiment in which each factor was investigated at two levels. The polymerization could be initiated at low catalyst concentrations and temperatures by preactivating the Al‐TiCl4 mixture, that is, partially converting it to aluminum chloride and titanium(III) chloride. Optimum catalyst efficiency was obtained at an Al/TiCl4 mole ratio of 0.5 to 1.0; the aluminum concentration was 0.0028 to 0.04% based on weight of solvent. Polyethylene yields as great as 1873 parts/part total catalyst were obtained at aluminum concentrations of 0.0028 to 0.008% and ethylene pressures of 150 to 280 psi. Liquid aliphatic hydrocarbons were more effective than aromatic hydrocarbons as media for the polymerization. Low molecular weight polymers and high‐density waxes were produced when hydrogen was used in the polymerization. The statistical study showed that the induction period was reduced by increasing the ethylene pressure and by decreasing the Al/TiCl4 mole ratio. The average reaction rate was increased by increasing the pressure, temperature, and aluminum concentration. A kinetic analysis of the data showed that the length of the induction period was inversely proportional to the first power of the pressure and titanium(IV) chloride concentration. The rate equation for the polymerization was found to be

where P is the ethylene pressure. Formation of high molecular weight polymers was favored by high monomer concentrations and low titanium(IV) chloride concentrations. High‐density polyethylene (0.950–0.960 g./cc.) can be produced conveniently, safely, and economically at low pressures (40 to 280 psi) and low temperatures (50 to 85°C.) with the use of preactivated Al‐TiCl4 catalyst.
Radiation‐induced solid‐state polymerization of ring compounds
Authors: Okamura Seizo , Hayashi Koichiro , Kitanishi Yasuhisa 
Published: April 2003

AbstractRing compounds such as trioxane, β‐propiolactone, diketene, and 3,3‐bischloromethylcycloxabutane can be polymerized only in the solid state by γ‐radiation. These ring compounds polymerize by a ring‐opening, ionic mechanism to highly crystalline, high molecular weight, linear polymers. In general, the conversion vs. irradiation time curves reach a limiting value at relatively low yield. These saturation phenomena are due to the disruption of unreacted monomer lattice by the formed polymer. The polymers obtained from large‐monomer crystals are found to have outward appearances of large crystals which suggest the monomer crystalline lattice has influenced that of the polymer. Moreover, the polymers from large crystalline monomer have higher polymerization rate and better orientation of the crystallites, as ascertained through x‐ray diffraction and polarizing microscopic analyses. Polarizing microscopic photographs of the polymers show birefringence clearly. These facts indicate that the structure of the monomer lattice directly imposes order and orientation upon the polymer. X‐ray diffraction analyses show that the polydiketene chain has a spiral configuration and poly‐β‐propiolactone has a planar zigzag chain. Some consideration of the propagation mechanism in the crystalline state of 3,3‐bischloromethylcycloxabutene, γ‐propiolactone, diketene, and trioxane is made. Investigations of the binary systems with β‐propiolactone were carried out to determine the effects of additives upon the propagation mechanism.
On the mechanism of polymerization of caprolactam catalyzed by phosphoric acid. II
Authors: Geleji Frigyes , Szafner Alfréd 
Published: April 2003

AbstractIn the presence of water or catalysts giving off water, caprolactam is polymerized by several reaction mechanisms taking place simultaneously. It was investigated whether the formation of polyamide takes place according to a polycondensation or polyaddition mechanism in the presence of phosphoric acid. In order to prove the polycondensation mechanism, the formation at 250°C. of a mixed anhydride from the carboxylic acids and the orthophosphoric acid was studied. N‐phosphoryl aminocaproic acid has also been synthesized. No catalytic effect was exerted by this compound; on the basis of this fact it can be stated that in the case catalysis by orthophosphoric acid, the increase of the polyamide chain does not take place according to a polycondensation mechanism. The adduct of caprolactam and orthophosphoric acid is able to catalyze the polymerization of caprolactam. Polymerizations carried out at temperatures ranging from 170 to 200°C. proved that the acid—amide bond of the caprolactam ring is weakened by the phosphoric acid, thereby rendering possible the polymerization to take place at a lower temperature. At elevated temperatures (exceeding 160°C.), the ammonium salts of phosphoric acid undergo dissociation; thus, free orthophosphoric acid is always present in the mixture undergoing polymerization. Due to the dissociation at higher temperatures, the phosphoric acid yields a product having higher molecular weight than at lower temperatures. It has been established that the rate of polymerization is directly proportional to the square root of the molar concentration of the free orthophosphoric acid. The activation energy of the polymerization catalyzed by phosphoric acid was 46 kcal./mole.
Polymerization reactions in the presence of a metal salt
Authors: Mullier M. E. 
Published: April 2003

AbstractA kinetic study of a free radical‐initiated polymerization reaction in the presence of a copper salt has been undertaken. The results show that the polymerization of styrene initiated by benzoyl peroxide or α,α,‐azobisisobutyronitrile in either dioxane or dimethylformamide is not influenced by the presence of cupric octoate in the solution. The results show also that neither the initiation nor the reaction is affected when the cupric octoate is present. In contrast, the polymerization of styrene initiated by tert‐butyl hydroperoxide in dioxane is strongly influenced by the presence of cupric octoate in the solution. The results obtained can be partially explained by assuming the formation of a complex between the hydroperoxide and cupric octoate. At low concentration of copper salt and hydroperoxide, the rate of polymerization can be represented by an equation. Moreover, the values of the intrinsic viscosities of the polymers obtained show that the total chain transfer constant is not affected by the ratio tert‐butyl hydroperoxide/cupric octoate.
The swelling of polymer solvents. III. Sorption of liquids by elastomers
Authors: Buckley D. J. , Berger M. 
Published: April 2003

AbstractSorption of liquids by elastomers is advanced as a means of studying polymer structure. Liquids represent a wider versatility in this regard over vapors since they allow choices of molecular sizes, shapes, and configurational distributions, and thermal effects not available with vapors. Configurations, coiling versus stretched‐out molecules, are examined and shown to be of considerable importance in the sorption process. The problem of determination of the concentration dependence is attacked by use of a binary solution as a sorbent or swelling agent. The binary solution is so chosen that one liquid may be considered the solvent and the other liquid a nonsolvent for the particular elastomer. The ternary solution of butyl network—hexane—acetone was used in sorption experiments at 25°C. The total uptake of the binary liquid was measured from zero time to equilibrium in an optical swelling apparatus. Simultaneously, the composition of the binary liquid sorbed at any time was measured in a recording differential refractometer. The two sets of data were combined to calculate the ratio of the two liquids sorbed. The dilution procedure succeeded in varying the apparent activity of the solvent hexane. Preferential sorption of hexane was observed, but significant amounts of the nonsolvent acetone enter the network. The known equilibrium uptake values of hexane from the binary solutions are used to determine the concentration dependence of the diffusion of liquid hexane in a butyl network at 25°C. D0 = 2 × 10−9 cm.2 sec.−1 and a concentration dependence of 10 were obtained by this method. “Activities” for the hexane in the diluted form are calculated for an elastically calibrated network. The activities for the entire concentration range studied agree well with those of a comparable swollen polymer—liquid system such as natural rubber—benzene vapor. Test of the generality of the present method is suggested. Such a test would involve examination of the dependence of the hexane activities so calculated on the nature of the nonsolvent used in the binary liquid.
Etude expérimentale des dismutations rapides que subissent la cellulose, la lignine et le bois dans l'eau sous pression au‐dessus de 280°c: le problème de la lignine
Authors: Gillet Alf. , Colson P. 
Published: April 2003

AbstractA la suite de recherches précédentes sur la cellulose, la conclusion suivante avait été proposée: c'est la décomposition progressive du kérogène qui, dans les conditions de la nature, aurait produit à la fois: les pétroles d'une part et, d'autre part, les houilles anciennes. La présente communication décrit la suite des měmes recherches expérimentales. Elle porte sur la lignine et sur le bois, soumis à leur tour à des conditions similaires à celles auxquelles fut soumise la cellulose. On a trouvé que, dans ces conditions (chauffage par exemple pendant 10 h à 275°C en solution alcaline): (a) Une lignine de composition centésimale: C 63; H 6,3; O 30,7—traitée en milieu alcalin à 275°C, produit, pour 21% de son poids, une matière réduite de composition: C 62,6; H 9,7; O 27,7 ou: C 72,4; H 8,6; O 19 + 0,55 H2O. (b) La měme lignine, traitée dans l'eau pure, produit pour 9,8% de son poids, une matière réduite de composition: C 60,3; H 11,27; O 28,4 (ou C 73,87; H 9,75; O 16,4 + 0,75 H2O). Un bois de chěne de composition: C 49; H 6,2; O 44,8, produit en milieu alcalin, pour 29,5% de son poids une matière réduite de composition: Essai I: C 61; H 7,85; O 34; Essai III: C 64,2; H 7,85; O 27,9 ou D 75; H 9,15; O 17 + 10 atomes d'oxygène fixés par oxydation accidentelle au cours des manipulations. La cellulose de composition: C 44,4; H 6,19; O 49,41, avait donné pour 14,8% de son poids, un produit réduit de decomposition: C 73.5; H 10,2; O 16,3 (C12H20O2). Composition type du Kérogène: C 75; H 8,6; O 16,4.
Incorporation of halogen endgroups in polymers and their detection by the dye test
Authors: Palit Santi R. , Saha Mihir K. 
Published: April 2003

AbstractThe incorporation of halogen endgroups in polymers has been established in the following cases for polymerization of styrene, methyl methacrylate and methyl acrylate: (1) chain transfer with halogenated hydrocarbons (chloroform, benzyl chloride, bromoform, ethylene dibromide, octadecyl bromide, ethyl iodide, cetyl iodide); (2) copolymerization with suitable components (vinyl bromide, tetrachloroethylene, trichloroethylene); (3) use of halogen atoms as initiators, e.g. FeCl3 (+hv), FeBr3 (+hv), HCl (+hv) and KBr + H2O2 (+hv); (4) chemical transformation of a group already present in a polymer, e.g., conversion of hydroxyl endgroup to halogen endgroup by a usual method; addition of hydrogen bromide to double bond in polymers. The method of detection consists in converting a polymer with halogen endgroups to a quaternary pyridinium halide by refluxing with pyridine, a few drops of glycerol being added in the case of chlorine endgroup to facilitate the reaction. The converted quaternary halogen endgroup is detected independently by two tests developed in this laboratory: the dyeinteraction test with rhodamine 6GX conc. (Calco) dye and also the dye‐partition test for cationic group with Bromophenol Blue or Disulfine Blue VN 150 as reagents.
Formation of hydroxyl endgroups in polymers and their detection by dye tests
Authors: Palit Santi R. , Mukherjee Asish R. 
Published: April 2003

AbstractThe following possibilities of introducing hydroxyl endgroups in polymers have been experimentally realized: (1) redox initiation by ferrous sulfate + H2O2 (Fenton's reagent), N2H4, H2O + H2O2, FeCl3 + H2O2; photoinitiation by Fe(OH)++ + light, H2O2 + ultraviolet light or sunlight, and initiation by unstable Ag+++ complex in dark; (2) copolymerization with a trace of allyl alcohol or with traces of vinyl acetate and allyl acetate and subsequent hydrolysis; (3) chain transfer with butyl alcohols. The method of detection consists in first converting hydroxyl endgroups to carboxyl endgroups by refluxing with phthalic anhydride or 3‐nitrophthalic anhydride in benzene and pyridine medium or with maleic anhydride in benzene medium and testing the resulting polymer for carboxyl endgroup by the dye‐interaction test with rhodamine 6GX dye extract. The hydroxyl endgroup was also quickly converted to a strong acid endgroup like OSO3H by reacting the polymer with chlorosulfonic acid in chloroform medium under controlled conditions and tested by the dye‐interaction test or a dye‐partition test with methylene blue. This test is not entirely satisfactory, as the reagent attacks the thermal polymers slightly.
Synthesis of high molecular polyoxamides at a liquid—gas interface
Authors: Sokolov L. B. 
Published: April 2003

AbstractThe principle of the new gas‐phase method of polycondensation consists of carrying out the polycondensation reaction of two high reactive compounds at a liquid—gas interface. The gas‐phase method permits the synthesis of polyamides with rapidly hydrolyzing diacid chlorides (e.g., oxalyl chloride), which cannot be used for liquid—liquid polycondensation. The gas‐phase synthesis of polyhexamethyleneoxamide from hexamethylenediamine and oxalyl chloride has been investigated in detail. The common features of gas‐phase and interfacial methods of polycondensation are due to the fact that in both cases the chemical reaction proceeds in the polymeric film. The gas‐phase methods can be used for the synthesis of a series of polymers.
Changes in the rate of anionic polymerization of octamethylcyclotetrasiloxane caused by the formation of complexes on silanolate active centers
Authors: Kučera Miloslav 
Published: April 2003

AbstractThe effect of bases on the anionic polymerization of octamethylcyclotetrasiloxane (tetramer) initiated by ∼Si—OK groups has been studied. In the presence of hydroxides of alkali metals or of other Lewis bases, in particular of anisole, complexes are formed on active centers which alter the reactivity of the centers. The effects of the presence of NaOH, LiOH, anisole, and excess KOH on the polymerization of tetramer initiated by ∼Si—OK groups have been determined at various temperatures. An explanation is proposed for the retardation effect of LiOH and NaOH on the polymerization of tetramer; the effects of anisole and excess KOH has been discussed. Also the molecular weight of polydimethylsiloxane is affected by the presence of bases. A hypothesis of the formation and decomposition of complexes on active centers has been formulated which can explain the observed changes in the molecular weight of the polymer. The overall energies of activation of tetramer polymerization initiated by KOH in the presence of LiOH, NaOH, excess KOH, and anisole have been measured. Also measured were values of equilibrium constants of reactions of formation and decomposition of complexes of ∼Si—OK groups with LiOH, NaOH, and KO∼Si— and the corresponding heats of reactions.
Stability of polyvinyl chloride in the presence of nitrating acid
Authors: Wolkóber Zoltán 
Published: April 2003

AbstractUnder the effect of sulfuric acid, oil of vitriol, or chlorosulfonic acid, with the simultaneous formation of sulfur dioxide, hydrochloric acid, and carbon dioxide, the polyvinyl chloride is transformed to a reticulated product which is insoluble in organic solvents and usable for ion‐exchange. The rate of reaction is dependent on the specific surface of polyvinyl chloride, the temperature, and the concentration of the sulfuric acid. In the presence of nitric acid, the reactivity of the polyvinyl chloride to the sulfuric acid changes fundamentally. Under duly chosen circumstances, and in the presence of several per cent of nitric acid, the polyvinyl chloride shows no appreciable change in composition in 100% sulfuric acid, even at 175°C., and it retains its thermoplastic properties and its solubility; only its molecular weight is decreased. At higher temperatures the polyvinyl chloride is slowly oxidized by the nitrating acid. On the basis of our investigations on the stabilizing effect of the nitric acid, conclusions can be reached concerning the rates of reactions initiating the decomposition of polyvinyl chloride and the subsequent reaction, the ratio of reaction rates, as well as the kinetics of the processes taking place in sulfonation and dehydrochlorination. The high stability of the polyvinyl chloride to the nitrating acid indicates that the zip reaction starts at one or two points of the individual molecules of polyvinyl chloride, and this reaction runs along the whole macromolecule. The strong stabilizing effect of the nitric acid can be attributed to the fact that it reacts with the double bond formed at the beginning of the decomposition at a higher rate than of the chain reaction of splitting off of hydrochloric acid from the allyl structure.
Struktur der dienpolymeren in zusammenhang mit der natur der katalytischen systemen
Authors: Dolgoplosk B. A. , Erussalimskiǐ B. L. , Kropatsheva E. N. , Tinyakova E. I. 
Published: April 2003

AbstractDie Struktur der Dienpolymeren ist in Zusammenhang mit der Natur der katalytischen Komplexen studiert worden. Es ist festgestellt worden, dass die Polymerisation der Diene durch den Chromoxydkatalysator zu kristallinen trans‐1,4 Polymeren führt. Polymerisation der Diene unter dem Einfluss von homogenen und heterogenen Systemen, die aus Dialkylaluminimumhalogeniden und verschiedenen Co‐Verbindungen (CoO, Co3O4, CoSO4, Co‐halogeniden, kohlenwasserstofflöslichen Co(CO)4 und Alkohol‐ und Pyridinkomplexen von CoCl2) zusammengesetzt sind, ist studiert worden. Die Struktur von Polybutadien und Polyisopren, die durch alle angeführten Systeme erhalten sind, ist für alle Fälle ziemlich gleich. Besonders aktiv und stereospezifisch wirkt das homogene System aus Dialkylaluminiumhalogenid und Alkohol‐ oder Pyridinkomplex von CoCl2, das eine Bildung von Polybutadien mit 95% von cis‐1,4 Kettenglieder hervorruft. Die Abhängigkeit des Molgewichtes von Polybutadien von der Konzentration des löslichen Pyridinkomplexes von CoCl2 entspricht der Gleichung M = KC1/2. Beim Studium der Zusammenwirkung zwischen Kobaltoxyden oder CoCl2 und AlEt2Cl ergab es sich, dass die Bildung vom katalytischen Komplex ist nicht von redox Reaktionen begleitet. In dem System aus Co(CO)4 und AlEt2Cl geht der Polymerisation das Stadium einer Bildung von unlöslichem katalytischen Komplex voran. Dessen Zusammensetzung ist studiert worden. Die Reaktion zwischen AlEt3 und Kobalthalogeniden ist erforscht; wie gezeigt, sie kann zur Auslösung der Polymerisation ausgenützt werden. Es ist festgestellt worden, dass ätherfreie magnesiumorganische Verbindungen die Polymerisation der Diene auslösen. Besonders einheitlich ist die Struktur von Polyisopren (96–99% 3,4‐Kettenglieder), durch grösste Polymerisationsgeschwindigkeit ist Chloropren ausgezeichnet. Cis‐trans Isomerization von Naturkautschuk durch aluminiumorganische Verbindungen, Titanhalogenide und wasserfreien Chlorwasserstoff ist studiert worden. Der Isomerisationsprozess verläuft bei verhältnismässig niedriger Temperatur und wird von einer Verminderung der Doppelbindungen begleitet.
Polymérisations anioniques: Polymeres ω‐ fonctionnels. Réactions de couplage et de greffage carbanionique
Authors: Finaz G. , Gallot Y. , Parrod J. , Rempp P. 
Published: April 2003

AbstractLa polymérisation de monomères vinyliques par voie anionique en milieu tétrahydrofuranne conduit à des polymères ω‐carbanioniques stables, mais susceptibles de donner des réactions avec diverses substances choisies pour leur électroaffinité. On peut ainsi obtenir à volonté des polymères possédant en bout de chaǐne des fonctions acide, alcool, amine, éthylénique, chlorure d'acide, cétone ou autres semblables. Ces réactions se font généralement avec des rendements élevés. Si on effectue des réactions du měme genre en utilisant des réactifs bifonctionnels et des polymères dicarbanioniques, il se produit une réaction de couplage multilatéral, une polycondensation secondaire pouvant conduire dans certains cas à des masses moléculaires très élevées, ce qui prouve le caractère quasi quantitatif de ces réactions de désactivation. En faisant réagir des polymères monocarbanioniques sur des substances macromoléculaires polyfonctionnelles adéquates, on obtient des polymères greffés, avec des rendements et des taux de greffage variables selon les conditions de la réaction et selon la longueur de la chaine du greffon. Les copolymères greffés ainsi obtenus sont très homogènes en composition et leur polydispersité en masse se ramène essentiellement à celle du polymère‐support de départ.