bluuebunny/crossref_metadata_2025_split huggingface dataset:
4‐Alkoxy‐2‐hydroxy‐4′‐vinylbenzophenones, ultraviolet‐absorbing monomers
Authors: Kamogawa Hiroyoshi , Takayanagi Yoko , Nanasawa Masato 
Published: April 2003

Abstract2,4‐Dihydroxy‐4′‐vinylbenzophenone (I) and its 4‐alkyl ethers (II), Me, Et, n‐Bu, n‐Oct, and n‐dodecyl, were prepared in three steps by Hoesch synthesis, starting with p‐(2‐bromoethyl) benzonitrile and resorcinol and its monoalkyl ethers. I and its precursor 2,4‐dihydroxy‐4′‐(2‐bromoethyl) benzophenone were also converted into their 4‐alkyl ethers with alkyl halides in dimethylformamide (DMF) in the presence of sodium hydrogen carbonate. Copolymerizations of I and II with styrene took place smoothly with satisfactory conversions to yield copolymers with ε‐values around 104 L/mol cm−1 per benzophenone unit over the ultraviolet (UV) range of 235–340nm.
Polymerization of cyclohexene oxide with aluminum complex‐silanol catalysts. Part III. Dependence of catalytic activity on bulkiness of silanol and its intramolecular hydrogen bond
Authors: Hayase S. , Ito T. , Suzuki S. , Wada M. 
Published: April 2003

AbstractPolymerization of cyclohexene oxide, especially the catalytic activity influenced by silanol structure, was examined by using an Al(acac)3–silanol compound catalyst. The catalytic activity increased as the acidity of silanol increased. It was prolonged by sterically hindered silanol compounds which prevented the silanol from self‐condensation and from joining with the epoxide. In addition, the greater catalytic activity produced by intramolecular hydrogen‐bonding silanol compounds is explained by the polymer effect.
Emulsifier‐free emulsion polymerization with cationic comonomer
Authors: Liu Li‐Jen , Krieger Irvin M. 
Published: April 2003

AbstractAn earlier article1 described the emulsion polymerization of styrene and various anionic comonomers, together with an anionic initiator, to give uniform latices at ca. 35% solids content. This article extends the work to cationic systems. Cationic comonomers 1,2‐dimethyl 5‐vinylpyridinium methylsulfate and 1‐ethyl 2‐methyl 5‐vinylpyridinium bromide were synthesized and used with azobis(isobutyramidine hydrocholoride) initiator in the emulsifier‐ free emulsion polymerization of styrene. Recipes and results were generally comparable to those of the anionic systems, excepts for the dependence of particle diameter on comonomers concentration. Here the initial decrease was followed by an increase in particle diameter at higher comonomer content. The surface charge increased sharply with comonomer content.
Surface reaction of particulate silica with polydimethylsiloxanes
Authors: Yu‐Fu Li , Yong‐Xia Xia , Dong‐Peng Xu , Guang‐Liang Li 
Published: April 2003

AbstractThe interaction of silica and oligomeric methylsiloxanes, methylsilicone oil as well as silicone gum at elevated temperature was studied. It was found that a reaction takes place between surface silanols and octamethylcyclotrasiloxane (D4) above 180°C. Part of the methylsiloxane replaces the surface silanols forming loops with the surface, while the other part is redistributed to its neighboring homologoues. The methylsiloxy surface groups thus formed can undergo further reaction with the other methylsiloxanes above 250°C. Methylsilicone oil behaves similarly. The reaction with silicone gum was demonstrated by the formation of “chemically bound rubber.” The mechanism of the reaction is discussed.
Diethylzinc/metal salt initiator systems. I. Stereospecific polymerization of N‐vinylcarbazole by ZnEt2/CoCl2‐quinoline
Authors: Biswas Mukul , Mishra Girish Chandra 
Published: April 2003

AbstractIn the presence of ZnEt2 the CoCl2‐quinoline complex polymerizes NVC with a rate increasing with ZnEt2 and CoCl2‐Q concentrations up to a certain concentration of ZnEt2 or CoCl2‐Q, thereafter becoming independent of either. At a fixed concentration of ZnEt2 and CoCl2‐Q the rate is second order with respect to NVC. The poly(NVC) obtained is freely soluble in benzene but leaves some insoluble fraction in methyl ethyl ketone, which has been characterized by 13C‐NMR to be a stereoblock polymer. X‐ray diffraction, IR, and thermal characteristics of the polymer have also been reported. [η] is virtually independent of monomer, in the concentration range 0.1–0.25 mol/L ZnEt2 and CoCl2‐Q concentrations. Oxygen as an additive inhibits the polymerization. A cationic coordination mechanism has been proposed and appropriate rate and degree of polymerization equations have been suggested.
Kinetics of polyesterification. I. Dibasic acid and glycol systems
Authors: Chen Show‐An , Hsiao Jui‐Chung 
Published: April 2003

AbstractPolyesterification of diacid and diol in the absence of foreign acid is carried out under constant reaction temperatures from 140 to 180°C (rather than under constant oil bath temperature as is usually done) and molar ratios r of diol to diacid from 1 to 3.55. The experimental data obtained cannot fit conventional rate equations as they appear in the literature. Based on ion pair formation and considering additional proton transfer from acid to alcohol, we propose a reaction mechanism and rate equations. The rate equation is found to fit our experimental data very well except for r = 1. At r = 1, the kinetic plot shows two straight lines rather than one as predicted. This is attributed to unremoved water due to the higher molecular weight (and therefore higher viscosity) at r = 1 which causes a reverse reaction and slower apparent reaction rate.
Binding of methyl orange and its homologs by polyion complexes in aqueous solution
Authors: Takagishi Toru , Kozuka Hiroshi , Kuroki Nobuhiko 
Published: April 2003

AbstractPolyion complexes of sodium poly(methacrylate) and piperidinium cationic polymers [I], which are insoluble in water and have an equal number of positive and negative charges, bind organic anions (methyl orange, ethyl orange, propyl orange, butyl orange, and pentyl orange) in aqueous solution. The strength of the binding is enhanced by an increase in the hydrophobicity of the polyion complex and the small cosolute. Moreover, strong cooperative interactions appear with increased uptake of the small molecule. Urea and an inorganic electrolyte (KCl) were examined for their effect on the binding, the amount of which is strongly suppressed by these additives. The significance of hydrophobic and electrostatic interactions which accompany the binding is described.
Synthesis and DSC study of model hard segments from diphenyl methane diisocyanate and butane diol
Authors: Camberlin Y. , Pascault J. P. , Letoffe J. M. , Claudy P. 
Published: April 2003

AbstractModel hard segments having different chain length and chain terminating groups, such as methyl, ethyl, octyl, and octadecyl, have been synthesized from diphenyl‐methane diisocyanate (MDI) and butanediol and studied by DSC. In the case of short chain ends (i.e., methyl, ethyl, and octyl), hard segments having up to three MDI units show an increase of melting temperature Tm, while those with octadecyl chain end have Tm increase continuously with the number of MDI units. Enthalpy and entropy decrease with the augmentation of the hard‐segment length. Side groups on the chain ends have a great influence on the melting properties.
New processable polyaromatic keto‐sulfones with internal acetylene units
Authors: Lin See , Kriek George R. , Marvel C. S. 
Published: April 2003

AbstractPolyaromatic ketone‐sulfones of high molecular weight have been obtained from bis‐(3‐carboxyphenyl) acetylene dichloride, isophthaloyl chloride, terephthaloyl chloride, and 4,4‐diphenoxydiphenyl sulfone in a Friedel‐Craft‐type polycondensation. The polymer products are white powders and form transparent, strong films. These polymers could be reacted by Diels–Alder cycloaddition with 1,4‐diphenyl‐1,3‐butadiene. These polymers showed only a very slight increase in viscosity over those that were not reacted with diphenylbutadiene.
Decomposition of polypropylene hydroperoxide by hindered amines
Authors: Carlsson D. J. , Chan K. H. , Durmis J. , Wiles D. M. 
Published: April 2003

AbstractThe hindered amine‐induced decomposition of polypropylene hydroperoxide was studied in the solid state and in the presence of a liquid solvent and the polymer was compared with model hydroperoxides. The high reactivity of the macrohydroperoxides appears to be related to the adjacent, hydrogen‐bonded hydroperoxide groups that occur in the polymer. The hindered amines are converted to nitroxides in the reaction via hydroxylamine intermediates. Amine‐induced decomposition of polypropylene hydroperoxide is faster in the absence of a liquid solvent for the amine than in the presence of the solvent, probably because of the strong amine‐hydroperoxide association that occurs in the solid state. The decomposition process in the solid state is sufficiently rapid for the reaction to contribute to the effectiveness of hindered amines in the light stabilization of polymers.
Coordination polymers. XIII. Synthesis and investigation of polymers obtained by the reaction of maleic acid with ZnO
Authors: Vancso‐Szmercsanyi I. , Kallo A. 
Published: April 2003

AbstractIn some cases metal dicarboxylates can be considered as polymers. Formation of crystalline or amorphous polymer depends on the type and ratio of the metal ion to the carboxylate ligand and on the preparation conditions. The “polymer salt” synthesized by the reaction of ZnO and maleic acid shows special feature due to the cis configuration of the dicarboxylic acid. The polymer prepared in a water medium has a fibrillar morphology with a helical structure which is changed by heat treatment: a molecular rearrangement takes place which leads finally to amorphous polymer. The reaction of ZnO and fumaric acid (trans configuration) results in monocrystals containing crystal water or, after heat treatment, in powderlike polymer.
Emulsion polymerization of styrene. I. Review of experimental data and digital simulation
Authors: Bataille P. , Van B. T. , Pham Q. B. 
Published: April 2003

AbstractIsothermal emulsion polymerization at 60°C of styrene in a batch reactor were studied by using sodium lauryl sulfate as surfactant and potassium persulfate as initiator source. The concentrations of surfactant and initiator were varied during the runs. The polymerization evolution was followed as samples were taken at regular intervals. These emulsion samples were analyzed for monomer conversion, rate of polymerization, as well as for the size and the size distribution of the particles. The molecular weight and molecular weight distribution were obtained by gel permeation chromatography. Our study showed that fresh nucleation takes place even at high conversion, causing a continuous shifting toward broadening of particle size distribution. Contrary to the theory of Smith and Ewart, which assumes a constant number of particles during interval II of the polymerization reaction, our digital simulation of the reaction presents better experimental results with a variable number of particles, and indicates that the Hui–Hamielec model for termination constant kt as function of conversion is not applicable under our working conditions.
Emulsion polymerization of styrene. II. Effect of Ag(I) and Fe(II) on the polymerization of styrene initiated by potassium persulfate
Authors: Bataille P. , Van B. T. , Pham Q. B. 
Published: April 2003

AbstractThe emulsion polymerization of styrene initiated by potassium persulfate catalyzed by Ag(I) and/or ferrous ions Fe (II) was studied. It was found that silver ions in conjunction with potassium persulfate accelerate the polymerization of styrene. Ferrous ions reduce the polymerization rate by termination reaction with primary radicals. Both silver ions and ferrous ions act as transfer agents with the result of lowering of the average molecular weight of the polymer.
Sulfonation and subsequent rections of ethylidene norbornane and dihydrodicyclopentadiene. The chemistry of some small molecule models for EPDM rubbers
Authors: Thaler Warren A. 
Published: April 2003

AbstractIonomers prepared by the sulfonation of EPDM rubbers have been the subject of considerable investigation with regard to their remarkable bulk and solution properties; however, relatively little is known about the chemistry of the sulfonation and the structure and subsequent reactions of the sulfonated intermediates. This article reports an effort to enlarge our understanding of sulfonate ionomers by examining the chemistry of small molecule analogs of the olefinic sites which are present in low concentrations in EPDMs. Ethylidene norbornane (ENBH) and dihydrodicyclopentadiene (DCPDH) were synthesized as models for EPDMs which use ethylidene norbornene and dicyclopentadiene as their respective termonomers. The sulfonated products from the two models were quite different, a sultone with a rearranged carbon skeleton being formed in the former case and a remarkable regiospecific sulfonic acid in the latter. Conditions necessary for hydrolysis and ammonolysis were established, the former proceeding essentially by a substitution mechanism, the latter via a retro‐Wagner Meerwein elimination. Rate studies showed the importance of solvent effects in these sulfonation reactions which were attributed to a combination of site reactivity and acetylsulfate solubility. Mixed solvents were effective in improving reactivity while maintaining the solvency necessary for EPDM polymers. The results of this model study are being used as a guide in studies of EPDM polymers.
Radiation‐induced graft copolymerization of mixtures of styrene and acrylamide onto cellulose acetate. I. Effect of solvents
Authors: Bhattacharyya S. N. , Maldas D. 
Published: April 2003

AbstractThe grafting of styrene and acrylamide, from both their binary and unitary systems, on cellulose acetate film was studied by means of the cobalt‐60 postirradiation grafting technique. The extent of grafting was found to be dependent on preirradiation dose, reaction time, and temperature, and the optimum conditions were evaluated. The effect of solvents, e.g., water, methanol, ethanol, isopropanol, and t‐butanol were studied. The composition of the binary mixture as well as the nature of the alcohol used as the solvent were found to have a strong influence in modifying the course of grafting. Each component of the binary monomer mixture was found to sensitize the grafting of the other, when the former is present in relatively large concentration. The observed results are discussed in detail in terms of relative molecular reactivity and reactivity ratios.
Synthesis of a polycarbonate by reaction of carbon dioxide, dipotassium 4,4′‐isopropylidenediphenolate and α,ω‐dihalo compounds
Authors: Rokicki Gabriel , Kuran Witold , Kiełkiewicz Jȩdrzej 
Published: April 2003

AbstractTo study the possibility of obtaining aliphatic‐aromatic polycarbonates the reactions of CO2, dipotassium 4,4′‐isopropylidenediphenolate, and different α,ω‐dihalo compounds were studied in polar aprotic solvents in the presence of various catalysts. It was shown that in addition to the crown ethers already in use as catalysts in this type of polycondensation reaction cryptates and polyglyme exhibit similar catalytic activity. The influence of temperature, CO2 pressure, solvent, and structure of the α,ω‐dihalo compound on the yield of the polymer formed was established. A relationship between the type and amount of catalyst used, especially crown ether, on the reaction yield was revealed, and some physicochemical properties of the polymers obtained were determined. Studies of the model reaction between CO2, potassium phenolate, and different α,ω‐dihalo compounds under conditions analogous to those of the studied reaction were carried out. On the basis of the results obtained attempts were made to explain the reaction mechanism.
Polymerization of 1‐chloro‐2‐phenylacetylene induced by UV irradiation of Mo(CO)6
Authors: Masuda Toshio , Kuwane Yoshinori , Higashimura Toshinobu 
Published: April 2003

AbstractPolymerization of 1‐chloro‐2‐phenylacetylene was effected by the catalyst formed by UV irradiation of Mo(CO)6 in carbon tetrachloride to provide in high yield a polymer whose weight‐average molecular weight reached 2 × 106. UV irradiation and an appropriate halogenated hydrocarbon were essential for the formation of active species. The formation of a metal carbene as active species was inferred. Poly(1‐chloro‐2‐phenylacetylene) was a light‐yellow solid having the structure $ \rlap{--} ({\rm CCl\dbondCPh\rlap{--} )}_n $. The polymer was soluble in aromatic and halogenated hydrocarbons, and a film could be formed from polymer solution.
Polyterephthalates of 2,3‐disubstituted butanediols‐1,4: Effect of aliphatic substituents on Tg and Tm of the polyesters
Authors: Florjanczyk Z. , Deopura B. , Stein R. S. , Vogl O. 
Published: April 2003

AbstractPoly(2,3‐dialkylbutanediol‐1,4 terephthalates) with the alkyl substituents CH3, C2H5, n‐C3H7, iso‐C3H7, n‐C4H9, and n‐C10H21, andn‐C16H33 were synthesized from the corresponding 2,3‐dialkylbutanediols‐1,4 and dimethyl terephthalate or terephthaloyl chloride. The substituents of the butanediol‐1,4 portion of the polyterephthalates influence the 13C NMR chemical shifts of the carbon atoms near the branching site, the glass transition (Tg), and the crystallizability. Small alkyl substituents do not change the Tg of the polymers, whereas bulky substituents such as the isopropyl group increase the Tg and long normal alkyl groups as substituents decrease the Tg of the polymers. Crystallinity in these polyterephthalates was found only with CH3 and C16H33 as the 2,3‐dialkyl substituents in the butanediol‐1,4 portion of the polyester. This crystallinity of polyterephthalate of 2,3‐di‐C16H33 substituted butanediol‐1,4 could be assigned to side‐chain crystallization of the paraffinic groups.
Thermally degrading polyethylene studied by means of factor‐jump thermogravimetry
Authors: Dickens Brian 
Published: April 2003

AbstractDegradation of polyethylene in both linear (NBS 1475) and branched (NBS 1476) form has been studied in the range 410–475°C using factor‐jump thermogravimetry. In vacuum, the rate of weight loss was erratic because of bubbling in the sample. The apparent overall activation energy was determined to be 65.4 ± 0.5 kcal/mol (273 ± 2 kJ/mol). There was no distinguishable difference between linear and branched samples. In slowly flowing N2 at 8 mmHg (1 mmHg = 133 Pa), the overall activation energy was determined to be 64.8 ± 0.3 kcal/mol (271 ± 1 kJ/mol) for linear PE and 64.4 ± 0.2 kcal/mol (269 ± 1 kJ/mol) for a sample of PE with one percent branches. In N2 at 800 mmHg, the values were 62.6 ± 0.5 kcal/mol for linear PE and 61.2 ± 0.6 kcal/mol for the branched sample, the rate of weight loss being smooth in both cases. Changing the linear flow velocities over the range 1–4 mm/sec at 800 mmHg did not affect the results. From the insertion of typical values in the equation relating the overall activation energy for weight loss from linear polyethylene to the activation energies of the component steps, a degradation mechanism involving scission β to allyl groups, with rapid hydrogen abstraction, slower subsequent β scission, and bimolecular termination, is indicated. The activation energy of β scission for secondary alkyl radicals is estimated to be 33 kcal/mol. The reason for the lower activation energies in N2 is related to the effects of preformed molecules. The average molecular weights of the volatiles in vacuum and for 8 and 800 mmHg N2 have been shown to be in the ratios 1 to 1/4 to 1/10, respectively, at these imposed rates of weight loss. The activation energies to use for the initial stage of degradation are 70.6 kcal/mol (295 kJ/mol) in vacuum and 67.8 kcal/mol (284 kJ/mol) at atmospheric pressure.
Direct synthesis of a polyamide by an enol phosphite and imidazole
Authors: Yamaguchi Kazuo , Rokicki Gabriel , Kawanobe Wataru , Nakahama Seiichi , Yamazaki Noboru 
Published: April 2003

AbstractDirect polycondensation of various dicarboxylic acids and diamines was effected under mild conditions by using an enol phosphite, diethyl 1‐methyl‐3‐oxo‐1‐butenyl phosphite (I), in the presence of imidazole. To check the activity of the enol phosphite and various organic bases in an amidation reaction, the model reaction of acetic acid and aniline was carried out, and the yield of acetanilide was estimated by means of gas chromatography. Among organic bases, imidazole was the best in terms of yield of acetanilide. Polycondensation performed by varying solvents, temperature, and amount of imidazole resulted in high yields of polyamides with inherent viscosities of 0.1‐0.25.
Preparation of ion exchange resins from carbonaceous adsorbents
Authors: Ford Warren T. , Beasley Glenn H. , Chong Berni P. , Neely James W. 
Published: April 2003

AbstractCarbonaceous adsorbents are obtained by thermolysis of sulfonated macroreticular polystyrene ion exchange resins at 300‐500°C. The hard, spherical, carbonaceous particles react exothermally with elemental chlorine to form products containing up to 38% Cl. The chlorinated particles react readily with polyamines to form anion exchange resins with capacities of up to 2.2 meq/g dry resin. Less than 60% of the nitrogen atoms in the particles are utilized as ion exchange sites. The carbonaceous particles can also be chloromethylated with chloromethyl methyl ether or chlorinated with sulfuryl chloride and then aminated with polyamines to form anion exchange resins, sulfonated with sulfuric acid or chlorosulfonic acid to form strongly acidic cation exchange resins, or chlorosulfonated and then aminated with polyamines to form anion exchange resins. Model structures of the thermolyzed resins containing polycyclic aromatic hydrocarbon fragments are proposed to explain their chemical reactivities.
Kinetics of epoxide resins formation from epichlorohydrin and bisphenol‐A
Authors: Enikolopyan N. S. , Markevitch M. A. , Sakhonenko L. S. , Rogovina S. Z. , Oshmyan V. G. 
Published: April 2003

AbstractThe kinetics of formation of epoxide resins based on epichlorohydrin and bisphenol‐A via synthesis with one‐ or two‐step addition of alkali are considered. The kinetics of the reaction were studied by taking into account the consumption of the alkali added and the change of molecular mass and epoxide value of epoxide oligomers. The results obtained are satisfactorily explained within the framework of a model containing the following postulates: all the alkali is bound as phenolate ions; all phenolic groups are of equal reactivity; the reactivity of epichlorohydrin is higher than that of glycidyl ethers; the stage of dehydrochlorination of chlorohydrin ethers in the synthesis with one‐step addition of alkali is rapid and does not limit the process; the first stage of the two‐step synthesis is the formation of chlorohydrin ethers and the second stage their consumption. The factors leading to differences between the experimentally obtained parameters of the resulting epoxide resins (molecular weight, epoxide value) and their calculated values are discussed. The synthesis of epoxide resins with two‐step alkali addition is shown to possess certain advantages over the one‐step process.
Diffusion‐controlled vinyl polymerization. I. The gel effect
Authors: Soh S. K. , Sundberg D. C. 
Published: April 2003

AbstractIt is well known that the reaction rate and molecular weight of vinyl polymers can change markedly during the course of polymerization and that these changes are due to the influence of diffusion on the termination reaction. The chain length dependence of the termination rate constant has been considered in this work and has resulted in a general method of treating the polymerization kinetics and molecular weight distribution. This method is independent of the form of the chain length dependency and is capable of dealing with both disproportionation and recombination modes of termination. A specific model for the termination rate constant with chain length dependence is proposed and is based on free volume theory and entanglement coupling. Master curves for the characteristics of the reaction rate and molecular weight distribution are presented with the application of this model.