bluuebunny/crossref_metadata_2025_split huggingface dataset:
Poly(alkylene oxide) ionomers. XIII. Copolymers of trioxane with the epoxide and 1,3‐dioxolane of methyl 10‐undecenoate
Authors: Bansleben Donald A. , Janovic Zvonimir , Vogl Otto 
Published: April 2003

AbstractCationic copolymerization of 1,3,5‐trioxane with methyl 10,11‐epoxyundecanoate or methyl 7,8‐epoxyoctanoate and terpolymerization with 1,3‐dioxolane was successfully carried out. Co‐and terpolymerization of 1,3,5‐trioxane with 4‐(1‐carbomethoxynonyl)‐1,3‐dioxolane was also achieved. Feed compositions of the functional comonomers were varied from 5 to 40 mol %; in all cases the isolated copolymers contained less than 5% of the functional mer units. The composition of the copolymers showed that the methyl ω‐epoxyalkanoates were much less reactive than 1,3,5‐trioxane. A similar trend was observed with the functional dioxolane monomer, although significantly shorter induction periods were observed in comparison with the epoxy/trioxane copolymerizations. The oxymethylene copolymers and terpolymers were characterized primarily by their infrared spectra; however, the thermal and base stabilities of selected copolymers were also determined.
Development‐free vapor photoetching effect of azide‐type photopolymers
Authors: Hong Xiao‐Yin , Xiao Ji‐Qang , Zhou Zi , Pei Rong‐Xing 
Published: April 2003

AbstractA new dry photoetching process that dose not required development step had been developed, utilizing the development‐free vapor photoetching effect of cinnamate‐type photopolymers.1–3 In contrast to obtaining positive patterns with cinnamate‐type photopolymers, this process with azide‐type photopolymers, which consist of axide crosslinking agent and polymers, gives negative patterns. Some preliminary studies on the development‐free vapor photoetching effect of azide‐type photopolymers were made. The results indicate that the polymers in this process only play the role of forming a film on the surface of silicon dioxide; and the crosslinking agent is the most important factor, which leads the difference of etching rate between the exposed and unexposed areas.
Mechanism of the thickening reaction of polyester resins: Study on models
Authors: Judas Didier , Fradet Alain , Marechal Ernest 
Published: April 2003

AbstractThe thickening reaction of polyester resins is investigated using model compounds, diesters or polyesters of 1,2‐propanediol and phthalic acid with dihydroxy or dicarboxy end groups. Soluble magnesium acetylacetonate was found to be an effective thickener, and for the first time it was possible to study a thickening reaction in homogeneous media (THF solutions). The results are compared with those obtained with MgO. The proposed mechanism supposes that the central step consists of the formation and the aggregation of magnesium carboxylates in ionic areas, with entanglement of attached polyester chains. This fits our experimental results better than the hypothesis of coordination of magnesium carboxylates by ester or hydroxyl groups of the chains2–6 or than the hypothesis of the formation of linear high molecular weight compounds.7–9
Radiation‐induced copolymerization of vinylene carbonate with methyl trifluoroacrylate
Authors: Otsuhata Kazushige , Watanabe Terutaka , Ishigaki Isao , Tabata Yoneho , Okamoto Jiro 
Published: April 2003

AbstractCopolymerization of vinylene carbonate (VCA) with methyl trifluoroacrylate (MTFA) was carried out by gamma rays from 60Co at dose rates of 1 × 105 rad/h to 1 × 106 rad/h, temperatures of 0°C to 75°C, and molar ratios MTFA/VCA of 30/70 to 90/10 in the monomer mixture. By irradiation, VCA reacted with MTFA to give a white powder copolymer with low molecular weight. The copolymerization rate has a maximum at a concentration of 70 mol % VCA, and is proportional to the 0.92 power of dose rate. The apparent activation energy was 1.3 kcal/mol. Equimolar copolymer was obtained at molar ratio MTFA/VCA of 50/50 to 10/90. The reactivity ratios of both monomers, VCA and MTFA, were determined to be r(VCA) = 0.3 and r(MTFA) = 0.07, respectively.
New polypyromellitimide films based on cyclotriphosphazene and bisaspartimide derived diamines
Authors: Kumar Devendra 
Published: April 2003

AbstractThree new thermally stable polypyromellitimide films were made by the thermal cyclodehydration of the corresponding polyamic acids obtained by the polymerization of pyromellitic dianhydride with 4,4′‐bis{N2‐[4‐(4‐aminobenzyl)phenyl]aspartimido} diphenylmethane, 4,4′‐bis{N2‐[4‐(4‐aminophenoxy)phenyl]aspartimido} diphenylether, and bis(4‐aminophenoxy)tetrakis (4‐phthalamic acid phenoxy)cyclotriphosphazene. The bis(4‐aminophenoxy)tetrakis (4‐phthalamic acid phenoxy)cyclotriphosphazene was obtained from hexakis(4‐aminophenoxy)cyclotriphosphazene involving its reaction with phthalic anhydride. The structure of these materials and precursors were characterized by using Fourier‐transform‐infrared (FT–IR) and proton nuclear magnetic resonance spectroscopy. The thermal stabilities of the films were evaluated by the thermogravimetric analysis, showing char yields at 800°C ranging from 68% to 58% in a nitrogen atmosphere and 24% in air atmosphere.
Dependence of computed copolymer reactivity ratios on the calculation method. I. Effect of experimental setup
Authors: Hautus F. L. M. , Linssen H. N. , German A. L. 
Published: April 2003

AbstractFive calculation methods for estimating reactivity ratios are compared. Two of these methods are only valid at low conversion, two methods are assumed to be valid up to high conversion, and the fifth method is the integrated form of the copolymer equation. Data were simulated for selected couples of r‐values and two conversion levels. The data were randomly disturbed by normal error with mean zero. As (the) monomer feed ratio(s) will be drifting during the course of reaction, the influence of an approximated monomer feed ratio on the r‐values calculated was also examined. When conversion is low, all methods give estimates with low precision. High conversion results in larger precision, however, for several methods bias appears. For calculation methods that need information about an approximated monomer feed ratio, the influence of this approximation appears to be rather important especially if the r‐values are dissimilar or conversion is high.
Characterization and chemistry of polyaldehyde microspheres
Authors: Margel Shlomo 
Published: April 2003

AbstractThe chemical composition of polyacrolein (PA) microspheres of various types as well as polyglutaraldehyde (PGL) microspheres was elucidated. Nephelometric measurements were used for studying the stability properties of the polyaldehyde microspheres in different pH and salt concentrations. The stability of the aldehyde groups themselves at various pH and temperature was also determined. The polyaldehyde microspheres covalently bind amino ligands, e.g., proteins, antibodies, enzymes, and drugs in a single step. The effect of temperature and the influence of thiol compounds on the reaction between the polyaldehyde microspheres and amino ligands was examined. The reaction of the polyaldehyde microspheres with sodium hydrogen sulfite is also described.
Aqueous polymerization of methacrylic acid initiated by Ce4+ ‐glycolic acid redox pair
Authors: Misra G. S. , Arya B. D. 
Published: April 2003

AbstractThe aqueous polymerization of methacrylic acid (MAA) initiated by a Ce4+ ‐glycolic acid (GA) system was observed in a sulfuric acid medium at 35 ± 0.2°C in a nitrogen atmosphere. The rate of monomer disappearance was proportional to [MAA]1 and the rate of ceric ion disappearance was proportional to [GA][Ce4+]. An increase in the reaction temperature from 30 to 45°C raised the rate and the overall activation energy was 63 kJ/mol. The molecular weight increased with a rise in [MAA] and a reduction in [Ce4+]. The effect of varying [H2SO4] was also studied.
Photoinduced reversible pH change in aqueous solution of azoaromatic poly(carboxylic acid)
Authors: Ishihara Kazuhiko , Matsuo Tohru , Tsunemitsu Katsuaki , Shinohara Isao , Negishi Naoki 
Published: April 2003

AbstractTo regulate the pH value of an aqueous solution containing polyelectrolyte by photoirradiation, an azoaromatic poly(carboxylic acid), acrylic acid(AA)‐p‐phenylazoacrylanilide (PAAn) copolymer was synthesized and the photoresponse of the polymer solution was investigated. AA‐PAAn copolymer, which takes a compact form in the ordinary state owing to the presence of azoaromatic side chains, is transformed into an extended form when azoaromatic moieties are isomerized by photoirradiation. Thus, the pH value of the solution can be reversible regulated by irradiation and interruption of light through a change in polymer conformation. The range of the pH change was about 0.15. These phenomena can be explained on the basis of polarity change induced by the photoisomerization of azoaromatic side chains.
Synthesis and characterization of soluble aromatic polyazomethines from 2,5‐bis(4‐aminophenyl)‐3,4‐diphenylthiophene and aromatic dialdehydes
Authors: Imai Yoshio , Maldar N. N. , Kakimoto Masa‐Aki 
Published: April 2003

AbstractNew soluble aromatic polyazomethines with inherent viscosities of 0.4–0.8 dL/g were prepared by the solution polycondensation of 2,5‐bis(4‐aminophenyl)‐3,4‐diphenylthiophene, bis(4‐aminophenyl) ether, and aromatic dialdehydes in o‐chlorophenol at 20°C. The copolyazomethines are generally soluble in chlorinated hydrocarbons, amide‐type or phenolic solvents. The thermal stability of the polymers, which showed no weight loss up to 400°C in both air and nitrogen atmospheres.
A warning about structures of thiophene polymers
Authors: Gutierrez Mario H. , Ford Warren T. , Pohl Herbert A. 
Published: April 2003

Abstract2,5‐Dichlorothiophene, 2,5‐dibromothiophene, and tetrabromothiophene have been polymerized with anhydrous sodium sulfide in N‐methylpyrrolidone (NMP) at 250°C to insoluble products which contain structural fragments derived from both the starting thiophene and the NMP. The copolymers absorb 0.5 to 1.0 times their weights of iodine to give materials with electrical conductivities of about 10‐5 (ohm cm)‐1 at 16 kbar and 10‐7 (ohm cm)‐1 at atmospheric pressure.
Kinetics of oligomerization of methyl ester of dehydrated castor oil fatty acid over molybdenum oxide on silica–alumina catalyst in comparison with the thermal oligomerization process
Authors: Venkatachalam S. , Kumar V. G. , Rao K. V. C. 
Published: April 2003

AbstractA process is described for the oligomerization of methyl ester of dehydrated castor oil fatty acid over molybdenum oxide on silica–alumina catalyst. The process is compared with thermal oligomerization. The nature of the reaction in both the processes are shown to be the same from the structural elucidation of the product despite the variation in product composition. The percentage of dimer in the product in both the processes is observed to attain an equilibrium value at around 270°C. The catalytic process is shown to follow a second‐order kinetics with respect to the monomer, whereas the thermal reaction follows a first‐order kinetics. The kinetic scheme derived for the catalytic process is shown to be consistent with the steps of the general mechanism proposed for oligomerization reactions over transition metal catalysts [V. G. Kumar, S. Venkatachalam, and K.V.C. Rao, J. Poly. Sci. Polym. Chem. Ed., 22, 3850 (1984)].
Titanium and rare earth chloride catalysts for ethylene polymerization
Authors: Martin Joel L. 
Published: April 2003

AbstractAnhydrous chlorides of Mg, Mn, Y, and selected lanthanides were reacted with tri‐n‐butylphosphate and finally TiCI4 to prepare ethylene polymerization catalysts. With triethylaluminum as cocatalyst the highest activities were observed with Mg, Nd, and Pr, which correlate with the peak activity for Nd and Pr in diene polymerization catalysts prepared from the lanthanides. At a given hydrogen concentration molecular weights and molecular weight distributions and catalyst activities were similar for these three metals. The high activity for Nd and Pr is surprising because NdCI3 and PrCI3 adopt the UCI3 structure rather than a layer lattice structure common to MgCI2 and TiCI3.
Hydroperoxides as intermediates responsible for wavelength effects in photooxidation reactions
Authors: Bousquet J. A. , Fouassier J. P. 
Published: April 2003

AbstractA quantitative study of a model elastomer was performed to gain a deeper insight into photooxidation processes. Since the twofold role of hydroperoxides as excited sensitizer quenchers, and radical initiators has been amply demonstrated, we described the mechanism of energy transfer to repulsive excited states of these substances and quantitatively determined their distribution in the polymeric material, according to their reactivity. In addition, two irradiation wavelengths (λ = 254 nm and λ = 313 nm) were used to demonstrate that behavior of hydroperoxides depends on the nature and the concentration of excited chromophoric groups and accounts for the macroscopic wavelength effect usually observed in the photooxidation of polymers.
Functional monomers and polymers. CXXI. Methylation and interaction studies on adenine containing polymethacrylate derivatives
Authors: Fang Shi‐Bi , Inaki Yoshiaki , Takemoto Kiichi 
Published: April 2003

AbstractStudies of the methylation of polymethacrylate derivatives with adenine bases were made in comparison to those with uracil bases. The polymethacrylate derivatives with adenine bases were methylated by using methyl iodide in dimethyl sulfoxide solution to produce polymers that contained N1‐methyladenine and N1, N6‐dimethyladenine units. The products were identified by spectroscopic data and by preparing their model compounds. The methylated polymers obtained were further applied in a study of polymer complex formation with uracil‐base polymers.
Characteristics of microemulsion polymerized styrene with water‐soluble versus oil‐soluble initiators
Authors: Johnson P. L. , Gulari Esin 
Published: April 2003

AbstractThe effect of oil‐soluble versus water‐soluble free‐radical generators in the polymerization of styrene in oil‐in‐water (O/W) micromulsions were investigated by photon correlation spectroscopy. The microemulsions were formed by styrene, brine, sodium dodecyl sulfate (SDS), and pentanol. The polymerizations were carried out in two microemulsions that contained droplets differing by a factor of 2.4 in volume. Under the conditions of ϕ = 0.019 and NaCl/SDS > 2 the microemulsions were stable and the droplets were independent of one another. Both oil‐soluble and water‐soluble initiators produced polystyrene that contained fractions of two different sizes. In the case of the oil‐soluble initiator the droplet size in the microemulsion seemed to be correlated to the size of the product whereas in the case of the water‐soluble initiator, there seemed to be little relation.
Aromatic polyamides. XII. Effect of the polymeric unit linkage position on the thermal decomposition and flammability of the unsubstituted and halogen‐substituted aromatic polyamides
Authors: Kapuscinska M. , Pearce E. M. , Chung H. F. M. , Ching C. C. , Zhou Q. X. 
Published: April 2003

AbstractThe synthesis, thermal characterization, and oxygen index of aromatic polyamides varying with polymeric unit linkage positions (meta and/or para units) and halogen substitution have been reported. It has been found that polyamides containing para units are more thermal stable than those containing meta units. There is no significant effect of the main chain structure studied here on either the pyrolysis pathways or flammability of similarly halogen substituted polyamides.
Reaction epoxy‐amine: Suivi du mecanisme reactionnel et de la cinetique par RMN 13C, 15N et HPLC
Authors: Grenier‐Loustalot Marie‐Florence , Grenier Philippe 
Published: April 2003

AbstractThe curing reaction of diglycidyl ether of bisphenol A (DGEBA) with metaphenylene diamine (mPDA) was investigated with high performance liquid chromatography (HPLC) and Fourier transform nuclear magnetic resonance spectroscopy (FT NMR 13C and 15N). With the results obtained from a series of models a mechanism was proposed and the cure kinetics were obtained at 100°C. The major conclusion is that the cure proceeded mainly by chain extension, whereas crosslinking occurred in the reaction of hydroxyl groups with epoxides and resulted in the formation of ether linkages.
Short‐chain model studies on emission properties of poly(9‐vinylphenanthrene‐co‐p‐N,N‐dimethylaminostyrene): Exciplex quenching and subsequent formation of another fluorescent exciplex
Authors: Iwai Kaoru , Takemura Fukuo , Furue Masaoki , Nozakura Shun‐Ichi 
Published: April 2003

AbstractThe emission properties of 1‐(4‐dimethylaminophenyl)‐3‐(9‐phenanthryl)propane, Ph(CH2)3 DMA, and 1,3‐di‐(9‐phenanthyrl)propane, Ph(CH2)3Ph, were studied in comparison with those of poly(9‐vinylphenanthrene‐co‐p‐N,N‐dimethylaminostyrene). Ph(CH2)3DMA showed an intense intramolecular exciplex fluorescence in dioxane. Ph(CH2)3Ph did not exhibit a clear intramolecular excimer fluorescence. The quenching of the intramolecular exciplex by several electron acceptors was studied. As a result moderate electron acceptors, such as cyanobenzene, methyl benzoate, and acrylonitrile, selectively quenched the intramolecular exciplex, and in the case of cyanobenzene the subsequent formation of another fluorescent exciplex was observed. The results were discussed in terms of the reduction potentials of electron accepting quenchers.
Cationic polymerization of 1‐phenyl‐4‐ethyl‐2,6,7‐trioxabicyclo[2.2.2]octane
Authors: Uno Hitomi , Endo Takeshi , Okawara Makoto 
Published: April 2003

AbstractCationic polymerization of bicyclo ortho ester, 1‐phenyl‐4‐ethyl‐2,6,7‐trioxabicyclo[2.2.2]octane, was carried out with Lewis acids and cation sources to obtain the polyether containing ester group in the side chain. It was found that boron trifluoride etherate was the most active initiator in the Lewis acids. Magnesium perchlorate and triphenylcarbenium tetrafluoroborate, which have lower nucleophilic counter ions, initiated effectively the polymerization of bicyclo ortho ester.
Polymeric catalysis: Imidazoles grafted onto poly(vinylamine). II. Kinetics of the esterolysis of activated phenyl esters
Authors: Tomko Richard , Overberger C. G. 
Published: April 2003

AbstractIn the previous paper, some ω‐(1‐imidazolyl) and ω‐[4(5)‐imidazolyl]alkanoic acids were synthesized and grafted onto poly(vinylamine). These water soluble catalysts of varying apolarity contain both hydrophobic and electrostatic binding sites for neutral and charged substrates. The influence of side chain length, percent graft, and the substitution in the imidazole ring are described. The grafts possessing the longer side chains and lesser apolar weight were more efficient catalysts than the grafts containing numerous short side chains and greater apolar weight. These grafts exhibited slower rates than poly[4(5)‐vinylimidazole].
Grafting onto wool. XXV. Effect of acids on γ‐radiation‐induced graft copolymerization of methyl methacrylate onto wool fiber
Authors: Misra B. N. , Rawat B. R. 
Published: April 2003

AbstractGraft copolymerization of methyl methacrylate (MMA) onto Himachali wool fiber has been investigated in aqueous medium by using γ irradiation from a 2100 Ci60CO source as means of initiation. Graft copolymerization was carried out by the mutual method in nitrogen atmosphere as well as in air. Effect of mineral acids and acetic acid on percentage of grafting was studied. Percentage of grafting was determined as functions of total dose, concentration of monomer, and concentration of acids. Maximum percentage of grafting in the presence of acids occurred in nitrogen atmosphere at a total dose of 1.05 MR. All the acids were found to influence grafting and the reactivity of different acids towards graft copolymerization was found to follow the order: H2SO4 > HCl > HNO3 > HC1O4 > HOAc. An attempt has been made to explain the reactivity order of different acids in the light of the mechanism proposed for γ‐irradiation‐induced graft copolymerization of vinyl monomer onto wool fiber.
Study on triazine thiols. VI. Selective graft copolymerization of MMA on modified copper plates
Authors: Mori Kunio , Nakamura Yoshiro 
Published: April 2003

AbstractGraft copolymerization of MMA on copper surface which is initiated by Na2S2O8 in an aqueous solution proceeded selectively when copper plates are modified by 6‐unsaturated group‐1,3,5‐triazine‐2,4‐dithiol monosodium salts (UTD) and 6‐dimethylamino‐1,3,5‐triazine‐2,4‐dithiol monosodium salt (DMTD). Grafting weight was influenced by the molar ratio of UTD to DMTD in the aqueous solution that copper plates are treated. The former on copper surface is a coupling component of MMA radicals and initiator radicals. The latter is a catalyst which accelerates the formation of radicals acting with Na2S2O8. Selective graft copolymerization is due to the reason that radicals generate selectively in the neighborhood of copper surface and in this place there are monomers such as MMA and UTD.
Graft copolymerization. II. Grafting of benzyloxyethyl methacrylate on poly(vinyl alcohol)
Authors: Silberman Ruth , Kohn David H. 
Published: April 2003

AbstractNew graft copolymers were produced by grafting benzyloxyethyl methacrylate, the benzyl ether of HEMA, on high‐molecular‐weight poly(vinyl alcohol) in dimethyl sulfoxide solution with Ce4+ as initiator. The effects of the concentration of the initiator, the concentration of the monomer, the total concentration of the reactants, the temperature, and the duration of reaction on the percentages of grafting and conversion were investigated. Further, also the relationships between the initiator concentration and the percentages of grafting and of conversion in the reaction with poly(vinyl alcohol)s of lower molecular weight and of different degrees of hydrolysis were studied.
Molecular design of multicomponent polymer systems. VII. Emulsifying effect of poly(ethylene–b–styrene) copolymer in high‐density polyethylene/polystyrene blends
Authors: Fayt R. , Hadjiandreou P. , Teyssie Ph. 
Published: April 2003

AbstractPoly(butadiene–b–styrene) copolymers containing a pure, 1,4‐PB block have been synthesized by a “living” coordination process. The complete hydrogenation of the PB chain leads accordingly to a high‐density polyethylene (HDPE) block. The emulsifying efficiency of such a copolymer (H‐7) in HDPE/PS blends is compared with that of a previously reported poly(ethylene–butene–b–styrene) copolymer (SE‐7) obtained by the PB hydrogenation of an anionically prepared PB–b–PS. Microscopy examinations demonstrate unambiguously the interfacial activity of both copolymers in HDPE/PS blends. The tensile mechanical properties of the blends are significantly but also differently modified by the two emulsifiers. The copolymer H‐7 gives rise to the highest strengths, but, contrary to the copolymer SE‐7, provides a poor ductility to the blends. This different behavior is assumed to result in part from the different characteristics of the hydrogenated PB blocks. The elastomeric HPB chain of SE‐7 should form at the interface a more or less extended soft zone whereas a rigid interface would result from the cocrystallization of the HPB chain of H‐7 with the HDPE homopolymer.