bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adhesion behavior of rat lymphocytes on poly(γ‐benzyl L‐glutamate) derivatives having hydroxyl groups or poly(ethylene glycol) chains
Authors: Nishimura Takao , Sato Yuichi , Yokoyama Masayuki , Okuya Mashahiro , Inoue Shohei , Kataoka Kazunori , Okano Teruo , Sakurai Yasuhisa 
Published: April 2003

AbstractPoly[γ‐benzyl L‐glutamate (BLG)‐co‐N5‐(3‐hydroxypropyl)‐L‐glutamine (HLG)] (3) and polyBLG/poly(ethylene glycol) (PBLG/PEG) block copolymers (6) were synthesized, and the adhesion behavior of rat lymphnode lymphocytes on these polymers was examined by the column method. An increase in the HLG content of polymer 3 caused a slight decrease in lymphocyte adhesivity. Lymphocyte subpopulation B cells were found to be more adhesive to polymers 3 than T cells, by a factor of 1,4 – 1,6. On the other hand, an increase in the PEG content of PBLG/PEG block copolymer caused a remarkable decrease inlymphocyte adhesivity and an increase in selectivity in the adhesivity between B cells and T cells up to a factor of 2,3.
Vapour pressures of the system tert‐butyl acetate/polystyrene
Authors: Schotsch Kurt , Wolf B. A. 
Published: April 2003

AbstractAn apparatus is presented for the precise measurement of vapour pressures. It is tested with diethyl ether and applied to the system tert‐butyle acetate/polystyrene (weight‐average molecular weight Mw = 110000) up to polymer concentrations of ca. 60 wt.‐% in the temperature range from 10 to 90°C; by means of the Redlich‐Kister equation the results can well be described analytically. The data are evaluated to yield the Flory‐Huggins parameter in the subsequent article in conjunction with other experimental information.
Structure and stability of poly(vinyl chloride), 4. Unsaturated ketones and their role in the initiation of thermal degradation
Authors: Světlý Jarmil , Lukáš Rudolf , Michalcová Jaroslava , Kolíanský Miloslav 
Published: April 2003

AbstractThe thermal dehydrochlorination of poly(vinyl chloride) (PVC) in an inert atmosphere was investigated by the continuous potentiometric method. The effect of the structure of alicyclic and aliphatic α,β‐unsaturated ketones on the rate of dehydrochlorination was examined, and a new mechanism of initiation for the dehydrochlorination of PVC was suggested. The results obtained demonstrate that the basic cause of the thermal instability of PVC are structures of the type of cisoid α,β‐unsaturated ketone, dienone, or polyenone which by the dehydrochlorination of regular structural PVC units form isolated double bonds which, in turn, initiate the chain dehydrochlorination of PVC by allyl activation.
Gemischte Diester von 2,2′‐Methylendiphenolen mit Methacryl‐ und Crotonsäure und ihre Polymeren. 13C NMR‐Untersuchungen zur Strukturaufklärung
Authors: Böhmer Volker , Funk Rüdiger , Vogt Walter 
Published: April 2003

AbstractThe structure of mixed diesters of three 2,2′‐methylenediphenols with crotonic acid and methacrylic acid was studied by 13C NMR‐spectroscopy. The position of the two acyl groups, expected from the synthetic pathway, was unambiguously confirmed by comparison with the corresponding mono‐ and diesters containing the same acyl group. In the same way, it was shown that the crotonoyl residue is not involved in the radical polymerisation of these esters.
Investigations on linear segmented polyurethane elastomers, 1. Temperature dependence of microphase segregated structure
Authors: Tagawa Hiroyuki , Kurita Kimio , Wada Eiichi 
Published: April 2003

AbstractThe temperature dependence of microphase segregation in polyester and polyether segmented urethane elastomers has been studied by small‐angle X‐ray scattering, viscoelasticity, and infrared spectroscopy. The mean‐square electron density fluctuations distincitly decrease with increasing temperature above about 60°C. Their value estimated from the location of the first peak of the electron density correlation function increases with increasing temperature; at the same time the peak becomes flat and finally disappears. The infrared absorbance for the NH vibration decreases above about 80°C. These results correspond to an increase of the mean distance between the centers of the nearest neighbouring microdomains, mainly composed of the hard segments, and to intermixing of hard and soft segments in the boundaries of the domains by heat treatment. This fact suggests that a domain structure is formed by casting in these polyurethane elastomers. The dynamic storage moduli G′ for both samples investigated decrease in the two temperature ranges, −70 to −20°C and 60 to 120°C, the former corresponds to the dispersion of soft segments and the latter to the dissociation of hydrogen bonds.
Résines époxydes, 3. Etude de quelques prépolymères époxydes bromés par GPC, HPLC et NMR
Authors: Gulino Danièle , Galy Jocelyne , Pascault Jean‐Pierre , Pham Quang Tho 
Published: April 2003

AbstractExaminations by GPC, HPLC and NMR of several commercial prepolymers containing epoxy groups show that they are based on bisphenol A (DGEBA) and brominated bisphenol A (DGEBtBr). In some cases, brominated monepoxides are also added to the mixture to diminish its viscosity. Consequently, the three‐dimensional networks resulting from the polycondensation of brominated resins with diamines can be greatly affected by the presence of these monoepoxides that modify the epoxy/amine ratios.
Synthesis and investigation of the properties of polymers containing dicarbaundecaborate
Authors: Bekasova Nina I. , Komarova Ludmila G. , Kats Georgii A. , Korshak Vasilii V. 
Published: April 2003

AbstractPolymides containing dicarbundecaborate moieties (1) are formed by nucleophilic degradation of polyamides containing 1,7‐dicarba‐closo‐dodecaborane(12) (m‐carborane) moieties in the polymeric chain. The formation of polyamides 1 is accompained by decomposition of the polymeric chain. Potassium cations in the dicarbundecaborate moieties were shown to be easily replaced by protons. The structure of polymers containing exclusively dicarbaundecaborate units (2) was investigated by IR and 1H NMR spectroscopy. Some chemical and physico‐chemical properties of these polyamides were studied.
Kinetics of deactivation in the BuOTiCl3/AlEt2Cl initiated polymerization of styrene
Authors: Sehra Jagdish C. , Gundiah Subbaraya 
Published: April 2003

AbstractThe deactivation of the catalytic activity of the BuOTiCl3/AlEt2Cl initiated polymerization of styrene in heptane was found to follow a second‐order rate law. The varying slopes in the second‐order plots observed with varying catalyst concentrations are due to the heterogeneous nature of these colloidally dispersed catalysts. Site poisoning by reversible adsorption of the AlEtCl2 formed, is proposed as the probable reason for the deactivation.
Conformational analysis and reactivity in isotactic specific polymerization of C‐3 branched α‐olefins
Authors: Ammendola Paolo , Guerra Gaetano , Villani Vincenzo 
Published: April 2003

AbstractQuantitative conformational analysis of 3‐methyl‐1‐butene, 3‐methyl‐1‐pentene and 3‐ethyl‐1‐pentene seems to support the hypothesis that the conformation of these monomers in the active state of Ziegler‐Natta isotactic polymerization is either H‐skew + or H‐skew −. It seems, however, that the experimentally determined reactivities of the considered α‐olefins in the initiation steps of the isotactic polymerization could be accounted for quantitatively only by assuming somewhat different activation energies for the attack of the different monomers.
Synthesis of a propene—methyl methacrylate diblock copolymer via “living” coordination polymerization
Authors: Doi Yoshiharu , Koyama Tetsuya , Soga Kazuo 
Published: April 2003

AbstractA new diblock copolymer of propene and methyl methacrylate (MMA) was prepared by adding MMA during the living coordination polymerization of propene together with the soluble catalyst V(acac)3/Al(C2H5)2Cl at −78°C and subsequently by raising the polymerization temperature up to 25°C. The homopolymerization of MMA with this catalyst exhibits the characteristics of a living polymerization at the initial stage of polymerization. From the copolymerization of MMA with styrene, it was concluded that the polymerization of MMA occurs via a radical intermediate. It is suggested that a propene‐MMA diblock copolymer is formed via the transformation of a living polypropylene end to a radical end.
Aldehydes and acetals based on esters of methacrylic acid as potential monomers
Authors: Zábranský Jiří , Houska Milan , Kálal Jaroslav 
Published: April 2003

AbstractNew monomers containing aldehyde groups in the alcohol component of methacrylates were prepared. The structure of these monomers prevents undesired spontaneous intramolecular cyclization reactions of pendant aldehyde groups of the corresponding polymers. 2,2‐Diethoxyethyl methacrylate (1) and its saturated analog, 2,2‐diethoxyethyl pivalate (3) and 3,3‐diethoxypropyl methacrylate (2) were prepared. The conditions for a selective hydrolysis of the acetal function of these compounds, leading to the corresponding aldehydes, were studied.
Cinétiques de télomérisation, 1. Determination des lois applicables à la synthèse des télomères à DPn moyens en télomérisation radicalaire
Authors: Boutevin Bernard , Piétrasanta Yves , Bauduin Gérard 
Published: April 2003

AbstractThe kinetics of free radical telomerization was studied. The theoretical relations that can be applied in reactions of this type, were evaluated. When transfer predominates, the equations giving the variations of monomer, telogen and initiator as a function of time were established. Moreover, instantaneous and cumulated number and weight average degrees of polymerization were calculated. The resulting relations were checked on the example of the telomerization of 2,3‐epoxypropyl methacrylate with bromotrichloromethane in the presence of two initiators and two different temperatures. Comparison of the experimental results with the theoretical ones revealed the scope of application of the general formulae giving the average degrees of polymerization.
Substitutions in polymer complex systems
Authors: Bekturov Esen A. , Khamzamulina Rimma E. , Belgibaeva Zein K. 
Published: April 2003

AbstractThe substitution in polymer1‐fluorescence dye‐competitor systems was investigated by measurement of the dye fluorescence. It is ascertained that the main factor affecting the direction of the possible reaction is the nature of the competitor. According to their ability to substitute dyes, different competitors can be arranged in the following series: polyelectrolytes > nonionic polymers ≥ surfactants > metal ions.
Effect of the acid dimer on the α‐relaxation process of the methyl methacrylate‐acrylic acid copolymer
Authors: Kihira Yasuharu , Yamamura Hitoshi , Murakami Ichiro 
Published: April 2003

AbstractThe dielectric and mechanical α‐relaxation process and the IR spectra of a methyl methacrylate‐acrylic acid copolymer, prepared by radical copolymerization, were investigated at a wide temperature range across the glass‐transition temperature. From the temperature dependence of the relaxation strength for the α‐process, the dissociation energy for the acid dimer in the copolymer was estimated by dielectric and mechanical methods, similar to the case of the methyl methacrylate‐methacrylic acid copolymer. The α‐relaxation shifts to lower temperatures with increasing number of acrylic acid monomeric units. The fact is due to the increase of more flexible acrylic acid monomeric units, released from the acid dimer into the methacrylate polymer chain.
Polymeric peroxycarbamates: Synthesis, characterization and their initiation of styrene polymerization
Authors: Yilgör İskender , Baysal Bahattin M. 
Published: April 2003

AbstractThree different polymeric peroxycarbamates were synthesized using polyether glycols, a cycloaliphatic diisocyanate and a dihydroperoxide. The products were characterized by infrared spectroscopy, molecular weight measurements and isocyanate and peroxygen analyses. Thermal decomposition kinetics of these peroxycarbamates were studied in toluene or 1,4‐dioxane solutions at 80, 90 and 100°C. All reactions were found to proceed according to the first‐order kinetics with activation energies in the range of 123 to 145 kJ · mol−1, depending on the structure of the peroxycarbamate. One of the products was used to initiate styrene polymerization at 80°C, in bulk. The initiating activity of this polymeric peroxycarbamate was found to be better than that of some hydroperoxides.
Sequential analysis of polyesters by stepwise chemical degradation. Preparation of the reagent
Authors: Schmitz Franz P. , Windeln Johannes , Rossbach Volker 
Published: April 2003

AbstractN‐{2‐[4‐(N‐tert‐Butoxycarbonylamino)benzoylamino]ethoxycarbonyl}anthranilic acid (1) was synthesized as a reagent for the stepwise elimination of monomeric units from the chain ends of oligoesters and polyesters, especially of poly(ethylene terephthalate) and poly(tetramethylene terephthalate) type. The reagent is supposed to be applied for a stepwise chemical degradation and thus for a sequential analysis of these polyesters.
Poly(vinyl acetate) as a test of the roedel mechanism for short branch formation
Authors: Viswanadhan V. N. , Mattice Wayne L. 
Published: April 2003

AbstractProbabilities of configurations conducive to the intramolecular back‐biting abstraction of a hydrogen atom have been evaluated for growing unperturbed poly(vinyl acetate) chains. A realistic rotational isomeric state model was used for the chain statistics. Probabilities are found to be smaller than those seen in an earlier treatment of the polyethylene chain. The smaller probabilities of poly(vinyl acetate) contribute to the virtual absence of short branches. The present study therefore provides support for the validity of the Roedel mechanism for the formation of short branches in the free radical initiated polymerization of ethylene.
Continuous fractionation and solution properties of PVC, 2. Scrutiny of solvents, intrinsic viscosity
Authors: Geerissen Heinz , Roos Jürgen , Wolf B. A. 
Published: April 2003

AbstractInvestigations with ca. 100 organic liquids in a temperature range from −20°C to 90°C result in a survey of the solubility behaviour of PVC. The experimental results were compared with the predictions of the solubility parameter theory: Accepting δ = 9,75 (cal/cm3)1/2 as the solubility parameter for PVC, all solvents (except ketones in which PVC is soluble independent of their solubility parameters) are located within the range of δPVC ± 0,75. Only three of the 100 liquids examined turned out to be (endothermal) theta‐solvents, namely the aromatic solvents o‐xylene, phenetole and dimethyl phthalate. The theta‐temperatures in o‐xylene and phenetole were determined viscometrically by means of the temperature dependence of the Mark‐Houwink exponent to be 84 and 88°C, respectively. Viscosity measurements were also performed in the temperature range of 25 to 60°C with solutions of PVC 75 000 in 10 thermodynamically good solvents used for rheological investigations. In all cases the intrinsic viscosities decrease slightly with increasing temperature, i.e., all solutions are weakly exothermal. The binary cluster integral, β, was determined (taking the monomeric unit as the statistical segment) and the polar contribution, βe, was calculated from Yamakawa's theory. The correlations between the non‐polar part of (βn = β – βe) and the solubility parameter of the solvent, found by Utracki, were tested and found to be valid for the present systems, too.
Continuous fractionation and solution properties of PVC, 6. Pressure dependence of the viscosity — influence of molecular weight and composition
Authors: Geerissen Heinz , Roos Jürgen , Wolf B. A. 
Published: April 2003

AbstractViscosities were measured as a function of pressure and temperature with solutions of PVC 75 000 in cyclohexanone (CHO) and polymer contents ranging from 0,6 to 12 wt.‐%, by means of a Searle‐type (≥3 wt.‐%) and a rolling‐ball viscometer (<3 wt.‐%). Furthermore, the influence of molecular weight was determined with solutions of 8 wt.‐% of PVC 20 000, PVC 37 000 and PVC 100 000. (The numbers in the codes of the PVC specimens are their approximate molecular weights.) For all concentrations and molecular weights, the viscosity increases in a more or less exponential manner with increasing pressure. The ratio f1000 of the viscosity of the solution at 1 000 and 1 bar can be varied by the change of the polymer content from 2,5 (the value of the pure solvent, index s) to 3,5 (12 wt.‐% PVC 75 000) at t = 25°C and from 2,23 to 2,94 at t = 80°C. An increase of the molecular weight of the polymer raises f1000 in a similar manner as the polymer concentration. Using the reduced variables V≠/V≠ (ratio of the volumes of activation of the solution and the pure solvent) and c̃ (product of the polymer concentration and the intrinsic viscosity), all results obtained by variation of T, c and Mw can be represented by a master curve. This means that it is possible to calculate the pressure dependence of a given polymer solution of arbitrary polymer concentration from a mere measurement of the intrinsic viscosity at normal pressure. Criteria are presented which allow a forecast concerning the occurrence of minima in the concentration dependence of the energy of activation of the viscous flow E≠ and V≠.
Cinétique de télomérisation, 2. Détermination des lois applicables à la synthèse des télomères à DPn moyens par catalyse rédox
Authors: Boutevin Bernard , Piétrasanta Yves 
Published: April 2003

AbstractSome theoretical relations concerning the kinetics of redox catalysed telomerization were studied. Assuming that the transfer termination reaction to the metallic cation is the main termination reaction, equations were established giving, as a function of time, monomer and telogen concentrations. Moreover, instantaneous and cumulated number‐ and weight‐average degrees of polymerization could be calculated. As an example the telomerization of ethyl acrylate with carbon tetrachloride as telogen and with ferric chloride/benzoin as catalyst at four concentrations were carried out. The theoretical and the experimental results are in good agreement with the predictions.
Studies on methoxycarbonylcellulose: Conductivity measurements of solutions, 1
Authors: Trivedi Harikrishna C. , Patel Raman D. 
Published: April 2003

AbstractThe conductivity behaviour of a partially neutralized methoxycarbonylcellulose (carboxymethylcellulose, CMC) solution was investigated at different frequencies using a home made conductance bridge. The equivalent conductance of CMC solutions has very poor dependence on frequency contrary to the behaviour of simple ionic compounds. The effect of concentration on the polyelectrolyte behaviour was investigated conductometrically and it was observed that the polymer concentration has little effect on polymer charge fraction and polymer counterion fraction. Sodium ion‐binding on the polymer molecule was also investigated.
Kinetics of irreversible, stoichiometric polycondensations
Authors: Elias Hans‐Georg 
Published: April 2003

AbstractEquations are derived for the time dependence of the extent of functional group reaction, pA, for catalyzed and uncatalyzed, irreversible, stoichiometric polycondensations of the AB and AA/BB type following pseudo‐second‐order and third‐order chemical kinetics, resp., based on amount‐of‐substance concentrations. The resulting functions 1/(1 – pA) ‐ f(t) for pseudo‐second‐order polycondensations and 1/(1 – pA)2 ‐ f(t) for third‐order polycondensations are predicted to be non‐linear for low extents of reaction and practically linear for higher ones which agree with previous, hitherto unexplained experimental observations. The slope of the linear part does not give the true rate constant, contrary to traditional assumptions. The extent of non‐linearity at small conversions and the deviation of the apparent rate constant from the true one depends on the initial amount of A groups, the molar mass of the leaving molecules, and the initial mass of the reaction mixture, if the molar concentrations are based on masses (“molalities”). The density of the leaving molecules enters, in addition, if the molar concentrations are volume related (“molarities”). The equations predict, for a given system, that the range of the non‐linear region increases with decreasing rate constants, i.e., with decreasing temperature, in accordance with experimental observations.
Ziegler‐natta catalysis by Mg‐Ti complexes, 2 Ethylene polymerization by MgTiCl6·4CH3COOC2H5 and triisobutylaluminium
Authors: Giannetti Enzo , Albizzati Enrico 
Published: April 2003

AbstractThe reaction between the MgTiCl6·4CH3COOC2H5 complex and alkylaluminium compounds was studied. The solid samples, recovered after increasing reaction times, were analysed. Elemental analyses, X‐ray diffraction patterns, and IR spectra clearly indicated the formation of activated, high‐surface MgCl2. Polymerizations of ethylene were carried out employing, as the solid component of the catalyst system, both MgTiCl6·4CH3COOC2H5 and the recovered samples. The lower induction time in the latter case was related to the extent of MgCl2 formation and its degree of activation.
Hetero‐chain polymers based on natural amino acids. Synthesis of polyamides from Nα, Nε‐bis(trimethylsilyl)lysine alkyl esters
Authors: Katsarava Ramaz D. , Kharadze Darejan P. , Japaridze Nana Sh. , Omiadze Tina N. , Avalishvili Lamara M. , Zaalishvili Malkhaz M. 
Published: April 2003

AbstractHigh‐molecular‐weight polyamides based on the natural amino acid lysine were synthesized by condensation of Nα, Nε‐bis(trimethylsilyl)lysine alkyl esters (1a–c) with derivatives of aromatic dicarboxylic acids (2a–c). The best results were obtained with diacyl dichlorides. However, in the case of aliphatic dicarboxylic acid derivatives, preference should be given to their active diesters. The properties of the resulting polyamides were shown to be determined, to a considerable degree, by the nature of the reaction medium. Polyamides with free carboxyl groups, capable of further polymeranalogous conversions, were obtained by means of saponification of the side chain alkyl ester groups. The substituted phenols, resulting from the polycondensation of 1a–c with active diesters, could be used for the synthesis of polyamides with active ester groups in the side chains.
Thermally stimulated depolarization currents in thiourea‐formaldehyde polycondensate
Authors: Nalwa Hari Singh , Vasudevan Padma 
Published: April 2003

AbstractA thiourea‐formaldehyde polycondensate was synthesized in acidic medium using glacial acetic acid. It was characterized by elemental analysis, infrared spectroscopy and thermal techniques. The thermally stimulated depolarization (TSD) current characteristics were studied under different polarization and depolarization conditions. The TSD results indicate a transition at 126°C. Depolarization kinetics data of the thermoelectret are reported. The polarization and depolarization phenomena were correlated with physical as well as chemical changes occurring in the material.
Simultaneous dehydrochlorination and film formation of a vinylidene chloride copolymer by aqueous‐organic interface reaction
Authors: He Fei‐Feng , Kise Hideo 
Published: April 2003

AbstractThe interface reaction of a THF solution of a vinylidene chloride copolymer with an aqueous alkaline solution in the presence of a quaternary ammonium halide as a phase transfer catalyst affords a dehydrochlorinated polymer film with conjugated polyene structure. The degree of the reaction is dependent on the catalyst structure, and tetrabutylammonium bromide is the best among those used. KOH was found to be more effective than NaOH. The effects of the base and polymer concentration and of the nature of the solvent were also studied. The results are discussed in terms of the change of the rate of formation of ammonium hydroxide at the interface and of its diffusion in the organic phase. The doping of the obtained films with iodine vapor increases the electric conductivity up to 7 · 10−4 S · cm−1.