bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and characterization of isomeric biphenyl‐containing poly(aryl ether bisketone)s, 3. Polymers derived from 3,4′‐bis(4‐fluorobenzoyl)biphenyl and bisphenols
Authors: Mani Rajrathnam S. , Weeks Barry R. , Mohanty Dillip K. 
Published: April 2003

AbstractA series of high‐molecular‐weight amorphous and semicrystalline poly(aryl ether bisketone)s were prepared from bisphenols and 3,4′‐bis(4‐fluorobenzoyl)biphenyl via nucleophilic aromatic substitution reactions. Model compound studies were carried out with several substituted monohydric phenols, 3,4′‐bis(4‐fluorobenzoyl)biphenyl and 3,4′‐bis(4‐Chlorobenzoyl)biphenyl. The dihalo‐substituted aromatic ketones were synthesized by the reaction of 3,4′‐biphenyldicarboxylic acid with thionyl chloride, followed by Friedel‐Crafts acylation with the appropriate aryl halide. The required dicarboxylic acid was prepared starting from 4‐bromotoluene and 3‐methylcyclohexanone. Potassium carbonate mediated reaction of the monomers in dimethylacetamide or diphenyl sulfone gave high‐molecular‐weight polymers in excellent yield. The glass transition temperatures of the polymers are in the 170 to 190°C range. In addition, the polymers exhibit excellent thermal stability, as evidenced by both dynamic and isothermal thermogravimetric analysis, and afford tough films by compression molding.
Characterization of non‐homogeneous polymers with size‐exclusion chromatography by implementing an on‐line viscometer
Authors: Sanayei Ramin A. , Suddaby Kevin G. , Rudin Alfred 
Published: April 2003

AbstractThe viscosity distribution of a polymer sample can be obtained by using an on‐line viscometer as a detector in size‐exclusion chromatography. This newly defined viscosity distribution is closely related to the molecular weight distribution and expresses weight fraction times intrinsic viscosity of species i as a function of the corresponding molecular weight times intrinsic viscosity (wi[ηi] vs. Mi[ηi]). The intrinsic viscosity ([η]) and number‐average molecular weight (M̄n) can be obtained directly from a viscosity distribution. If the Mark‐Houwink exponent a is known (or approximately known) for non‐homogeneous polymer the M̄w/M̄n can be estimated from the viscosity distribution when the molecular weight distribution is approximated with a known distribution function. These estimates are independent of any other detector and are valid even for non‐homogeneous polymer samples. The relation between the moments of the viscosity distribution and the M̄w/M̄n is presented for two widely used distribution functions, the Log‐Normal and the Generalized Exponential Distributions. Polymer characterization based on the viscosity distribution is shown to be a robust technique. It is particularly attractive in characterizing non‐homogeneous polymers since it is solely obtained from on‐line viscometer.
Copolymerizations of sodium 10‐undecenoate with styrene and sodium acrylate
Authors: Arai Kenichiro 
Published: April 2003

AbstractCopolymerizations of sodium 10‐undecenoate (1) with styrene and sodium acrylate (2) were examined under irradiation with UV light. In the polymerization of 1 in the presence of styrene, solubilized in the aqueous solution of 1, 1 and styrene were found to polymerize independently of each other, and a copolymer was virtually not obtained. In the copolymerization of 1 with 2, at concentrations of 1 higher than its pre‐critical micelle concentration (0,04 mol · L−1, pre‐CMC), two kinds of copolymer were obtained, one consisting predominantly of 2 units, and another consisting of comparable amounts of both monomeric units. However, at concentrations of 1 lower than its pre‐CMC, only one kind of copolymer was obtained, where the composition of the copolymer was a function of the monomer feed ratio. Reactivity ratios of the monomers were estimated in the absence of micelles of 1 (conc. < 0,04 mol · L−1) to be r1 = 0,28 ± 0,09 and r2 = 3,0 ± 1,2, which is indicative of an ideal copolymerization system. The number‐average degrees of polymerization (DPn) of the copolymer did not exceed 7, a value much lower than that of poly(1) obtained in the homopolymerization of 1.
Modeling of molar mass distribution of poly(D‐(–)‐3‐hydroxybutyrate) during bacterial synthesis
Authors: Bradel Roman , Reichert Karl‐Heinz 
Published: April 2003

AbstractThe development of molar mass distribution of poly(D‐(–)‐3‐hydroxybutyrate) (PHB) was studied during the intracellular synthesis in Alcaligenes eutrophus H16 bacteria with fructose as substrate and ammonium sulfate as nitrogen source. The flask culture fermentation experiments were carried out with a high cell density preculture under polymer synthesis conditions at different temperatures, pH values and substrate concentrations. These parameters were kept constant throughout the fermentation process. Polymer samples were isolated from cells by extraction with chloroform. The molar mass distribution of PHB was determined by gel‐permeation chromatography in chloroform. A simple kinetic model based on Michaelis‐Menten kinetics is postulated for synthesis of PHB. With this model the molar mass distributions of PHB were calculated and fitted to the experiment by variation of the kinetic constants.
Cationic ring‐opening polymerization behavior of 2‐ethenyl‐4‐methylene‐1,3‐dioxolane
Authors: Park Jaekyeung , Yokozawa Tsutomu , Endo Takeshi 
Published: April 2003

AbstractThe cationic ring‐opening polymerization of 2‐ethenyl‐4‐methylene‐1,3‐dioxolane (3) was carried out. The unsaturated cyclic acetal 3 was prepared by dehydrochlorination of 4‐chloromethyl‐2‐ethenyl‐1,3‐dioxolane, which was readily obtained from acrolein and epichlorohydrin, with sodium methoxide at ambient temperature. The cationic polymerization of 3 with BF3OEt2 or CF3SO3H at −78°C afforded cross‐linked polymers, whereas the polymerization by CH3SO3H gave a soluble poly(keto‐ether) which consisted of a unit containing a carbon‐carbon double bond in the side chain (unit 4) and a unit containing a vinyl ether group in the main chain (unit 5). The reaction of 3 with ethanethiol in the presence of a protic acid was also carried out as a model reaction of the polymerization. The reaction was initiated by addition of a proton to the 4‐methylene group of 3, followed by quantitative ring‐opening isomerization to afford acyclic ketones containing the ethylthio group. On the basis of the model reaction, some speculation on the polymerization mechanism is disclosed.
Whiskers 5. Copolyesters of 4‐hydroxybenzoic acid and 2‐(4‐carboxyphenyl)‐5‐hydroxybenzoxazole
Authors: Kricheldorf Hans R. , Thomsen Sven A. 
Published: April 2003

Abstract2‐(4‐Carboxyphenyl)‐5‐hydroxybenzoxazole was obtained by a multi‐step synthesis starting from commercial 2,5‐dimethoxyaniline. Its homopolyester as well as its copolyester with 4‐hydroxybenzoic acid were prepared by polycondensation of the acetyl derivatives in an inert, liquid reaction medium at temperatures of 320, 350 or 400°C. The resulting polyesters are highly crystalline (>90% crystallinity), infusible and isoluble materials. They were characterized by elemental analyses, IR spectroscopy, WAXS and DSC measurements, and electron microscopy. The WAXS powder patterns show that the benzoxazole monomer does not fit well into the crystal modification 1 of poly(4‐hydroxybenzoic acid). Whisker‐type single crystals were obtained only when the 4‐oxybenzoate units represent 90% of the copolyesters. Polycondensations of monomers having silylated carboxyl groups did not yield better results.
Highly isospecific SiO2/MgCl2bisupported catalyst for propene polymerization
Authors: Lu Honglan , Xiao Shijing 
Published: April 2003

AbstractThe propene polymerization with SiO2/MgCl2/TiCl4/D (D = dibutyl phthalate) (SMTD) bisupported catalyst was studied, MgCl2/TiCl4/D (MTD) catalyst was used for comparison. It was found that the Mg content of the catalyst has a remarkable effect on the catalyst activity. The molecular weight distribution (MWD) of polypropene (PP) obtained was similar for both the SMTD and the MTD catalyst. In contrast, the kinetic curves of propene polymerization are largely different in both cases. With the SMTD catalyst the polymerization rate increases with time, while for MTD mainly a decay‐type curve is obtained. The microstructure of PP obtained with SMTD is highly isotactic in comparison to the PP obtained with MTD catalyst, although the ester content in SMTD catalyst is much lower than in MTD. The morphology of the polymer particles obtained with SMTD catalyst is mainly controlled by the morphology of the SiO2used for preparation of the catalyst. Thus, some template effect occurred during polymerization with this catalytic system.
Cross polarization between 1H and 13C nuclei in isotactic poly(propylene). Effects of crystallinity and crystallographic form
Authors: Tanaka Hiroshi , Fujiwara Yasuna , Asano Tsutomu , Polizzi Stefano 
Published: April 2003

Abstract13C spectra of monoclinic (α), hexagonal (β) and smectic isotactic poly(propylene) (PP) with different degrees of crystallinity were obtained by the cross polarization/magic angle spinning (CP/MAS) method. In order to estimate the effects of cross polarization, an accurately weighed poly(oxymethylene) (POM) rod was packed into a rotor together with the sample and the ratio of the peak area of PP to that of POM was measured precisely. Taking the crystallinity into consideration, the cross polarization seems to occur rather effectively in smectic PP. This result indicates that there are constrained chains in the amorphous regions of the smectic PP, which contribute effectively to the cross polarization. The ratio of the peak are of α‐and β‐PP is nearly equal, indicating that the cross polarization occurs mainly in the crystalline regions in both samples and not in the amorphous regions. The 1 H spin‐lattice relaxation time in the rotating frame decreases with decreasing crystallinity, indicating the presence of imperfect crystallites in the smectic PP.
Copolymers of 1,5‐cyclooctadiene and [2.2]paracyclophane‐1,9‐diene: metathetic preparation and structure analysis
Authors: Thorn‐Csányi Emma , Pflug Kai Patrick 
Published: April 2003

AbstractCopolymers of 1,5‐cyclooctadiene (COD) and [2.2] paracyclophane‐1,9‐diene (PCPDE) were prepared by methathesis reaction using a well‐defined tungsten carbene complex as catalyst. UV/Vis and 1H NMR spectroscopy give evidence for a dissection of the opened PCPDE molecule into separate p‐phenylenevinylene units in the course of the polymerization. These units are distributed randomly in the polymer chain. This was confirmed by the metathetical preparation and spectroscopic investigation of a model substance and the comparison with spectra of compounds similar to the p‐phenylenevinylene units in the copolymer.
Preparation of poly(urethane/vinyl) block copolymers initiated by polyurethane‐type macroazo initiators
Authors: Kinoshita Hiroshi , Tanaka Nobuo , Araki Takeo , Ooka Masataka 
Published: April 2003

AbstractPoly(urethane/vinyl) block copolymers (PU‐PV) were obtained in high yields by the polymerization of vinyl monomers (butyl methacrylate (BMA), ethyl acrylate (EA), and methyl methacrylate (MMA)) in the presence of polyurethane‐type macroazo initiators (PUMAI). PUMAI was prepared via addition reaction of azodialcohol, dipropylene glycol and hexamethylene diisocyanate. The PU‐PBMA's, as typical examples of PU‐PV's were purified by solvent extraction. Characterization of the purified PU‐PBMA's by 1H NMR, IR, together with extraction behavior, supported the block nature of PU‐PBMA. Film tensile strength and elongation measurements in comparison with the corresponding blend samples also supported the block nature of PU‐PV.
Effects of non‐mesogenic comonomers on the phase behaviour, the structure and the miscibility of side chain liquid‐crystalline polymers
Authors: Braun D. , Neumann H. J. , Hellmann G. P. 
Published: April 2003

AbstractThe phase behaviour of methacrylic side chain liquid‐crystalline (LC) copolymers, with a spacer‐decoupled mesogen in one comonomer and a methyl (MMA) or stearyla (SMA) substituent in the other comonomer, was studied. The mesogen is of the phenyl benzoate type and has a methoxy end group. The LC homopolymer (PLC) has a smectic and a nematic phase. The comonomers MMA and SMA destabilize the LC phase. This effect is compared to the destabilisation caused by end groups in oligomers of PLC. The SMA side chains crystallize so that the SMA copolymers assume a smectic‐crystalline bilayer structure. Finally, it is shown that the order of the copolymers affects their mutual miscibility.
Multicolor electrochromic behavior of polyaniline composite films combined with polythiophene and poly(3‐methylthiophene) films
Authors: Morita Mitsuyuki 
Published: April 2003

AbstractThe electrochromic behavior of polyaniline‐poly(sodium acrylate) composite films (CPAn‐PAcNa) combined with electrochemically synthesized polythiophene (EPT) and poly(3‐methylthiophene) (EPMeT) films was investigated in LiClO4–CH3CN aprotic non‐aqueous solution. The combination was achieved by chemical deposition of CPAn‐PAcNa on EPT and EPMeT. The combined films showed spectra overlapped with the absorption of each component polymer by electrochemical oxidation. The individual electrochromic processes of the components did not influence each other. The electrochemical stability of EPT and EPMeT improved by their combination. Each electrochromic change of the component polymers in a combined film was controllable individually to some degree by applying the potential giving rise to the specific visible absorption of each component when the combined film was prepared with an appropriate quantity of EPT and EPMeT.
Synthesis and characterization of rigid‐rod polyesters bearing 3‐hydroxypropyl and 3‐acetoxypropyl side groups
Authors: Steuer Martin , Rehahn Matthias , Ballauff Matthias 
Published: April 2003

AbstractA description of the syntheses of two structurally well‐defined aromatic polyesters having polar 3‐hydroxypropyl or 3‐acetoxypropyl side groups is given. The hydroxy derivative was prepared by reacting a soluble precursor polyester bearing 2‐propenyl substituents with 9‐borabicyclo‐[3.3.1]nonane, followed by an oxidative work‐up procedure. The acetoxy‐substituted polyester was obtained treating the hydroxy polymer with acetic anhydride. The reaction conditions for these steps were studied in detail by using model compounds to minimize cleavage of the ester bonds during the conversions. The analysis of the polyesters by NMR spectroscopy and osmometry proved that under suitable conditions almost no degradation occurs during the conversions of the polyesters.
Microstructure of poly(vinyl alcohol) hydrogels investigated with differential scanning calorimetry
Authors: Cha Won‐Ill , Hyon Suong‐Hyu , Ikada Yoshito 
Published: April 2003

AbstractThe physical state of water in poly(vinyl alcohol) (PVA) hydrogels was studied with differential scanning calorimetry to elucidate their microstructure. PVA hydrogels were prepared after three different methods, viz. chemical crosslinking with glutaraldehyde, annealing of dried film and crystallization at low temperature. The water in PVA hydrogels could be classified into three types: free water, intermediate water and bound water. The concentration of bound water is practically not dependent on the total water content of the hydrogels when prepared by low‐temperature crystallization or annealing of the PVA film. The gel prepared by low‐temperature crystallization contained less bound water than the gel obtained by annealing of a cast film. Furthermore, the concentration of bound water increases as the degree of polymerization (DP) of PVA increases, whereas the reverse tendency was observed for the intermediate water. From these results it was concluded that the low‐temperature crystallization method results in a larger free space between the PVA microcrystallites and a larger size of microcrystallites than the annealing method. It is also likely that PVA of higher DP provides a larger amount of free PVA chains which are not involved in microcrystallites.
Conductivity relaxation of polyaniline
Authors: Lee Hsun‐Tsing , Liao Chien‐Shiun , Chen Show‐An 
Published: April 2003

AbstractMeasurements on polyaniline using dielectric analysis (DEA, −50°C to 240°C, 0,4 Hz to 105 Hz), differential scanning calorimetry (DSC, 30°C to 240°C) and infrared spectroscopy (IR) after heat treatment from 25°C to 300°C are carried out. After conversion of DEA results to complex electric modulus, the conductivity relaxation time distribution can be obtained, which remains unchanged for temperatures below 160°C and becomes narrower in the temperature range from 180°C to 240°C due to the occurrence of crosslinking reactions, as is confirmed by the exothermic behavior above 160°C and by the decrease of the relative intensity of quinoid absorption with respect to that of the aromatic ring. The crosslinking reaction causes a decrease in dc conductivity, a narrowing in conductivity relaxation time distribution and an increase in activation energies for conductivity and conductivity relaxation.
Terpolymerization of ethene, acrylonitrile and vinyl acetate
Authors: Buback Michael , Panten Kristen 
Published: April 2003

AbstractThe free‐radical terpolymerization of ethene, acrylonitrile and vinyl acetate was studied at 2000 bar in the temperature range from 170°C to 240°C in a continuously operated tubular‐type reactor. Polymerization was induced either thermally or chemically by di‐tert‐butyl peroxide as the initiator. Addition of vinyl acetate to ethene and acrylonitrile substantially enlarges the range for polymerization in the homogeneous fluid phase as compared to the binary copolymerization of ethene with acrylonitrile; a terpolymer with a high content of nitrile functional groups can be obtained from a single‐phase reaction. The six reactivity ratios of this terpolymerization, rEA, rEV, rAE, rAV, rVE and rVA are derived by applying first‐order Markov‐chain simulations. As ethene is the major component in the monomer mixtures, rEA and rEV are obtained with higher accuracy. For rEA the Arrhenius expression rEA = 2,6 · exp(−2,1 · 103 · (T/K)−1) is found (for 2000 bar). rEV = 0,9 ± 0,2 appears to be independent of temperature. The accuracy of the reactivity ratios rVE, rAV, rVA and rAE is not sufficient to detect a temperature dependence. The terpolymerization is also treated as a quasi binary copolymerization of ethene/vinyl acetate and acrylonitrile.
Chromatographic investigations of macromolecules in the critical range of liquid chromatography, 5. Characterization of block copolymers of decyl and methyl methacrylate
Authors: Pasch Harald , Augenstein Michael 
Published: April 2003

AbstractBlock copolymers of decyl and methyl methacrylate were analyzed by liquid chromatography at the critical point of adsorption. The molar mass and the polydispersity of the decyl methacrylate block was determined using chromatographic conditions resulting in a critical mode for poly(methyl methacrylate). In addition, using the same column system, the total molar mass and polydispersity of the block copolymers were determined, operating at chromatographic conditions insuring a size exclusion mechanism for both components.
Surface tension of poly(fluoroalkylsilsesquioxane)s
Authors: Kobayashi Hideki 
Published: April 2003

AbstractPoly(3,3,3‐trifluoropropylsilsesquioxane) (Prf‐T) and poly(3,3,4,4,5,5,6,6,6‐nonafluorohexylsilsesquioxane) (Hxf‐T) were synthesized via the hydrolysis of trichloro‐3,3,3‐trifluoropropylsilane and trichloro‐3,3,4,4,5,5,6,6,6‐nonafluorohexylsilane, respectively. The related resin‐like fluorosilicone polymers containing dimethylsiloxy units were also prepared. Contact angle measurements were carried out after the polymers were crosslinked by condensation. The solid surface tensions were determined from the combined Owens‐Wendt/Young equation using water and methylene diiodide contact angles. The value obtained for Prf‐T resin (20 mN/m) is similar to the value for poly(methylsilsesquioxane) as the unfluorinated silsesquioxane analogue (21,5 mN/m). On the other hand, the Hxf‐T polymer shows a very low surface tension, 7 mN/m, lower than that of the corresponding polysiloxane with linear structure, poly[methyl‐(3,3,4,4,5,5,6,6,6‐nonafluorohexyl)siloxane]. The surface tensions based on other approaches, such as the Girifalco‐Good‐Fowkes‐Young equation and the Zisman critical surface tension of wetting, were also determined.
Copolymerization of ethylene oxide and sulfur dioxide initiated by lewis bases
Authors: Florjańczyk Zbigniew , Raducha Dorota 
Published: April 2003

AbstractSulfur dioxide undergoes copolymerization with ethylene oxide in the presence of Lewis bases capable of forming onium ions (such as amines, phosphines, diethyl sulfide, dimethyl sulfoxide, N,N‐dimethylformamide) yielding poly(ethylene sulfite) bearing also a small amount of ethylene oxide monomeric units homosequencies. After 4–6 h of reaction at 50°C in bulk, the monomer conversion reaches 70–90%. The copolymer obtained is a mixture of linear and cyclic products which tend to degrade to yield ethylene sulfite. At 50°C this decomposition is very slow when unreacted SO2 is completely removed. However, it proceeds very rapidly, within a few hours, in the presence of compounds with strong electrophilic properties like BF3, H3PO4, or chlorotrimethylsilane. Studies of model reactions indicate that in the systems studied the macrocyclization results mainly from the attack of sulfite or alcoholate active species at the carbon atoms in polysulfites. Chain transfer reactions with the solvent occur also in reactions carried out in ethanol.
Monomer‐isomerization polymerization, 37. Effect of transition metal chlorides on monomer‐isomerization polymerization of 2‐butene with TiCl3/Al(C2H5)3 as catalyst
Authors: Endo Kiyoshi , Ueda Ryuichi , Otsu Takayuki 
Published: April 2003

AbstractThe effect of transition metal chlorides (MtClx) as isomerization catalysts was examined in the monomer‐isomerization polymerization of cis‐2‐butene with TiCl3/Al(C2H5)3 as a catalyst. The isomerization and polymerization depend on both, MtClx and MtClx/TiCl3 mole ratio. The rate of polymerization of 2‐butene with TiCl3/Al(C2H5)3/MtClx (mole ratio Al/Ti = 3,0, Mt/Ti = 1,0) as catalysts decreases in the following order: NiCl2 > CoCl2 > FeCl3 > None > MnCl2 > CrCl3. This order was found to be in a good agreement with the electronegativity of the metal atom in the chloride.
Photocrosslinking of 1,4‐polybutadiene with α‐thiocyanatoketones as photoinitiators
Authors: Kern Wolfgang , Hummel Klaus 
Published: April 2003

AbstractThe photocrosslinking of 1,4‐polybutadiene with various α‐thiocyanatoketones 1 as photoinitiators was examined. An excimer laser (308 nm) was used as light source, the samples were irradiated with an intensity of 6,2 mJ per pulse per cm2 under exclusion of oxygen. As initiators were used: phenacyl thiocyanate (1a), 1‐oxo‐1,2,3,4‐tetrahydro‐2‐naphthyl thiocyanate (1b), 1‐oxo‐2‐indanyl thiocyanate (1c), α‐phenylphenacyl thiocyanate (1d), 2‐naphthoylmethyl thiocyanate (1e) and 3‐phenanthrylcarbonylmethyl thiocyanate (1f). 1,4‐Polybutadiene samples that contained 20 mmol of initiator per 100 g were irradiated with 200 to 1000 pulses. 1a and 1b showed the highest crosslinking efficiency. The photochemistry of 1a in solution (2‐propanol, benzene and (Z,Z)‐1,5‐cyclooctadiene) was investigated. Analysis of the photochemical reaction products by combination of gas chromatography (GC) and mass spectrometry (MS) confirmed that the radical cleavage into benzoylmethyl and thiocyanato radicals is the first step of the reaction. Tetrafunctional crosslinks in allyl position were found in traces by means of metathesis degradation followed by GC/MS.