bluuebunny/crossref_metadata_2025 huggingface dataset:
Crystallization of carboxylic acid salts in poly(ethylene oxide) oligomers at higher temperatures
Authors: Ohno Hiroyuki , Kawanabe Hisashi , Ito Kaori
Published: April 2003

Many alkali metal carboxylates when dissolved in poly(ethylene oxide) (PEO) oligomers, are phaseseparated by heating. These were revealed to be the crystals of the initially dissolved corresponding salts from the X‐ray diffraction patterns. Some acetate salts achieve the lower limit of the lattice energy for phase separation of ordinary inorganic salts by heating in PEO oligomers. These carboxylate salts were therefore expected to show crystallization behavior in PEO oligomers by heating. The effects of cation size, alkyl chain length and molecular weight of PEO on the solubility are summarized. Negative temperature dependence of solubility of these acetate salts is seen in the PEO oligomers only when the salts have long alkyl chains. The salts containing larger cations needed a longer chain length of PEOs for crystallization by heating. These salts with longer alkyl chains showed positive temperautred dependence in lower molecular weight polyethers, but negative temperature dependence in solubility in PEO with molecular weights higher than 400. In PEO400, all the carboxylates with longer alkyl chains were phase separated by heating.
Coalescence of polystyrene nodules in soft poly(butyl acrylate)‐based films
Authors: Hidalgo Manuel , Cavaillé Jean‐Yves , Cabane Bernard , Chevalier Yves , Guillot Jean , Ríos Leonardo , Vassoille René
Published: April 2003

A two‐stage emulsion polymerization procedure was used in order to obtain core–shell polymer particles having a core of polystyrene (PS), covered by a shell of either pure poly(butyl acrylate) (PBA) or a methacrylic acid‐functionalized PBA. Films were then cast from these latexes, and their properties were studied without further treatments (“as‐dried” films), as well as after a 3 hr heat treatment intended to provoke the coalescence of PS domains (“annealed” films). “As‐dried” and “annealed” film samples were studied by dynamic mechanical analysis (DMA), scanning electron microscopy (SEM) and small angle neutron scattering (SANS). DMA and SEM results, as described in previous works, showed that for unfunctionalized films, the percolated PS domains coalesced under the annealing treatment, while for the functionalized films, they did not. On the other hand, SANS results presented here showed that even in the case of functionalized films, the presence of coalescence could be detected. It was concluded that while DMA and SEM reveal large‐scale modifications provoked by the heat treatment, SANS is capable of detecting very smallscale changes which do not have a direct effect on the bulk physical properties of the samples.
Transmission electron microscopy observations of composite polymer colloid nucleated by functionalized silica
Authors: Gauthier C. , Thollet G. , Vigier G. , Bourgeat‐Lami E. , Guyot A.
Published: April 2003

In this work, functionalized nanometric silica particles were engaged in emulsion polymerization of ethyl acrylate. The morphological characterization of this composite material was performed by transmission electron microscopy (TEM) and small angle X‐ray scattering (SAXS). We were particularly interested in the state of encapsulation of the silica particles and their distribution in the latex film. Initialy, we successively studied both components of the composite: polymer beads and silica particles differ by their size and also by their contrast. In addition, it was possible to perfrom dark field TEM to study this system of two amorphous phases because their respective amorphous halos are not too close. Hence, we investigated the colloid material in aqueous media and after film formation. Although no ideal encapsulation is observed in the colloid in aqueous media, the distribution of silica in the latex film is good. SAXS results are in good agreement with TEM observations.
Interpenetrating blends of rigid aromatic fractal polyamides and nylon‐6
Authors: Aharoni Shaul M.
Published: April 2003

Blends of nylon‐6 and up to 20% rigid aromatic fractal polyamides (FPs) were prepared by precipitation from a mutual solvent and by two melt‐processing procedures. In general, no grafting of the flexible linear nylon chains onto the rigid FPs took place, but in several instances of melt‐blending of nylon with FPs whose amine end‐groups were exposed, a low level of grafting occurred.

The glass transition temperature and the tensile modulus and yield strength of the blends were greatly elevated as function of the FP concentration in the blends. This was demonstrated to be caused by the openness and rigidity of the FPs, and the connectivity of the FP segments through rigid branchpoints. The great porosity of the FPs allows the chains of the amorphous fraction of the nylon to interpenetrate and pass through the FPs, and the stiff segments of the FPs to suppress the chain motions of the nylon, which accounts for the enhanced glass transition temperature (Tg) and tensile properties. When non‐porous amorphous silica particles or stiff linear or essentially unbranched zigzag polyamides were blended with the nylon, the Tg of the nylon either did not change at all or changed only very little. Several analytical procedures were used to verify that the nylon chains occupied most of the free space in the pervaded volumes of the FPs in the as‐prepared blends and filled this space completely when these blends were compression‐molded. The point where the FPs filled all the volume of the amorphous fraction of the nylon‐6 was reached between 5 and 7.5% FP concentration. Below this, traces of the original nylon‐6 Tg could be occasionally detected. Above it, only the high Tg of the nylon chains interpenetrated in the FPs was detected.
Synthesis and properties of the addition polymer of benzenedithiol with divinylbenzene
Authors: Kobayashi Eiichi , Kuribayashi Ryotaro , Aoshima Sadahito
Published: April 2003

Polyaddition of 1,4‐benzenedithiol (BDT) to 1,4‐divinylbenzene (DVB) was carried out with 2,2′‐azobisisobutyronitrile initiator in toluene at 75°C under a nitrogen atmosphere. The polymerization proceeded without an induction period, to give a white polymer with a high molecular weight (M̄w = 110,000) in ca. 90% yield for 2 hr. It was confirmed by 1H‐NMR (nuclear magnetic resonance), IR (infrared) and sulfur contents that the polymer had an alternating structure of DVB and BDT units. The end‐capping reaction of the polymer was also achieved by addition of thiophenol and/or styrene to the polymerization solution at a final stage of the polymerization. The polymer film exhibited a reversible phase transition between a transparent state and an opaque one by thermal mode. The thermal property of the polymer was studied by differential scanning calorimetry (DSC) analysis and polarized optical microscope observation with the polymer film. The detailed DSC analysis showed that the end‐capped polymer with a relatively low molecular weight (M̄W = 4400–9600) exhibited similar to liquid crystalline behavior. A diffuse reflectance spectrum of the polymer coated on an aluminum plate showed a marked difference in reflective light intensity in the ultraviolet and visible regions: the reversible phase transition between an opaque and a transparent polymer layers was induced by thermal mode. The light transmittance of the polymer film, which was measured by depolarized light intensity method, was very sensitive toward the temperature variation.
ABA triblock copolymer containing two crystallizable components
Authors: Shih Hsiao‐Yi , Kuo Wen Faa , Pearce E. M. , Kwei T. K.
Published: April 2003

A triblock copolymer of the ABA type in which both components were crystallizable was synthesized. The A block was poly(ethylene oxide), PEO, and the B block, poly(dimethyl siloxane), PDMS. Upon cooling from the melt to liquid nitrogen temperature, the PEO block crystallized at around 40°C. When the copolymer was heated from −170°C after quenching, glass transition, crystallization and melting of the PDMS middle block were identified in the thermogram at −117°C, −74°C and −42°C, respectively. The degree of crystallinity of the PDMS block was estimated from the heat of fusion to be about 27%. The growth rates of the PEO spherulites were reduced by the presence of the middle block.
Emulsion copolymerization of styrene with monomeric emulsifiers
Authors: Goebel K.‐H. , Stähler K.
Published: April 2003

Monomeric emulsifiers with different copolymerization reactivities were used as stabilizers in emulsion polymerization of styrene initiated by 2,2′ azobisisobutyronitrile (AIBN). A significant change in emulsifier function was observed between equal micellar concentrations of surface‐active sodium sulfopropyl alkyl maleates and the corresponding sodium sulfopropyl dodecyl fumarate. In the presence of less reactive maleates, copolymerization mainly occurs in the interface of the monomer swollen particles, while copolymerization with the fumarate in the first period of emulsion polymerization leads to polyelectrolyte formation in the water phase.
Emulsion copolymerization of styrene with a nonionic styrenic polymerizable surfactant
Authors: Filet A. , Guillot J. , Hamaide T. , Guyot A.
Published: April 2003

Among the variety of possible structures for polymerizable surfactants, it seems clear that the most interesting should be those with the reactive group located in the hydrophobic part of the molecule. We report here a study based on such a surfactant. Its general formula is

A set of surfactants has been produced with m varying from 23 to 48 and n = 6 or 12. The compounds have been characterised by 1H‐NMR (nuclear magnetic resonance), size exclusion chromatography, surface tension measurements and turbidimetry.

These surfactants have been copolymerized with styrene in emulsion polymerization. The coagulum is rather important, except if m is large enough. Although the incorporation of the surfactant in the latex is rather high. Most of the anchored surfactant remains at the surface and is not too buried inside. The particle size decreases with both the amount of surfactant and the length of its hydrophilic part. The use of these polymerizable surfactants leads to an excellent stability of the latex against the addition of electrolytes, and also against freeze‐thawing constraints.
Preparation and characterization of cationic poly(n‐isopropylacrylamide) copolymer latexes
Authors: Meunier F. , Elaïssari A. , Pichot C.
Published: April 2003

Cationic poly(N‐isopropylacrylamide) (NIPAM) copolymer latexes have been prepared at 70°C using methylene‐bisacrylamide (MBA) as the crosslinking agent,2‐2′‐azobis‐(2‐amidinopropane hydrochloride) (V50) as the initiator and in the presence of 2‐aminoethyl‐methacrylate hydrochloride (AEM). It was found that the concentration of AEM plays a major role in the polymerization kinetics and particle nucleation. However, too high a concentration (2–5 mol%/NIPAM) caused the latex to be polydispersed together with the production of large amounts of polyelectrolytes. The presence of surface amino groups on the final particles under the protected form was revealed both by an ultraviolet spectrometry and nuclear magnetic resonance methods. It was indirectly evidenced through the electrophoretic mobility behavior of the latex particles (below and above the lower critical solubility temperature of the poly(NIPAM)) as well as by their stability against a monovalent electrolyte.
Interactions between temperature‐sensitive hydrogel microspheres and granulocytes
Authors: Achiha Koji , Ojima Rika , Kasuya Yuji , Fujimoto Keiji , Kawaguchi Haruma
Published: April 2003

Poly(N‐isopropylacrylamide) (PNIPAM) has a low critical solution temperature (LCST) at 32°C in water and the hydrophilicity changes through the LCST. The microspheres whose surface was composed of PNIPAM exhibited phase transition behavior around 32°C. Therefore, the interactions between PNIPAM micropheres and granulocytes depended on the temperature. That is, the oxygen consumption and active oxygen production by cells in contact with PNIPAM‐containing microspheres and adhesion of the microspheres to the cell surface were more enhanced above the LCST of PNIPAM than below it, whereas no significant temperature dependence of cell–microspheres interaction was observed in nonthermosensitive microsphere systems. It was suggested that the function of cells could be controlled with temperature using the temperature‐sensitive microspheres.
Mixing device for polymer blends of very different molecular weights using a mixing nozzle process
Authors: Saeda Shigeru , Suzaka Yukinori
Published: April 2003

A new method of blending two polymers with very different molecular weights, i.e. different melt viscosities, in which the polymer mixture is forced to pass through a nozzle with a conical taper is proposed in this study.

High density polyethylenes with very high and very low molecular weights were used as the samples in the blending process, and the parameters that affected the homogeneity of the blended polymers were studied. The homogeneity was found to be better at a lower shear rate, smaller orifice diameter, higher compression ratio of the cross‐sectional area of the nozzle entrance and orifice, and a small length‐to‐diameter ratio of the orifice. This blending process, the nozzle blend, was found to make the droplets of a high molecular weight component extend to thin fibers along the conical section of the nozzle.

The nozzle blend system has been proved to be useful in obtaining both macroscopic and microscopic homogeneity, and has been estimated to be comparable to a few minutes of roll‐mill blending.
Mixing efficiency for polymer blends of very different molecular weights by using a mixing nozzle
Authors: Saeda Shigeru , Suzaka Yukinori
Published: April 2003

A way to mix polymer blends of very high and low molecular weights by using a mixing nozzle is presented. An array of blend nozzles with a conical inlet attached to a single screw extruder was used to blend polyethylene homopolymers with very different molecular weights. Using extruders with 30 and 50 mm barrel diameters, the effects of nozzle dimensions and operation conditions with respect to the homogeneity were studied.

The device proved useful in obtaining a good macroscopic and molecular homogeneity up to 30 kg/hr by the 50 mm extruder, though care must be taken to avoid the degradation of polymers by heat and shear, especially in the extruder.

The key factor ruling the efficiency of blending was found to be the compression ratio, i.e. the ratio of the cross sectional areas of the entrance of the nozzle and that of the orifice, and the shear rate at the orifice.

For the nozzle with geometrically similar figure, the critical shear rate at which the homogeneity began to worsen was the same. Scale‐up of the nozzle could be accomplished by enlarging the diameter of the diameter of the orifice, yet maintaining a geometrically similar figure. The maximum output of the nozzle is proportional to the third power of the orifice diameter.
Effective formation of fullerenes by pyrolysis of decacyclene
Authors: Minakata Takashi
Published: April 2003

The pyrolysis of polyconjugated hydrocarbons containing five‐membered rings such as decacyclene and acenaphthylene under argon atmosphere was carried out. The vaporized source molecules were heat‐treated above 700–1000°C to yield a black soot product, which was subsequently extracted with chloroform to give a black amorphous solid. Formation of C60, as the main product was confirmed by mass spectroscopy. These results indicated a new preparation process of C60 from hydrocarbons, which differs from the conventional method of vaporization of carbon. The formation mechanism of fullernes by the pyrolysis of polyaromatics is discussed.
The environmental stress cracking of linear ethylene copolymers
Authors: Saeda Shigeru , Suzaka Yukinori
Published: April 2003

A new method of measuring the environmental stress cracking (ESC) of polymers at constant strain is proposed in which an occurrence of fracture is detected automatically. The new method showed a very good reproducibility within 10% compared with a few hundred percent by conventional methods.

The ESC values obtained by the new method was found to be proportional to those by the conventional Bell Telephone Laboratory method in which the ESC was determined by the occurrence of small cracks, with a proportionality contant of 2.8. From the fact that the difference of both ESCs were also proportional to the ESC determined by the BTL method, it was concluded that the value of the ESC was proportional to the velocity of crack propagation. These conclusions were supported by the observation of the test pieces by a scanning electron microscope.

The study of the blended polymers revealed that the additivity of logarithmical ESC with weight fraction holds for a wide range of polymes, which enables estimation of ESCs up to millions of hours.

Using this technique, the ESCs of a wide range of molecular weights and a number of short chain branches were studied. It was found that the branches in the high molecular weight polymer were much more effective on the ESC than those in the low molecular weight polymer. This makes it possible to design a good resin with a good ESC.
Electrical conductivity of alternate layer deposition of pentancene and tetracene superlattices
Authors: Minakata Takashi , Mori Yoshihiko
Published: April 2003

Superlattice thin films of pentacene (PEN) and tetracene (TET) were fabricated by alternate layer deposition using the sublimation method. The film showed a highly crystalline structure that was due to the strong aggregation tendency of polyacene compounds to form a layered monomolecular column structure. The crystalline structure of the films was drastically changed by doping with iodine. The doped films showed a highly ordered structure where an iodine monomelecular layer was intercalated between molecular columns of acene compounds in both PEN and TET. The doped films exhibited a large lateral conductivity of 10 Ω−1 cm−1 and attained giant anisotropy above 1012. This indicated that molecular columns of TET remained insulating upon doping to form a perfect two‐dimensional conductor in the superlattice thin films.
Phase behavior and structure formation in ternary blends: studies on blends of PVDF/PMMA/PVAC
Authors: Classen S. , Vogt M. , Wendorff J. H.
Published: April 2003

The phase behavior of ternary blends was analyzed on the basis of the lattice approach. Both compatibilization and incompatibilization effects are predicted to occur depending on the relative magnitudes and the sign of the interaction parameters of the binary subsystems. Thermodynamic, structural and kinetic properties were investigated for a ternary model blend composed of poly(vinylidene fluoride), poly(methyl methacrylate) and poly(vinyl acetate). This particular ternary system is characterized by a specific symmertry with respect to the interactions in the binary subsystems. This symmetry affects both thermodynamic and structural properties. The experimentally determined interaction parameters were used to model the phase diagram on the basis of the lattice model: the theoretical phase diagram was found to be close to the experimental one. The crystallization processes were analyzed both for the binary and the ternary systems on the basis of a modified Turnbull–Fisher equation. The conclusions are that the properties of the ternary systems can be understood to a first approximation on the basis of those of the corresponding binary systems and the symmetry of the interactions.
Functionalization of montmorillonite by acrylamide polymers containing side‐chain ammonium cations
Authors: Biasci Luca , Aglietto Mauro , Ruggeri Giacomo , D′Alessio Aldo
Published: April 2003

Stable polyacrylamide (polyAA)–montmorillonite adducts were prepared by two distinct processes: (1) free radical copolymerization of AA with alkaline clay previously treated with 2‐(N‐methyl‐N,N‐diethyl ammonium iodide)ethylacrylate (QD1) and (2) direct interactions of alkaline montmorillonite with various preformed copolymers of AA with QD1. The structure of the adducts as determined by Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry and X‐ray diffraction was shown to consist of AA macromolecules inserted between lamellar layers whose spacing was larger than in the polymer‐free clay. The polymer was strongly attached to the inorganic surfaces, probably due to cooperative formation of electrostatic bonding. The thermal stability of the organic polymers in the resulting complexes was substantially enhanced while the mobility of macromolecules decreased.
Solid‐phase rheology of an anisotropic polymer (vectra A)
Authors: Devens Douglas A. , Denn Morton M.
Published: April 2003

The solid‐phase rheology of a thermotropic polyester which is liquid crystalline in the melt (Vectra A) was studied for one‐dimensional finite‐amplitude deformations, including step‐strain and recovery, step‐stress and recovery, and step‐strain followed by small‐amplitude oscillations. The rheology is complex, and cannot be described by existing models. Below a critical strain, which is history‐dependent, Vectra A deforms as a linear viscoelastic solid. Above the critical strain the deformation is both viscoplastic and viscoelastic. There appears to be a maximum recoverable strain of about 0.03, beyond which all deformation is nonrecoverable. A large number of relaxation modes is required to describe the stress, and one time scale is inadequate to describe the time‐dependence of yielding and plastic flow.
Organic electroluminescent device with an aromatic amine‐containing polymer as a hole transport layer (I): Poly[N‐[p‐N′ ‐phenyl‐N′‐[1,1′‐biphenyl‐4′‐[N″‐phenyl‐N″‐(2‐methylphenyl)amino]‐4‐amino]]phenyl methacrylamide]
Authors: Kido Junji , Komada Masaki , Harada Gaku , Nagai Katsutoshi
Published: April 2003

Electroluminescent devices were fabricated using a holetransporting polymer, poly[N‐[p‐N′ ‐phenyl‐N′‐[1,1′‐biphenyl‐4′‐[N″‐phenyl‐N″‐(2‐methylphenyl)amino]‐4‐amino]]phenyl methacrylamide] (PTPDMA), and tris(8‐quinolinolato)aluminum(III) complex, Alq, as the hole transport layer and the emitter layer, respectively. A device structure of glass substrate/indium–tin–oxide/PTPDMA/Alq/Mg:Ag was employed. Hole injection from the electrode through the PTPDMA layer to the Alq layer and concomitant electroluminescence from the Alq layer were observed. Bright green luminescence with a luminance of 20,000 cd/m2 was obtained at a drive voltage of 14 V.
Orientation studies in polyacrylonitrile films uniaxially drawn in the solid state
Authors: Bashir Zahir , Tipping Alison R. , Church Stephen P.
Published: April 2003

Polyacrylonitrile (PAN) films were made by casting a dimethyl sulphoxide (DMSO) solution. After drying, the films were uniaxially drawn by an essentially solid‐state drawing procedure. Using polarised‐infrared (IR) spectroscopy, the dichroism of the nitrile‐stretching vibration was monitored as a function of draw ratio. The dichroism results were converted to plots of chain‐orientation factor versus draw ratio. For this, α, the transition‐moment angle of the vibration, has to be known. Though a value of 68–73° has been suggested in the literature, for the present samples α cannot be 70° or less, and 73° is the most appropriate. The meaning and nature of the transition‐moment angle in the context of a flexible‐chain polymer molecule is discussed. The IR spectrum also showed dichroism in the SO stretch and the CH3 rocking vibrations from the (residual) DMSO present in the film, indicating that the solvent molecules were also orientated. It is proposed that this occurred due to dipolar interactions between the SO and the CN groups, which led to solvent molecules being bound to the polymer chains. X‐ray diffraction studies indicated ‘lateral‐ordering’ consisting of hexagonally packed, rod‐like chains with no c‐axis order. The diffraction patterns obtained here were the ‘standard’ ones for PAN, in contrast to those observed previously in solvent‐containing PAN gels.
Optical activity measurements in solids 5. Optical rotation of natural polymers
Authors: Bartuš Ján , Vogl Otto
Published: April 2003

The optical activity of ten natural‐type polymers [poly(α‐aminoacids), polysaccharides, proteins and nucleic acids] was measured in solution, as solid powders in suspension, and where possible in the form of films. In some cases the specific rotation of powder samples showed significant differences to the values obtained from solution measurements. The discrepances seem to reflect the arrangements of polymer chains in supermolecular assemblies in the polymer solid state.
Crystalline oligomeric stereocomplex as an intermediate compound in racemic poly(DL‐lactic acid) degradation
Authors: Li Suming , Vert Michel
Published: April 2003

Hydrolytic degradation of intrinsically amorphous poly(DL‐lactic acid) was re‐examined in pH 7.4 isoosmolar phosphate buffer at 37°C. Size‐exclusion chromatogarphy, X‐ray scattering and differential scanning calorimetry were used to monitor molecular weight and morphology changes up to the ultimate degradation stage. It was found that heterogeneous degradation of poly(DL‐lactic acid) yielded a crystalline residual material of low molecular weight. Comparison with a stereocomplex made of equimolar poly(L‐lactic acid) and poly(D‐lactic acid) showed that the poly(DL‐lactic acid) degradation residue was actually an oligomeric stereocomplex. The formation of stereoregular oligomeric enantiomers agreed well with the predominantly isotactic structure of poly(DL‐lactic acid) obtained by ring‐opening polymerization of DL‐lactide and argued in favour of the stereodependence of main chain ester bond cleavage.
Alternating, all‐trans polyenynes: Model compounds for poly(diacetylene)s with defined conjugation length
Authors: Giesa Reiner , Schulz Rolf C.
Published: April 2003

The syntheses of polyenynes as model compounds for poly(diacetylene)s (PDAs) are described. Variation of properties (UV–VIS, Raman, NMR and bond geometries) as a function of the chain length was investigated. After extrapolation to infinite chain length these data were compared to those for PDAs. From UV–VIS spectra a value of λ = 551 nm (2.25 eV) was calculated corresponding to the electronic transition of a single polyenyne chain. This energy is located at the low energy end of a yellow PDA solution spectrum. From Raman scattering v(CC) = 2108–2128 cm−1 and v(CC) = 1505–1532 cm−1 were calculated after extrapolation. Similarly sp‐C13C NMR data yielded a shift of δ = 100 ppm. These data are almost identical to data known for yellow PDA solutions. Bond geometries are almost identical to those of poly(diacetylene)s and theoretical data.
Thermal and spectroscopic properties of the polydiacetylene derived from docosa‐10,12‐diyne‐1,22‐diylbis(phenylacetate)
Authors: Lindsell W. Edward , Preston Peter N. , Tomb Peter J.
Published: April 2003

Polydiacetylene (2) of varying molecular weight has been formed by UV‐ or 60Co γ‐irradiation of the diacetylene PhCH2CO2(CH2)9‐CCCC(CH2)9O2CCH2Ph (3), with conversion of 30−>95%. Samples of (2) with differing physical properties have been studied, in the bulk phase, by CPMAS 13C NMR and VIS/UV spectroscopy and by DSC; complementary spectroscopic data on solutions of (2), including fluorescence studies, are also reported. Spectroscopic studies support the presence of an extended planar conjugated backbone in ‘as polymerised’ blue–black samples of (2), from which various forms of red‐coloured polymer, with shorter conjugation lengths, can be obtained. Studies of the thermal behaviour indicate the existence of several differing thermal transitions for these materials and the results are discussed.
Synthesis of styrene–isoprene A2B2 hetero‐armed star copolymers
Authors: Wright Simon J. , Young Ronald N. , Croucher Terence G.
Published: April 2003

Styrene–isoprene A2B2 star copolymers having two arms of polystyrene and two of polyisoprene have been synthesised. Two routes have been followed. In the first, 2 moles of polydienyl lithium were coupled, without loss of carbanionic character, by reacting with 1 mole of 1,3‐bis(1‐phenylethenyl) benzene. The difunctional adduct was then used to initiate the polymerisation of styrene in the presence of a small amount of triethylamine which served to ensure a rapid crossover. In the second route, 2 moles of polystyrl lithium were coupled with 1 mol of SiCl4 in benzene; no attendant formation of three‐armed star was detected. Introduction of large excess of polyisoprenyl lithium, together with triethylamine as catalyst, generated the star which was isolated by fractional precipitation.
Relative reactivities and graft distributions of polystyrene Macromers® in vinyl chloride copolymerization
Authors: Schulz Gerald O. , Milkovich Ralph
Published: April 2003

Polystyrene macromonomers terminated with methacrylate, vinyl ether, or maleic half ester functionalities were evaluated in free radical initiated copolymerizations with vinyl chloride in aqueous suspension polymerization. Macromers® (M1) terminated with methacrylate disappeared very rapidly in copolymerization with vinyl chloride (M2). The relative reactivity ratio, r2, was determined to be 0.05 in good agreement with literature values of about 0.04. Vinyl ether‐terminated Macromers® had unexpectedly uniform reactivity with vinyl chloride in early conversion samples, but macromonomer conversion was incomplete. Macromers® having maleic half ester functionality were incorporated rapidly in vinyl chloride copolymerization at pH 2.5 (r2 = 0.13). However, at pH 10 these Macromers® had reduced reactivity (r2 = 0.34), which improved graft polymer uniformity. These Macromer® copolymerization relative reactivities are shown to be useful in predicting and controlling graft densities and graft polymer heterogeneity which influence morphology, processing, and mechanical properties.
Rates of carbonate bond formation: Implications for macrocyclization
Authors: Aquino Eugene , Brittain William J. , Brunelle Daniel J.
Published: April 2003

High yields of cyclic oligomeric carbonates can be prepared using an amine‐catalyzed reaction of bisphenol A–bischloroformate. We have studied the mechanistic aspets of this carbonate macrocyclization by the isolated study of key chemical events. Using stopped‐flow FT‐IR spectroscopy, we have found that the rate of carbonate formation between the intermediate acyl ammonium salt and 4‐isopropylphenol is the same for the acyl ammonium salt derived from tri‐n‐butylamine, triethylamine and diethylmethylamine. Previously, we found that conversion of acyl ammonium salt to urethane was also insensitive to amine structure while the formation of acyl ammonium salt is profoundly dependent on amine structure. These results are consistent with a mechanism in which the selectivity toward macrocyclization versus linear oligomer or high polymer formation is related to acyl ammonium salt concentration.
Partial crystallisation in liquid polymer electrolytes based on co‐polymers of ethylene oxide/propylene oxide
Authors: Cameron G. Gordon , Ingram Malcolm D. , Qureshi M. Younus , Russell Graham M. , Wood Graeme I.
Published: April 2003

Solutions of lithium perchlorate in a low molecular weight ethylene oxide/propylene oxide (EO/PO) co‐polymer were studied by differential scanning calorimetry. The pure co‐polymer was found to crystallise partially, while addition of the salt impaired crystallisation first by slowing crystal growth then by slowing nucleation. At high salt concentrations (∼1·0 molal) no crystallisation occurred. The solvation of Li+‐ions and the introduction of ‘transient crosslinking’ between cations and anions effectively suppresses the separation of the polymer into microregions of EO and PO. The crystallisation phenomena are relevant to the use of these copolymers as ‘model’ polymer electrolyte systems.
Mutual diffusion in aqueous gel solutions
Authors: Gutsalyuk V. M. , Guly I. S. , Mel'nichenko Yu. B. , Klepko V. V. , Vasil'ev G. I. , Avdeev N. N.
Published: April 2003

Concentration relations for mutual diffusion coefficients Dm(C) in water of polyelectrolyte gelatin macromolecules at different temperatures were studied by optical interferometry. It is shown that Dm(C) values are in agreement with scaling predictions and are similar to those observed for solutions of neutral macromolecules under θ‐conditions. However, they are greatly influenced by the square‐law term C2, having a correlation to the conventional scaling law Dm ∝︁ C, and the mobility of solution components is influenced by physical gelation processes under certain thermodynamic conditions. It is demonstrated that the temperature relation of the diffusion coefficient at infinite dilution D0(C → 0) for the three gelating samples with various physico‐chemical properties can be described by a universal function.
Elastic moduli of liquid crystalline copolymers
Authors: Jawad S. Abdul
Published: April 2003

Dynamic tensile and shear moduli measurements have been carried out on highly oriented thermotropic liquid crystalline copolymers formed by random copolymerization of 2‐hydroxy‐6‐naphthoic acid, terephthalic acid and p‐aminophenol. This liquid crystalline copolymer is known as HNATA. Application of the aggregate model of units of structure gives rise to an estimation of the orientation angle θ = 5° and a chain modulus Ec = 230 GPa. The fall in tensile modulus with increasing temperature is related to two factors: a decrease in the intrinsic chain modulus and a reduction in the shear modulus.
Dipole moments of poly(allyl methacrylate) prepared by group transfer polymerization
Authors: Erbil Candan , Çatalgil‐Giz Huceste , Uyanik Nurseli
Published: April 2003

Dipole moments of poly(allyl methacrylate) prepared by group transfer polymerization and of allyl methacrylate were determined from dielectric constant, refractive index increment and density measurements performed on their dilute benzene and carbon tetrachloride solutions within a temperature range of 25–60°C. Dipole moments ratios and temperature coefficient, d ln〈μ2〉/dT, where 〈μ2〉 is the mean‐square dipole moment of the chain, were calculated. These results are compared with earlier results.
The method of incorporating organofunctional silane‐based agents into rubber compounds: Effects on the properties of an SBR‐based compound filled with synthetic calcium silicate
Authors: Kadivec Irena , Šušterič Zoran , Strle Marjetka , Kaučič Venčeslav
Published: April 2003

Synthetic calcium silicate, pretreated with various quantities of organofunctional silane (Si‐69®)‐based coupling agents, has been investigated in a compound based on styrene–butadiene rubber. The properties of the rubber compound with untreated synthetic calcium silicate and those observed after direct addition of an adequate quantity of Si‐69® during the mixing period have been compared.
Unexpected effect of the monomer concentration on the rate of a radical polymerization
Authors: Casinos Ismael
Published: April 2003

The radical polymerization of vinyl monomers is usually initiated by physical and chemical means. After an increasing polymerization rate, Rp, at low monomer concentrations, some reactive systems show an unexpected minimum for Rp at high enough monomer concentrations. The radical polymerization of methyl methacrylate (MMA) initiated by the redox system D‐glucose–ceric ion at varying MMA concentration is discussed. The peculiar behaviour of Rp is explained by the presence of two circumstances: the initiation rate from D‐glucose radicals does not depend on MMA concentration when most of the D‐glucose radicals formed react by adding to monomer, and the radical chains initiated by D‐glucose radicals undergo mutual termination with a portion of the radical chains initiated by monomer radicals. Some information about the nature of the polymer end‐groups is reached from the mechanistic approach.
Use of inverse gas chromatography to assess the compatibility of polyurethane foam with liquids at different temperatures
Authors: Jackson Paul L. , Huglin Malcolm B.
Published: April 2003

A crosslinked polyurethane foam has been used as the stationary phase in inverse gas chromatography to measure the solubility parameter (δ2) of the polymer at several temperatures (T) within the range 298–383 K. Values of δ2 = 29.5(MPa)1/2 at 298K and dδ2/dT = −0.06(MPa)1/2 K−1 were yielded. Linear decreases with temperature of the solubility parameters (δ1) of water, ethanol and methanol were obtained by calculation from relevant properties of the liquids. The results were used to assess the conditions for the polyurethane foam to act as a non‐interacting barrier against liquids of different polarities for which the criterion is that |δ1 − δ2| should be large. The findings highlight the need to consider both the nature of the liquid and the temperature regime.
Preparation, characterization and alkali metal ion permeation through cross‐linked poly(styrene‐co‐maleic acid) membranes
Authors: Philip Kalathiparambil C. , Pillai Vadasseril N. Sivasankara
Published: April 2003

Membranes were prepared from poly(styrene‐co‐maleic acid) under different conditions and characterized by measuring thickness, swelling, electrical resistance, membrane potential and permselectivity. Permeability coefficients of KCl, NaCl, Na2SO4, NaOH, urea and creatinine were evaluated from dialysis experiments. The charged membranes facilitated the active transport of alkali metal ions under a pH gradient. The energy for this movement comes from the simultaneous counter transport of protons.
Desorption of the surfactant from the particle surface during latex film formation
Authors: Kientz E. , Dobler F. , Holl Y.
Published: April 2003

Properties of latex films are very dependent on the distribution of the surfactants in the film. It has been recognized that distribution itself depends on the desorption characteristics of the surfactant from the particle‐water interface during film formation. This article deals with this problem of surfactant desorption in the particular situation of latex film formation. First, FTIR spectroscopic evidence is presented for desorption of hexadecyl pyridinium chloride (HPCI) in poly(2‐ethyl hexyl methacrylate) (P2EHMA) latex films. Some consequences of desorption or non‐desorption of various surfactants on the structure and properties of P2EHMA latex films are then presented. This concerns the crystallization of cationic surfactants, HPCI and hexadecyl trimethylammonium bromide (HTAB), in the films and the mechanical properties of films containing ethoxylated nonyl phenol with 10 ethoxy segments (NP10) or sodium dodecyl sulphate (SDS). In the last part, the determination of the fraction of SDS desorbing from the particle–water interface in a model poly(styrene–butyl acrylate–methacrylic acid) latex coalescing in water is described. Other methods for studying desorption are proposed.
Kinetics of liquid crystallization for lyotropic liquid crystalline polymers
Authors: Lin Jiaping , Wu Herong , Li Shijing
Published: April 2003

The kinetics of liquid crystalline phase transition from the isotropic state to the anisotropic state, which is by analogy termed liquid crystallization, for poly(p‐benzamide)(PBA)/H2SO4 and PBA/Nylon 6/H2SO4 systems was investigated by the depolarized light intensity (DLI) technique and polarized light microscopy (PLM). The experimental data were analysed using the Avrami equation. The n value, according to the Avrami equation, is about 1 for both PBA/H2SO4 and PBA/Nylon 6/H2SO4 systems, which suggests that the liquid crystallization of PBA/H2SO4 and PBA/Nylon 6/H2SO4 systems is a process of instantaneous nucleation with one‐dimensional growth. The introduction of Nylon 6 into PBA/H2SO4 does not have any significant effect on the Avrami exponent n. The results also show that the Avrami exponent n and the half‐time for the liquid crystallization are temperature dependent.
Synthesis of polyvinyl acetate‐graft‐poly‐2‐oxazolines
Authors: Dworak Andrzej , Schulz Rolf C. , Panchev Ivan , Trzebicka Barbara , Velitshkova Rumiana
Published: April 2003

Poly(vinyl acetate‐co‐vinyl chloroformate) (1) was synthesized via phosgenation of poly(vinyl acetate‐co‐vinyl alcohol). It was shown that (1) is capable of initiating the polymerization of 2‐phenyl‐2‐oxazoline and 2‐methyl‐2‐oxazoline, when the counter ion is exchanged using potassium iodide. Polyvinyl acetate‐graft‐poly‐2‐phenyl‐2‐oxazoline and polyvinyl acetate‐graft‐poly‐2‐methyl‐2‐oxazoline are obtained in the grafting reaction.
A hydrocarbon‐soluble difunctional orgaolithium anionic initiator. Synthesis of 2,2‐bis[3‐(1‐lithio‐2,3‐dimethylpentyl)‐4‐methoxyphenyl]propane
Authors: Sanderson Ronald D. , Roediger Andrew H. A. , Summers Gabriel J.
Published: April 2003

The reaction of stoichiometric amounts of sec‐butyllithium with 2,2‐bis[3‐(1‐propenyl)‐4‐methoxyphenyl]propane (4) produces a new difunctional organolithium initiator, 2,2‐bis[3‐(1‐lithio‐2,3‐dimethylpentyl)‐4‐methoxyphenyl] propane, which is soluble in hydrocarbon solvent in the absence of any polar additive. Following isolation and purification by gas liquid chromatography, the structures of (4) and the methanolysis product of the difunctional initiator were characterized by 1H NMR, FTIR and mass spectroscopy and elemental analysis. The dilithium initiator is effective for the polymerization of 1,3‐butadiene and allows the preparation of polybutadienes with predictable molecular weights, narrow, monomodal molecular weight distribution and low 1,2‐diene microstructure.
Regular network polyamide and copolyamide films from trimesic acid and aliphatic diamines
Authors: Kiyotsukuri Tsuyoshi , Murata Mitsuya , Sugimoto Mariko , Tsutsumi Naoto
Published: April 2003

Regular network polyamide films made from trimesic acid (Y) and aliphatic diamines as well as copolyamide films made from hexamethylene diamine (6) and dodecamethylene diamine (12) with Y were prepared. Prepolymers obtained by melt polycondensation for a short period of time were cast from a DMF solution and successively post‐polymerized at 300°C to form a network. The resultant films were transparent, flexible and insoluble in any solvents. Heat distortion temperature (Th) measured by a penetration mode of thermomechanical analysis rapidly increased with increasing post‐polymerization time, and then levelled out after 0.5–1 h. Th was 238, 231, 232, 216, 207, 187, 176 and 163°C for 4Y, 5Y, 6Y, 7Y, 8Y, 9Y, 10Y and 12Y post‐polymerized for 4h, respectively. Degrees of reaction estimated from the infrared absorbance of ester and methylene groups were 88 and 83% for 6Y and 12Y post‐polymerized for 4h, respectively. Two diffraction peaks appeared in the wide angle X‐ray scattering (WAXS) pattern, suggesting some ordered structure owing to the regular networks. Density increased with increasing post‐polymerization time and was 1.266, 1.236, 1.214, 1.175, 1.162, 1.145, 1.130 and 1.107 g/cm3 for 4Y, 5Y, 6Y, 7Y, 8Y, 9Y, 10Y and 12Y post‐polymerized for 4h, respectively. WAXS patterns of copolymer films of 12/6‐Y suggested the continuous change of network structure with copolymer composition. It was found that comonomer disturbs the formation of ordered network structure, and decreases the packing of networks, thus decreasing density, Th and tensile properties, and increasing dye absorption of copolymer films. From the dye absorption behavior, it was suggested that these regular network films could be utilized as membranes for the separation of molecules by varying the chain length between crosslinked sites.
Effect of some structural features of the polymer support on synthesizing 2,4,6‐tribromophenyl benzyl ether in a triphase catalysis
Authors: Wang Maw‐Ling , Peng Ching‐Zou
Published: April 2003

The substitution reaction of benzyl bromide and 2,4,6‐tribromophenol in an organic solvent/alkaline aqueous solution of KOH by triphase catalysis in which tributylamine was immobilized on a polymer support was investigated. Our main purpose was to evaluate the effect of some structural features of the polymer‐supported pellet on the conversion of the organic‐phase reactant (benzyl bromide). The polymer‐supported pellet was obtained from copolymerization of styrene and chloromethylstyrene monomers. The reaction was identified as occurring both on the surface and within the particles of the polymer support when using a highly polar solvent. The effects of the structural features of the polymer support, which are related to the degree of cross‐linking, ring substitution, lipophilicity of the polymer pellet, the chloride density and the solvents, on the conversion of benzyl bromide were investigated in detail. The experimental results indicate that 2% of cross‐linking with 10% ring substitution of the macroporous polymer support provides a rapid reaction and high conversion of benzyl bromide reactant.
Depolarization current characteristics of cellulose acetate–butyrate polymer films
Authors: Reddy N. Venugopal , Rao V. V. R. Narasimha
Published: April 2003

Cellulose acetate–butyrate films of thickness 5μm were grown by a solution growth technique. Thermally stimulated depolarization currents (TSDCs) were studied on these films as a function of polarizing field strength and polarizing temperature at a constant heating rate. In the present study, the TSDC spectra consist of a single current maximum, which was found to be independent of polarizing field strength. However, the current maximum shifted to higher temperatures with increasing polarizing temperature. The activation energies, relaxation parameters, charge associated with the current maximum and equivalent frequencies were evaluated. Based on these results, the origin of the TSDC was attributed to space charge polarization with some contribution arising from dipolar orientation.
Azeotropy in terpolymerization of 2‐pyrimidyl acrylamide with different alkyl acrylates and acrylonitrile
Authors: El‐Hamouly S. H. , Azab M. M.
Published: April 2003

2‐Pyrimidyl acrylamide monomer (2PA) has been prepared by the reaction of 2‐amino pyrimidine with acrylolyl chloride in the presence of triethylamine as catalyst. Its structure was confirmed by IR and1H NMR spectroscopy. Ternary copolymerizations of 2‐pyrimidyl acrylamide monomer (2PA) with methyl acrylate (MA), methyl methacrylate (MMA), ethyl acrylate (EA), butyl acrylate (BuA) and acrylonitrile (AN) were carried out in THF at 65°C in the presence of a free radical initiator. Experimental terpolymerization data agree well with calculations based on the Alfrey–Goldfinger equation. The determination of unitary, binary and ternary azeotropies of the various systems studied were easily handled by a computer. The ternary azeotropic compositions for 2PA–MA–AN and 2PA–MMA–AN were 32.20:17.5:50.30 and 13.54:52.64:33.82mol%, respectively. Pseudo‐azeotropic regions were identified where the deviation between feed and polymer composition is very small.
Sorption studies in a polyurethane–β‐cyclodextrin blend
Authors: Sreenivasan K.
Published: April 2003

The sorption of toluene, butanol, methanol and n‐hexane in polyurethane and a polyurethane–β‐cyclodextrin blend has been studied. The time to reach equilibrium absorption was several times less in the blend in spite of nearly identical diffusion coefficients and % equilibrium absorptions of the diffusants in both materials. The study indicates that rapidity in polymeric membrane mediated separation can be attained by blending β‐cyclodextrin.
Encapsulation of benzil in the cavities of crosslinked styrene‐based copolymers and its conversion to benzilic acid
Authors: Kuriakose Sunny , Pillai V. N. Rajasekharan
Published: April 2003

Crosslinking copolymerization of styrene with divinylbenzene, butanediol dimethacrylate and ethyleneglycol dimethacrylate in the presence of benzil in the dissolved state results in benzil‐encapsulated crosslinked polymers. Resins with various crosslink densities were prepared by adjusting the monomer/crosslinker ratio. The benzil entrapped in the cavities was subjected to benzil‐benzilic acid rearrangement. The precursor resins and the rearrangement products were characterized by IR and 13C NMR spectroscopy. The surface properties of polystyrene and benzil‐encapsulated polystyrene were compared by scanning electron micrography.