bluuebunny/crossref_metadata_2025_split huggingface dataset:
Miscibility of DMPC‐TMPC copolycarbonate/SMMA copolymer blends and their interaction energies of binary pairs involved in blends
Authors: Yoo JE , Kim CK 
Published: August 2004

AbstractThe isothermal miscibility map and phase‐separation temperatures caused by lower critical solution temperature‐type phase behavior for blends of poly[2,2,‐propane‐bis{4‐(2‐methyl phenyl)} carbonate]‐poly[2,2,‐propane‐bis{4‐(2,6‐dimethyl phenyl)} carbonate] (DMPC‐TMPC) with poly[(styrene)‐co‐(methyl methacrylate)] (SMMA) copolymers have been determined. SMMA copolymers containing equal to or less than 37 wt% MMA formed miscible blends with DMPC‐TMPC copolycarbonates containing equal to or more than 60 wt% TMPC. The observed phase‐separation temperatures indicate that the miscibility decreases as the DMPC content in DMPC‐TMPC increases, while addition of MMA to the styrene initially increases miscibility with DMPC‐TMPC but ultimately leads to immiscibility. The binary interaction energies involved in these blends were calculated from the phase boundaries using the lattice‐fluid theory combined with the binary interaction model. The spinodal temperatures predicted from the lattice‐fluid theory using the calculated interaction energies are similar to the experimental phase‐separation temperatures. Copyright © 2004 Society of Chemical Industry
Moisture sorption and permeation in polyamide 6/clay nanocomposite films
Authors: Low HY , Liu TX , Loh WW 
Published: August 2004

AbstractThe moisture transport properties of a polyamide 6/clay nanocomposite have been studied through moisture sorption and permeation rate measurements. The temperature and concentration dependence of the steady state moisture uptake and permeation rate from the two types of experiment are distinctly different. The activation energy of moisture permeation obtained from the sorption experiment is lower than that derived from the permeation measurement. The interaction and contribution of the diffusion parameter and solubility parameter shows a complex moisture transport behavior in these nanocomposite films. Copyright © 2004 Society of Chemical Industry
Crystallization of the γ form in random propylene‐ethylene copolymers
Authors: Marigo Antonio , Causin Valerio , Marega Carla , Ferrari Paolo 
Published: August 2004

AbstractWide‐angle X‐ray scattering and differential scanning calorimetry measurements have been conducted on seven random copolymers of propylene with ethylene in order to study the γ phase formation as a function of the comonomer content. The lamellar morphology of the samples was also investigated by small‐angle X‐ray scattering. The content of the γ phase was found to go through a maximum with crystallization temperature and to increase with comonomer concentration, up to a point (ethylene ≥6.5 wt%) where the latter parameter became less influential. The multiple melting endotherms behaviour of the samples was studied by DSC and temperature‐controlled diffractometric techniques. The attribution of the DSC peaks to the different isotactic polypropylene polymorphs that form in these conditions was confirmed. The results obtained permitted us to ascertain that, in the experimental conditions chosen, some further formation of crystallites takes place during the quenching to room temperature after the crystallization isotherm. In this phase, the chains organize themselves in stacks with thin lamellae, forming a distinct population with respect to those formed on isothermal crystallization. The melting of the thinner lamellae determines a convergence of the two populations into just one, still retaining an organization in stacks, that gradually disappears until complete melting of the material. Copyright © 2004 Society of Chemical Industry
Measurement of the thermal diffusivity and specific heat capacity of polyethylene foams using the transient plane source technique
Authors: Almanza O , Rodríguez‐Pérez MA , de Saja JA 
Published: August 2004

AbstractThermal diffusivity and specific heat at constant pressure of a collection of crosslinked closed cell polyethylene foams have been measured at room temperature using the transient plane source (TPS) method. A theoretical model to predict the thermal diffusivity has been proposed. The predictions of this model are in good agreement with the observed experimental trends. The theoretical model predicts a dependence of the thermal diffusivity on the density and other foam characteristics such as carbon black content and cell size. Copyright © 2004 Society of Chemical Industry
Frontal copolymerization of 2‐hydroxyethyl methacrylate and ethylene glycol dimethacrylate without porogen: comparison with suspension polymerization
Authors: Pujari NS , Vishwakarma AR , Pathak TS , Mule SA , Ponrathnam S 
Published: August 2004

AbstractNetworked, crosslinked poly[(2‐hydroxyethyl methacrylate)‐co‐(ethylene glycol dimethacrylate)] (HEMA‐EGDM) was synthesized by frontal polymerization (FP) using azobisisobutyronitrile as initiator. HEMA‐EGDM copolymers of similar composition were also synthesized by suspension polymerization. The two sets of copolymers were characterized for functional groups (IR), pore volume (mercury intrusion porosimetry), surface area (nitrogen adsorption) and morphology (scanning electron microscopy). FP‐generated polymeric network structures had higher internal pore volumes and surface areas but their surface morphologies were inferior to those of copolymers synthesized by suspension polymerization. Copyright © 2004 Society of Chemical Industry
Effects of molecular weight distribution on the spinodal temperature of polymer mixtures
Authors: Kim JW , Kim Y , Kim CK 
Published: August 2004

AbstractThe effects of molecular weight distribution on the phase stability of polymer mixtures were explored theoretically and experimentally. Based on the lattice‐fluid theory and volume‐fluctuation thermodynamics, the spinodal conditions for a lattice‐fluid mixture of two polymers with molecular weight distribution were derived. The results indicated that the phase stability of a polymer mixture decreases by increasing the molecular weight distribution of polymers in the blend. To confirm the theoretical results with experiments, the changes in the spinodal temperatures of poly(ethyl methacrylate)/polystyrene (PEMA/PS) blends and tetramethyl polycarbonate/polystyrene (TMPC/PS) blends were examined when each component has a different molecular weight distribution. When the weight‐average molecular weight of each component is the same, a blend composed of polymers having broad molecular weight distribution always exhibited lower phase separation than that composed of polymers having narrow molecular weight distribution at the same blend composition. Copyright © 2004 Society of Chemical Industry
PBT blends with rigid polymer and elastomer inclusions: the effect of component type and reactivity on mechanical behaviour
Authors: Kelnar Ivan , Kotek Jiří , Munteanu Bogdanel S , Kaprálková Ludmila 
Published: August 2004

AbstractThe present study shows the potential of the poly(butylene terephthalate) (PBT) matrix to form ternary blends with well‐balanced properties, analogous to Polyamide 6 (PA6) systems with a very fine (<100 nm) separately dispersed rigid polymer (poly(styrene‐co‐maleic anhydride)) and elastomer (maleated ethylene‐propylene elastomer). The use in PBT blends of maleated components analogous to those in the PA6 systems was much less effective, due to the presence of larger particles. Enhancement of all properties, including toughness, was found in the case of a blend containing at least one component with epoxide groups, such as rigid styrene‐glycidyl methacrylate copolymer or elastomeric poly[(ethylene)‐co‐(methyl acrylate)‐co‐(glycidyl methacrylate)]. In this case, the reactive compatibilization of the epoxy‐group‐containing component caused refinement of particle size of the other component due to enhanced viscosity. As a result, more advantageous micromechanical behaviour of this ternary in comparison with the binary system occurs. The PBT matrix offers a similar potential to PA6 in synergistic influencing of both well‐dispersed phases. This work supports the universality of rigid polymer‐elastomer combination for the enhancement of the properties of pseudoductile polymers. Copyright © 2004 Society of Chemical Industry
Structure and property study of nylon‐6/clay nanocomposite fiber
Authors: Yoon KwanHan , Polk Malcolm B , Min Byung G , Schiraldi David A 
Published: August 2004

AbstractThe crystal structures of nylon‐6 and nylon‐6/clay fibers were investigated on annealing and drawing. Annealing increased the γ‐crystalline form of both fibers, as indicated by the DSC curves, and its effect was dominant in nylon‐6/clay fiber. On drawing, the γ‐crystalline form was easily converted into the α form in nylon‐6, whereas it was still observed at a relatively high spin‐draw ratio in nylon‐6/clay fiber. However, although the α‐crystal form was dominant in nylon‐6, the γ‐crystal form was dominant in nylon‐6/clay with annealing and drawing, on the basis of the XRD data. The fast crystallization rate of nylon‐6/clay compared with pure nylon‐6 was confirmed, on the basis of the Avrami exponent. The initial modulus of nylon‐6/clay fiber was 30 % higher than the neat nylon‐6 fiber. The reinforcing effect of clay on the dynamic storage modulus was observed. Copyright © 2004 Society of Chemical Industry
Preparation and properties of poly(L‐lactic acid) scaffolds by thermally induced phase separation from a ternary polymer–solvent system
Authors: Li Shirong , La Carrubba Vincenzo , Piccarolo Stefano , Sannino Diana , Brucato Valerio 
Published: August 2004

AbstractPoly(L‐lactic acid) (PLLA) foams for tissue engineering were prepared via thermally induced phase separation of a ternary system PLLA/dioxane/tetrahydrofuran (THF) followed by double solvent exchange (water and ethyl alcohol) and drying. An extension to solidification from solution of a previously developed method for solidification from the melt was adopted. The technique is based on a continuous cooling transformation (CCT) approach, consisting in recording the thermal history experienced by rapidly cooled samples and then analyzing the resulting sample morphology. Different foams were produced by changing the relative amount of dioxane and THF in the starting solution while the amount of polymer was kept constant. Results show that the final morphology and crystallinity (measured by DSC) depend on solvent power, which in its turn was determined by the ratio dioxane/THF, and a minimum of pore size, optimum final crystallinity and crystallization rate were achieved for a system containing 70 % of dioxane. Under this condition, a higher bulk density (evaluated by Hg intrusion porosimetry) and a larger specific surface area (measured by BET N2 sorption technique) was achieved. Copyright © 2004 Society of Chemical Industry
FTIR study of poly(propylene carbonate)/bisphenol A blends
Authors: Fei Bin , Chen Cheng , Peng Shuwen , Zhao Xiaojiang , Wang Xianhong , Dong Lisong 
Published: August 2004

AbstractA systematic investigation by FTIR spectroscopy was undertaken on blends of poly(propylene carbonate) (PPC) and bisphenol A (BPA). It provided direct evidence of the hydrogen bond (H‐bond) between BPA OH groups and PPC CO groups. Using a curve‐fitting method, qualitative as well as quantitative information concerning this H‐bond interaction was obtained. The inter‐H‐bond in PPC/BPA blends was weaker than the self‐H‐bond in BPA. The absorptivities of the free and the H‐bonded CO groups were nearly equal. The fraction of H‐bonded CO in the blends increased with BPA content and leveled off at a value close to 40 %. Finally, FTIR–temperature measurements of pure PPC and a representative blend were reported: by monitoring the peak areas of CO absorptions, the dissociation of the inter‐H‐bonds and the thermal degradation of PPC were observed. It revealed that the presence of BPA clearly retarded the thermal degradation of PPC. Copyright © 2004 Society of Chemical Industry
Direct electrochemical generation of conducting polymer microcontainers on silicon substrate
Authors: Yuan Jinying , Zhang Deqiang , Qu Liangti , Shi Gaoquan , Hong Xiaoyin 
Published: August 2004

AbstractPolypyrrole microcontainers with morphology like bowls, cups, goblets and bottles have been electrochemically generated by direct oxidation of pyrrole on a p‐type silicon wafer in aqueous solution of camphorsulfonic acid. The well‐ordered microcontainers stand upright on the working electrode surface and changing the electrochemical polymerization conditions can easily control their morphological features. The growing process of microcontainers was studied by scanning electron microscopy. The microcontainers were characterized as being made of polypyrrole films in the doped state by Raman and IR spectroscopies. Copyright © 2004 Society of Chemical Industry
UV‐radiation‐induced preirradiation graft copolymerization of methacrylic acid and acrylic acid onto jute fibre
Authors: Khan Ferdous 
Published: August 2004

AbstractUV‐radiation‐induced graft copolymerization of methacrylic acid and acrylic acid onto jute fibre was carried out using a preirradiation method with 1‐hydroxycyclohexyl‐phenylketone as a photoinitiator. 2‐methyl‐2‐propene 1‐sulfonic acid, sodium salt was incorporated into the grafting solution in suppressing the homopolymer/gel formation and facilitating graft copolymerization. In comparison, results showed that the type of monomer significantly influence on grafting. The results of the characterisation showed that the graft weight and the type of monomer have significant influence on the mechanical and water absorption properties in the case of grafted samples. Copyright © 2004 Society of Chemical Industry
Effect of α‐cyclodextrin on the crystallization of poly (3‐hydroxybutyrate)
Authors: He Yong , Inoue Yoshio 
Published: August 2004

AbstractThe effect of α‐cyclodextrin (α‐CD) on the crystallization behavior of poly(3‐hydroxybutyrate) (PHB) was investigated with polarized optical microscopy, differential scanning calorimetry, and wide‐angle X‐ray diffraction. We found that the addition of α‐CD can greatly accelerate the crystallization of PHB and that α‐CD has a potential not only to enhance the nucleation but also to accelerate the crystallization of PHB. Compared to a conventional nucleation agent, such as talc, α‐CD is a natural product and has many advantages because it is environmentally friendly and safe to humans. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3461–3469, 2004
Large melting point depression of 2–3‐nm length‐scale nanocrystals formed by the self‐assembly of an associative polymer: Telechelic, pyrene‐labeled poly(dimethylsiloxane)
Authors: Jones Bryce A. , Torkelson John M. 
Published: August 2004

AbstractLarge melting point depressions for organic nanocrystals, in comparison with those of the bulk, were observed in an associative polymer: telechelic, pyrene‐labeled poly(dimethylsiloxane) (Py‐PDMS‐Py). Nanocrystals formed within nanoaggregates of pyrenyl units that were immiscible in poly(dimethylsiloxane). For 5 and 7 kg/mol Py‐PDMS‐Py, physical gels resulted, with melting points exceeding 40 °C and with small‐angle X‐ray scattering peaks indicating that the crystals were nanoconfined, were 2–3 nm long, and contained roughly 18–30 pyrenyl dye end units. In contrast, 30 kg/mol Py‐PDMS‐PY was not a gel and exhibited no scattering peak at room temperature; however, after 12 h of annealing at −5 °C, multiple melting peaks were present at 5–30 °C. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3470–3475, 2004
Two‐dimensional correlation gel permeation chromatography study of aggregate–aggregate interactions during acid‐catalyzed polymerization of triethoxysilyl‐terminated polystyrene
Authors: Suzuki Keita , Oku Jun‐Ichi , Izawa Kenichi , Okabayashi Hiro‐Fumi , Noda Isao , O'Connor Charmian J. 
Published: August 2004

AbstractThe three‐step polymerization of a well‐defined polymeric silane coupling agent, triethoxysilyl‐terminated polystyrene, catalyzed by acid (H3PO4), was traced as a function of the reaction time with gel permeation chromatography (GPC). Time‐resolved GPC traces collected during the polymerization process were then used to construct two‐dimensional (2D) correlation maps via generalized 2D correlation analysis. The results demonstrated that the synchronous and asynchronous 2D correlation GPC spectra directly reflected the dynamic variation of aggregate–aggregate interactions during each step of the polymerization. In particular, it was found that the formation of aggregates among the cyclic trimers (or tetramers) and monomers was critical for the preferential production of pentamers in the reaction system. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3447–3460, 2004
Phosphoproteome analysis of mouse liver using immobilized metal affinity purification and linear ion trap mass spectrometry
Authors: Jin Wen‐Hai , Dai Jie , Zhou Hu , Xia Qi‐Chang , Zou Han‐Fa , Zeng Rong 
Published: August 2004

AbstractSince protein phosphorylation is a dominant mechanism of information transfer in cells, there is a great need for methods capable of accurately elucidating sites of phosphorylation. In recent years mass spectrometry has become an increasingly viable alternative to more traditional methods of phosphorylation analysis. The present study used immobilized metal affinity chromatography (IMAC) coupled with a linear ion trap mass spectrometer to analyze phosphorylated proteins in mouse liver. A total of 26 peptide sequences defining 26 sites of phosphorylation were determined. Although this number of identified phosphoproteins is not large, the approach is still of interest because a series of conservative criteria were adopted in data analysis. We note that, although the binding of non‐phosphorylated peptides to the IMAC column was apparent, the improvements in high‐speed scanning and quality of MS/MS spectra provided by the linear ion trap contributed to the phosphoprotein identification. Further analysis demonstrated that MS/MS/MS analysis was necessary to exclude the false‐positive matches resulting from the MS/MS experiments, especially for multiphosphorylated peptides. The use of the linear ion trap considerably enabled exploitation of nanoflow‐HPLC/MS/MS, and in addition MS/MS/MS has great potential in phosphoproteome research of relatively complex samples. Copyright © 2004 John Wiley & Sons, Ltd.
Adducts of N‐terminal valines in hemoglobin with isoprene diepoxide, a metabolite of isoprene
Authors: Fred C. , Cantillana T. , Henderson A. P. , Golding B. T. , Törnqvist M. 
Published: August 2004

AbstractIsoprene (2‐methylbuta‐1,3‐diene) is a multi‐site carcinogen in rodents. To evaluate the role of the diepoxide metabolite (1,2:3,4‐diepoxy‐2‐methylbutane) in carcinogenesis, measurements of in vivo doses of the diepoxide are needed. The in vivo dose may be inferred from levels of reaction products with hemoglobin (Hb adducts). This report presents in vitro studies of the adduct formation by the diepoxide of isoprene with valinamide and oligopeptides as model compounds of N‐terminal valines in hemoglobin (Hb). In the reaction with valinamide it was shown that isoprene diepoxide forms as the main product a ring‐closed adduct, which is a pyrrolidine derivative [N,N‐(2,3‐dihydroxy‐2‐methyl‐1,4‐butadiyl)valinamide, MPyr‐Val]. The analysis was performed by gas chromatography/mass spectrometry (GC/MS) (EI and PICI) after acetylation. The ring‐closed adduct was also identified by liquid chromatography/electrospray ionization mass spectrometry (LC/ESI‐MS) as the main product in the reaction between isoprene diepoxide and standard hepta‐ or (2H8)octapeptides, corresponding to the N‐terminal peptides of the α‐chains in mouse and rat Hb. These peptides, alkylated with isoprene diepoxide, to be used as internal standards and calibration standards for quantification of MPyr‐adduct levels in vitro and in vivo, were analyzed with respect to the degree of MPyr‐alkylation by two independent methods, amino acid analysis and HPLC‐UV; similar results were obtained using these methods. A method for measurement of Hb adducts as modified peptides, used earlier to measure a similar adduct to N‐terminal valines in Hb from the diepoxide of 1,3‐butadiene, has in the present work been tested for application to isoprene diepoxide. The method is based on tryptic degradation of globin and LC/ESI‐MS analysis of N‐terminal Pyr‐heptapeptides of the Hb α‐chain enriched by HPLC. MPyr‐adduct levels in isoprene diepoxide alkylated hemolysate from mouse erythrocytes incubated with different concentrations of isoprene diepoxide (2 and 10 mM) for 1 h were quantified. The adduct level was about 50 nmol/g α‐chain Hb per mM × h. From the adduct levels the rate constant of isoprene diepoxide for reaction with N‐terminal valine was calculated to be about 1.6 times faster than for diepoxybutane. Copyright © 2004 John Wiley & Sons, Ltd.
Subthalamic nucleus lesions alter basal and dopamine agonist stimulated electrophysiological output from the rat basal ganglia
Authors: Zahr Natalie May , Martin Lynn Pauline , Waszczak Barbara Lee 
Published: August 2004

AbstractThe subthalamic nucleus (STN) is an important link in the “indirect” striatal efferent pathway. To assess its role on basal ganglia output via the substantia nigra pars reticulata (SNr), we monitored the single unit activities of SNr neurons in chloral hydrate‐anesthetized rats 5–8 days after bilateral kainic acid lesions (0.75 μg/0.3 μl/side) of the STN. Consistent with loss of an excitatory input, the average basal firing rate of SNr neurons was significantly reduced in STN‐lesioned animals. Moreover, the lesions modified the responses of SNr neurons to individual and concurrent stimulation of striatal D1 and D2 receptors. Bilateral striatal infusions of the D1/D2 agonist apomorphine (10 μg/μl/side) into the ventral‐lateral striatum (VLS) were previously shown to cause significant increases in SNr cell firing (to 133% of baseline) in normal rats. However, in STN‐lesioned rats, identical infusions caused no overall change in SNr activity (mean, 103% of basal rates). Conversely, selective stimulation of striatal D2 receptors by bilateral co‐infusion of the D2 agonist quinpirole and the D1 antagonist SCH 23390 that previously caused little change in SNr firing in normal rats significantly inhibited their firing in STN‐lesioned rats. Finally, the modest excitatory responses of SNr neurons to selective stimulation of striatal D1 receptors by co‐infusions of SKF 82958 with the D2 antagonist YM09151‐2 were not altered by lesions of the STN. These results implicate the STN as a mediator of excitatory response of SNr neurons to D2, and mixed D1/D2, dopamine receptor agonists in normal rats, and challenge conventional views on the role of the STN and the “indirect” pathway in regulating dopamine‐stimulated output from the SNr. Synapse 54:119–128, 2004. © 2004 Wiley‐Liss, Inc.