bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interaction of proteins with polymeric latexes
Authors: Basinska Teresa , Kowalczyk Dorota , Miksa Beata , Slomkowski Stanislaw 
Published: April 2003

AbstractSyntheses, modifications and properties of latexes containing polyacrolein, suitable for the covalent immobilization of proteins, are described. Results of the studies of physical adsorption and covalent attachment of human serum albumin and gamma globulins are discussed. Procedures allowing immobilization of the enzyme, horseradish peroxidase, are described. Changes in protein molecules, owing to their contact with latex particles, are analyzed. Applicability of polyacrolein containing latexes for diagnostic purposes is discussed.
Coagulation of antibody‐sensitized latexes in the presence of antigen
Authors: Ouali L. , Stoll S. , Pefferkorn E. , Elaissari A. , Lanet V. , Pichot C. , Mandrand B. 
Published: April 2003

AbstractThe paper describes a study of the kinetics and mechanism of the coagulation of two types of immunoassays using sensitized latexes. The positive response to the first test is based on the aggregation of the gamma globulin (IgG)‐coated polystyrene latexes in the presence of IgM rheumatoid antigen. The second test is relative to the heteroaggregation of two types of sensitized latexes induced by the presence of human chorionic gonadotropin (HCG). In the latter test, two identical polystyrene latexes bearing carboxylic acid surface groups were sensitized by covalent coupling of monoclonal antibodies specific for the αHCG determinant on one type of latex and for the βHCG determinant on the other type. Using the Coulter Counter method, the aggregate size distribution c(n) was determined as a function of the number n of elementary constituents, thus enabling calculation of the number N(t) and weight S(t) average sizes of the aggregates. The temporal variations of the average sizes were compared with typical situtions of reaction‐limited aggregation processes in order to characterize the mechanism of aggregation induced by antibody–antigen reactions.
Three‐component photopolymers based on thermal crosslinking and acidolytic de‐crosslinking of vinyl ether groups. 2. effects of acid components on photopolymer characteristics
Authors: Moon Seongyun , Yamaoka Tsuguo 
Published: April 2003

AbstractThe three‐component photopolymers consisting of poly(p‐hydroxystyrene) (PHS) or poly(styrene‐co‐acrylic acid) (PSA) as the binder polymer, 2,2‐bis(4‐(2‐(vinyloxy)ethoxy)phenyl)propane (BPA‐DEVE) or 1,1,1‐tris(4‐(2‐(vinyloxy)ethoxy)phenyl)ethane (THPETEVE) as the crosslinking agent, and a photoacid generator were investigated with regard to their lithographic characteristics and thermal crosslinking reactivity because of the acidity of the acid component. The thermal crosslinking rate can be represented as the pseudo first‐order reaction. The PSA copolymer with an acrylic acid unit has the higher crosslinking rate and sensitivity, and the lower activation energy. Under low baking temperatures at which crosslinking does not take place, dual‐mode resist behavior is observed.
Liquid crystalline behavior of comb–branch copolymers of di‐[6‐(4‐methoxy‐4′‐biphenyloxy)hexyl]‐2‐methylene butane‐1,4‐dioate with two non‐mesogenic chiral monomers
Authors: Cowie John M. G. , Hunter Hugh W. 
Published: April 2003

AbstractA mesogenic monomer di‐[6‐(4‐methoxy‐4′‐biphenyloxy) hexyl]‐2‐methylene butane‐1,4‐dioate, has been copolymerized with non‐mesogen monomers, one racemic and one optically pure, with a view to examining the potential for using these to induce chiral liquid crystal line phases in the copolymer. This proved to be ineffective, with the copolymer exhibiting only smectic A or smectic B phases. Transition temperature–copolymer composition diagrams have been constructed for both copolymer series and their features have been contrasted. Monomer reactivity ratios have been derived for both copolymer systems.
The pockels coefficient of new polymers for nonlinear optics and its time dependence after poling, compared with dielectric measurements
Authors: Wedekind F. , Siegel J. , Gujber J. , Hummel M. 
Published: April 2003

AbstractEpoxy polymers with donor–acceptor type side groups were synthesized for application in nonlinear optics. The stability of the Pockels coefficient was measured in thin films after poling. The relaxation times and their temperature dependence seem to be correlated with dielectric measurements. Guest–host systems (polystyrene and polymethylmethacrylate with dimethylaminonitrostilbene) were investigated for comparison.
Electrical conductivity of hexacene doped with iodine
Authors: Minakata Takashi , Imai Hideaki , Ozaki Masaru 
Published: April 2003

AbstractHexacene (HEX) and derivatives such as dihydrohexacene and dihydroxyhexcane quinone were synthesized and thin films of them were prepared by the sublimation method. The structure and conductivity of the films both before and after doping with iodine were studied. The doped HEX film showed the conductivity of 3 × 10−2 S/cm at room temperature, which was lower than expected since the conductivity of highly ordered pentacene was above 100 Ω−1 cm−1. The reason for the low conductivity was considered to be the disorder in molecular alignment since the HEX film showed an amorphous structure. A reversible change in the conductivity of the HEX film was observed in air and in vacuum.
Fabrication of a gas sensor using pentacene thin films as a detector
Authors: Minakata Takashi 
Published: April 2003

AbstractHighly sensitive gas sensors for both acidic and basic gases were fabricated based on conducting thin films of polyacene compounds. Gas sensors formed with pentacene thin films deposited on various kinds of substrates were found to exhibit high sensitivity in detecting subppm concentrations of NO2 or Cl2 by monitoring the conductivity of the thin film. Improvements in the conductance and duration period for detection were achieved by changing the shape of electrodes and substrate. The sensors with PEN thin films initially doped with iodine could detect ppm concentrations of ammonia gas, since iodine molecules were dedoped upon exposure to ammonia, causing the reduction of the conductivity.
Photocrosslinkable second‐order nonlinear optical polymers synthesized by cationic copolymerization
Authors: Hashidate Sadahito , Nagasaki Yukio , Kato Masao , Matsuda Hiro , Nakanishi Hachiro 
Published: April 2003

AbstractPhotocrosslinkable second‐order nonlinear optical (NLO) polymers were synthesized from cationic copolymerization of a vinyl ether monomer bearing 4′‐nitrobiphenyl‐4‐oxy group as the NLO chromophore with a vinyl ether monomer bearing cinnamoyl group as the photoreactive moiety. To obtain a suitable poling method involving photocrosslinking, which is capable of inducing a higher and more stable second‐order nonlinear coefficient, d33, for NLO polymer films, some poling procedures were investigated. An optimized poling method was as follows. Ultraviolet (UV) irradiation is performed for 90 sec during poling at 50°C for 20 min, followed by poling at 150°C for 20 min. By using this poling method NLO polymer films exhibited a higher and considerably stable d33 value at room temperature, even though they had rather lower glass transition temperatures before photocrosslinking. Some photocrosslinking mechanism for NLO polymers investigated here were considered.
Flexural behavior of unidirectional polyethylene–glass fiber–PMMA hybrid composites
Authors: Saha Nirmal , Banerjee Amar Nath , Mitra B. C. 
Published: April 2003

AbstractUnidirectional hybrid laminates based on glass fibers (GF) and high performance polyethylene fibers (PEF) were prepared with a partially polymerized methyl methacrylate (MMA) matrix at room temperature followed by heating at 55°C for the stipulated time (well below the softening point of PEF). The ultimate flexural strength (UFS), flexural modulus (FM) and interlaminar shear strength (ILSS) of the composites were determined and analyzed. An interesting observation of the study was the change in flexural behavior, which was largely dependent on the position of GF and PEF ply/plies in the compression and tension sides. When the ply/plies of PEF were at the tension side, the UFS and FM showed a higher value than that when GF plies were in the tension side of the hybrid composites. The ILSS also follows the same trend regarding the position of the GF and PEF plies.
The effect of nucleating agents on the crystallization kinetics of polypropylene
Authors: Dolgopolsky I. , Silberman A. , Kenig S. 
Published: April 2003

AbstractCompositions of neat polyproylene (PP), PP–PE (polyethylene) blend and PP–PE–DBS (dibenzylidene sorbitol) were studied with respect to their crystallization kinetics by means of differential scanning calorimetry in isothermal mode. A modified Avrami equation was applied to obtain the crystallization parameters of PP, PP–PE and PP–PE–DBS. Optical and hot‐stage microscopy and dynamical analysis were used for structure determination.Experimental results have indicated that PE addition inhibits PP crystallization rate and acts as a plasticizer, while addition of DBS changes the crystallization kinetics. A detailed study of the DBS nucleation effects indicates that owing to the high surface energy, nuclei are formed during primary crystallization, leading to a fine PP crystalline structure and improved mechanical properties.
Emulsion copolymerization of tribromophenyl maleimide with styrene
Authors: Yuan Yumin , Siegmann Arnon , Narkis Moshe , Bell James P. 
Published: April 2003

AbstractEmulsion copolymerization of Tribromophenyl Maleimide (TBPMI) and styrene was conducted by semi‐batch and batch processes. The effects of monomer composition and copolymerization method on copolymerization rate, molecular weight and molecular weight distribution, latex particle size and size distribution, glass transition temperature (Tg), thermal stability and mechanical properties were investigated. A kinetic study has shown that the rate of copolymerization in the batch process increased with increasing TBPMI content in the monomer feed. For the semi‐batch polymerized samples, molecular weight decreased and molecular weight distribution increased with increasing TBPMI content in the monomer feed. For the batch polymerized samples, molecular weight also decreased but no obvious tendency was observed for the molecular weight distribution when TBPMI content increased. Compared with the batch copolymers, the semi‐batch copolymers have a higher molecular weight at the same initial monomer mixture composition. Latex particle size decreased, while particle size distribution slightly increased with increasing TBPMI content in both semi‐batch and batch latices. The semi‐batch samples exhibit only a single Tg, the value of which increses linearly with increasing TBPMI content. For the batch copolymers, two Tgs were found, reflecting a mixture of styrene‐rich and TBPMI‐rich copolymer chains. TGA results indicate that the thermal stability of the semi‐batch copolymers increased with increasing TBPMI concentration. Young's and flexural moduli increased, while tensile and flexural strengths decreased by increasing the TBPMI content for both the semi‐batch and batch specimens. The semi‐batch specimens have higher tensile and flexural strenghts than the batch ones.
Interfacial reciprocal grafting by free radical reactions in polymer blends
Authors: Seadan Manus , Lambla Morand , Narkis Moshe , Siegmann Arnon , Tzur Aliza 
Published: April 2003

AbstractRecent developments in the field of reactive compatibilization of polymer blends prepared by melt processing focus on the addition of low molecular weight compounds. This work deals with in situ compatibilization through the formation of graft or crosslinked copolymers at the interface. Mixtures of semicrystalline hydrocarbon polymers have been subjected to free radical reactivity, in a co‐rotating twin screw extruder (ZSK 30) in a single step. The particular system, high density polyethylene and polyamide 6, was blended in the presence of a peroxide and a reactive bifunctional monomer, maleic anhydride. Because of a combined effect, the reaction appears to occur mainly at the interface, where the resulting grafted copolymer acts as an anchor for the final stabilization of the biphasic system. Different analytical techniques, such as differential scanning calorimetry, scanning electron microscopy and tensile testing, helped in characterizing the resulting blends and confirmed the high level of interfacial grafting and the expected improvement in mechanical properties.
Characterization and properties of carbon/PMR‐15 composites
Authors: Kim Dae Su , Lee Jae Rock 
Published: April 2003

AbstractPMR (polymerization of monomer reactants) ‐15 was formulated to use as a matrix resin for high performance carbon fiber‐reinforced composite materials. Monomers for the PMR‐15 were characterized using Fourier transform infrared spectroscopy. Molecular weight change during cure was investigated using gel permeation chromatography. Thermal analysis was carried out to investigate glass transition and thermal degradation. Cure behavior of a glass/PMR‐15 prepreg was investigated using a dynamic mechanical analyzer. Flexural strength of a cured carbon/PMR‐15 composite was affected by cure temperature and pressure. The morphology of the cured carbon/PMR‐15 was affected by cure conditions as well as by the surface conditions of the carbon fibers. A scanning electron micrograph of the composite made of untreated carbon fibers showed a void‐trapped morphology.
Acrylamide/maleic acid hydrogels
Authors: Saraydin Dursun , Karadaǧ Erdener , Güven Olgun 
Published: April 2003

AbstractAcrylamide/maleic acid hydrogels in the form of rods were prepared by γ‐irradiating ternary mixtures of acrylamide–maleic acid–water with 2.00–5.71 kGy γ‐rays. The influence of dose and relative content of maleic acid on the spectroscopic, thermal and mechanical properties, swelling properties, diffusional behavior of water and diffusion coefficients of hydrogel systems are examined. Acrylamide/maleic acid hydrogels were swelled in the range of 1000–2800%, While polyacrylamide hydrogels were swelled in the range of 650–700%. Water diffusion to hydrogels in non‐Fickian type diffusion. The diffusion coefficients varied from 4.5 × 10−2 to 12.2 × 10−7 cm2 sec−1.
Thermal and acid‐catalyzed reaction of bifunctional vinyl ether urethane in nonionic and ionic polymer matrices
Authors: Chen Zheliu , Ajayagohosh A. , Yamaoka Tsuguo , Sukigara Mitsunori 
Published: April 2003

AbstractA bifunctional vinyl ether urethane derivative (BVU) was synthesized and characterzed. Photoresist systems consisting of BVU and a photoacid generator (PAG) along with various matrix polymers were prepared and the photoresist characteristics were evaluated. In the presence of BVU and a PAG, poly(methylmethacrylate‐co‐acrylic acid) and poly(methylmethacrylate) exhibited positive and negative tone behavior, respectively, where as poly(p‐hydroxystyrene) showed both positive and negative working properties depending on the prebake temperature of the system. The depandence of the photoresist behaviors on these matrix polymers was studied. The mechanism of the thermal and photochemical reactions was revealed.
Novel crosslinked polyurethanes with second‐order nonlinear optical effects
Authors: Liang Zhaoxi , Yan Xingzhong , Cai Zhigang , Yang Peiqing , Li Qingxing 
Published: April 2003

AbstractA series of push–pull chromophores (R‐HANB) based on 4′(N,N′‐dihydroxyethyl)amino‐4‐nitro azobenzene has been designed and synthesized. R‐HANB chromophores show a strong tendency to undergo intramolecular charge transfer and show high nonlinear optical effects. During the poling process, the trimer of hexamethylene diisocyanate reacted with R‐HANB to give four various thermosetting polyurethanes simultaneously at higher temperature. The second harmonic generations (SHG) of three crosslinked polyurethane films are fairly high and stable at ambient temperature. The real‐time measurement of SHG intensity vs. poling voltage indicates that orientation of chromophores is still feasible in this crosslinked system.
Network polyester films from glycerol and dicarboxylic acids
Authors: Kiyotsukuri Tsuyoshi , Kanaboshi Masato , Tsutsumi Naoto 
Published: April 2003

AbstractThis paper presents information on the preparation of the network polyester films from glycerol (Yg) and aromatic dicarboxylic acids of phthalic anhydride (P), dimethyl isophthalate (I) and dimethyl terephthalate (T), as well as aliphatic dicarboxylic acids of adipic, sebacic, 1, 10‐decanedicarboxylic and 1, 12‐dodecanedicarboxylic acids, and their properties. Yg and dicarboxylic acid were polycondensed immediately before the gelation started. The prepolymers obtained were cast from DMF solution and successively post‐polymerized at various temperatures and times to form networks. The resultant films were transparent, flexible and insoluble in organic solvents. Heat distortion temperature (Th) measured by a penetration mode of thermomechanical analysis increased with increasing post‐polymerization temperature and time, and then leveled out. Th values corresponded well to the glass transition temperature (Tg) measured by differential thermal analysis (DTA). Th was 152°C, 162°C and 197°C for YgP, YgI and Yg T post‐polymerized at 270°C for 6 h, respectively. Th values of network films made from aliphatic dicarboxylic acids could not be observed until complete probe penetration occurs, as a result of thermal decomposition because the Tg is lower than room temperature. The degree of reaction estimated from the IR absorbance of hydroxyl and methylene groups was in the range of 60–80%. Two diffraction peaks appeared in the wide‐angle X‐ray scattering pattern, suggesting some ordered structure owing to the regular networks. Density decreased with increasing post‐polymerization time and temperature, in the order YgP > YgI > YgT. Network films made from aliphatic dicarboxylic acids had much lower tensile strength and Young's modulus, and greater elongation, than those made from dicarboxylic acids, as a result of the Tg being below room temperature.
Control of debromination in solution polymerisation of copper(I) 4‐bromobenzenethiolate
Authors: Archer Adrian C. , Lovell Peter A. 
Published: April 2003

AbstractDebromination of poly(1,4‐phenylene sulphide), PPS, chains during formation by solution polymerisation of copper(I) 4‐bromobenzenethiolate, CBT, in quinoline and quinoline/pyridine mixtures at temperatures in the range 180–225°C has been investigated. The results are consistent with previously‐reported model compound studies and show that debromination is insignificant if the polymerisation temperatures is ≤ 200°C. Pyridine was shown not to be essential for the formation of high molar mass PPS. The optimum conditions for preparing high molar mass PPS in high yield with no significant debromination were polymerisation of CBT at a concentration of 1.0 mol dm−3 in dry quinoline under a flowing dry nitrogen atmosphere at a controlled temperature of 200°C for about 24 h.
Effects of plasma treatment on mechanical properties of rubber/cellulose fibre composites
Authors: Ahlblad Gustav , Kron Anna , Stenberg Bengt 
Published: April 2003

AbstractNatural rubber materials reinforced with cellulose fibres have been studied with respect to crosslink density, tensile strength and stress relaxation. The fibres have been grafted with butadiene or divinylbenzene by plasma treatment. Chemiluminescence analysis was used to indicate the grafting on the surface of the cellulose fibres and also to estimate the effect of the plasma on the cellulose fibres. The results indicate the possibility of obtaining a surface layer on the fibres, which is a conceivable way of improving the mechanical properties of rubber composites.
Thermal and X‐ray investigations of ethylene–α‐olefin copolymers obtained with highly active supported Ti–Mg and V–Mg catalysts
Authors: Echevskaya L. G. , Zakharov V. A. , Marathe S. , Sehra J. C. , Jog J. P. , Sivaram S. 
Published: April 2003

AbstractCopolymers of ethylene with propylene, butene‐1 and hexene‐1 were prepared using a titanium–magnesium (TMC) or a vanadium–magnesium catalyst (VMC). The copolymers were examined for thermal stability by TGA, melting and crystallization behaviour by DSC and crystallinity by XRD. Fractionated samples of ethylene–hexene‐1 copolymers were also similarly characterized. Results indicate that VMC produces copolymers with a higher degree of crystallinity and greater compositional homogeneity than TMC.
Cationic ring‐opening polymerization of hexamethylcyclodisilazane: General aspects and tentative mechanisms
Authors: Duguet Etienne , Schappacher Michèle , Soum Alain 
Published: April 2003

AbstractThe ring‐opening polymerization of hexamethylcyclodisilazane (D2NMe), initiated by methyl triflate in 1,2‐dichloroethane, forms in the first, fast kinetic step both linear polymer and cyclic dimer (D4NMe). Subsequently a slow depolymerization process occurs leading to exclusively cyclotrisilazane (D3NMe). On the basis of kinetic measurements carried out using an adiabatic calorimetric technique and complementary experiments, mechanisms of both propagation, cyclization and back‐biting reactions are proposed. The influence of the reaction temperature was also studied; it is demonstrated that, at low temperature, polymerization does not lead to cyclic oligomer formation. In such conditions, the polymerization presents a ‘living’ character.
Synthesis and characterization of poly(methyl methacrylate) star polymers
Authors: Efstratiadis Vasilis , Tselikas Giannis , Hadjichristidis Nikos , Li Jianbo , Yunan Wan , Mays Jimmy W. 
Published: April 2003

AbstractStar‐branched poly(methyl methacrylate)s (PMMA) were synthesized by linking ‘living’ arms (produced by anionic polymerzation) with ethylene glycol dimethacrylate. Stars having arm molecular weights of 10000 and 40000 and between 4.9 and 18.7 branches were produced. The polymers were characterized using light scattering, size exclusion chromatography, and viscometry. It was found that well‐defined PMMA stars were obtained only at the higher (40000) arm molecular weight. The stars prepared using the lower molecular weight (c. 10000) arms contained very high molecular weight gel components.
Anionic synthesis and characterization of ω‐formyl‐functionalized polystyrenes
Authors: Quirk Roderic P. , Kuang Jianxin 
Published: April 2003

Abstractω‐Formyl‐functionalized polystyrenes can be synthesized in quantitative yield by reacting poly(styryl)lithium (Mn = 2 × 103−8 × 103 g/mol) in benzene with a 0.1−0.4 molar excess of 4‐morpholinecarboxaldehyde followed by methanol termination and precipitation into methanol. Narrow molecular weight distribution ω‐formyl‐functionalized polystyrenes were characterized by hydroxylamine end‐group titration, thin layer chromatography and both 1H and 13C NMR spectroscopy. The mechanism of the functionalization was studied by trapping the tetrahedral α‐amino alkoxide intermediate with diphenylphosphinic chloride.