bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimum preparation conditions of amidoxime hollow fiber synthesized by radiation‐induced grafting
Authors: Saito Kyoichi , Yamaguchi Takeo , Uezu Kazuya , Furusaki Shintaro , Sugo Takanobu , Okamoto Jiro 
Published: April 2003

AbstractThe preparation process of amidoxime hollow fiber consists of three steps: (1) radiation‐induced graft polymerization of acrylonitrile (AN) onto porous hollow fiber (AN grafting), (2) chemical conversion of the cyano group into an amidoxime group (amidoximation), and (3) conditioning of the hollow fiber with alkaline solution (alkaline treatment). Systematic optimization of this preparation process was found to improve the adsorption rate. For the AN‐grafted hollow fiber having 130% degree of grafting, the optimum reaction was 1 h each for amidoximation and alkaline treatment, respectively. Also the change in the structure of the amidoxime hollow fiber with alkaline treatment was discussed based on measurements of water content, swelling and pore volume distribution, and observation of morphology of cross section by SEM.
Nonlinear dynamics and the problem of polymer fracture
Authors: Manevitch L. I. , Zarkhin L. S. , Enikolopian N. S. 
Published: April 2003

AbstractThe results of the experimental and molecular‐dynamics study of the process of mechanical degradation of polymer chain, testifying to the essential role of nonthermal channels of dissipation of elastic energy accumulated during deformation, have been discussed. High‐energy molecular products of mechanical degradation, which are able to induce a chain branching process leading to “explosive” formation of submicrocrackes, have been discovered. It has been noted that a considerable part of polymer chain energy is concentrated in localized excitations of a soliton type, which play the determining role at all the stages of mechanical degradation under consideration.
1H‐NMR studies on water in methacrylate hydrogels. I
Authors: Yamada‐Nosaka Atsuko , Ishikiriyama Kazuhiko , Todoki Minoru , Tanzawa Hiroshi 
Published: April 2003

AbstractThe behavior of water contained in a hydrophilic hydrogel poly(hydroxyethyl methacrylate) membrane and a hydrophobic hydrogel poly(methyl methacrylate) membrane was studied by proton nuclear magnetic resonance (NMR) spectroscopy. Significant differences between the two hydrogels were observed in their relaxation times, the temperature dependence, and frequency dependence of these relaxation times, and changes of signal intensity of water protons on freezing and thawing. The water in these hydrogels was classified into three states: free, intermediate, and bound states. Poly(hydroxyethyl methacrylate) contains relatively more water in bound and intermediate states than poly(methyl methacrylate). The mobility of water decreases in the order, free water, intermediate water, bound water. The correlation times of the three states were roughly estimated to be 10−11, 10−9, and 10−6 s, respectively. The mobility of water in poly(methyl methacrylate) is several orders of magnitude higher than that in poly(hydroxyethyl methacrylate). In poly(hydroxyethyl methacrylate), the exchange between intermediate and free water is slow in the NMR time scale: the apparent exchange rate and the activation energy were estimated to be 3.6 × 102 s−1 (28°C) and 2.0 kcal/mol, respectively.
Studies on the preparation and properties of conductive polymer. I. Novel method to prepare metalized plastic from metal chelate of poly(vinyl alcohol)
Authors: Yen Chih‐Chao , Chang Teh‐Chou , Kakinoki Hideo 
Published: April 2003

AbstractA novel and easily processed conductive polymer was prepared from poly(vinyl alcohol)(PVA). Metal chelate onto PVA film exhibited excellent surface resistivity around 100–102 Ω/cm2 when it was treated with reducing agents. The surface of these films was treated with reducing agents which possessed a definite metallic luster. The conducting surface proved to be metallized by x‐ray and FSCA analysis. The strongly adhering metal on the film was believed to be responsible for the enhancement of electrical conductivity. The factors that affect the conductivity of metallized film were also studied.
Effect of mica on the curing behavior of an amine‐cured epoxy system: Differential scanning calorimetric studies
Authors: Bajaj P. , Jha N. K. , Kumar R. Ananda 
Published: April 2003

AbstractDifferential scanning calorimetry has been used to follow the cure behavior of mica filled epoxy system using an aromatic diamine (4,4′‐diaminodiphenylmethane) as a crosslinking agent. Both dynamic and isothermal methods have been adopted. The effect of mica on the kinetic parameters and the Tg of the cured system has been studied. It was found that mica accelerates the curing process, and decreases the Tg of the fully cured system to some extent.
The separation of water–ethanol mixtures by pervaporation through hydrophilic—hydrophobic composite membranes
Authors: Ruckenstein E. , Park J. S. 
Published: April 2003

AbstractA new kind of polymer composite membrane, which we refer as hydrophilic–hydrophobic composite membrane, is prepared by the concentrated emulsion polymerization method6,7 and employed to separate permselectively ethanol–water mixtures. This composite contains polyacrylamide as the dispersed phase and crosslinked polystyrene as the continuous phase. The swelling in water of this composite membrane is around 4 g water/g polymer and its swelling in ethanol is negligible. The permeation of the composite membrane by pervaporation decreases with increasing ethanol concentration in the feed and increases with increasing polyacrylamide fraction in the composite. The rate of permeation is in the range of 30–103 g/m2 h. The selectivity of the membrane ranges between 2 and 50 and increases with increasing ethanol concentration in the feed and increasing polyacrylamide fraction in the composite. The permeation increases and the selectivity decreases with increasing feed temperature. The activation energy of permeation varies between 1.8 and 4.9 kcal/mol, depending upon the compositions of the feed and membrane.
Evaluation of thermal history of polymeric films and fibers using DSC/TMA/DMA techniques
Authors: Khanna Y. P. 
Published: April 2003

AbstractDetermining the thermal history of a semicrystalline polymer is an area of extreme importance when it comes to understanding the structure‐propety relationships. For nylon 6 film and fiber products, we have shown that techniques such as differential scanning calorimetry (DSC), thermomechanical analysis (TMA), and dynamic mechanical analysis (DMA) can reveal the thermal history of the polymer. We believe that the basis of correlation between the heat setting (annealing) conditions and the thermal/mechanical data is the formation of microcrystallites within the amorphous phase upon thermal treatment. Based on a previously published X‐ray study, we must mention that a number of changes within the crystalline phase also occur concurrently during the heat setting process of nylon 6. DMA of a highly annealed nylon 6 has helped us identify a broad α‐relaxation in the vicinity of 170°C, tentatively assigned to the mobility of interfacial amorphous domains. We propose that the occurrence of α‐relaxation parallels the crystalline phase changes observed in X‐ray studies during the heat setting of nylon 6 products. Although most of the work presented in this manuscript is based on nylon 6, the proposed correlation between the thermal history and DSC/TMA/DMA techniques can be expected for any semicrystalline polymeric film or fiber.
Fluorosilicone antifoams
Authors: Owen Michael J. , Groh Julianne L. 
Published: April 2003

AbstractAntifoam compositions for aqueous surfactants are usually emulsions of insoluble oils containing hydrophobic solids. The emulsion allows easy access to the aqueous environment. The oil droplets carry the solid particles to the foam interfaces by spreading, which also contributes to foam rupture. The particles provide a disruptive dewetting surface and may also adsorb the foam stabilizer. This theory requires both oil and solid to have lower surface tension than the foaming surfactant and explains the ineffectiveness of conventional silicone antifoams based on polydimethylsiloxane against silicone and fluorocarbon aqueous surfactants. Some fluorosilicones have lower surface tensions than polydimethylsiloxane and should produce more effective antifoams. To test this idea the liquid surface tensions of a series of fluorosilicone‐containing copolymers were measured. These fluids were formulated into antifoam compounds and emulsions and tested against selected surfactants. Equilibrium and dynamic surface tensions of these test surfactants were also measured. The new antifoams are more effective than conventional silicones against silicone surfactants but are ineffective against fluorosurfactants. The implication of these results on the spreading/dewetting theory is discussed.
Composites of starch and poly(ethylene‐co‐acrylic acid). Complexing between polymeric components
Authors: Fanta G. F. , Swanson C. L. , Doane W. M. 
Published: April 2003

AbstractExtrusion‐blown film prepared from a semidry mixture of starch and poly(ethylene‐co‐acrylic acid) (EAA) cannot be sharply separated into its polymeric components by selective solvent extraction, and the two polymers have the outward appearance of being compatible. Also, the starch portion is resistant to enzyme attack, and starch domains are not visible by SEM. Further studies were therefore made on the starch–EAA system to determine reasons for the apparent compatibility between the two polymers, and evidence for polymer complex formation was obtained. Combination of aqueous ammonia solutions of starch and EAA led to an increase in viscosity, and a coprecipitate of starch and EAA separated from solution. Moreover, solvent extraction would not separate physical mixtures of starch and EAA prepared from aqueous solutions. Although both the linear (amylose) and branched (amylopectin) components of starch formed an apparent complex with EAA, a low molecular weight starch fraction and a high molecular weight dextran (a polysaccharide with α‐(1→6) linked glucopyranosyl units) did not. These observations support the theory that a helical inclusion complex is formed from starch and EAA, which is similar to the well‐known complexes produced from starch and fatty acids.
Processing–morphology–property relationships in epoxy resins containing “fortifiers”
Authors: Mijović Jovan 
Published: April 2003

AbstractAn investigation was carried out into the effect of an additive called “fortifier” on curing, morphology, and thermomechanical properties of epoxy resins. Differential scanning calorimetry, electron microscopy, and a series of mechanical measurements were performed on bifunctional and tetrafunctional formulations. It was found that the addition of fortifier resulted in an increase in the fracture surface roughness, the size of morphological inhomogeneities observed in the fractographs, and the ultimate tensile strength. At the same time, the glass transition temperature was found to decrease by at least 25°C in going from 0 to 15 phr of the fortifier in a formulation. The presence of fortifier had little effect on the rate of cure and on the strain energy release rate.
The preparation and characterization of new polyether ketone‐tetraethylorthosilicate hybrid glasses by the sol‐gel method
Authors: Noell John Lee W. , Wilkes Garth L. , Mohanty Dillip K. , McGrath James E. 
Published: April 2003

AbstractIn recent years, tetraethyl orthosilicate (TEOS) has been used as a precursor in preparing inorganic glasses. The technique, known as the sol‐gel process involves a two step poly(hydrolysis‐condensation)reaction sequence. The work presented here is concerned with the utilization of a suitably functionalized oligomeric “glassy” organic polymeric component in this two step sequence. In particular, an amine terminated amorphous poly(arylene ether) ketone, (PEK), end capped with isocyantonropyl triethoxy silane was used to synthesize a hybrid network with TEOS. Low incorporation of the PEK oligomers into the network caused by early vitrification can be eliminated by carrying out reactions at elevated temperatures. A systematic change in mechanical and physical properties of the hybrid glass has been found with TEOS content and the annealing temperatures. A model for the network has been proposed based on structural and morphological evidence.
Preparation of high‐modulus and high‐strength fibers from high molecualar weight poly(ethylene terephthalate)
Authors: Ito Masayoshi , Takahashi Katsumi , Kanamoto Tetsuo 
Published: April 2003

AbstractHigh molecular weight poly(ethylene terephthalate) (PET) was obtained by solid‐state polymerization of solution‐grown crystals of PET that were prepared from commercially available PET. The intrinsic viscosities of the sample before and after the polymerization were 0.67 and 2.41 dL/g, respectively. As‐spun fibers from the high molecular weight material were prepared by a solution spinning method using two kinds of solvents: nitrobenzene (NB) and a mixture of hexafluoro‐2‐propanol and dichloromethane (HD). Both as‐spun fibers could be drawn up to a draw ratio of 12–13 by a two‐stage drawing technique. The highest tensile modulus and strength of 275 g/d (34.4 GPa) and 15 g/d (1.9 GPa), respectively, were obtained for the drawn fibers from the HD system. These values were 15%–20% higher than those achieved for the drawn fibers from the NB system. The difference was explained on the basis of the morphological differences of asspun fibers and the extent of molecular degradation during processing observed between the two series.
Graft copolymerization of collagen with N, N, N′, N′‐tetra (2‐hydroxypropyl) ethylene diamine methacrylate by use of potassium persulfate as an initiator
Authors: Patil D. R. , Smith D. J. 
Published: April 2003

AbstractGraft copolymerization of collagen with N,N,N′,N′‐tetra (2‐hydroxypropyl) ethylene diamine methacrylate (THPEDM) was carried out in an aqueous medium using potassium persulfate as the radical initiator. Collagen‐g‐poly(THPEDM) was characterized by the percent yield and the copper chloride test. The percentage of grafting was determined as functions of concentration of monomer, concentration initiator, reaction time, and temperature.
Observation technique of polymer micelle by using transmission electron microscope
Authors: Ishikawa Satoshi , Fukutomi Takashi 
Published: April 2003

AbstractThe method, established by Price et al. to observe the polymer micelle, was modified and applied to the region of high polymer concentration. The novelty of our method consists of the preparative method of the specimen for transmission electron microscopy. Polymer solution was diluted and solvent was evaporated rapidly before the micelle was decomposed. As a result, dilution ratio had no effect on the decomposition of polymer micelle, and the original micelle structure was conserved over 10 wt % block copolymer solution if the operations were carried out within 30 min. This time limit related to the concentration of solution.
Thermal degradation of poly(aryl‐ether‐ether‐ketone): Experimental evaluation of crosslinking reactions
Authors: Day M. , Sally D. , Wiles D. M. 
Published: April 2003

AbstractPoly(aryl‐ether‐ether‐ketone) (PEEK) has been heated at 400°C in both nitrogen and air. The extent of thermal degradation has been monitored by a variety of techniques including: solution viscometry, UV‐visible spectroscopy, 13C high‐resolution cross‐polarization/magic angle spinning nuclear magnetic resonance and Fourier transform infrared spectroscopy. The results indicate, that in a nonoxidative environment such as nitrogen, PEEK is relatively stable at 400°C for periods up to 6 h. Under oxidative conditions chain scission reactions occur and crosslinks are formed causing a reduction in the crystallizability of the material and discoloration of the polymer. The spectroscopic evidence suggests that the chain cleavage occurs adjacent to the carbonyl functional groups. Subsequent hydrogen abstraction from the aromatic ring then leads to crosslinking between adjacent aryl rings.
Cement hydrate catalyzed hydrolysis of polyimide lightweight materials
Authors: Sugama T. , Kukacka L. E. , Carciello N. 
Published: April 2003

AbstractPolymide (PI) resins which are produced by an in situ imidization condensation reaction of polyamic acid (PAA) precursors were evaluated for use as binders in high‐temperature performance lightweight cement‐filled material systems. Unfortuanately, the presence of partially hydrated cement in the system led to strength retrogression at room temperature. Significant mechanical failure was observed upon exposure of the specimens to steam at > 150°C. This was found to be due mainly to alkali catalyzed hydrolysis of the functionaries of unreacted PAA adjacent to the cement surfaces and the imide rings of PI matrices. The formation of Ca‐complexed carboxylate salts derived from the hydrolysis resulted in chain scission of the polymer, thereby decreasing the mechanical strength, and making the composites unsuitable for use in aqueous environments.
Nitrogen plasma treatment of polyethylene and polystyrene in a remote plasma reactor
Authors: Foerch Renate , Mcintyre N. S. , Sodhi R. N. S. , Hunter D. H. 
Published: April 2003

AbstractThe effect of a remote nitrogen plasma on polyethylene and polystyrene was studied. The gas flow rate, the dilution of reactant gas, exposure times, and reactor base pressure were all found to have a large impact on the efficiency of nitrogen incorporation. Optimum conditions caused 18 atom % nitrogen to be incorporated within 20 seconds for polyethylene and 10 seconds for polystyrene. Studying a remote nitrogen plasma treated polyethylene sample over a period of 1 month indicated that except for a drop in the % N on initial exposure to air the concentration of nitrogen on the surface remained steady within the experimental limits. Angle resolved photoelectron spectroscopy indicated that nitrogen is incorporated to a depth below the analysis depth of XPS.
Surface characteristics of fluoroalkylsilicone—poly(methyl methacrylate) block copolymers and their PMMA blends
Authors: Inoue Hiroshi , Matsumoto Akihiro , Matsukawa Kimihiro , Ueda Akira , Nagai Susumu 
Published: April 2003

AbstractSurface properties of fluoroalkylsilicone—poly(methyl methacrylate) block copolymers and their poly(methyl methacrylate) (PMMA) blends have been intensively studied to draw a relationship between surface segregation behavior and adhesion performance. The fluoroalkylsilicone—PMMA block copolymers containing thre kinds of fluoroalkyl side chains (i.e., 3,3,3‐trifluoropropyl) (CF3CH2CH2−, abbreviated as TFP), tridecafluoro‐1,1,2,2‐tetrahydrooctyl [F3C(CF2)5CH2CH2−, TFO], and heptadecafluoro‐1,1,2,2‐tetrahydrodecyl groups [F3C(CF2)7CH2CH2−, HFD] on the siloxane chains were prepared according to the macroazoinitiator method. Contact angle measurement and X‐ray photoelectron spectroscopy (or ESCA) were used to obtain structural information on the surface of the solution‐cast films. A significant effect of fluroalkyl groups on the surface accumulation not only in silicon but also fluorine atoms were observed for relatively long fluoroalkyl side chains (i.e., TFO and HFD). On the contrary, TFP group was found to be effective to orient to the hydrophilic surfaces (i.e. glass‐side surfaces). The surface accumulation of fluoroalkyl groups in the films was also reflected by the 180° peel strength against pressure‐sensitive adhesives as a measure of the adhesion performance. These results indicated that incorporation of relatively long fluoroalkyl groups much enchanced the surface hydrophobicity (and/or oleophobicity) of solution‐cast films in addition to that of the siloxane‐enriched surfaces. The composition and orientation of the functional groups on the surface were also speculated based on ESCA data.
Solvent effect on thermal degradation of polystyrene
Authors: Sato Shimio , Murakata Tadahiro , Baba Syunji , Saito Yasunobu , Watanabe Sinya 
Published: April 2003

AbstractThe thermal degradation of polystyrene (PS) in various kinds of solvents was studied in the temperature range from 300 to 450°C. The conversion of PS to low molecular weight products was dependent on the hydrogen donating ability of the solvents used: Solvents with greater donating ability resulted in less conversion of PS. A different degradation behavior was evident when phenols or other kind of solvents were used. These reaction properties are explained with a proposed degradation mechanism that includes hydrogen transfer steps from solvents to Intermediate PS radicals and from PS to the solvent radicals.
Viscoelastic properties of UV‐curing ink systems
Authors: Amari Takeshi , Kishi Susumu , Watanabe Koichiro 
Published: April 2003

AbstractMechanical properties such as tensile strength, relaxation modulus, creep compliance, and storage and loss moduli of UV‐curing ink systems were examined at various drying stages. Acrylic‐based binder consisting of epoxy acrylate prepolymer and trifunctional monomer were used as UV‐curing systems. For the UV‐cured specimen containing a large quantity of trifunctional monomer a highly crosslinked network structure was formed at comparatively short irradiation time, however, the sample lacks toughness and nonlinear rheological behavior was observed. On the other hand, for the specimen containing a large amount of epoxy prepolymer, a uniform network structure was formed and the ultimate strength increased with the growing network structure. In the temperature sweep experiments for storage and loss moduli, two transitions were observed. The transition observed above 10°C shifts to higher temperature and becomes broader with increasing irradiation time. The transition which is associated with a relaxation in the crosslinks was observed at −70°C and the height of the G″ peak increased with increasing irradiation time.
Adsorption of γ‐globulin on polymer surfaces having various chemical and physical structures
Authors: Kumakura Minoru , Yoshida Masaru , Asano Masaharu 
Published: April 2003

AbstractThe adsorption of human γ‐globulin on polymer surfaces having various chemical and physical structures was studied. The γ‐globulin adsorption on the crosslinked, rigid polymers of polyethyleneglycol dimethacrylate was considerably affected by the length of oxyethylene chains, in which the hydrophilicity of the polymers increased as the oxyethylene chains lengthened. The γ‐globulin adsorption on the rigid polymers of tetraethyleneglycol dimethacrylate (or diacrylate) was lower than other soft polymers such as hydrogel, owing to the presence of oxyethylene chains. The polymer having a porous structure appeared to be a high adsorption material for the γ‐globulin and the degree of the adsorption varied with pore size.
Graft copolymerization of acrylic acid onto jute fibers initiated by quinquivalent vanadium
Authors: Samal Rajani K. , Dash Sabyasachi , Sahu Abani K. 
Published: April 2003

AbstractGraft copolymerization of acrylic acid onto jute fibers was carried out with quinquivalent vanadium as initiator in an aqueous sulphuric acid medium under nitrogen atmosphere. The graft yield was influenced by reaction time, temperature, concentrations of acid, monomer, initiator, reaction medium, and base polymer. Grafting has also been carried out in presence of various organic solvents. It has been observed that the maximum graft yield 56.7% was obtained at 50°C for [AA] = 1.453 M, [V+5] = 15 X 10−3 M, acid (2.12 M) and for a reaction time of 6 h. The tensile properties, dye‐uptake ability, and absorption of water and water vapours of the grafts have also been studied.