bluuebunny/crossref_metadata_2025_split huggingface dataset:
The role of surfactants in synthesizing polyurea microcapsule
Authors: Chao D. Y. 
Published: April 2003

AbstractOur lab has successfully synthesized microcapsules using interfacial polymerization technique. The core material and the wall of these microcapsules have been illustrated to be crystal violet lactone and polyurea, respectively, by both infrared and ultraviolet spectra. To make unique microcapsules, the presence of ethylene diamine in toluene diisocyanate system is important. Use of methyl cellulose with longer ethylene oxide chain length of nonylphenyl polyoxyethylene ether in a toluene diisocyanate system containing ethylene diamine will form small particles of polyurea microcapsules. Furthermore, in the presence of a fixed amount of sodium lauryl benzene sulfonate as an emulsifier, sodium carboxy methyl cellulose is better than methyl cellulose for use in making polyurea microcapsules in terms of their particle sizes. © 1993 John Wiley & Sons, Inc.
Sorption of water vapor by hydrophilic polyurethane‐ureas
Authors: Petřík S. , Hadobaš F. , Šimek L. , Bohdanecký M. 
Published: April 2003

AbstractSegmented polyurethane‐ureas were prepared from low‐molecular weight homopolymers or triblock (PEP) copolymers of ethylene and propylene oxides and 4,4′‐diphenylmethane diisocyanate with hydrazine as chain extender. Equilibrium sorption of water vapor at 23°C was measured at eight to nine values of relative vapor pressure, 0.08 ≤ p/p0 ≤ 0.97. The effect of the structure (composition and length) of soft segments was studied. Sorption capacities were found to be lower than the reference values computed under the assumption that the contributions to sorption by the chain constituents are additive. This finding was assigned to the shielding effect of hard segment domains on the interaction of water molecules with hydrophilic (ethoxamer) groups of soft segments. © 1993 John Wiley & Sons, Inc.
Comparison of analytical and preparative TREF analysis: A mathematical approach to correcting analytical TREF data
Authors: Pigeon Michael , Rudin Alfred 
Published: April 2003

AbstractAnalysis of analytical temperature rising elution fractionation (TREF) data involves conversion of elution temperature information to branching information via a calibration curve relating the two. The curve is generated by analysis of polymer fractions recovered using preparative TREF techniques. In preparative TREF a stepwise temperature ramp is used to recover these fractions so that samples with sharp branching distributions are obtained. A continuous temperature ramp, as in analytical TREF, produces samples that differ in branching properties from the stepwise ramp at the same temperatures. The analytical TREF data can be corrected for these differences by an iterative computer program so that a calibration curve generated by preparative techniques can be used to convert the analytical TREF data to branching distributions. Analytical TREF results should be corrected for fraction overlap before relating these data to polymer properties. © 1993 John Wiley & Sons, Inc.
Grafting of poly(acrylonitrile) onto guar gum using potassium persulfate/ascorbic acid redox initiating system
Authors: Bajpai U. D. N. , Mishra Veena , Rai Sandeep 
Published: April 2003

AbstractThe grafting of poly(acrylonitrile) onto guar gum in aqueous medium initiated by the potassium presulfate/ascorbic acid redox system has been studied gravimetrically at the temperature of 35 + 0.2°C in the presence of atmospheric oxygen. A plausible mechanism of graft copolymerization has been suggested on the basis of experimental results. The effect of grafting on the water and saline retention capacities has been studied and compared with the values obtained for ungrafted guar gum. © 1993 John Wiley & Sons, Inc.
The phase behavior, mechanical, and rheological characteristics of blends containing nitrile polymers and poly(ethylene‐co‐maleic anhydride)
Authors: Percec Simona , Melamud Lucy 
Published: April 2003

AbstractThe phase behavior of binary blends of acrylonitrile/methyl acrylate/butadiene terpolymer (B210) and poly(ethylene‐co‐maleic anhydride) (PEMA) was examined based on thermal analysis and optical microscopy. Miscibility of these polymer blends was recognized over a wide range of compositions. The appearance of phase separation during subsequent heatings above the glass transition temperature (Tg) of these blends was associated with a lower critical solution temperature (LCST) behavior. Rheological characteristics such as shear storage modulus (G′), loss modulus (G″) and complex viscosity have been shown to depend on the amount of PEMA in the blend. Mechanical properties including the tensile strength and flexural modulus also were found to be related to the composition of the blend. © 1993 John Wiley & Sons, Inc.
A study of graft polymerization of methacrylic acid to polycaproamide using a reversible redox system containing CU2+ ions
Authors: Smirnova N. V. , Gabrielyan G. A. , Gal′Braikh L. S. 
Published: April 2003

AbstractGraft polymerization of methacrylic acid to polycaproamide, initiated by the K2S2O8Na2S2O3Cu2+ reversible redox system, has been studied. Kinetic characteristics of graft polymerization have been investigated in a wide concentration range of every component of the initiating system. Cu2+ ions have been found to catalyze graft polymerization in the 1.0 · 10−5−1.2 · 10−4M concentration range, whereas at concentrations higher than 1.2 · 10−4M, Cu2+ ions are involved in the kinetic chain termination. A mechanism of graft polymerization is proposed. © 1993 John Wiley & Sons, Inc.
Analysis of volatiles evolved during high‐temperature treatment of thermally stable polymers. I. Nitrogen‐containing acetylene‐terminated resin
Authors: Mera Ann E. , Walton Theodore R. 
Published: April 2003

AbstractCured samples of a nitrogen‐containing acetylene‐terminated resin, N,N′‐(1,3‐phenylene‐dimethylidene)bis(3‐ethynylaniline), have been heated at 10°C/min up to 900°C in a pyroprobe attached to a gas chromatograph/mass spectrometer (GC/MS). Analysis of the volatiles evolved during heating identified both gases and higher boiling compounds. The major higher boiling compounds are benzene, toluene, xylene, aniline, benzonitrile, m‐methylaniline, and m‐methylbenzonitrile; the gases include ammonia, methane, and traces of carbon dioxide. Correlations between sample temperature and the evolution of each of these compounds have been made. The onset of all volatile formation occurs between 450 and 500°C. The higher boiling volatiles peak, then end by approximately 700°C, while the gases peak then fall off but are still being evolved at 900°C. Average weight loss measurements of 13.6% at 700°C and 15.7% at 900°C agree with previously published thermogravimetric analysis (TGA) data. © 1993 John Wiley & Sons, Inc.
Influence of polyacrylamide on the oxidative decomposition of sodium dithionite: Implications for vat dyeing processes
Authors: Etters J. N. 
Published: April 2003

AbstractA statistical analysis was made of the halftimes of oxidative decomposition of sodium dithionite at 25°C in alkaline aqueous solutions, having geometrically spaced specific surfaces and concentrations of polyacrylamide. The analysis reveals a strong relationship between solution‐specific surface and resulting halftime, with halftime decreasing as specific surface increases; however, only the highest concentration of polyacrylamide, with a correspondingly high solution viscosity, is revealed to have a consistently significant effect on the rate of oxidative decomposition of dithionite. No significant effect on dithionite decomposition is observed for polyacrylamide concentrations that conceivably would be used in commercial vat dyeing processes. The findings suggest that the beneficial effect of high molecular weight polymers such as polyacrylamide in commercial vat dyeing is due solely to the function of the polymer to decrease the specific surface of the dithionite solution on the fabric, leading to decreased decomposition rates. © 1993 John Wiley & Sons, Inc.
Solubility and demixing of polyethylene in supercritical binary fluid mixtures: Carbon dioxide–cyclohexane, carbon dioxide–toluene, carbon dioxide–pentane
Authors: Kiran Erdogan , Zhuang Wenhao , Sen Yasar L. 
Published: April 2003

AbstractSolubility of polyethylene in three different supercritical binary solvent systems—carbon dioxide–cyclohexane, carbon dioxide–toluene, and carbon dioxide–pentane—have been studied. Solvent compositions that lead to complete dissolution at pressures below 70 MPa have been identified. Demixing pressures have been determined for a range of polymer concentrations at temperatures up to 200°C. It is shown that the behavior of the solutions depends strongly on the fluid composition. In the composition ranges studied, solutions in cyclohexane–carbon dioxide mixtures were found to show lower critical solution temperature (LCST) behavior. It is found that the behavior of solutions in carbon dioxide–toluene and carbon dioxide–pentane mixtures shifts from upper critical solution temperature (UCST) to LCST with increasing toluene or pentane content. © 1993 John Wiley & Sons, Inc.
Preparation and permeability of solutes through acrylic acid‐g‐methylcellulose copolymer membranes
Authors: Huh Hoon , Lee Soon Hong , Lee Young Moo , Kim Kea Yong , Kim Jin Il 
Published: April 2003

AbstractGraft copolymer membranes from the methylcellulose and the acrylic acid were prepared and their properties and the permeability of four solutes were estimated. Acrylic acid‐g‐methylcellulose (AA‐g‐MC) copolymer dissolved in aqueous acetone solvent was cast to prepare membranes followed by the subsequent crosslinking either with aluminium potassium sulfate or by the thermal‐curing method. The equilibrium water content in the membrane increased with the volume fraction of acetone in the aqueous acetone solvent system. Membrane, the ionically crosslinked with the aluminum potassium sulfate, showed the water content in the range of 38.5 and 58.4% and 0.25–0.33 kg/mm2 of the tensile strength in the wet state. Compared with ionically crosslinked membranes, thermally dried membranes exhibited a more dense structure, resulting in lower water contents and higher mechanical strength. Experimental results on the permeation of four small and midsize solutes through the graft copolymer membranes revealed the molecular weight dependence of the permeability coefficient. The higher the degree of swelling, the greater the permeability coefficient. Ionically crosslinked membranes had higher solute permeability than the commercial Cuprophane membrane had. © 1993 John Wiley & Sons, Inc.
Inhibition of deterioration of rubbers by hydroaromatics
Authors: Kubo Junichi 
Published: April 2003

AbstractBased on the results obtained from our previous works, which concluded that hydrogen donating hydroaromatics can be available as radical scavengers in inhibiting the deterioration of hydrocarbon products at lower oxygen partial pressure, a hydroaromatic type inhibitor which contains various hydroaromatics as its main components produced from coal tar fraction was examined by adding it to natural rubber (NR) and styrene‐butadiene rubber (SBR). It was found that the inhibitor was as effective as the conventional aminetype inhibitor. From practical viewpoint, heavy hydroaromatics from petroleum (HHAP) was produced by the hydrogenation of the highly aromatic oil from the heavy fraction of petroleum to improve the physical properties of the previous inhibitor from coal tar fraction. From the deterioration tests for NR, SBR, and chloroprene (CR), the following results could be obtained: (1) HHAP showed excellent inhibiting abilities toward NR and CR, exceeding the conventional inhibitor; (2) inhibiting effect toward SBR could be recognized, but it was not so high as the conventional one; (3) physical properties such as Mooney viscosity and flex cracking were improved by the addition of HHAP. From these results, the hydrogen donation from hydroaromatics is considered to be effective in inhibiting the deterioration of rubbers. © 1993 John Wiley & Sons, Inc.
Toughness improvement of an epoxy/anhydride matrix. Influence on processing and fatigue properties of unidirectional glass–fiber composites
Authors: Urbaczewski‐Espuche E. , Gerard J. F. , Pascault J. P. , Reffo G. , Sautereau H. 
Published: April 2003

AbstractWet filament winding processing for unidirectional composites uses specific reactive systems with low viscosity and long‐pot life. This work describes improvement of toughness of an epoxy/anhydride matrix using, first, the increasing of the average molecular weight of the diepoxy prepolymer and, second, the introduction of a functionalized elastomer. Thermomechanical behaviors (glass transition temperature, elasticity, plastic, and fracture properties) are discussed in terms of (1) the increase of the average molecular weight between crosslinks in the first case and(2) the amount of elastomer dissolved in the matrix in the second case. Dynamic mechanical spectroscopy confirms that phase separation occurred, during curing, between the epoxy system and the elastomer. A good correlation is obtained between matrix toughness and fatigue behavior of unidirectional composites. © 1993 John Wiley & Sons, Inc.
Sulfur‐free lignins as composites of polypropylene films
Authors: Košíková B. , Demianová V. , Kačuráková M. 
Published: April 2003

AbstractTo elucidate the effect of lignin addition, polypropylene films containing 2–10 wt % of spruce organosolv lignin and/or beech wood prehydrolysis lignin were compared with lignin‐free polymers with respect to tensile strength and elongation before and after aging. The physicochemical properties of the lignin‐containing films were investigated by conductivity measurements, surface behavior, and UV and IR spectroscopy. © 1993 John Wiley & Sons, Inc.
Evaluation of interfacial adhesion in sheath/core composite fibers
Authors: Tao Weiying , Collier John R. , Collier Billie J. 
Published: April 2003

AbstractRayon/nylon sheath/core composite fibers were produced using a wire coating‐type process. Fumaric acid (FA) was chosen as an adhesion promoter to pretreat the nylon core fiber before rayon coating to improve the adhesion between skin and core. Different FA pretreatment concentrations and times were used and the effects of the pretreatment conditions on the adhesion were evaluated. A fiber pull adhesion test technique was developed to determine the interfacial shear strength of the composite fibers. The results indicated that the interfacial adhesion in the rayon/nylon composite fibers was significantly improved for specific sets of FA application conditions. Adhesion results were confirmed with electron microscopy. © 1993 John Wiley & Sons, Inc.
Morphological effects of ballistic impact on fabrics of highly drawn polyethylene fibers
Authors: Desper C. Richard , Cohen Samuel H. , King Abram O. 
Published: April 2003

AbstractChanges in crystalline structure of high‐tenacity ultra‐high‐molecular‐weight polyethylene fabric brought on by ballistic impact from a small projectile were determined by X‐ray diffractometry. A suitable X‐ray diffraction method that averages out the fiber orientation effects in the diffraction pattern was used. The Spectra 1000™ polyethylene fabrics were successfully characterized in terms of both the predominant orthorhombic and the minor monoclinic crystal content. Crystallinity values for the undamaged fabric are consistent from sample to sample and show an average orthorhombic fraction of 0.61 and an average monoclinic fraction of 0.04. Fabric damage by the projectile impact results in either an increase in monoclinic fraction, attributed to recrystallization at temperatures nearing the normal polyethylene melting point, or disappearance of monoclinic material as that temperature is exceeded. The latter predominates where ballistic penetration is complete. However, actual melting need not be involved: Transformation to the hexagonal (“rotator”) phase and the disappearance of the monoclinic phase could have occurred rather than true melting. © 1993 John Wiley & Sons, Inc.
Effect of steric restrictions on the enhancement of miscibility through hydrogen bonding in blends of modified poly(α‐methyl styrene) with polymers containing acceptor sites
Authors: Cowie J. M. G. , Reilly A. A. N. 
Published: April 2003

AbstractTwo series of copolymers have been prepared from α‐methylstyrene and α‐methylstyrene units modified by the incorporation of the hydrogen‐bond donor units, methyl carbinol and trifluoromethyl carbinol, designated PαMS (I) and PαMS (II), respectively. It has been observed that if the concentration of the donor unit exceeds 4 mol %, one‐phase blends can be prepared with a series of polymers containing hydrogen‐bond acceptor sites such as poly(vinyl acetate), poly(vinyl pyrrolidone), poly(4‐vinyl pyridine), and some poly(alkyl acrylate)s, none of which are miscible with the unmodified PαMS. All the one‐phase blends formed are stable at temperatures above the glass transition temperature, Tg, of the blend, but eventually phase separate when the temperature is increased sufficiently. These lower critical cloud‐point curves have been measured for a wide range of the blends and act as an indicator of the effectiveness of the hydrogen bonds in enhancing one‐phase blend formation. The Tg's of the blends are in many cases higher than those calculated from the simple rule of mixtures and reflect the reduction in chain mobility in the blends caused by extensive hydrogen bonding. The results demonstrate the effect that specific interactions have in enhancing miscibility in binary polymer blends. © 1993 John Wiley & Sons, Inc.
Adhesion properties of glow‐discharge‐plasma‐treated polyethylene surface
Authors: Yu. Kuznetsov A. , Bagryansky V. A. , Petrov A. K. 
Published: April 2003

AbstractA geometric method proposed by Kaelble and Moacanin for analyzing energetic characteristics of solid surfaces is discussed. It is shown that a number of characteristics can be presented in a visual geometric form. The method is applied to the analysis of adhesion in a three‐component system. Results of the analysis, concerned with the problem of creation of biocompatible materials, support the Andrade hypothesis that materials with zero interfacial tension of their water–solid interface show maximum biocompatibility. Data are obtained on wetting of polyethylene by different liquids before and after glow discharge plasma treatment. The analysis of these data in terms of geometric method shows the plasma treatment increased the polar component of the polymer surface energy to change the surface adhesiveness toward probable enhancement of polymer biocompatibility. That is consistent with available data on glow‐discharge‐treatment enhancement of biocompatibility for a number of polymers. © 1993 John Wiley & Sons, Inc.
Flammability and thermal behavior of phosphorus‐containing polyamide‐6
Authors: Mateva Rosa P. , Dencheva Nadya V. 
Published: April 2003

AbstractAn investigation is reported on the flammability and thermal behavior of polyamide‐6, obtained by anionic polymerization of ϵ‐caprolactam, carried out in bulk, in the presence of the following N‐substituted phosphorus‐containing lactam derivatives: diethyl‐(N‐caprolactam)‐phosphonite (PL1), diethyl‐(N‐caprolactam)‐phosphonate (PL2), and 2,5‐dichlorophenyl‐bis(N‐caprolactam)‐phosphinate (PL3). Phosphorus‐containing lactam derivatives PL,1 and PL3 are used as activators of the anionic polymerization of ϵ‐caprolactam, and PL2, as a modifying additive. The phosphorus‐containing polyamide‐6 possesses improved flame retardancy, as well as improved thermo‐ and thermooxidative resistance. Destruction kinetics were studied in nitrogen and air atmospheres, and the activation energy for thermal and thermooxidative destruction have been determined. The effect of PL1 PL2, and PL3 on the melting temperature (Tm) and glass‐transition temperature (Tg) of polyamide‐6 was established. © 1993 John Wiley & Sons, Inc.
The structure of crosslinked poly(glyceryl methacrylate) hydrogel networks
Authors: Leung Billy Kar‐On , Robinson Garth B. 
Published: April 2003

AbstractPoly(glyceryl methacrylate) hydrogels with different degrees of hydration (75–98% H) and cross‐linking densities (X = 0.005–0.05 mol tetraethylene glycol dimethacrylate/mol glyceryl methacrylate) have been prepared by solution polymerization. Cross‐linking densities of the fully swollen hydrogels were analyzed using a modified Flory equation. Poly(glyceryl methacrylate) gels polymerized with no added cross‐linker were found to be highly cross‐linked, the degree of cross‐linking depending upon monomer dilution at polymerization. Modeling studies indicated that entanglement of polymer chains explained the highly cross‐linked nature of these materials. Gels polymerized with tetraethylene glycol dimethacrylate exhibited higher cross‐link densities than did gels polymerized with no added cross‐linker. However, for gels polymerized with cross‐linker, but at different initial dilutions, cross‐linking densities varied depending upon initial concentration, indicating that entanglement contributed appreciably to cross‐linking. These hydrogels may be regarded as highly swollen entangled networks, contrary to previous views. Correlation of these findings with those from earlier studies on the ultrafiltration behavior of the poly(glyceryl methacrylate) hydrogels suggested that the packing density of polymer fibers in the matrix may be more predictive of ultrafiltration behavior than is mesh size. © 1993 John Wiley & Sons, Inc.
The modification of secondary high molecular weight guayule rubber with metachloroperoxybenzoic acid
Authors: Thames S. F. , Poole P. W. 
Published: April 2003

AbstractThe epoxidation of secondary high molecular weight guayule rubber has been accomplished. The reaction is performed using metachloroperoxybenzoic acid as the epoxidation agent in various stoichiometric ratios including 5, 10, 20, and 50 mol %. The products were characterized by infrared spectroscopy, 1H‐ and 13C‐nuclear magnetic resonance (NMR), differential scanning calorimetry, and elemental analysis. 1H‐NMR is used quantitatively to calculate epoxidation levels that are compared to stoichiometry. DSC results record a linear relationship between percent epoxidation and Tg. © 1993 John Wiley & Sons, Inc.
Synthesis and conformational properties of poly(N4‐1‐phenylethyl‐L‐asparagines)
Authors: Chen Yun , Jung Shin‐Shing , Wang Jenn Hwa 
Published: April 2003

AbstractPoly(N4‐1‐phenylethyl‐L‐asparagines) (1a, 1b, and 1c) containing DL‐, (R)‐, and (S)‐ side group chirality were prepared by aminolysis of poly(β‐methyl‐L‐aspartate) (PMLA) with DL‐, (R)‐ (+)‐, and (S)‐ (−)‐1‐phenylethylamine, respectively. The PMLA was synthesized by ring‐opening polymerization of β‐methyl‐L‐aspartate‐N‐carboxy anhydride (NCA) using triethylamine as initiator. The conformations of these polypeptides in the film state were investigated by IR and circular dichroic spectra. The PMLA, 1a, and 1b exist mainly in β‐sheet conformation, while 1c forms α‐helix that is induced by the (S)‐chirality of the side groups. © 1993 John Wiley & Sons, Inc.
Emulsion pathway for gelatin cross‐linking
Authors: Xu G. , Ruckenstein E. 
Published: April 2003

AbstractA new method for gelatin cross‐linking is suggested that starts with the generation of an emulsion between an aqueous solution containing gelatin and a surfactant, and a monomer (MMA) that contains an initiator (AIBN). The emulsion is prepared at 50°C under intense stirring, but is brought, subsequently, to room temperature. There are conditions under which the gellike emulsions thus obtained are transparent and extremely stable at room temperature. A slow cross‐linking reaction occurs in the latter gels that leads to a material that is insoluble in water. The swelling of this material in water, which is very large after 5 days, reduces appreciably after 25 days of reaction. The cross‐linking occurs only when MMA contains the initiator. © 1993 John Wiley & Sons, Inc.