bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biodegradation of nitrate esters. II. Degradation of nitrocellulose by a fungus isolated from a double‐base propellant
Authors: Sharma A. , Sundaram S. T. , Zhang Y.‐Z. , Brodman B. W. 
Published: April 2003

AbstractAn organism found to be growing on moist double‐base propellant, containing nitrocellulose (NC) and nitroglycerine aerobically degraded NC in submerged cultivation. This organism, which was subsequently identified as Penicillium corylophilum Dierckx, was able to degrade the NC (13.17%N) when it was present as the sole nitrogen source, in conjunction with either starch or xylan as a carbon source. It was found that 20% of the NC was utilized in a 3‐day period. Also, NC degradation was studied utilizing Fusarium solani IFO 31093, a denitrifying fungus, in combination with P. corylophilum; however, no increased utilization was observed. Evidence for the degradation includes a decrease in the NC weight, an increase in the biomass weight, the presence of celluloytic and denitrifying enzymes, and other appropriate growth parameters. © 1995 John Wiley & Sons, Inc.
Size‐exclusion chromatography with two‐angle laser light‐scattering (SEC‐TALLS) of high molecular weight and branched polymers
Authors: Mourey Thomas H. , Coll Hans 
Published: April 2003

AbstractThe accuracy and precision of results obtained from light‐scattering detection at two angles (TALLS) for size‐exclusion chromatography (SEC) are examined for linear narrow molecular weight distribution polystyrenes between 1,290,000 and 20,000,000 MW and for branched polyesters. The ratio of light‐scattering intensities at 15° and 90° is used to calculate weight‐average molecular weight, M̄w, and an average root‐mean‐square radius, r̄gu, equivalent to the z‐average radius. A shape for the polymer molecule is assumed and an analytical relationship for the particle‐scattering function is required. It is shown that analysis of the data using the particle‐scattering function for a random coil is valid for both high molecular weight, linear polystyrenes and long‐chain branched polyesters. The radius, r̄gu, is determined with high precision by using the ratio of light‐scattering signals, which is insensitive to errors in sample concentration and changes in the eluent flow rate. The correct average radius for the whole polymer is obtained despite using low‐efficiency, large‐particle diameter SEC columns; however, axial dispersion significantly affects molecular weights and radii calculated at each retention volume that can limit the utility of plots used to deduce polymer conformation. © 1995 John Wiley & Sons, Inc.
Synthesis and characterization of new flame‐retardant polyaryl phosphoramide esters containing furan and thiophene units
Authors: Kannan P. , Umamaheshwari N. , Kishore K. 
Published: April 2003

AbstractTwo series of new flame‐retardant polyaryl phosphoramide esters were synthesized by low‐temperature solution polycondensation from arylphosphorodichlorides with 3,4‐bis(4‐ami‐nophenyl)2,5‐diphenylfuran and 2,5‐bis(4‐aminopheny1)3,4‐diphenylthiophene. The polymers were characterized by IR, 1H, 13C, and 31P NMR spectroscopy and elemental analysis. The thermal stability and flammability were studied by thermogravimetry and limiting oxygen index, respectively. © 1995 John Wiley & Sons, Inc.
Plasma graft polymerization of vinylimidazole onto Kapton film surface for improvement of adhesion between Kapton film and copper
Authors: Inagaki N. , Tasaka S. , Masumoto M. 
Published: April 2003

AbstractKapton film was modified by means of the plasma graft polymerization of vinylimidazole for the improvement of the adhesion with copper metal. Argon plasma exposure generated hydroperoxides at the surface of the Kapton film. Hydroperoxides generated by the argon plasma exposure could initiate the graft polymerization of vinylimidazole. The graft polymerization was restricted at the surface of the Kapton film and never occurred on the inside of the Kapton film. The graft polymer layer was 150–200 nm thick. The surface modification by the plasma graft polymerization of vinylimidazole led to the improvement of adhesion between Kapton film and copper metal. A part of the copper metal made a complex with imino groups in the vinylimidazole chains graft‐polymerized onto Kapton film. The complex is considered to contribute to the improvement of the adhesion. © 1995 John Wiley & Sons, Inc.
Effects of chemical structure of hardener on curing evolution and on the dynamic mechanical behavior of epoxy resins
Authors: De Nograro F. F. , Guerrero P. , Corcuera M. A. , Mondragon I. 
Published: April 2003

AbstractA diglycidyl ether of bisphenol‐A‐type difunctional epoxy resin was cured with different amine‐type curing agents at stoichiometric ratios. The crosslink process was followed by viscosimetry and differential scanning calorimetry. The gelation time and the apparent activation energy were found to be strongly dependent on the structure of the hardener. The heat of reaction did not vary significantly when the hardener was changed. An interpretation based on structural aspects such as amine reactivity, steric hindrance, and chain rigidity is proposed for the variations corresponding to the curing process. Master viscosity curves have been built up for all mixtures. The effect of the hardener on the glass transition temperatures of the different mixtures has been analyzed taking into account the crosslink density, measured by the rubber modulus obtained by dynamic mechanical studies, and the chemical structure of the hardener chains. © 1995 John Wiley & Sons, Inc.
Number‐average molecular weight and functionality of poly(tetramethylene glycol) by multidetector SEC
Authors: Harrison Catherine A. , Mourey Thomas H. 
Published: April 2003

AbstractMultidetector size exclusion chromatography (SEC) is used to simultaneously determine molecular weight and number of reactive end groups per chain (functionality) of poly(tetramethylene glycol)s. Hydroxyl groups are first quantitatively derivatized with phenyl isocyanate, providing an end‐group‐selective UV‐absorbing tag. The number of end groups per chain is then determined from the SEC chromatogram using a UV detector. Molecular weight at each retention volume and the number‐average molecular weight of the whole polymer are calculated by four methods involving (1) a concentration detector and a narrow standard log M calibration curve, (2) the UV detector and a narrow standard log M calibration, (3) a viscometry detector and a universal calibration curve, and (4) combined differential viscometry and concentration detectors using a universal calibration curve. The multidetector experiment provides a unique opportunity to assess the accuracy and limitations of each approach on low‐molecular‐weight polymers. In particular, the effect of end groups on the concentration detector response and the application of universal calibration principles at small molecular sizes are important factors. It is shown that the concentration response can be corrected by a simple relationship between detector response and reciprocal molecular weight. Also, the quality of calibration curves is critical to the calculation of accurate molecular weight. In general, log M calibration curves provide superior results to universal calibration methods. © 1995 John Wiley & Sons, Inc.
Desorption of free radicals in semibatch emulsion polymerization of methyl acrylate
Authors: Chern C. S. 
Published: April 2003

AbstractDesorption of free radicals from particles can cause an emulsion polymerization system to deviate from Smith–Ewart case II kinetics. A mechanistic model has been developed to predict the effect of desorption of radicals from particles on the kinetics of semibatch emulsion polymerization of methyl acrylate under the monomer‐starved condition. Experimental data available in the literature are used to assess the proposed kinetic model. The model predicts the experimental data reasonably well for a wide range of monomer feed rates. The rate of polymerization increases with an increase in the rate of monomer addition. The kinetic data are also useful in evaluating the desorption rate constant (K′d) for methyl acrylate. The best fitted value of K′d at 50°C is 4 × 10‐12 cm2/s, which is in good agreement with the theoretical values predicted by desorption theory. © 1995 John Wiley & Sons, Inc.
Novel polyurethane–silicone hydrogels
Authors: Lai Yu‐Chin 
Published: April 2003

AbstractPolyurethane hydrogels derived from polysiloxane‐based ultraviolet‐curable polyurethane prepolymers and hydrophilic monomers were prepared and their properties were evaluated. The polyurethane prepolymers used in this study contained different arrangements of hard and soft segments and were derived from isophorone diisocyanate, neopentyl glycol, diethylene glycol, 1,4‐butanediol, hydroxy‐terminated polydimethylsiloxane, and 2‐hydroxyethyl methacrylates. The hydrophilic monomers used were 2‐hydroxyethyl methacrylate and N,N‐dimethyl acrylamide. All compositions can be cured under ultraviolet (UV) and form hydrogels after hydration. The oxygen permeabilities of the hydrogels are much higher than those of nonsilicone hydrogels and decreased as the water contents increased. The tear strengths and moduli decreased as the water contents of the hydrogels increased. All hydrogels prepared showed good hydrolytic stability and did not absorb lysozyme. © 1995 John Wiley & Sons, Inc.
Application of dielectric spectroscopy and DSC to the study of relaxations in some copolymeric hydrogels
Authors: Ahmad Mansor Bin , O'Mahony John P. , Huglin Malcolm B. , Davis Thomas P. , Ricciardone Adam G. 
Published: April 2003

AbstractThe nature of water in copolymeric N‐vinyl pyrrolidone/methyl methacrylate hydrogels has been investigated using dielectric thermal analysis (DETA) and differential scanning calorimetry (DSC). Dielectric tan δ measurements are reported over a frequency range 500 Hz‐20 kHz and a temperature range of −140 to +20°C. The observed complex relaxations were attributed to the mobility of water and the relaxation processes of the copolymer matrix. In addition DSC was used to measure the melting endotherm of water in gels partially swollen to a pseudoequilibrium. The resultant data were fitted to a two‐phase approximation model. © 1995 John Wiley & Sons, Inc.
Gel formation in free‐radical crosslinking copolymerization
Authors: Naghash Hamid J. , Okay Oǧuz , Yildirim Hüseyin 
Published: April 2003

AbstractPolymer gels with varying amounts of crosslinker and solvent were prepared by solution free‐radical crosslinking copolymerization of methyl methacrylate/ethylene glycol dimethacrylate (MMA/EGDM) and styrene/p‐divinyl benzene (S/p‐DVB) comonomer systems. The structural characteristics of the gels were examined using equilibrium swelling in toluene and gel fraction measurements. Experimental results were compared with the predictions of a kinetic model developed recently for free‐radical crosslinking copolymerizations. Experimental data on S/EGDM networks reported by Hild, Okasha, and Rempp were also used to test this model. It was found that the model correctly predicts the development of the gel properties in free‐radical crosslinking copolymerization. © 1995 John Wiley & Sons, Inc.
Dissolving poly(tetrafluoroethylene) in low boiling halocarbons
Authors: Tuminello William H. , Brill Donald J. , Walsh David J. , Paulaitis Michael E. 
Published: April 2003

AbstractAn apparatus and methodology are described for dissolving poly(tetrafluoroethylene) in relatively low boiling perhalocarbons at temperatures as high as 330°C and up to about 20 MPa pressure. Cloud points are reported for these solutions with the following solvents: n‐perfluorohexane, perfluorodecalin, Freon® 113 (1,1,2‐trichloro‐1,2,2‐trifluoroethane) and Fluorinert® FC‐75 (a perfluorocarbon ether). Most of the solutions were studied above the critical temperatures of their solvents. © 1995 John Wiley & Sons, Inc.
Novel polymeric alcohols by controlled catalytic polymer functionalization
Authors: McGrath Martin P. , Sall Erik D. , Forster Denis , Tremont Samuel J. , Sendijarevic A. , Sendijarevic V. , Primer D. , Jiang J. , Iyer K. , Klempner D. , Frisch K. C. 
Published: April 2003

AbstractNovel EPDM (ethylenepropylenediene monomer) and polybutadiene polyols can be synthesized by a two‐step process of controlled hydroformylation and then reduction of the formyl groups to place a desired amount of pendant alcohol groups along the polymer chain. The degree of functionalization can be controlled by measuring gas uptake from a calibrated reservoir during hydroformylation. Hydroformylation can be performed in solution or under simulated melt‐phase conditions using either HRh(CO)(PPh3)3 or Rh(acac) (CO)2 as catalysts. Reduction of the polyaldehyde by NaBH4 generates the polymeric alcohol without further reaction of the remaining double bonds. Polymer functionalization and further modifications were followed by H‐NMR and FTIR. These unique hydrophobic polyols can be reacted further to produce other polymer systems. As an example, urethanes have been made with these polyols by reaction with diisocyanates. © 1995 John Wiley & Sons, Inc.
Catalyst–accelerator method for the preparation of wood–polymer composites at ambient temperature
Authors: Elvy Shane B. , Dennis Gary R. , Ng Loo‐Teck 
Published: April 2003

AbstractWood–polymer composites (WPC) are materials which may be prepared by impregnating wood with a variety of monomers which are subsequently polymerized by either gamma irradiation or by conventional radical initiators. The inclusion of the polymer into the wood matrix improves the physical properties of the composite compared to plain wood. The catalyst–accelerator method allows in situ polymerization of vinyl monomers at ambient conditions and thus reduces the loss of the volatile monomer during curing, which is a major disadvantage of the heat–catalyst method. The combination of peroxide initiators with an aromatic amine accelerator was optimized for the methyl methacrylate system. Polymer loadings and mechanical properties of WPC prepared from Pinus radiata using the catalyst–accelerator method were compared with those obtained using the gammaradiation method. © 1995 John Wiley & Sons, Inc.
Conversion of plastic/cellulose waste into composites. I. Model of the interphase
Authors: Hedenberg Peter , Gatenholm Paul 
Published: April 2003

AbstractThis article proposes a mechanism for a significant improvement in the mechanical performance of a simulated waste fraction, composed of an immiscible low‐density polyethylene (LDPE) and high‐impact polystyrene (HIPS) blend (70:30 proportion), when chemithermomechanical pulp (CTMP) fibers and maleic acid anhydride grafted styrene–ethylene/butylene–styrene block copolymer (MAH‐SEBS) were added. SEM micrographs of composites showed an increased contact between the continuous LDPE phase and CTMP fibers when the functionalized compatibilizer (MAH‐SEBS) was used. By employing a model study using LDPE and regenerated cellulose, we investigated the interphase properties between the plastic phase and the cellulosic component. The model study utilized ESCA, FTIR, and contact angle analysis to follow the reaction between the cellulose surface and the functionalized compatibilizer. All three methods showed that MAH‐SEBS was bonded to the surface of the cellulose. The single‐fiber fragmentation test showed that the adhesion between cellulose fibers and the plastic matrix was significantly improved for MAH‐SEBS–modified samples. The effect of enhanced adhesion on increased mechanical properties of cellulose composites is also discussed, and a prediction of composite strength given, based on interfacial adhesion promotion and fiber properties. © 1995 John Wiley & Sons, Inc.
Effect of addition of saccharose on gelation of aqueous poly(vinyl alcohol) solutions
Authors: Yamaura Kazuo , Mitsuishi Masami , Fukuda Mari , Tanigami Tetsuya , Hoei Yoshio , Matsuzawa Shuiji 
Published: April 2003

AbstractThe properties of poly(vinyl alcohol) (PVA) hydrogels containing saccharose were examined. The effect of the addition of saccharose to atactic PVA (α‐PVA) gels on their melting temperatures was larger than that for syndiotacticity‐rich PVA (s‐PVA) gels and the melting temperature was above 100°C for α‐PVA gels with saccharose contents of 60 wt %. However, the fusion enthalpy (ΔH) of the α‐PVA gels was at most 100 kJ/mol. The release of solvent (water/saccharose) from gels in air decreased with an increase in the saccharose content and the equilibrium was achieved after standing for 20 days for the α‐PVA and s‐PVA gels with saccharose contents above 40 and 20 wt %, respectively. © 1995 John Wiley & Sons, Inc.
Characterization of Nafion solutions and films and observation of the casting process using basic dyes as optical probes
Authors: Otsuki Soichi , Adachi Kimihiro 
Published: April 2003

AbstractThe absorption spectrum of methylene blue and crystal violet (CV) in ethanol–water in the presence of Nafion exhibited metachromasy, but a little or no formation of the large aggregates of the dye was observed. This indicates that the dye molecules are bound to the surface of the miceller particles of the polymer, but the ability of Nafion to induce the aggregation of the dye is weak. The absorption spectrum of malachite green (MG) and CV was measured in a cast film of Nafion at varying ambient humidity. The spectral change with humidity indicates that the decrease in the water content of the film causes the increase of H+‐ion concentration in the hydrophilic cluster of Nafion and, hence, leads to the protonation of the dyes. The absorption spectrum of a Nafion solution containing MG or CV was recorded in the process of casting. The dyes changed to the protonated form right after evaporation of most solvent from the solution. This suggests that the phase inversion occurs in the casting process. © 1995 John Wiley & Sons, Inc.
Thermal degradation of aliphatic–aromatic polyamides: Kinetics ofN,N′‐Dihexylisophthalamide neat and in presence of copper lodide
Authors: Broadbelt Linda J. , Klein Michael T. , Dean Barry D. , Andrews Stephen M. 
Published: April 2003

AbstractAn experimental study to determine the effect of copper (I) iodide (Cul) on the rate and product distribution of degradation of a model of an aliphatic–aromatic polyamide was carried out.N,N′‐Dihexylisophthalamide (DHI) was reacted in both an inert argon atmosphere and a pure oxygen environment at 350°C with CuI added in amounts ranging from 0 to 20% by weight. The rate of disappearance of DHI was enhanced by an order of magnitude when 0.5% by weight of CuI was added and was an increasing function of increasing CuI loading. Reaction in pure O2increased the rate of DHI degradation by two orders of magnitude over that for neat DHI pyrolysis. The rate of disappearance of DHI in O2was relatively unchanged when 5% CuI by weight was added. The transformations of DHI and its products are organized in terms of a set of reaction rules. This “reaction operator” formalism allowed computer generation of the reaction network and facilitated estimation of kinetic parameters. © 1995 John Wiley & Sons, Inc.
A paradoxical flame‐retardant effect of nitrates in ATH‐filled ethylene–vinyl acetate copolymer
Authors: Zhu Weiming , Weil Edward D. 
Published: April 2003

AbstractIn the course of a study of metal salts as flame retardants, it was surprisingly found that metal nitrates reduced the flammability of ATH‐filled ethylene–vinyl acetate copolymer (EVA). The limiting oxygen index (LOI) of ATH‐filled EVA was increased by the nitrates in the order of Cu(NO3)2·3H2O > (NH4)2Ce(NO3)6 > Zn(NO3)2·6H2O > Fe(NO3)3·9H2O > Al(NO3)3·9H2O > NaNO3. The effects were not caused by the water of hydration. All metal nitrates except NaNO3 reached a UL 94 V‐2 rating at 3 phr. Based on TGA, DSC, FTIR, and gas detection, the proposed mechanism of the flame‐retardant effect of nitrates is the oxidative degradation of the polymer to produce noncombustible products (CO2 and nitrogen oxides) at a rate sufficient to interfere with the normal combustion process despite the exothermicity of the oxidative degradation. It is possible that surface carboxylic acid structures also contribute to the flame‐retardant effect. © 1995 John Wiley & Sons, Inc.
Interfacial adhesion in polyethylene–kaolin composites: Improvement by maleic anhydride‐grafted polyethylene
Authors: Hindryckx F. , Dubois Ph. , Patin M. , Jérôme R. , Teyssié Ph. , Marti M. Garcia 
Published: April 2003

AbstractPolyethylene–kaolin composites were investigated with a special emphasis on the control of the interfacial adhesion. Both matrix and filler were modified for this purpose. A stearic acid and maleic anhydride‐grafted polyethylene were used as potential interfacial agents and the efficiency of aminosilane‐surface‐treated kaolin was considered. Tensile strength, elongation, impact strength, and melt index were currently measured in relation to the processing conditions. Enhanced interfacial filler‐polymer adhesion progressively results in an decreased melt index. This has been clearly shown by comparing the effect of two polymeric additives to the polymer matrix, i.e., a maleic anhydride‐grafted HDPE (MAGPE) and an unmodified HDPE of a similar melt index. Compared to low molecular weight additives, such as stearic acid and aminosilane, MAGPE has proved to be a very efficient additive in improving the impact resistance of HDPE–kaolin composites even at low contents. © 1995 John Wiley & Sons, Inc.
Properties of henequen cellulosic fibers
Authors: Aguilar‐Vega Manuel , Cruz‐Ramos Carlos A. 
Published: April 2003

AbstractThe physical properties, thermal stability, and interaction with liquids of cellulosic fibers isolated from henequen fibers (Agave fourcroydes) by an alkaline digestion process were determined. Physical dimensions, apparent length, and diameter of henequen cellulosic fibers were determined by optical microscopy in a random sample of 125 fibers. Other properties such as crystallinity, specific gravity, and cellulose type were also determined. The sorption of several liquids in these cellulosic fibers was measured and correlated to the polar and hydrogen bonding components of the solubility parameters of the liquids. The results show that, in general, henequen cellulosic fibers have properties that are in close agreement with those found in other cellulosic materials from natural sources. © 1995 John Wiley & Sons, Inc.
β‐nucleators and β‐crystalline form of isotactic polypropylene
Authors: Huang Mei‐Rong , Li Xin‐Gui , Fang Bo‐Rong 
Published: April 2003

AbstractDifferent levels of β‐form crystallinity in isotactic polypropylene (iPP) were produced by blending a series of additives. X‐ray diffraction analyses showed that the Kx values varied from 0 to 0.05. Indigosol Brown IRRD, Indigosol Red Violet IRH, Cibantine Orange HR, Indigosol Pink IR, Cibantine Blue 2B, Indigosol Golden Yellow IGK, and Indigosol Grey IBL were found to be effective β‐nucleators. The respective Kx values of the iPP samples containing the above seven β‐nucleators of 0.05 wt % are 0.54, 0.68, 0.82, 0.82, 0.86, 0.92, and 0.95. All the β‐nucleators possess fused benzene rings or heterocycles in their molecular structures. X‐ray diffraction studies on them revealed a mutual character in that the strongest or the second‐strongest reflections almost locate at the d‐spacing of 2.83 Å. The magnitude is about half of that of the β‐spherulites possess a bright color and that their Maltese Crosses display some concentric banding of a rather spiky, jagged character. Their lamellae exhibit a correlated and dendritic structure seen by a scanning electron microscope. © 1995 John Wiley & Sons, Inc.