bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ion cyclotron resonance mass spectrometric study of ion—molecule reactions in toluene—pyridine mixtures
Authors: Katritzky Alan R. , Dega‐Szafran Zofia , Ramanathan Ragulan , Eyler John R. 
Published: May 2005

AbstractIon—molecule reactions in toluene, toluene‐d8, pyridine, 4‐methyl‐, 4‐ethyl‐ and 4‐terr‐butylpyridine and quinoline and their mixtures were studied by ICR mass spectrometry at 10‐7 Torr (1 Torr = 133.3 Pa). The reactions of benzyl (m/z 91), benzyl‐d7 (m/z 98), methylbenzyl (m/z 105), and azabenzyl (m/z 92) ions with pyridines and quinoline were observed. The reactions of protonated pyridines with unprotonated molecules leading to homoconjugated ions (BHB)+ were detected.
Efficiency of collision‐induced ionization of fast neutrals: Effects of neutral internal energy and neutral translational energy
Authors: Harnish David , Holmes John L. 
Published: May 2005

AbstractThe ionization efficiencies of fast beams of CO and C2H4, with oxygen as target gas were shown to increase with increasing translational energy and to decrease with increase in internal energy. The latter may arise from a greater probability of homolysis in the neutral projectile species; it is not likely to arise from increased ionization of the target. Experimental parameters (and their validity) relating to the measurement of collision‐induced dissociative ionization mass spectra and which are also applicable to the reionization step in neutralization—reionization mass spectra were investigated.
Mechanism of stereospecific alcohol elimination from cyclohexane trans‐1,3‐dicarboxylates under electron impact ionization
Authors: Etinger A. , Idina A. , Mandelbaum A. 
Published: May 2005

AbstractDiesters of cyclohexane trans‐1,3‐dicarboxylic acid give rise to major [M  ROH]+·. ions under electron impact ionization. A mass spectral study of the isomeric mixed methyl ethyl esters of the diacid, substituted by a methyl group at position 1 and deuterium labelled at position 3, indicates a stepwise mechanism for this alcohol elimination; the 3‐hydrogen (or deuterium) is transferred to the carbonyl of the 1‐ester group in the initial step. Subsequent migration of that hydrogen (or deuterium) to the alkoxyl of position 3 results in the highly site‐ and stereospecific alcohol elimination. CID spectra of the [M  ROH]+. ions obtained from the stereoisomeric diesters clearly show that they have different structures (or are different mixtures of structures).
Fragmentation of collisionally activated hydroxyphenoxide anions in the gas phase
Authors: Binkley Roger W. , Dillow Glen W. , Flechtner Thomas W. , Winnik Witold , Tevesz Michael J. S. 
Published: May 2005

AbstractLow‐energy collisionally activated dissociation of O‐deprotonated dihydroxybenzenes (catechol, resorcinol, hydroquinone) in the gas phase causes both fragmentation to form [C6H4O2]– ions by loss of the remaining oxygen‐bound hydrogen atom and intramolecular hydrogen atom migration from O to C. The rearranged anions then undergo ring‐cleavage reactions which are different in each case. Both catechol and hydroquinone produce fragments which are the result of the loss of two carbon atoms and both oxygen atoms but the proposed mechanisms are different. Resorcinol also produces a fragment which derives from the loss of carbon dioxide. For this process a mechanism is proposed which involves a 6‐methylpyranone anion intermediate.
Curie‐point pyrolysis gas chromatography/mass spectrometry in the identification of paint media
Authors: Carbini Massimo , Volpin Stefano , Traldi Pietro 
Published: May 2005

AbstractCurie‐point pyrolysis gas chromatography/mass spectrometry has been applied to different model paint samples containing proteinaceous (egg yolk) and oily (linseed oil) media. Results of pyrolysis at 610°C are highly reproducible, and among the different pyrolysis products some compounds diagnostic for the different binders have been identified. The application of the method to real samples, i.e. from the oil painting ‘Ritratto’ by Giuseppe Nogari (1669–1763) and from the tempera paint on the ligneous roof of S. Giobbe church (16th century) in Venice, proves its effectiveness in the identification of binding media.
Formation of nanocomposites of styrene and its copolymers using graphite as the nanomaterial
Authors: Uhl Fawn M. , Yao Qiang , Wilkie Charles A. 
Published: May 2005

AbstractGraphite‐polymer nanocomposites were prepared by melt blending of various graphites (virgin graphite, expandable graphites, and expanded graphite) with polystyrene and its copolymers (acrylonitrile‐butadiene‐styrene (ABS) and high‐impact polystyrene (HIPS)). Nanocomposites were characterized by X‐ray diffraction, cone calorimetry, thermogravimetric analysis and evaluation of mechanical properties. Nanocomposite formation occurs at higher loadings (3–5%) of expandable graphites but not for virgin or expanded graphite. Copyright © 2005 John Wiley & Sons, Ltd.
Fire retardancy of polyethylene‐alumina trihydrate containing clay as a synergist
Authors: Zhang Jinguo , Wilkie Charles A. 
Published: May 2005

AbstractThe fire behavior of polyethylene combined with alumina trihydrate (ATH) and an oligomerically‐modified clay has been studied. The combination of polyethylene with 2.5% inorganic clay and 20% ATH gives a 73% reduction in the peak heat release rate (PHRR), which is the same as that obtained when 40% ATH is used alone. A further increase in the clay loading does not improve the fire properties. Mechanical properties, such as elongation at break, can be improved in comparing compounds with or without clay at the same reduction in PHRR. The oligomerically‐modified clay can also facilitate the melt blending process. Copyright © 2005 John Wiley & Sons, Ltd.
Model compound studies on the amine cure of epoxy resins
Authors: Byrne Catherine A. , Hagnauer Gary L. , Schneider Nathan S. , Lenz Robert W. 
Published: May 2005

AbstractMonoepoxy phenyl glycidyl ether, curing agent p‐chloroaniline, and the substituted urea type accelerator Monuron were used as a model system for studying the amine cure of epoxies. Reactions were carried out at 120°C with amine to epoxy equivalent rations of 0.25 and 1.0 Reaction mixtures were analyzed primarily by reverse phase high performance liquid chromatography. Three types of reactions occur; simple amine addition to epoxy, homopolymerization of epoxy, and epoxy polymerization involving the addition products. In the absence of accelerator the reaction involved simple addition. With the accelerator, there was competition between addition and polymerization, the balance depending on the amine to epoxy equivalent ratio. Both addition and polymerization were important for a ratio of 1, but polymerization far outweighed addition for a ratio of 0.25.
Fatigue characteristics of high glass content sheet molding compound (SMC) materials
Authors: Mallick P. K. 
Published: May 2005

AbstractStatic and fatigue properties of high glass content sheet molding compound (SMC) materials were studied at various temperatures. It was shown that the matrix plays an important role in both fatigue characteristics and failure mechanism of such randomly oriented short fiber composites. Specifically, vinyl ester matrix shows better fatigue properties and post‐fatigue performance than the polyester system considered here.
Strength improvement of short graphite fiber‐reinforced polypropylene
Authors: Weiss R. A. 
Published: May 2005

AbstractThe Improvement of the tensile strength of discontinuous graphite fiber‐reinforced polypropylene is described. Two methods were employed: (1) modification of the polymer backbone by the introduction of acrylic acid grafts and (2) varying the chemistry of the fiber sizing. The strength improvements attained are attributed to intermolecular interactions, such as hydrogen bonding, which improve the adhesion between the fiber and the polymer.
Fatigue crack growth and fracture in glass sphere‐filled nylon 6
Authors: Friedrich K. , Karsch U. A. 
Published: May 2005

AbstractThe common degrading effect of glass beads on the static fracture energy and the fatigue crack propagation response in nylon 6 materials is examined by conducting fracture mechanics tests and by considering the progress of cracks through the composites. The scanning electron micrographs indicate that the cracks travel through regions of polymer matrix and also along the interfaces between polymer and glass beads. It is demonstrated that, although fracture of the polymer regions requires considerable energy, cracking of the interfaces usually absorbs very little. Thus, the crack propagation is preferably concentrated on these microstructural regions, which is the cause of the decrease in fracture energy and increase in fatigue crack growth rate with increasing amount of glass spheres in the composite. Partial properties of the matrix and the interface are introduced in order to describe the fracture behavior and to improve the understanding of the gross fracture processes. The combination of these partial properties with the volume fraction of filler and certain geometrical factors by a modified rule of mixture leads to critical values for the failure of the composites, which are in reasonable accord with the measured fatigue and fracture data.
Tribological properties of polyesterimide and its composites
Authors: Ghosh U. K. , Jagga C. R. , Maiti S. , Vasudevan P. 
Published: May 2005

AbstractPolyesterimide (PEI) and phenol formaldehyde (PF) samples were synthesized, and composites of the two polymers, as well as composites with carbon, were prepared. Using a pinon‐disc machine, the friction and wear properties of the following samples were studied in the load range of two to eight bars:
Phenolformaldehyde vs. steel
Phenol formaldehyde cured with hexamethylenetetramine vs. steel
Polyesterimide vs steel
Polyesterimide and carbon composite vs steel
Phenol formaldehyde vs polyesterimide
Phenol formaldehyde and polyesterimide composite vs. phenol formaldehyde
Phenol formaldehyde and polyesterimide composite vs. steel.

The data obtained from these experiments were compared with literature data on poly(tetrafluoroethylene) and nylon, conventionally used for tribological applications. It is seen that, in terms of thermal stability, friction, and wear, PEI and PF are promising for tribological applications.
The extrusion and performance of plasticized poly(vinyl chloride) hose reinforced with short cellulose fibers
Authors: Goettler Lloyd A. 
Published: May 2005

AbstractShort fibers of natural cellulose treated to provide dispersability and strong interfacial bonding are ideal reinforcements for plasticized vinyl compounds. The development of substantial strength and stiffness in unidirectional composites indicates the reinforcing potential of these high aspect‐ratio fibers in soft compositions. Special extrusion dies developed to control fiber directionality in rubber extrudates are equally applicable to vinyl hose. The unusual expanding geometry of these tools aligns the fibers toward the circumferential direction to provide optimum reinforcement against contained pressure loading. Thus, reinforced poly(vinyl chloride) air and water hoses can be produced in a single extrusion step, since all of the necessary reinforcement is contained in the compound.
Stress relaxation properties of some reaction injection molded (RIM) and reinforced RIM systems
Authors: Turner R. B. 
Published: May 2005

AbstractThis study examined the stress relaxation properties of six urethane reaction injection molded (RIM) systems, both reinforced and non‐reinforced RIM systems from room temperature to 100°C. Data is presented which shows the dynamic mechanical (DMS), differential scanning calorimetry (DSC), physical properties, and stress relaxation data. The major conclusion from this work is that the state of hard segment (amorphous or crystalline) makes a vast difference in the polymer's reaction to stress.
Mechanical properties and morphology of polypropylene composites. Talc‐filled, elastomer‐modified polypropylene
Authors: Stamhuis J. E. 
Published: May 2005

AbstractThe balance of impact strength and rigidity of polypropylene can be significantly improved by physical blending of the polypropylene with a talc filler and a variety of elastomer types. Unsaturated elastomers were found to be effective impact strength improvers in 70/15/15 percent PP/elastomer/talc composites, whereas saturated elastomers gave rise to a high stiffness of such compounds. This is attributed primarily to different tendencies of the elastomers to coat the filler surface. Studies on a wider range of compositions, using a butadienestyrene‐butadiene (SBS) block copolymer and a ethylene‐propylene‐diene (EPDM) terpolymer as representatives of the two elastomer classes, indicated that at high stiffness levels (flexural modulus > 1.6 GN/m2), the composites with SBS show the best balance of properties, whereas at higher impact levels EPDM leads to a higher rigidity and impact strength. On the basis of morphological studies such differences can be explained qualitatively, in spite of the complex structure of these composites.
Influence of glass fiber content on the morphology and mechanical properties in injection molded polypropylene composites
Authors: Xavier S. F. , Misra A. 
Published: May 2005

AbstractPropropylene was reinforced with various concentrations of glass fiber (0, 10, 20, 28, and 35 percent by weight) and standard test samples were prepared by injection molding under identical conditions. The influence of fiber concentration on the morphology and mechanical properties was investigated using polarizing microscope, scanning electron microscope, Instron universal testing machine, etc. Tensile strength, tensile modulus, and flexural strength were found to increase with glass fiber content, while impact strength was reduced. These observed changes in mechanical properties were explained in terms of alterations in skin‐core morphology, spherulite size, transcrystallinity, etc. The efficiency of reinforcement factor (K) was calculated for all the composites. It was found that K decreases with the increase of fiber concentration. This study attempts to correlate fiber concentration and polymer morphology with mechanical properties and the overall efficiency of reinforcement. This would help in optimizing the fiber content to prepare molded composites with desired mechanical properties.
Solid state extrusion of semicrystalline polymers
Authors: Krjutchkov A. N. , Dorfman I. Y. , Prut E. V. , Enikolopyan N. S. 
Published: May 2005

AbstractThe dynamics of solid state extrusion of polypropylene, high density polyethylene, and poly(tetrafluorethylene) have been investigated at various extrusion temperatures and piston velocities. A model of solid state extrusion of semicrystalline polymers is proposed. The formulae are obtained relating the value of the extrusion pressure with the parameters of the process and polymer properties. It has been found that for certain values of the parameters, defects of two main types emerge. A mechanism of defect formation is suggested.
Engineering analysis of reaction injection molding process of epoxy resin
Authors: Kim Do Hyun , Kim Sung Chul 
Published: May 2005

AbstractAn engineering analysis of reaction injection molding (RIM) process of epoxy resin was carried out through numerical simulation and actual experiment. In order to simulate the RIM process, and reaction kinetics and the viscosity function of the epoxy system were obtained from thermal analysis and rheological measurement, and the balance equations of the chemical species, momentum, and energy within a mold cavity were set up in cylindrical coordinates. As the result of the simulation, the temperature and conversion profiles within a disc type mold were obtained and a moldability analysis was made to find the optimum molding conditions. The temperature change during the curing reaction, at a fixed point within the mold cavity, was measured through the actual RIM experiment on a small scale, and was compared with the simulated results.
Characterization of thermoset cure behavior by differential scanning calorimetry. Part II: Effects of low‐profile additives
Authors: Lam P. W. K. 
Published: May 2005

AbstractAn autocatalyzed second‐order kinetic model was adopted to compare the isothermal and dynamic cure behavior of low‐profile polyester resins in terms of kinetic parameters such as degree of cure, cure rate, half‐life, onset cure temperature, reaction order, and Arrhenius parameters. The reaction orders of low‐profile unsaturated polyesters appear to be almost independent of isothermal cure temperatures. The ultimate conversion, conversion at peak maximum, onset cure temperature, and Arrhenius parameters of polyesters are only slightly affected by the concentration and type of low‐profile additives in the resins. Low‐profile additives, in general, tend to retard the cure rate and suppress the exothermicity of polyester resins because of dilution effects. For low‐profile additives such as poly(vinyl acetate) and polyurethane, which are “quite” compatible with polyesters before cure, the overall reaction rates of the resins are substantially enhanced over those of less compatible additives. However, the ultimate conversion of low‐profile polyesters is found to be slightly greater than that of neat polyester, in most cases.
Thermal properties of nickel powder filled polypropylene composites
Authors: Maiti S. N. , Mahapatro P. K. 
Published: May 2005

AbstractThe thermal properties of nickel powder filled polypropylene composites were measured over a range of filler concentrations. The thermal conductivities increased with filler concentration. Data were compared with predictions by theoretical models for two phase systems. The equation of Cheng‐Vachon gave reasonable agreement with measurements. A TGA (thermogravimetric) study of the composites showed that the presence of nickel powder increases the thermal stability of polymer through an increase in activation energy to a maximum at a critical filler concentration, beyond which the stability decreased. The Vicat softening point of the composites was also increased in the presence of Ni powder.
Assessment of fiber arrangement and contiguity in composite materials by image analysis
Authors: Wimolkiatisak Angel S. , Bell James P. , Scola Daniel A. , Chang Jemei 
Published: May 2005

AbstractThe overall objective of this research was to correlate the processing—fiber arrangement—properties relationships of composites. In order to do this, an experimental technique to quantitatively characterize the fiber arrangement was developed. Using this technique, the compression molded graphite/epoxy composites, CMC, were found to have a standard deviation of fiber spacing of about twice the value of those from the simulated random composites, SRC. The standard deviation of fiber volume fraction for CMC was about 4 times the value of SRC. In other words, the fibers in this laboratory CMC were poorly distributed relative to SRC.
Friction and wear behavior of graphite fiber‐reinforced composites
Authors: Shim Hyun H. , Kwon Oh K. , Youn Jae R. 
Published: May 2005

AbstractFriction and wear behavior of continuous graphite fiber composites was studied for different fiber orientations against the sliding direction. The effect of fiber orientation on friction and wear of the composite and on deformation of the counterface was investigated experimentally. A pin on disk type testing machine was built and employed to generate friction and wear data. A graphite fiber composite plate was produced by the bleeder ply molding in an autoclave and machined into rectangular pin specimens with specific fiber orientations, i.e., normal, transverse, and longitudinal directions. Three different wear conditions were employed for two different periods of time, 24 and 48 hours. The wear track of the worn specimens and the metal counterface was examined and a scanning electron microscope (SEM) to observe the damaged fibers on the sliding surface of the specimen and wear film generation on the counterface. A wear mechanism of the continuous graphite fiber composite during sliding wear is proposed based on the experimental results.
A method for studying damage in a fiber reinforced thermoplastic by masking viscoelastic effects
Authors: Tonda R. D. 
Published: May 2005

AbstractA technique and some preliminary results of a study of the damage state of a long fiber reinforced thermoplastic composite are presented, emphasizing the difficulty encountered when the matrix material contributes significant viscoelastic effects to the material response. The type and origin of these effects are reviewed, as is the theory that has been developed allowing for removal of the superimposed viscoelastic effects. It is demonstrated that the complicating effect of the superimposed viscoelasticity can be successfully removed, thereby providing a less confusing presentation of the data and offering the potential for greatly simplified design and analysis.
Bioabsorbable composites. I: Fundamental design considerations using free radically crosslinkable matrices
Authors: Storey Robson F. , Wiggins Jeffrey S. , Mauritz Kenneth A. , Puckett Aaron D. 
Published: May 2005

AbstractBioabsorbable composites have been fabricated, consisting of poly (glycolic acid) surgical mesh embedded in free radically crosslinked poly (D, Iactide‐co‐8‐caprolactone) fumarate‐ or poly(D, Iactide‐co‐‐glycolic acid) fumarate‐based matrices. Styrene and methyl methacrlate were investigated as hydrophobic comonomers and were found to significantly improve the degree of crosslinking, tensile strength and retention of physical properties during the initial stages of degradation particularly styrene. Hydrolytic degradation studies showed that the neat poly(D, L‐lactide‐co‐8caprolactone) fumarate matrix dwas excessively hydrophilic, failing after 10 days of immersion; a matrix modified with 25 wt% styrene underwent a steady, nearly linear loss in mass over a period of 35 days without fragmentation. A composite based on neat poly (D, L‐lactide‐co‐8‐caprolactone) fumarate displayed a tensile strength of 37 Mpa and modulus of 107 Mpa; addition of 25 wt% styrene yielded tensile strength and modulus of 64 Mpa and 689 Mpa, respectively. A silane coupling agent was shown to dramatically improve the fiber‐matrix interfacial adhesion; tensile strength of a poly(D, L‐lactide‐co‐glycolic acid) fumarate compsite was increase from 84 to 92 MPa upon fiber pretreatment. Improved adhesion was also demonstrated using SEM. Bioabsorbable composites are rigid at biological temperatures, but some can be custom formed at elevated temperatures, which might be useful in certain surgical applications.
Effect of catalyst concentrations on one‐shot polyether flexible urethane foams
Authors: Sandridge R. L. , Gemeinhardt P. G. , Saunders J. H. 
Published: May 2005

AbstractVariations were made in the concentration of tin and amine catalysts used in a typical one‐short polyether flexible foam system. Differences in foaming characteristics and foam stability were correlated with the relative rates of the chemical reactions which are believed to occur during the foaming process. Physical properties measured on the samples showed in many cases a dependence on the balance between the tin and amine catalysts.