bluuebunny/crossref_metadata_2025_split huggingface dataset:
A new amorphous heat‐resistant aromatic polymide fiber prepared by wet‐spinning
Authors: Jager Jan , Krins Bas , Sikkema Doetze J. 
Published: April 2003

AbstractA new amorphous heat‐resistant aromatic polyamide was prepared by solution polymer‐ization in N‐methylpyrrolidone, (NMP) from equimolar amounts of 4,4′‐methylenedianiline, p‐phenylenediamine, isophthaloyl chloride, and terephthaloyl chloride. After neutralization of the byproduct HCl, with calcium hydroxide, the as‐polymerized polymer solution (15.7% polyamide in NMP) was spun directly on a horizontal wet‐spinning device. Yarn drawing of as‐spun fibers, near the glass transition temperature of the polymer, was performed on a hot‐drawing equipment. To determine the optimal drawing conditions, the influence of the draw ratio on the tensile properties was studied in detail. On the basis of these results, a draw ratio of 1.7 was applied to prepare a larger quantity of drawn polyamide multifilament yarn (f330 and f500). Tensile properties of both fibers and filaments were determined by standard methods. The fibers are characterized by an excellent thermal stability as indicated by temperature‐dependent tensile measurements, long‐term heat resistance, boiling‐water shrinkage, hot‐air shrinkage, etc., of the fibers. Despite the amorphous character of the polyamide fiber, it offers an excellent resistance to common organic solvents (except to THF and DMF). Moreover, the fiber exhibits a good resistance toward diluted inorganic acids, salts, and bases. Depending on the specific properties of the polyamide fiber, the material may find applications in, e. g., hot‐air filter fabrics, protective clothing, electrical insulation paper, or advanced structural materials. © 1993 John Wiley & Sons, Inc.
Synthesis and properties of segmented polyurethane using phenolphthalein as chain extenders
Authors: Rajan H. , Rajalingam P. , Radhakrishnan Ganga 
Published: April 2003

AbstractThree series of novel polyurethane elastomers containing phenolphthalein as chain extenders were synthesized. The structure of the polyurethane was analyzed using IR and wide‐angle X‐ray diffraction studies. Tensile strength and percentage of elongation of all the series of polymers were studied. Thermal decomposition was studied using differential scanning calorimetry. © 1993 John Wiley & Sons, Inc.
Grafting of acrylic acid with diethyleneglycol–dimethacrylate onto radioperoxided polyethylene
Authors: Gineste Jean‐Luc , Garaud Jean‐Luc , Pourcelly Gerald 
Published: April 2003

AbstractAcrylic acid and diethyleneglycol–dimethacrylate are grafted onto 25μm low‐density and 130μm high‐density polyethylene previously peroxidized by irradiation in air under the electron beams of an accelerator. Mohr's salt and methylene blue are used to prevent monomer homopolymerization. It is shown that sulfuric acid and Mohr's salt, respectively, enhance acrylic acid and diethylene glycol–dimethacrylate grafting. When they are combined, the influence of the monomer content on grafting kinetics is studied. Monomer content is determined by exchange capacity measurements. © 1993 John Wiley & Sons, Inc.
Photon emission during deformation of glass‐fiber‐reinforced bisphenol‐a‐polycarbonate
Authors: Fuhrmann Jürgen , Nick Leo , Dickinson J. Thomas , Jensen Leslie C. 
Published: April 2003

AbstractWe give a survey on mechanically induced emission phenomena (acoustic emission [AE], neutral particle emission [NE], electron and charged particle emission [EE/PIE], radio wave emission [RE] of polymers and briefly summarize these effects in unfilled and glass‐fiber‐reinforced bisphenol‐A‐polycarbonate. A general treatment of the photon emission kinetics in terms of analysis and description, using a convolution function, is proposed. The kinetics obey a power law decay in time. By examining a model mechanism for the interfacial failure of the composite, i.e., by peeling of glass/polymer laminates, we show that the origin of the photon emission is the polycarbonate matrix after cleavage of the glass/polymer interface. Spectral characteristics of mechanically induced luminescence of glass‐filled polycarbonate and of the peeling spectra of the model system of glass/polycarbonate laminates are discussed. Different brands of polycarbonate yield identical spectra. Spectra recorded during peeling in vacuum are very similar to those recorded during deformation of the composite. Polarized fluorescence spectroscopy and electronbeam luminescence were used to obtain further information about the intrinsic polycarbonate–chromophores that are available for mechanically induced photon emission. © 1993 John Wiley & Sons, Inc.
Urea–resorcinol–formaldehyde adhesives of low resorcinol content
Authors: Scopelitis E. , Pizzi A. 
Published: April 2003

AbstractLow resorcinol content cold‐setting urea–resorcinol–formaldehyde (URF) resins were prepared. Most of these adhesives had water‐resistant properties, whereas some also presented weather‐ and boil‐proof adhesive characteristics and performance. URF resins of acceptable adhesive performance were also prepared by inducing branching by introducing a certain amount of resorcinol or of polyflavonoid mimosa tannin extract as a branching unit. Resorcinol content as low as 12.7 and 12.15% on total liquid resin were obtained by this method while still maintaining adhesive performance and water‐resistant properties. © 1993 John Wiley & Sons, Inc.
Toughened thermoplastic composite. I. Cross‐linkable phenol formaldehyde and epoxy resins‐coated cellulosic‐filled polypropylene composites
Authors: Sain M. M. , Kokta B. V. 
Published: April 2003

AbstractComposites of polypropylene (PP) or maleic‐anhydride‐modified polypropylene (MAH‐PP) with uncoated or thermosetting resincoated sawdust or explosion pulp (V‐pulp) were prepared by dynamic cross‐linking and their properties were compared to those of unmodified and uncross‐linked composites. The effects of modification and dynamic cross‐linking on the interfacial adhesion between polymer and filler have also been investigated by a solvent extraction study and microscopic analysis. The new method of dynamic cross‐linking in combination with the additional effect of compatibilization suggests a practical route to obtain high‐strength, toughened thermoplastic composites. Dynamically cross‐linked epoxyor phenolic resin‐coated sawdust or V‐pulp that can be grafted or can have affinity to MAH‐PP was found to improve tensile strength as well as elongation at yield point. The tensile toughness of the dynamically cross‐linked‐compatibilized composites is better than that of an uncross‐linked composite of MAH‐PP and sawdust. The improved toughness of the dynamically cured composites appears to be that further chemical bonds form between coated filler and MAH‐PP in addition to grafting of MAH‐PP onto cellulose chain. © 1993 John Wiley & Sons, Inc.
New lightweight materials: Balsa wood‐polymer composites based on ethyl α‐(hydroxymethyl)acrylate
Authors: Wright J. R. , Mathias L. J. 
Published: April 2003

AbstractIt is clearly demonstrated here that ethyl α‐(hydroxymethyl)acrylate (EHMA) is a unique monomer for increasing the dimensional stability and physical properties of balsa wood. Copolymers containing EHMA, and especially EHMA‐styrene mixtures, were shown to improve the dimensional stability (water soak test) and the absolute mechanical properties of balsa wood. Improvements in specific modulus and specific toughness (absolute properties divided by specific gravity) were achieved using an EHMA‐styrene monomer mixture with polybutadiene diacrylate as cross‐linker and toughening agent, with the best results obtained at low (10–40%) weight gain. This is the first report that we are aware of describing specific property improvement greater than expected based on density increase. These improvements in modulus and toughness were ascribed to efficient penetration of monomers into the cell walls. Solid‐state NMR and scanning electron microscopy confirmed strong interaction of the copolymers generated in situ with wood cell wall components, consistent with the property improvements obtained. The combination of a light‐weight, renewable wood precursor with synergistic reinforcement by this combination of monomers offers unique opportunities for increased use of wood‐polymer composites in a wide variety of structural and insulating applications. © 1993 John Wiley & Sons, Inc.
Die drawing technology of high molecular weight polyethylene
Authors: Lee Y. W. , Li J. X. 
Published: April 2003

AbstractA comprehensive investigation of the die drawing technology of a high molecular weight polythylene (HMWPE) rod has been carried out. The effect of draw temperature, draw speed, nominal draw ratio, and exit diameter of the dies has been studied. The oriented HMWPE products were characterized mainly by the determination of the three‐point bend modulus and the tensile strength. The tensile strength and the modulus of the drawn HMWPE rod could reach 700 MPa and 18 GPa, respectively. In addition, it was found that forced cooling at the die exit was essential when drawing billets with large section areas. © 1993 John Wiley & Sons, Inc.
Characterization of grafted jute fiber by optical and scanning electron microscopy
Authors: Kundu S. K. , Ray P. K. , Sen S. K. , Bhaduri S. K. 
Published: April 2003

AbstractRaw and partially delignified jute fibers were grafted with acrylonitrile and methyl meth‐acrylate monomers, using the redox system of initiation with ceric ammonium sulfate. Grafting was also carried out in a mixed monomer system with acrylonitrile and methyl methacrylate monomers in different proportions. The optimum grafting condition depends on the duration of grafting treatment and proportion of grafting monomers. The monomers entered the fiber matrix with high add‐on and, at still higher graft add‐ons, the ultimate fibers suffered disintegration. The surfaces were increasingly covered with grafted materials and longitudinal cracks developed on the fiber surface with higher add‐on. © 1993 John Wiley & Sons, Inc.
Structure and surface properties of diaminocyclohexane plasma polymer films
Authors: Gölander C‐G. , Rutland M. W. , Cho D. L. , Johansson A. , Ringblom H. , Jönsson S. , Yasuda H. K. 
Published: April 2003

AbstractPlasma polymers of three isomers of diaminocyclohexane (DACH) were deposited on polyethylene, SiO2, and mica at 20°C. The deposition rate was measured as a function of plasma density and power; a maximum was observed in the latter function. The deposition rate was highest for the monomer with the highest flow rate. The film refractive index was observed to increase with both power density and the degree of fragmentation in the plasma. Film composition was measured by elementary analysis, and was found to be almost identical for each of the three isomers; a mechanism for the polymerization reaction is proposed. The percentage of primary amino groups decreased with increasing power density and with film thickness. Surface force measurements of the thickness and refractive index agreed well with the corresponding ellipsometry values in dry air, and am adhesive force, independent of power density, was measured. When the film was exposed to water vapor, it swelled considerably and the adhesion was determined by capillary forces. Associated with swelling, at high power, was an extremely regular 2‐ply rope pattern of protruding material. © 1993 John Wiley & Sons. Inc.
Semicontinuous miniemulsion terpolymerization: Effect of the operation conditions
Authors: Unzué María J. , Asua José M. 
Published: April 2003

AbstractThe effect of solids content, initiator concentration, feed‐flow rate, and amount of cosurfactant on the kinetics of the high solids content, semicontinuous miniemulsion terpolymerization of butyl acrylate, methyl methacrylate, and vinyl acetate was studied. In addition, the effect of the operation variables on the feasibility of obtaining a 65 wt% solids content latex with low amount of coagulum was investigated. The operation variables studied were: (1) partition of the monomer between the initial charge and the feed, (2) type and concentration of emulsifier; (3) feed‐flow rate; and (4) sonication. © 1993 John Wiley & Sons, Inc.
Copolymerization of N‐phenyl maleimide and γ‐methacryloxypropyl trimethoxysilane
Authors: Choudhary Lalita , Varma D. S. , Wang Francis W. , Choudhary Veena , Varma I. K. 
Published: April 2003

AbstractCopolymerisation of N‐phenyl maleimide (NPM) and γ‐methacryloxypropyl trimethoxy‐silane (MTS) in dioxan solution using benzoyl peroxide as an initiator is described. The rate of copolymerisation depended on the mole fraction of NPM in the initial feed and decreased with an increase in NPM content. Copolymers having a mole fraction of NPM varying from 0.29 to 0.55 exhibited similar thermal behaviour in terms of initial decom‐position temperature or temperature of maximum rate of weight loss. However, char yield at 600°C depended on NPM content, showing a tendency to increase with the increase in NPM content. © 1993 John Wiley & Sons, Inc.
Probing interphase domains in blend‐like polymer particles by transient fluorescence technique
Authors: Pekcan Önder 
Published: April 2003

AbstractSmall molecule (1‐naphthylmethyl privalate) (NMP) diffusion into poly (methyl methacrylate) (PMMA) particles sterically stabilized by polyisobutylene (PIB) were studied by the transient fluorescence technique. Mean lifetimes of NMP increased as it diffused into the interphase region indicating that diffusion is accompained by quenching of excited NMP molecules by PIB phase. A delayed Fickian diffusion model is fitted to experimental data and a diffusion coefficient is measured around 10−19 cm2/s at room temperature. PIB density distribution in the interphase domain is found to be Gaussian. A supporting experiment is performed in Anthracene labelled PMMA particles using the direct‐energy transfer method. Reversed Gaussian distribution is detected for the PMMA density in the interphase domain. © 1993 John Wiley & Sons, Inc.
Mid‐ and near‐infrared spectroscopic investigations of reactions between phenyl glycidyl ether (PGE) and aromatic amines
Authors: Fu J. H. , Schlup J. R. 
Published: April 2003

AbstractMid‐infrared (MIR) and near‐infrared (NIR) spectroscopies have been employed to examine the reactions between phenyl glycidyl ether (PGE) and five aromatic amines. Although MIR spectroscopy can effectively study the kinetics of PGE/aromatic amine cure reactions, the OH and NH stretching bands overlap and the NH in‐plane bending band overlaps with an aromatic ring stretching band of PGE. This significantly reduces the utility of MIR spectroscopy for quantitative studies of PGE cure reactions. In contrast, the absorption bands of these functional groups in the NIR spectrum are well separated from the absorption bands of other functional groups. The utility of NIR spectroscopy for studying the kinetics of epoxy resin cure reactions has been clearly established. Absorbances in the NIR spectra suitable for quantitative studies of epoxy resin reaction kinetics have been identified. The ability of in situ NIR spectroscopy to obtain isothermal kinetic data has been demonstrated. © 1993 John Wiley & Sons, Inc.
Transport properties of dichloromethane in glassy polymers. III. Drawn atactic polystyrene films
Authors: Vittoria V. , Filho A. Ruvolo 
Published: April 2003

AbstractTransport properties of dichloromethane vapor were measured in atactic polystyrene (aPS) samples, oriented by drawing at 95°C to different draw ratios (3 and 4.5) and analyzed after controlled aging times at different temperatures. The diffusional behavior is characterized by three zones, depending on vapor activity: In Zone I, at low activity, the diffusion coefficient is independent of vapor concentration; Zone II is characterized by concentration‐dependent diffusion and by the appearance of non‐Fickian sorption curves; and in Zone III, the strong interaction polymer‐solvent induces disorientation of the samples. The diffusional behavior is very similar to that of undrawn aPS, and also the extrapolated parameters coincide, showing that in the case of amorphous polymers, the drawing does not influence the diffusion. The aging, both at room temperature and at 70°C, decreases the diffusion parameters and leads to the appearance of anomalous sorption curves. The sorption curve as a function of vapor activity does not show any difference for the fresh and aged at room temperature‐oriented samples; furthermore, it coincides with that of aPS. At variance, the oriented samples aged at 70°C show a lower sorption at low activity. As in the case of aPS, the presence of ordered domains, impermeable to the penetrant at low activity, was suggested for the oriented samples. © 1993 John Wiley & Sons, Inc.
Novel cation‐exchange composites resulting from polymerization / cross‐linking of acrylic acid / N‐methylolacrylamide mixtures with cellulose
Authors: Ibrahim N. A. , Abo‐Shosha M. H. 
Published: April 2003

AbstractNovel cation‐exchange composites were prepared by polymerizing / cross‐linking of mixtures of acrylic acid (AA) and N‐methylolacrylamide (NMA) in the presence of cellulose pulp using ammonium persulfate in conjunction with a sodium thiosulfate, sodium metabisulfite, or glucose initiating redox system. The (NH4)2S2O8/Na2S2O3. 5H2O redox system proved to be efficient for aqueous polymerization/ cross‐linking reactions and/or interactions of cellulose with highly concentrated mixtures of NMA and AA, used as commercially available, at very low polymerization temperature (30°C) and for a very short duration of polymerization (90 s) using a liquor‐to‐cellulose ratio of 6.25 L/kg. Various parameters that affect the synthesis of these composites, such as reaction temperature, concentration of redox system components, and drying temperature as well as AA and NMA concentrations, were reported. Four kinds of cation‐exchange composites of different nitrogen and carboxyl contents were synthesized and characterized by investigating their potentiometric titrations, water solubilities, and swellabilities as well as their durabilities. © 1993 John Wiley & Sons, Inc.
Appraisal of a molecular weight distribution‐to‐rheology conversion scheme for linear polyethylenes
Authors: Mavridis H. , Shroff R. 
Published: April 2003

AbstractA theoretical scheme relating quantitatively the rheology of linear polymer melts to molecular weight distribution (MWD) would be of great significance in that it can help interpret polymer rheology and processing behavior in terms of molecular weight characteristics. The present paper is concerned with the appraisal of such a theory—the partition model of Bersted. The theory involves four parameters that are fitted to experimental data on a variety of linear polyethylenes. Although the model does fit the data with better than 10% accuracy, the parameters show some variability that points to theory limitations. An error analysis also shows that this variability is partly accounted for by experimental errors in MWD determination that are amplified in the predicted rheological properties. The rheological properties are shown to be heavily influenced by the high molecular weight tail of the MWD. Errors in MWD determination are detrimental for a MWD‐to‐rheology conversion, even if a conversion scheme were perfectly accurate. Low levels of long‐chain branching that may possibly be present are also detrimental to an MWD‐to‐rheology conversion. The inverse problem of determining the complete MWD from rheology appears to be practically infeasible for broad MWD polymers. © 1993 John Wiley & Sons, Inc.
Preparation and characterization of polyureas from divalent metal (Ba, Sr, Pb, Zn) salts of sulfanilic acid
Authors: Qiu Wulin , Zeng Wenxiang , Zhang Xuexian , Li Can , Lu Lude , Wang Xin , Yang Xujif , Sanctuary Bryan C. 
Published: April 2003

AbstractMetal‐containing polyureas containing ionic linkages in the main chain can be obtained by the polyaddition reactions of 2,4‐tolylene diisocyanate with mixtures of divalent metal salts of sulfanilic acid (p‐aniline sulfonic acid [ASA] ) and 4,4′‐diaminodiphenylmethane. Ba, Zn, Pb, and Sr were used as divalent metals, and their structures were characterized by 1H‐NMR, 13C‐NMR, and IR. The polyureas were obtained with ASA(M) up to 100% in feed diamines and they were all soluble in DMF and DMSO. The inherent viscosity of the polyureas decreased markedly with an increase in metal content. The thermal properties of these polyureas were also investigated by DSC and TG. It was found that introducing the metal into the polyurea increased the thermal stability. © 1993 John Wiley & Sons, Inc.
Silane coupling agent having dithiocarbamate group for photografting of sodium styrene sulfonate on glass surface
Authors: Kobayashi Takaomi , Takahashi Syun , Fujii Nobuyuki 
Published: April 2003

AbstractFor a photograft‐polymerization of sodium styrene sulfonate onto a glass surface, glasses were treated with a photosensitive silane coupling agent (N, N‐diethylamino) dithio‐carbamoylpropyl (trimethoxy) silane (DATMS). The characteristics of the glass surfaces were examined by UV and IR spectroscopic methods and the contact‐angle technique. The contact angles of air and n‐octane in water were measured to estimate interfacial energy of the surfaces. © 1993 John Wiley & Sons, Inc.
Bimodification of polyacrylonitrile (PAN) fibers
Authors: Mathur R. B. , Mittal J. , Bahl O. P. 
Published: April 2003

AbstractA new technique for the modification of PAN fibers has evolved, in which the starting precursor material is impregnated with an aliphatic carboxylic acid, as well as KMnO4. The bimodification of PAN, attempted by us for the first time, is aimed at achieving dual advantages in plasticization effect, as well as in a catalytic effect in a single treatment. The unmodified, unimodified, and bimodified precursors have been characterized for their mechanical, thermal, and physical behavior during various stages of processing to carbon fibers. These results are discussed in detail. The study further shows an 18% improvement in the mechanical properties of carbon fibers, prepared from bimodified precursor, as compared to that of unmodified precursor. One of the reasons for such improvement is the lowering in diameter of PAN fibers and in the resulting carbon fibers. © 1993 John Wiley & Sons, Inc.
Surface characterization of segmented siloxane–urethane block copolymers
Authors: Benrashid R. , Nelson G. L. , Linn J. H. , Hanley K. H. , Wade W. R. 
Published: April 2003

AbstractNew siloxane–urethane block copolymers were synthesized and the effect of a siloxane moiety on microphase segregation in soft/hard block copolymers was studied by several analytical methods. Scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) provided topographical and bulk composition information. Electron Spectroscopy for Chemical Analysis (ESCA) provided surface chemical information. Fourier Transform Infrared Spectroscopy (FTIR) provided chemical bond information for the near‐surface region. Thermogravimetric Analysis (TGA) provided information concerning the thermal stability of the polymers. Differential Scanning Calorimetry (DSC) provided information on the soft and hard block segments within the polymer. These studies showed that the block copolymer contained and enhanced silicone‐containing surface. For films cast on glass, less silicon was detected in the bulk (exposed by physically removing the surface material), and on the backside (glass) of the polymer film, than on the air‐exposed surface. Of particular interest is the fact that data also show that the solvents, from which the polymers were cast, have a significant influence on microphase segregation. The films cast from THF have higher silicone concentrations at the surface as compared to polymers cast from DMAC/CH2CL2 or dioxane. © 1993 John Wiley & Sons, Inc.