bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies of polymer mobility in composite blends of poly(vinyl butyral) and alumina
Authors: Parker A. A. , Opalka S. M. , Dando N. R. , Weaver D. G. , Price P. L.
Published: April 2003

Solid‐state NMR and thermal analysis techniques were used to compare the mobility of poly(vinyl butyral) (PVB) in the presence and absence of both alumina filler particles and plasticizer. The relative mobility of main‐chain and side‐chain carbons increases in the presence of both plasticizer and alumina as seen from an increase in the average cross‐polarization rates, 〈TCH〉, and from a general decrease in the rotating frame spin‐lattice relaxation rates, CT1ρ. Unlike the main‐chain carbons, inversion recovery cross‐polarization (IRCP) data on solution cast composites show that the side‐chain methyl groups in neat PVB samples are best characterized by a monoexponential cross‐polarization model. However, in the presence of alumina, a fraction of the methyl groups becomes less mobile as indicated by the biexponential IRCP behavior. Polymer phase mobility also increases below the critical pigment volume concentration (CPVC) as seen from decreasing transition temperatures using dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). This is accompanied by an increase in the rigidity of a portion of the polymer phase above the CPVC as indicated by an increase in the apparent Tg, along with an increase in the mobility of another portion as indicated by the appearance of a low‐temperature DMA transition. These trends are consistent with an increase in polymer chain packing heterogeneity in the presence of alumina. © 1993 John Wiley & Sons, Inc.
Photografting of acrylonitrile and methacrylic acid on polyethylene film under air atmosphere
Authors: Kubota Hitoshi
Published: April 2003

Photografting of acrylonitrile (AN) and methacrylic acid (MAA) on low‐density polyethylene film (thickness 70 μm), on which benzophenone was coated earlier, was investigated at 60°C in water medium under air atmosphere. In the case of AN monomer, where grafted polymer was formed predominantly, oxygen in the system promoted the formation of both grafted polymer and homopolymer. With MAA monomer, in which homopolymer was formed preferentially compared to the formation of grafted polymer, the formation of homopolymer was accelerated by the presence of oxygen while suppressing that of grafted polymer. The formation of polyethylene peroxides by photoirradiation seemed to be a factor for the accelerated polymerization under air atmosphere. It was found that additives such as hydrazine and metallic ions (Fe2+, Cu2+, and Ni2+) are useful for enhancing the photografting under air atmosphere. © 1993 John Wiley & Sons, Inc.
Effect of water on the glass transition temperature of hydrophilic polyurethanes
Authors: Schneider Nathaniel S. , Illinger Joyce L. , Karasz Frank E.
Published: April 2003

The depression of the glass transition temperature by water was studied in a set of polyurethanes in which the soft segment consisted of polyethylene oxide (sample I) or a block copolymer of poly(propylene oxide) terminated with poly(ethylene oxide) in various proportions (sample set II). DSC measurements were made at two added water contents for each type of sample and at various temperatures. The Tg reduction appeared to be governed solely by the nonfreezing bound water and was much larger in sample I than in samples of set II. The more limited effect on the Tg of set II samples is attributed to restricted mobility arising from coupling of the short terminal poly(ethylene oxide) to rigid hard‐segment units. Therefore, the data for sample I are preferred as a test of the predictive relations for the Tg depression. On this basis, it appears that the simple Fox mixing equation is more reliable than is the available free volume approach, which required unrealistically high values of the thermal expansion coefficient for water to fit the data for sample I. © 1993 John Wiley & Sons, Inc.
Procedure for zone winding of extended‐length netted composite shells
Authors: Pichugin V. S. , Kestelman V. N.
Published: April 2003

The subject of this paper is the extended‐length netted wound composite shells operating in cantilever loading conditions. The winding method that enables the attainment of various thicknesses of the netted shell zonewise is discussed. The distinguishing feature of this formation is the introduction of the sectional expansion mandrel into the production process. The efficiency of the elaborated method is based on the known dependence of the composites' mechanical properties on the tension of the reinforcing filler. On completion of winding, the blank is heated and, with the mandrel sections moved apart in the axial direction, the required level of fiber tension is created in each zone. The improved quality of the material enables increasing of the load‐carrying capacity of the items at the simultaneous reduction of their mass. Use of the procedure is most expedient for the manufacture of items from high‐modulus reinforcing materials. The field of application is the production of vital shell structures, such as helicopter tail booms, masts of vessels, and power transmission line supports. © 1993 John Wiley & Sons, Inc.
Enhanced laminate damping via modification of viscoelastic interlayer
Authors: Liao Fu‐Sen , Hsu Tzu‐Chien J. , Su A. C.
Published: April 2003

This study sought to develop a sandwich‐type vibration damping laminate suitable for room‐temperature applications. The laminate consisted of a polymeric interlayer that was sandwiched between two steel sheets. The study was initiated to promote the relatively low‐damping capability of a maleic anhydride‐grafted polypropylene (mPP)‐based laminate, which failed to meet the requirement that the loss factor of the laminate should be greater than 0.05 for effective damping. Modifications of mPP by incorporation of a dynamically vulcanized PP/butyl rubber blend were then followed. The modifications were based on the theoretical analysis proposed by Rose, Ungar, and Kerwin (RUK) for a general polymer‐based laminate. The design criteria for the polymeric interlayer, i.e., the preferred range of storage modulus G′ for a set of reasonable values of loss tangent (tan δ), were first established from calculations by use of the RUK theory. The theoretical calculations revealed that the low damping of the mPP‐based laminate resulted primarily from the high G′ and low tan δ of the interlayer. Incorporation of butyl rubber into the polymeric interlayer led to a strong decrease in G′ and a moderate increase in tan δ. These modifications resulted in significantly improved damping capability of the laminate, as predicted by the RUK theory. © 1993 John Wiley & Sons, Inc.
Modeling and simulation of semibatch emulsion polymerization
Authors: Li Bogeng , Brooks Brian W.
Published: April 2003

By taking advantage of recent theoretical developments in emulsion polymerization and radical polymerization kinetics at high conversion, a model is developed for simulating seeded semibatch emulsion polymerization. The model is used to calculate the time evolution of the polymerization rate, the monomer conversion, the instantaneous degree of polymerization, the monomer concentration in particles, the average radical number per particle, and the propagation rate coefficient and termination rate coefficient over the whole course of the polymerization. Experimental observations by previous workers, including the existence of steady‐state phenomenon and the broad distributions of molecular weight, are reproduced in the results of the simulation. The gel effect on emulsion polymerization and the open‐loop stability of the semibatch process are discussed. © 1993 John Wiley & Sons, Inc.
Graft polymerization of fluorinated monomer onto corona‐treated PVA and cellulose films
Authors: Hoebergen A. , Uyama Y. , Okada T. , Ikada Y.
Published: April 2003

Surface graft polymerization of a hydrophobic monomer, 2,2,3,3,3‐pentafluoropropyl methacrylate (5FMA), onto hydrophilic poly(vinyl alcohol) (PVA) and cellulose films was studied after corona discharge of the films. It was found that grafting strongly depended on the reaction medium; especially, addition of alcohol to the monomer greatly accelerated graft polymerization. For instance, when an ethanol/ water /5FMA mixture (65/25/10, by volume) was used as the polymerization medium. the PVA and cellulose films corona‐discharged for a few minutes exhibited a high contact angle up to 100° after 30 min polymerization, the graft density being approximately 170 μg/cm2 for cellulose and 80 μg/cm2 for PVA. © 1993 John Wiley & Sons, Inc.
Toughening of epoxy resins by N‐phenylmaleimide‐N‐cyclohexylmaleimide–styrene terpolymers
Authors: Iijima Takao , Sato Ken , Fukuda Wakichi , Tomoi Masao
Published: April 2003

N‐Phenylmaleimide (PMI)‐N‐cyclohexylmaleimide (CMI)‐styrene (St) terpolymers were used to improve the touchness of bisphenol‐A diglycidyl ether epoxy resin cured with p,p′‐diaminodiphenyl sulfone (DDS). The terpolymers were effective as modifiers for toughening of the epoxy resin system. The most suitable compositions for the modification of the epoxy resin were inclusion of 10 wt% of the terpolymer (45 mol % PMI, 5 mol % CMI, and 50 mol % St units) with Mw higher than 247,000, which led to ca. a 140% increase in the fracture toughness (KIC) of the cured resin with a medium expense of mechanical properties. The glass transition temperatures of the modified resins were equal to or higher than that of the parent epoxy resin. The morphologies of the modified resins were dependent on the terpolymer molecular weight and concentration. On addition of 5 wt % of the terpolymer (Mw 400,000), the modified resins had two‐phase morphologies and the terpolymer‐rich dispersed particles in the epoxy matrix. On addition of more than 8 wt % of the terpolymer, the morphologies of the cured resins changed drastically and showed a tendency to from cocontinuous phases. The toughening mechanism was discussed in terms of the morpho‐logical behaviors of the modified epoxy resin systems. © 1993 John Wiley & Sons, Inc.
A new amorphous heat‐resistant aromatic polymide fiber prepared by wet‐spinning
Authors: Jager Jan , Krins Bas , Sikkema Doetze J.
Published: April 2003

A 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

Three 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

Acrylic 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

We 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

Low 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

Composites 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

It 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

A 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

Raw 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

Plasma 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

The 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

Copolymerisation 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

Small 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

Mid‐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

Transport 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

Novel 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

A 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

Metal‐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

For 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

A 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

New 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.
Preparation of fibrous adsorbents containing amidoxime groups by radiation‐induced grafting and application to uranium recovery from sea water
Authors: Kabay N. , Katakai A. , Sugo T. , Egawa H.
Published: April 2003

Polypropylene fibers and polyethylene hollow fibers were used as trunk polymers and were irradiated by electron beams with a dose of 200 kGy under N2 atmosphere. Grafting of acrylonitrile to those irradiated fibers was carried out at 40°C for different periods of time. The degree of grafting was determined as a function of time. The fibrous adsorbents containing amidoxime groups were prepared by the reaction of acrylonitrile‐grafted polymers with 3% hydroxylamine in a methanol–water mixture (1 : 1). Distribution of copper ions complexed with amidoxime groups at various adsorption times was obtained by electron‐probe X‐ray microanalysis. The amidoxime groups are homogeneously distributed in the cross section of fibrous adsorbents. The fibrous adsorbents based upon polypropylene fiber of 40 μm showed a remarkable kinetic behavior for Cu2+. Even after 15 min, the adsorption capacity was 2.32 mmol Cu2+ per gram of fiber. Also, the functionalization with hydroxylamine was carried out at different conditions to compare the adsorption characteristics of the resultant adsorbents. Despite having superficially different properties (elemental microanalysis, ion‐exchange capacities, adsorption capacity for UO), the polypropylene‐based fibrous adsorbents showed similar adsorption properties for uranium from sea water. The adsorption tests proved the performance of the polypropylene‐based fibrous adsorbents as a promising material for uranium recovery from sea water. In addition, uranium uptake of fibrous adsorbents increased in proportion to the volume of sea water. © 1993 John Wiley & Sons, Inc.
Natural rubber and butadiene rubber blend using diblock copolymer of isoprene–butadiene as compatibilizer
Authors: Bualek Sauvarop , Ikeda Yuko , Kohjiya Shinzo , Phaovibul Orapin , Phinyocheep Pranee , Suchiva Krisda , Utani Kazunori , Yamashita Shinzo
Published: April 2003

Blends of natural rubber (NR) and butadiene rubber (BR) have been studied with or without diblock copolymers of isoprene–butadiene (BIR). It was found that NR/BR blends displayed the optimal properties at about 4 wt % of BIR from the tensile measurements of NR/BR blends. Increase of molecular weight of BIR resulted in the decrease of tensile properties, but had no significant effect on their hardness. Abrasion resistance of rubber blends containing BIR was about 30% higher than that without BIR. The molecular weight of BIR did not show a remarkable effect on the abrasion index. Differential scanning calorimetry and dynamic mechanical analyses of rubber blends suggested a two‐phase structure even in the presence of BIR. © 1993 John Wiley & Sons, Inc.
The properties of polymer protective coatings of optical fibers. I. The influence of active diluent concentration on the properties of UV‐cured epoxyacrylate coatings
Authors: Rayss J. , PodkośCielny W. M. , Widomski J.
Published: April 2003

The strong relationship between the properties of UV‐cured epoxyacrylate coatings of optical fibers and their compositions was found. The epoxyacrylate oligomer‐to‐acrylate monomer active diluent ratio was used to give a simple explanation of the mechanism of polymerization reaction of UV‐curable epoxyacrylate compositions. © 1993 John Wiley & Sons, Inc.
Modeling the process‐zone kinetics of polycarbonate
Authors: Kim A. , Garrett L. V. , Bosnyak C. P. , Chudnovsky A.
Published: April 2003

A thermodynamic model for the equilibrial process zone ahead of a crack in polycarbonate is developed from the recently proposed Chudnovsky model and experimental characterization of the process zone. Based on the model, the force for evolution of the process zone is proposed from the consideration of irreversible thermodynamics and chemical reaction theories. The experimental data reported in our previous paper are well described by the equilibrial process zone model and a new kinetic equation. © 1993 John Wiley & Sons, Inc.
Investigation of the sequence distribution of bulk and emulsion styrene–acrylic acid copolymers by 1H‐ and 13C‐NMR
Authors: Wang Shouting , Poehlein Gary W.
Published: April 2003

The sequence distribution of homogeneous styrene (S)–acrylic acid (A) copolymers, obtained by low conversion (<10%) bulk copolymerization, has been studied by 1H‐ and 13C‐NMR. The reactivity ratios ra and rs were determined by the Kelen–Tudos method. The sequence distributions at the triad level were assigned and verified by Alfrey–Mayo kinetics. The sequence distributions of emulsion copolymers formed at different reaction conversions were investigated and compared with the results obtained from bulk copolymers. © 1993 John Wiley & Sons, Inc.
Ternary blends of poly(amide‐6)/polycarbonate/poly(ε‐caprolactone)
Authors: Kim Woo‐Nyon , Park Chan‐Eon , Burns Charles M.
Published: April 2003

Blends of poly(amide‐6) (PA) and poly(ε‐caprolactone) (PCL) prepared by solution casting and screw extrusion have been investigated by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). From the measured melting point (Tm) of the solution‐cast PA/PCL blends, a Tm depression of the PA was observed for the investigated compositions. No Tm depression was found for the extruded PA/PCL blends, however. In the SEM study of the morphology of the solution‐cast PA/PCL blends, phase separation was observed between the PA phase and the PCL phase for all blend compositions. For the extruded PA/PCL blends, however, more pronounced phase separation was observed for all blend compositions. Ternary blends of PA, PCL, and bisphenol‐A polycarbonate (PC) have also been prepared by screw extrusion. From the study of morphology and extrudate swell of the PA/PC binary blends and the extruded PA/PC/PCL ternary blends, it appears that PCL could be used as a compatibilizer for the extruded PA/PC/PCL blends. © 1993 John Wiley & Sons, Inc.
Coemulsion and electrodeposition properties of mixtures of polyoxypropylene‐modified cationic epoxy resin and nonionic trimethylolpropane–toluene diisocyanate–2‐ethylhexanol crosslinker
Authors: Yang Chin‐Ping , Chen Yahn‐Haur
Published: April 2003

The emulsification and electrodeposition properties of mixtures of polyoxypropylene‐(POP) modified cationic epoxy resin (III) and nonionic trimethylolpropane–toluene diisocyanate–2‐ethylhexanol (TMP–TDI–2EH, V) were investigated and the compositions of their electrodeposited films were obtained by Fourier Transform Infrared (FTIR) quantitative analysis to study the effects of “soft segment” (oxypropylene groups) contained in resin III on the coemulsion and electrophoretic behavior. The results indicate that the deposition yield and throwing power of emulsion of resin III are highly dependent on its average molecular weight (Mw). Resin III with higher Mw has higher deposition yield but lower throwing power. Moreover, the deposition yield of V/III coemulsion also increases with increasing the Mw of III. On the other hand, the throwing power of V/III coemulsion is not related to the Mw of III but is influenced by the amount of soft segments in III. Increasing soft segment content in III increases the throwing power of the coemulsion. Furthermore, at the conditions providing stable coemulsion, the composition of the electrodeposited film is almost equal to the resin composition of the coemulsion. © 1993 John Wiley & Sons, Inc.
Effect of toluene on the polymerization of AN initiated by Ce(IV)–sucrose redox system in the presence of surfactants
Authors: Das H. K. , Singh B. C.
Published: April 2003

The effects of toluene on the kinetics of polymerization of acrylonitrile (AN) initiated by the Ce(IV)/sucrose redox system were studied in the presence of an emulsifier, N‐cetyl‐trimethylammonium bromide (NCTAB) in the temperature range 35–45°C. The effects of concentration of metal ion, monomer, sulfuric acid, substrate (sucrose), emulsifier, toluene, some inorganic salt, and organic solvent on Rp have also been investigated. The remarkable features of the investigation involve the derivation of the rate expression for the above system with the calculation of activation energy. © 1993 John Wiley & Sons, Inc.
An aromatic amine as a co‐curing agent in epoxy‐bisimide blends
Authors: Saraf M. N. , Gupta R. K. , Raman S. V. , Rajagopalan P. T.
Published: April 2003

The structural properties of epoxy can be retained and thermal stability improved by blending epoxy with bismaleimide (BMI) and curing them simultaneously. Depending on the curing agent, the overall viscoelastic properties of the cured material can be varied. In the present work, diaminodiphenylmethane and diaminodiphenyl sulfone have been used as curing agents to prepare blends of epoxy and BMI. The blends were characterized by DSC, TG, DMA, and SEM. Results indicate that an excellent interpenetrating network forms in both the cases and that the DDM‐cured system gives better thermal stability than that of the DDS‐cured system. © 1993 John Wiley & Sons, Inc.
In situ compatibilization of low‐density polyethylene and polydimethylsiloxane rubber blends using ethylene–methyl acrylate copolymer as a chemical compatibilizer
Authors: Santra R. N. , Samantaray B. K. , Bhowmick A. K. , Nando G. B.
Published: April 2003

The effect of the ethylene–methylacrylate copolymer as a chemical compatibilizer in the 50:50 blend of low‐density polyethylene (LDPE) and polydimethylsiloxane rubber (PDMS) has been studied in detail. Ethylene–methylacrylate (EMA) reacted with PDMS rubber during melt‐mixing at 180°C to form EMA‐grafted PDMS rubber (EMA‐g‐PDMS) in situ, which acted as a compatibilizer in the LDPE–PDMS rubber blend. An optimum proportion of the compatibilizer (EMA) was found to be 6 wt % based on results of dynamic mechanical analysis, adhesion studies, and phase morphology. Lap shear adhesion between the phases increased significantly on incorporation of 6 wt % of EMA. Dynamic mechanical analysis showed a single glass transition (Tg) peak at −119°C. This was further supported by X‐ray diffraction studies, which exhibited a remarkable increase in the degree of crystallinity and phase morphology and showed a drastic reduction in the size of the dispersed phase at the optimum concentration of EMA. © 1993 John Wiley & Sons, Inc.
Thermal analysis of poly(vinyl fluoride)
Authors: Hanes Mark D. , Lando Jerome B.
Published: April 2003

A sub‐Tm transition at approximately 50°C in poly(vinyl fluoride) has been attributed to a number of physical factors. We have studied this effect using differential scanning calorimetry. The rate dependence of the endothermic peak at approximately 50°C indicates that it is a second order transition. However, the recovery behavior is time dependent. It is observed in perfect head‐to‐tail, perfectly linear polymer and thus is not a consequence of head‐to‐head or tail‐to‐tail defects or branch points. The transition appears to be a time dependent rearrangement of the polymer chains. © 1993 John Wiley & Sons, Inc.
Thermal decomposition of acrylic–SO2 copolymers
Authors: Tsonis C. P.
Published: April 2003

The oxidative thermal degradation of acrylic–SO2 copolymers was investigated by TG, DTG, and DTA. Their thermograms show that the copolymers decompose in several reaction stages with different weight loss, accompanied by several exo‐ and endothermic effects. Acrylonitrile–SO2 and methacrylate–SO2 copolymers exhibit a two‐stage thermal decomposition, whereas the polysulfones of the acrolein–SO2 and acrylamide–SO2 systems decompose in four stages. Both the number of SO2 units present in the copolymer and the polarity of the pendant group on the organic monomer have some effect on the thermal stability and the glass transition temperature of the polymers. © 1993 John Wiley & Sons, Inc.
The estimation of mechanical properties of polymers from molecular structure
Authors: Seitz J. T.
Published: April 2003

The use of semiempirical and empirical relationships have been developed to estimate the mechanical properties of polymeric materials. Based on these relationships, properties can be calculated from only five basic molecular properties. They are the molecular weight, van der Waals volume, the length and number of rotational bonds in the repeat unit, as well as the Tg of the polymer. Since these are fundamental molecular properties, they can be obtained from either purely theoretical calculations or from group contributions. The use of these techniques by polymer chemists can provide a screening technique that will significantly diminish their bench time so that they may pursue more creatively the design of new polymeric materials. © 1993 John Wiley & Sons, Inc.
Improving graft level during photoinduced graft‐copolymerization of styrene onto cotton cellulose
Authors: Shukla S. R. , Rao G. V. Gopala , Athalye A. R.
Published: April 2003

Styrene was graft‐copolymerized onto cotton cellulose using photoinitiators uranyl nitrate (UN), ceric ammonium nitrate (CAN), and benzoin ethyl ether (BEE) under ultraviolet radiation. UN gave somewhat higher graft add‐on. Preswelling of the substrate or using divinyl benzene in the grafting bath gave an increased level of graft, the later technique being more efficient. The moisture regain and tenacity decreased, whereas thermal stability increased in proportion to the graft add‐on. © 1993 John Wiley & Sons, Inc.
Shellac film coating on metal sheets by electrochemical polymerization
Authors: Bhadani Suraj N. , Kumari Madhuri , Gupta Sumanta K. Sen
Published: April 2003

The electrolysis of shellac in the aqueous ammoniacal solution leads to formation of adherent films onto different metal anodes such as Fe, Cu, Pt, and Pb. The yield of deposited films increases with the time of electrolysis and current levels and is dependent on the nature of electrode materials. Therefore, the film thickness is well controlled by the impressed current level and electrolysis time. The addition of methylacrylamide to the shellac solution gives more adherent and smoother coatings onto the metal sheets than those obtained in the absence of the monomer. The film formation also takes place potentiodynamically. A plausible reaction mechanism of the shellac coating is suggested. © 1993 John Wiley & Sons, Inc.