bluuebunny/crossref_metadata_2025 huggingface dataset:
Structure–property relationship in heat‐set poly(ethylene terephthalate) fibers. III. Stress–relaxation behavior
Authors: Gupta V. B. , Ramesh C. , Gupta A. K.
Published: April 2003

Stress–relaxation studies between room temperature and 140°C were made on oriented multifilament poly(ethylene terephthalate) (PET) yarn and on four other samples which had been prepared by heat‐setting this yarn at 180 and 230°C while free to relax and when held taut at constant length. Using the time–temperature superposition principle, the data were superimposed, and the master curves of relaxation modulus were constructed for each sample; the relaxation–time spectra for these samples were computed using the Alfrey approximation. The results revealed that (i) the free‐annealed samples show higher visco‐elasticity than the corresponding taut‐annealed samples and (ii) the relaxation–time spectra show two prominent relaxation processes on logarithmic time scale in the case of all the samples; the two relaxations being more intense in the free‐annealed samples. These observations are interpreted in terms of fiber structure and morphology, which had been studied earlier; the amorphous orientation in the free‐annealed samples is low, and they have a more distinct separation of the crystalline and amorphous phases. These factors facilitate molecular relaxation processes in the non‐crystalline phase; the relaxation are therefore relatively more intense in these samples, and they exhibit more viscoelasticity.
Structure–property relationship in heat‐set poly(ethylene terephthalate) fibers. IV. Recovery behavior
Authors: Gupta V. B. , Ramesh C. , Gupta A. K.
Published: April 2003

This study describes the recovery behavior from tensile strains of up to 0.15, of oriented poly(ethylene terephthalate) (PET) fibers, which were heat‐set at different temperatures while free to relax and when held taut at constant length at room temperature. The taut annealed samples showed superior recovery behavior over the strain range studied. From structural studies on these samples, and also from FTIR studies of structural changes during deformation on similar shapes, it is concluded that, while the recovery behavior in the free‐annealed samples is dominated by the amporphous phase, both the crystalline and the amorphous phases influence the recovery behavior of the taut‐annealed samples.
Surface studies of polystyrene–poly(methyl methacrylate) diblock copolymers precipitated by different precipitants
Authors: Sohn Jeongin , Ree Taikyue
Published: April 2003

Diblock copolymers of polystyrene (PS) and poly(methyl methacrylate) (PMMA) with varying compositions in the mole fractions of PS were prepared, and were obtained in particle state by different methods of precipitation. The morphology of the precipitates was studied by electron spectroscopy for chemical analysis (ESCA), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and viscometry. From these studies it was found that the precipitates of diblock copolymers have core‐micelle structures, the components of the core and the surrounding micelle being different by precipitation histories.
Bimodal crystalline orientation in polypropylene: Mechanism of formation
Authors: Sakthivel A. , Abhiraman A. S.
Published: April 2003

Melt‐spun polypropylene fibers have two sets of crystallites, each with a different preferred orientation. A probable kinetic mechanism of nucleation and growth of the two sets of crystallites, based on an analysis of crystallization in oriented polymers, is proposed. Experimental data on the fractions of these two sets of crystallites in as‐spun fibers and the effect of subsequent drawing or thermal annealing on the relative amounts of these two sets are presented.
Thioetherglycidyl resins. IV. Products of condensation of isomeric di(mercaptomethyl)xylene with epichlorohydrin
Authors: Charmas Władysław , Podkościelny Wawrzyniec
Published: April 2003

Thioetherglycidyl resins produced by condensation of isomeric di(mercaptomethyl)xylene with epichlorohydrin were obtained by heterophase alkaline condensation in water and isopropyl alcohol solution using sodium hydroxide. The structure of thioetherglycidyl resins was determined by elemental analysis, infrared, and NMR spectra, and their physical and chemical properties were defined. Some properties of the resins, cured chemically or thermally with typical for epoxy resins, and thermal and mechanical properties of the cured compounds were determined.
Polymer surface reconstruction by diffusion of organic functional groups from and to the surface
Authors: Gagnon David R. , McCarthy Thomas J.
Published: April 2003

Three nonpolar organic polymers containing small amounts of polar functionality were studied with regard to their surface characteristics. Two of the materials, potassium chlorate/sulfuric acid‐oxidized polyethylene and poly(ethylene‐co‐acrylic acid) display variable surface polarities which can be reversibly accessed by heating films of the polymers in air or aqueous sodium hydroxide. Sodium‐reduced Teflon–FEP did not exhibit this characteristic. A combination of contact angle, ESCA, and ATR IR data are used to display that the surface changes are caused by migration of functional groups within the outer few tens of angstroms of the surface.
Optical characterization of solid‐state coextruded PET
Authors: Sun T. , Kyu T. , Sheng J. , Lefebvre D. , Stein R. S. , Porter Roger S.
Published: April 2003

Amorphous poly(ethylene terephthalate) has been solid state coextruded to a series of draw ratios up to 4.4 at 50, 60, 70 and 90°C. These uniaxially drawn samples have been examined by optical microscopy and light scattering and for increases in crystallinity and birefringence as a function of draw ratio and draw temperature. The birefringence for PET may be among the highest yet reported—0.21.
Thermally induced phase separation in homogeneous blends of poly(2,6‐dimethyl‐1,4‐phenylene oxide) with poly(o‐fluorostyrene‐co‐p‐chlorostyrene) and with poly(o‐fluorostyrene‐co‐o‐chlorostyrene)
Authors: Vuković R. , Kureǎević V. , Karasz F. E. , Macknight W. J.
Published: April 2003

The phase separation behavior of initially compatible blends of poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) with poly(o‐fluorostyrene‐co‐p‐chlorostyrene) [poly(oFS‐co‐pCIS)] and with poly(o‐fluorostyrene‐co‐o‐chlorostyrene) [poly(oFS‐co‐oCIS)] was studied by DSC. It was found that copolymers of poly(oFS‐co‐pCIS) containing between 15 and 62 mol % pCIS have shown no phase separation after annealing at temperatures up to 320°C. It was also observed that blends containing this copolymer with 74 mol % pCIS show phase separation at 250°C, which depended on blend composition. Additionally, all PPO/poly(oFS‐co‐oCIS) blends exhibit phase separation after annealing to a temperature of 230°C. Thermal degradation of the polymer blends was not observed at the temperatures studied.
Characterization of cis‐1,4‐polyisoprene polymerized with lanthanide catalyst system (Ln‐PIR)
Authors: Baogong (Chien, Pao‐Kung) Qian , Fuseng Yu , Rongshi Cheng , Wanjun Ruan Meina Zhang , Shentian Li , Yanshou Zhang , Yuhua Yang
Published: April 2003

The PIR raw rubber samples, Ln–PIR and Ti–PIR, were subjected to molecular characterization, which shows that Ln–PIR contains microgel particles, but the least branching in its macromolecular chains; its cis‐1,4 content is about 96% and molecular weight distribution is rather broad. The value of α in the Mark‐Houwink viscosity equation for molecular weight Mη is determined as 0.70. The abnormal stress–relaxation behavior can be normalized by the introduction of an entanglement reduction factor, e.g., Mη/Mc for maximum relaxation time. This reduction is subsequently verified by evaluating the molecular weight dependence on bulk viscosity with 3.45th power. The starting of a yield process is equivalent to that of a disentanglement process, since both processes have approximately the same activation energy, 8 kJ/mol. For the onset of yield or of entanglement, the critical molecular weight Mc as estimated independently by yield strength method or by relaxation spectrum is equal to (5.4 ± 0.2) × 104. It is confirmed by the reduced yield strength method by calculating Me from the equation Me = 3gNρRT/EeN with gN = 1.22 and then by extrapolation, where EeN is the equilibrium modulus due to entanglement.
Pore size evaluation for fine porous freeze‐dried cellulose acetate membrane by gas separation
Authors: Tanioka A. , Ishikawa K. , Kakuta A. , Kuramoto M. , Ohno M.
Published: April 2003

The pore size for a fine porous freeze‐dried cellulose acetate membrane was evaluated by gas separation methods, where the Present–deBethune equation was applied. Separation coefficients were referred to the calculated value for each pore size from this equation. Nuclepore, Millipore VS, and Millipore VC, whose pore sizes were already known by bubble point method, were tested for this method. Pore diameters for this cellulose acetate membrane, thus determined, were about 25 and 40 Å from Ar–Kr and N2–Kr separation systems, respectively, which agreed well with the results from electron microscope (50 Å) and N2 gas permeability (50 Å). However, it is impossible to apply this method to He gas separation, since He gas permeability is higher than the expected value as Knudsen flow, which indicates that some channels are existing in this membrane, where He gas is more permeable than the other gases.
Modified acrylamide polymers for enhanced oil recovery
Authors: Khune G. D. , Donaruma L. G. , Hatch M. J. , Kilmer N. H. , Shepitka J. S. , Martin F. D.
Published: April 2003

Copolymers of sodium acrylate and N‐methyl‐, N‐isopropyl‐, N‐n‐butyl‐, and N‐t‐butylacrylamide were prepared. The viscosities of these copolymers in 0.01% and 2.00% NaCl and their resistances to shear were compared with those of several partially hydrolyzed polyacrylamides. The poly(N‐alkylacrylamide‐co‐sodium acrylate demonstrated somewhat better retention of viscosity in brine than did analagous partially hydrolyzed polyacrylamides. N‐alkyl substitution increased sensitivity to shear in low salt solutions.
Viscoelastic and thermoelastic properties of general purpose commercial vulcanized natural rubber
Authors: Nishida Noboru , Murai Masaki , Sasaki Naoki
Published: April 2003

Viscoelastic and thermoelastic properties of general purpose vulcanized natural rubber were investigated focusing attention on its nonideal or irreversible natures. The master curve is not composed by simple horizontal shift of stress–relaxation curves at various temperatures by the time–temperature superposition principle. In order to compose a smooth master curve, both horizontal and vertical shifts are necessary. The relative stress–time relation elucidates the fact that the stress–relaxation mechanism is caused by the chemical scission by oxidation occurring in the network system. The value of vertical shift increases with increasing temperature or strain. This phenomenon has the same meaning as the one derived from the relative stress–time relation. The activation energies are calculated using the horizontal shift factors determined empirically. The result suggests the existence of two concurrent relaxation mechanisms with different activation energies. From the stress–temperature relation at any given strain, energetic and entropic components of the stress–strain curve are obtained. The energetic component is very significant as compared with the case of ideal crosslinked natural rubber. This phenomenon is considered to be caused by the internal friction and/or chemical scission of bonds in the system associated with the deformation process of sample.
Estimation of molecular weight averages from intrinsic viscosity
Authors: Chee K. K.
Published: April 2003

The weight‐average molecular weight is estimated by an extrapolation technique based on a linear relation between the viscosity‐average molecular weight Mv and a Mark–Houwink–Sakurada constant. This method may also be used to assess the unperturbed dimensions of polymers. If the Mv data are known with high accuracy, then the straight line may be stretched to reach the number‐average molecular weight confidently. The slope of the linear plot is associated with the molecular weight distribution and as such can be utilized to compute the polydispersity index.
Mechanism of void formation in cable covering
Authors: Titomanlio G. , Piccarolo S.
Published: April 2003

Solidification after extrusion of coaxial cables has been experimentally simulated. Solidification tests were performed with two HDPE grades and under several pressures; the extrusion velocity was varied in a suitable range so as to detect the critical velocity for void formation. A qualitative analysis of the void formation mechanism is carried out, and the predicted trends favorably compare with the critical velocity data.
High temperature GPC of polypropylene
Authors: Grinshpun V. , Rudin Alfred
Published: April 2003

The highest temperature at which molecular weight distributions can be characterized by current techniques is 145°C. Supermolecular aggregates may exist at this temperature in polypropylene solutions in trichlorobenzene and other solvents. Dissolution procedures at higher temperatures are ineffective in this case because of the limited thermal stability of polypropylene. Aggregate‐free solutions can be prepared, however, by controlling storage times at 145°C in mixtures with added stabilizers. Low angle laser light scattering measurements can be used to determine when true solutions have been produced. This occurs when measured second virial coefficients agree with values predicted for the Mw measured in the light scattering experiment. GPC–LALLS measurements of Mw and Mz provide similar information about the effects of storage time on dissolution of aggregates and polymer degradation.
Blends of nylon 6 with an ethylene‐based multifunctional polymer. I. Rheology–structure relationships
Authors: Han Chang Dae , Chuang Hsiao‐Ken
Published: April 2003

An experimental study was conducted to investigate the rheological behavior of a heterogeneous polymer blend system consisting of nylon 6 and an ethylene‐based multifunctional polymer (CXA 3101, DuPont Co.). For comparison purposes, we also investigated the rheological behavior of two additional blend systems, namely blends of nylon 6 with a chemically modified polyolefin (Plexar 3, Chemplex Co.) and blends of nylon 6 with ethylene–vinyl acetate copolymer (EVA). We have investigated the thermal and thermomechanical behavior of the blend systems, using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Also, we have attempted to identify the chemical structure of the functional groups present in the CXA 3101 and Plexar 3 resins, using infrared (IR) spectroscopy. This information has enabled us to interpret the observed rheological behavior. Furthermore, we have used both optical and scanning electron microscopies to investigate the state of dispersion of the constituent components in each of the blend systems. We have concluded that, during melt blending, chemical reactions have taken place between carboxyl or anhydride groups present in the CXA 3101 resin and the amino end groups of the nylon 6, forming a graft copolymer which then acted as an “interfacial agent.”
The effect of hygrothermal fatigue on physical/mechanical properties and morphology of neat epoxy resin and graphite/epoxy composite
Authors: Mijović Jovan , Lin King‐Fu
Published: April 2003

The effect of moisture absorption, desorption, and thermal spiking on the physical/mechanical properties of TGDDM/DDS epoxy resin was investigated and compared to the Gr/Ep composite. The mechanism of moisture diffusion in the neat resin was described on the morphological level. The diffusion rate of moisture in epoxy resin was found to depend on the mobility of molecular chains within an inhomogeneous epoxy network. Two well‐known concepts of plasticization of amorphous polymers, the lubricity theory and the gel theory, were invoked to describe the interactions between the absorbed moisture and the resin network. Slight permanent changes in properties of the neat resin were observed after one absorption‐desorption cycle. In the thermal spiking experiment, only the spiking temperature above the glass transition of the moisture saturated epoxy resins changed their internal structure and produced very small (thin) microcracks. By comparison with the neat epoxy resin, the Gr/Ep composites contain the reinforcement‐matrix boundary region, characterized by the highest restrictions to molecular mobility. The absorbed moisture during the static hygrothermal fatigue cannot effectively plasticize this region. But during thermal spiking, the formation of microcracks is observed within the reinforcement‐matrix boundary region as well as an increase in the moisture content.
Structure development in melt spinning poly(vinylidene fluoride) fibers and tapes
Authors: Wang Yimin , Cakmak Mukerrem , White James L.
Published: April 2003

A series of poly(vinylidene fluoride)s of varying molecular weight have been melt spun to form fibers and tapes. These have been characterized with wide angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC), birefringence, and small angle light scattering (SALS). WAXD and DSC have detected both the α and β crystal structures in melt spun fibers with the relative amount of β increasing with drawdown stress. WAXD and birefringence have been used to detect orientation in the fibers. Hermans–Stein orientation factors have been computed for the α‐phase as a function of drawdown stress. Superstructure has been investigated using SALS. The mechanical properties of fibers have been determined with a tensile testing machine and correlated with orientation and spinline stress.
Relationships between structure and mechanical properties of rubber‐modified epoxy networks cure with dicyanodiamide hardener
Authors: Bartlet Philippe , Pascault Jean‐Pierre , Sautereau Henry
Published: April 2003

Epoxy network systems based on DGEBA and dicyanodiamide (DDA) and modified with a low molecular weight rubber (CTBN) were prepared and characterized. The kinetics of the adduct formation is followed using GPC analysis. The phase separation of the rubber phase is evidenced with DSC and SEM for all samples up to 20% CTBN. The GPC analysis of the soluble fraction demonstrates a chemical modification of the network. The mechanical properties and specially the impact strength behavior are enhanced with CTBN, but exhibit a maximum for 15% CTBN. In connection with SEM of fracture surfaces, these results are discussed and both modification of the rubber morphology and decrease in crosslinking density are taken into account.
Amidoxime‐group‐containg adsorbents for metal ions synthesized by radiation‐induced grafting
Authors: Okamoto J. , Sugo T. , Katakai A. , Omichi H.
Published: April 2003

Amidoxime‐group‐containing fibrous adsorbents for metal ions were synthesized by radiation‐induced grafting of acrylonitrile followed by amidoximation of cyano groups with hydroxylamine. The degree of amidoximation and the distribution of amidoxime groups in the fiber were follwed by means of electron probe X‐ray microanalysis. The efficiency of adsorbing metal ions was increased by alkaline treatment of the adsorbent at high temperature for a short period before use. The order of adsorption for various bivalent metal ions was Hg > Cu > Ni > Co > Cd. From the distribution pattern of metal ions in the fibrous adsorbent, the adsorption was found to be controlled by the diffusion of the solution containing metal ions inside the adsorbent. It was found that confining amidoxime groups superficially and making short chain length of grafts were effective to obtain a high degree of adsorption.
The differential viscometer. I. A new approach to the measurement of specific viscosities of polymer solutions
Authors: Haney Max A.
Published: April 2003

A new type of solution viscometer is described that measures the specific viscosity directly. This is accomplished with a balanced network of four capillaries arranged in a manner analogous to a Wheatstone bridge. A differential pressure transducer measures the increase in pressure across the bridge when a solution is injected into one of the capillaries while solvent flows continuously in the other three capillaries. The differential pressure is proportional to the specific viscosity of the solution. The differential viscometer is about 10 times more sensitive than a conventional glass tube viscometer, permitting precise measurements of specific viscosities of 0.01 or less. The measurements are also inherently fast, averaging about 3 min per sample. Precision is about 1% RSD. Accuracy was investigated by running standard solutions of sucrose in water, polystyrenes in toluene, and polyethylenes in decalin. The agreement was within 2–3% of the standard values in most cases.
Infrared spectra of poly(ethylene terephthalate) yarns. Fitting of spectra, evaluation of parameters, and applications
Authors: Heuvel H. M. , Huisman R.
Published: April 2003

A quantitative model for fitting infrared spectra of polyethyleneterephthalate samples over the region from 1100 to 720 cm−1 has been evaluated. The absorbance was described as the sum of a linear base line and a set of symmetrical bell‐shaped Pearson VII curves. Using this model, experimental transmission spectra of yarns, measured with the electric vector parallel and perpendicular to the fiber axis, were fitted. It was found that each of the trans bands near 972 and 845 cm−1 consists of two components, a narrow and a broad one. These two components represent the crystalline and amorphous phases respectively. The band due to the out of plane benzene ring CH deformation vibration at about 875 cm−1 appeared also to be composed of two contributions. In this case, the narrow component was found to be due to molecules having interactions with direct neighbors. So this narrow component not only contains the molecules in the crystalline phase but also those forming part of bundles which are too small to be detected by x‐ray diffraction. For a detailed insight into the molecular arrangement of the amorphous regions, the infrared detection of trans‐guache transitions, fold content, detection of bundlelike structures, and molecular stress on tie molecules turned out to be of great practical importance. The structural details, which can be revealed by the infrared technique, cannot be obtained by other means. The potential of the method is illustrated with some practical examples.
“Equatorial small‐angle x‐ray scattering study of porosity and pore‐size distribution in polyester and their influence on dyeing behavior”
Authors: Kulshreshtha A. K. , Rao M. V. S. , Dweltz N. E.
Published: April 2003

For explaining the dyeing behavior of polyester (PET) fibers, the important role played by pores has been speculated upon in modern dyeing theories. In the present work, an attempt has been made to characterize the pore size spectrum in morphologically very different PET fibers by means of equatorial small‐angle X‐ray Scattering (SAXS). The analysis of the scattering curves reveals that all the samples analyzed in the present work have a two‐phase structure, consisting of pores of widely different sizes dispersed within a matrix of the polymer network. This polydispersity of pore sizes is revealed from Guinier plots, as well as from an analysis of intensities in the tail of the scattering curves, which are found to obey Porod's Law. Estimates have been made of pore radii, pore concentration in the substrate, and specific surface. The pore size distribution function has been obtained using a new procedure. Various parameters of the pore size spectrum are discussed in relation to the morphological structure of fibers, as well as their significance to dyeing. The diffusion behavior of solvent molecules within PET is also discussed.
Effect of curing agents on some properties of a polysulfide sealant
Authors: Ramaswamy R. , Achary P. Sasidharan
Published: April 2003

The effect of curing agents on the properties of a polysulfide sealant composition was investigated. Commercially used curing agents, namely, lead dioxide, manganese dioxide, and ammonium dichromate, were selected for this study. It was established that curing agents affect joint strengths, stress–strain properties, dynamic mechanical properties, and thermal stability of the sealant. Sealant cured with ammonium dichromate had highest shear bond strength, ultimate tensile strength, modulus, and thermal stability, whereas these properties were lowest for lead‐dioxide‐cured sealant. Peel bond strength and elongation at break were highest for lead‐dioxide‐cured sealant. The observed changes in properties were attributed to the difference in crosslink density of the cured sealant, produced by the curing agents. The curing agents have no appreciable effect on the fuel resistance of the polysulfide sealant.
Polyacrylic acid macromolecule—complexed zinc phosphate crystal conversion coatings
Authors: Sugama T. , Kukacka L. E. , Carciello N. , Warren J. B.
Published: April 2003

When water‐soluble polyacrylic acid (PAA) macromolecules are introduced into zinc phosphating liquids, significant improvements in the yield of conventional zinc phosphate conversion films deposited on carbon steel surfaces are obtained. The improvements include controllability of crystal dimensions, degree of crystallinity, and coating weight. The conversion layer formed is a composite microstructure consisting of a bulk PAA polymer and complexed PAA continuously overlaying a uniform array of fine dense zinc phosphate crystals. Interfacial studies of the composite layer using infrared spectroscopy, energy‐dispersive X‐ray spectrometry associated with scanning electron microscopy, and X‐ray photoelectron spectroscopy indicated that the functional carboxylic acid groups in the PAA molecules were strongly chemisorbed by the Zn atoms at the outermost surface sites of the crystal layers. The intermolecular bridging action of the surface Zn atoms which connect the PAA and the zinc phosphate crystal layers results in good adhesion at the PAA–crystal interfaces. In addition, the plasticized complex formation plays an essential role in increasing the stiffness and the ductility of the normally conventional crystal films. The flexibility of the complex coating surface and the thickness and surface roughness of the thin PAA overlayer all affect the adhesive force at the interface between the organic polymer topcoat and the complexed coating.
The application of coherent optics to the study of adhesive joints. I. Speckle photography
Authors: Vallat M. F. , Martz P. , Fontaine J. , Schultz J.
Published: April 2003

A new technique of coherent optics, speckle photography, has been applied to the study of the behavior of adhesive joints under shear stress. This technique allows the determination of the in‐plane motion by a point‐by‐point analysis with a sensitivity of about 3 μm. This property has been used to measure the interfacial displacement of model glass‐glass joints bonded by different types of adhesive when submitted to shear. The experimental results permit direct verification of Volkersen's theory as well as the determination of the actual shear modull of the thin adhesive layer. The simplicity of use and interpretation of the technique of speckle photography should lead to significant application of this method in the future for the study of adhesive joints.
Plasma surface modification of polymer powders with application to thermal energy storage
Authors: Loh In‐Houng , Cohen R. E. , Baddour R. F.
Published: April 2003

The rotating bed plasma reactor described here permits uniform surface modification of relatively large amounts of powder materials. Scale‐up to even larger batches of solids appears to be feasible. Some preliminary experimental data on the plasma surface modification of polymer powders have been presented. The results show that the flow rate, time of treatment, and type of feed gas are important operating parameters which influence the final surface character. One particular application of plasma‐modified polymer powders was explored; by crosslinking and/or chemically modifying only the outermost surface regions of these powders, various polymeric materials may be rendered useful for use in thermal storage slurries. The major advantage of the surface‐modified plasma treated powders over the bulk‐modified powders used previously is the retention of essentially all of the pristine polymer heat of fusion in the surface‐modified materials.
Analysis of nonsolvent–solvent–polymer phase diagrams and their relevance to membrane formation modeling
Authors: Yilmaz L. , McHugh A. J.
Published: April 2003

Calculations have been carried out, based on Flory–Huggins solution theory, to analyze the behavior of the ternary nonsolvent–solvent–polymer phase diagram for typical membrane‐forming systems. Consideration is given to the behavior of the spinodal as well as binodal curves, tie‐line slopes, and critical points as a function of various parameters, most especially those related to the concentration dependency of the interaction parameters. Implications regarding membrane structure formation are discussed, and the suitability of different functional forms for the interaction parameter concentration dependence is also analyzed.

The net result of these calculations is to demonstrate the importance of the various parameters in controlling the phase‐diagram behavior and particularly to show the critical role of the concentration dependence of the solvent–polymer interaction parameter in affecting the nature of the miscibility gap.
Dielectric studies of the cure of epoxy matrix systems
Authors: Lane John W. , Seferis James C. , Bachmann Michael A.
Published: April 2003

Dielectric spectroscopy was used to monitor the curing process of two epoxy resin systems. The basic system (system I) consisted of DGEBA (a difunctional epoxy) and a polyamide in a 50–phr mixture. In addition, a comparative analysis was performed on a high–performance resin system (system II) used primarily in unidirectional composite applications. This system contained TGDDM (a tetrafunctional epoxy) and DDS (a tetrafunctional amine) in a 25–phr mixture. The dielectric data were obtained using a simple yet functional sample cell electrode designed and constructed in the laboratory. For system I, isothermal dielectric data were used to determine apparent activation energies for the temperature range from 22 to 70°C. The data showed that the activation energy was a function of temperature and increased as the temperature of the cure increased. This indicated that the reaction mechanism was also a function of temperature. For system II, data were collected between 140 and 190°C and an overall activation energy for that temperature range was determined. The overall activation energies for both systems, calculated using dielectric spectroscopy, compared favorably to those obtained using differential scanning calorimetry. Also, using a wider frequency range (240 Hz to 2 MHz), Argand diagrams were constructed and modeled with the Cole–Cole empirical equation for systems with a distribution of relaxation times. This justified the calculation of average relaxation times, which could then be related to the bulk physical properties of the polymer, such as viscosity. Modified Argand diagrams, where ε″ is plotted against ε′ at one frequency as a function of time, were also constructed, which aided in the understanding of the curing processes for these thermosetting systems.
Studies on chitin. IX. Crosslinking of water‐soluble chitin and evaluation of the products as adsorbents for cupric ion
Authors: Kurita Keisuke , Koyama Yoshiyuki , Taniguchi Akihiko
Published: April 2003

Water‐soluble chitin was successfully crosslinked to varying extents with glutaraldehyde in homogeneous aqueous solutions to improve the properties as an adsorbent for metal cations, and the effects of crosslinking were discussed. Complete insolubilization was achieved with the fivefold excess aldehyde, but, in terms of adsorptivity of Cu2+, the chitin crosslinked at an aldehyde/amino group ratio of 1.0 was found to exhibit remarkable capacity and was much superior to others. The desorption of Cu2+ from the adsorption complex was also attained effectively at pH 2.0. These results indicated that the loose crosslinking was quite simple and efficient to produce high capacity adsorbents for practical use. Thermal behavior of the crosslinked chitin was examined by TMA and TGA; a softening phenomenon was observed at 145°C.
Static tensile and dynamic mechanical properties of hydroxypropylcellulose films prepared under various conditions
Authors: Suto Shinichi , Kudo Masataka , Karasawa Mikio
Published: April 2003

The films of hydroxypropyl cellulose (HPC), which is a lyotropic and thermotropic liquid crystal, were cast under various conditions of temperature and concentration. The effects of the casting conditions on the static tensile and dynamic mechanical properties of the cast films were determined, and the results were compared with those of films prepared by means of hot compression. The tensile properties of the films prepared by both processes (cast and hot compression) were unsatisfactory in comparison with other liquid crystalline polymers, and this was partly due to water absorbed during the test. In dynamic properties, two distinct transitions were detected. The higher one, around 110°C, was associated with the rotation of an unhydroglucose ring and the lower one, around 25°C, was associated with the Tg. There were no marked differences in the properties between cast films and hot‐compressed films, except the disappearance of the Tg for hot‐compressed film prepared at a relatively higher temperature. The basis for defining the liquid crystalline structure in cast and hot‐compressed films are not directly given in this preliminary paper. However, judging from the dynamic mechanical properties and refractive index data for films prepared by both processes, it appears that dimethylacetamide‐cast films and films compressed at 180 and 200°C may have some structures related to liquid crystalline phase and that inter‐ and intramolecular hydrogen bonding play an important role in lyotropic and thermotropic liquid crystalline behavior for HPC.
Effect of temperature on the soda and kraft cooking of corn stalks
Authors: Nagieb Zeinat A.
Published: April 2003

This study included soda and kraft process of corn stalks at constant active alkali, the kraft liquor having 25% sulfidity. Five cookings were made at different temperatures, 80, 120, 140, 160, and 180°C, each for 1 h. Under the condition of the study the following temperature effects were noted: (1) Delignification could be approximated by a first‐order reaction. (2) The kraft process exhibited twice the rate of lignin removal as the soda of the same digestion temperature. (3) The rate of removal of carbohydrates in the kraft process is faster than soda process due to presence of sulfide ion. (4) The carbon content of thiolignin increased hydrogen and oxygen content decreased while in soda lignin the opposite occurs. (5) The amount of phenolic OH increased with increasing the cooking temperature and was more noticeable in thiolignins than in soda lignins. (6) Demethoxylation occurs in kraft cooking at elevated temperature rather than soda cooking.
Cold‐drawing behavior of naturally aged poly(ethylene terephthalate)
Authors: Avramova N. , Fakirov S. , Schultz J. M.
Published: April 2003

The cold‐drawing behavior of naturally aged poly(ethylene terephthalate) (PET) is investigated and an attempt is made to compare the mechanical behavior of unaged commercial PET and material which has been naturally aged for 11 years. Mechanical, viscometric, DSC and IR measurements are applied. The previously observed unusual ability of fresh PET bristles to be cold drawn up to 15:1 is not achieved for the naturally aged material. This fact is related to chemical cross‐linking occurring on the surface of bristles after drawing and thermal treatment. The cross‐linked skin is unsoluble, infusible, and uncrystallizable. The natural aging defeats the ability of PET to respond to external treatments which would otherwise change the internal structure. Such a “stabilization” of material properties is a result of the transformation, during natural aging, of the original physical network into a chemical network consisting of covalent bonds.
Chelating polymer bearing triazolylazophenol moiety as the functional group
Authors: Onari Yasuo
Published: April 2003

The chelating polymer‐bearing triazolylazophenol moiety as the functional group was synthesized, its metal adsorption properties for 6 divalent heavy metal ions; Co2+, Ni2+, Cu2+, Zn2+, Cd2+, and Pb2+ were investigated. The capacity of the polymer for Cu2+ achieved 8.7 mEq/g in pH 5.3 solution. The polymer showed remarkable color changes from orange to red violet or blue violet with its chelations to the heavy metal ions. The metal adsorption rates of the polymer were rapid in performing complete capacity saturation of heavy metal ions in about 30 min. The capacities varied little the presence of alkali or alkaline earth metal ions in solutions. The perfect elimination of metals from the polymer–M2+ chelates were performed with mineral acid solutions. The metal ions; Cu2+ and Ni2+ in plating‐process solutions were effectively removed by the chelating polymer, and the polymer can be practically used for the removal of these ions from waste water.
Gas chromatographic determination of acid‐catalyzed transesterified antioxidant additive irganox 1076® in polypropylene
Authors: Hayashi Hiromichi , Matsuzawa Shuji
Published: April 2003

The transesterification by means of methyl alcohol of a low vapor pressure antioxidant additive, n‐octadecyl‐β‐(3,5‐di‐tert‐butyl‐4‐hydroxyphenyl)propionate‐Iraganox 1076® (produced by Ciba‐Geigy) was studied. The classical method to prepare methyl esters from triglycerides in lipids was applied with use of sulfuric acid as a catalyst. The optimum reaction conditions were sulfuric acid concentration of 1 w/v% in methyl alcohol, temperature of 75°C, and time of 2 hours. The contents of the additive were determined by gas‐liquid chromatography (GLC) of a portion of transesterificate using 10% SE‐30 on Gaschrom Q (60–80 mesh) or 5% Silicone OV‐17 on Shimalite W (80–100 mesh) as a packing reagent. Irganox 1076 in polypropylene was extracted with n‐hexane. Many interfering substances in the GLC could be completely removed by the Florisil column treatment of n‐hexane extract. The relative standard deviation was 2.7% for Irganox 1076 at levels corresponding to 0.0142 wt% in polypropylene. The limit of detection was 5 μ/g in polypropylene.
Effect of nucleating agents on the temperature‐dependent melt crystallization kinetics of poly(1‐butene)
Authors: Icenogle R. D. , Chatterjee A. M.
Published: April 2003

The effect of additives (mostly nucleating agents) on the crystallization rate of isotactic poly(1‐butene) has been investigated by differential scanning calorimetry. Isothermal crystallization half‐times and crystallization temperatures have been measured for polymer‐additive blends. The crystallization temperature and the cooling rate at which the ultimate fraction transformed becomes less than 1 is calculated as a function of nucleation density, and this is used to characterize the effect of the additives on crystallization rate. The relationship between the isothermal crystallization half‐time and the crystallization temperature is also calculated theoretically and is compared with experimental results.
Rheological measurements of cure rate of UV inks
Authors: Otsubo Yasufumi , Amari Takeshi , Watanabe Koichiro
Published: April 2003

The dynamic viscosity of UV inks during curing was measured at various film thickness using an oscillating plate rheometer. Logarithmic plots of the dynamic viscosity versus exposure energy are closely related by two‐straight lines. A useful concept in discussing the curability is the minimum exposure energy difined as the exposure energy at the intersection of two lines. On exposure to a monochromatic light of 365 nm, the minimum exposure energy increases exponentially with film thickness; this resulting from an exponential decay of the light intensity with depth in the film. Magenta ink shows the fatest cure rate at a given thickness, followed by yellow, cyan, and black inks in that order. The difference in cure rate is attributed to different absorbances of pigments. The UV curability on direct exposure to UV lamp is predicted from the spectral sensitivity of the photoinitiator and the viscosity data obtained during curing under 365 nm light. The model calculation shows good agreement with the experimental results.
Preparation of cellulose graft copolymers having polypeptide side chains and their blood compatibility
Authors: Miyamoto Takeaki , Takahashi Shin‐Ichi , Tsuji Sin‐Ichi , Ito Hiraku , Inagaki Hiroshi , Noishiki Yasuharu
Published: April 2003

Blood compatibility of cellulose graft copolymers with poly(γ‐benzyl‐L‐glutamate) and poly(N5‐2‐hydroxyethyl‐L‐glutamine) (Cell‐g‐PBLG and Cell‐g‐PHEG) was examined in vivo blood tests. For this purpose, Cell‐g‐PBLG graft copolymers with PBLG contents ranging from 7 to 60 mol % were prepared by polymerizing N‐carboxy‐γ‐benzyl‐L‐glutamate(γ‐BLG NCA) using aminoethyl cellulose (AE‐Cell) with degree of substitution of 0.05 as macroinitiator. Graft copolymerization was carried out under a variety of conditions at 20°C in dimethyl‐sulfoxide. Monomer conversion higher than 60% were obtained for all the polymerization runs. The solubility tests revealed that all of the AE‐Cell and the polypeptides formed were grafted. The Cell‐g‐PHEG graft copolymers were prepared by treating Cell‐g‐PBLG graft copolymers with 2‐amino‐1‐ethanol. Characterization of these graft copolymers were carried out by IR spectroscopy, DSC, and water content measurement. Tests for blood compatibility, in vivo, were made by a method of peripheral vein indwelling suture which was developed by one of the authors. The coating of graft copolymers on the polyester suture was made by casting either from formic acid solution of LiCl/dimethylacetamide solutions using water as the regenerating medium, and the polymer‐coated sutures were implanted into a jugular and femoral vein of a dog. The results showed that the graft copolymers examined have excellent antithrombogenic properties.
Thermal degradation of cellulose model compounds in inert atmosphere
Authors: Šimkovic Ivan , Ďurindová Mária , Mihálov Vincent , Königstein Jozef , Ambrovič Peter
Published: April 2003

Thermal degradation of cellulose model compounds was studied using thermogravimetry (TG), electric spin resonance (ESR) spectroscopy, and gas chromatography–mass spectrometry (GS–MS). The molecular weight of samples did not influence the activation energy of gasification. In the case of catalytic influence of NaOH on cellulose thermolysis formation of gaseous products in the temperature range 250–350°C increased and a greater amount of residue was formed at 350–400°C compared to noncatalytic thermolysis. Residues of compounds with hemiacetal groups showed higher concentration of unpaired electrons than residues obtained from models with the blocked hemiacetal group.
Calendering of non‐newtonian fluids
Authors: Wan Daud Wan Ramli
Published: April 2003

The calendering of non‐Newtonian fluids by two rotating cylinders to produce thin films of fluids finds wide application in polymer sheet‐making and food‐drying industries. Theoretical work has previouly been devoted to the symmetrical case where the cylinders are of equal diameters rotating at the same speed. The present work proposes a new one‐film theory of calendering of power law fluids for unequal radii and surface velocities of the calendering cylinders. The relationship between the dimensionless thickness of the calendered fluid, Δe* and that of the incoming fluid, Δi* is shown to be a function of the ratio of the surface velocities of the cylinders and the power law index. The result further shows that Δe* tends to asymptote after the second decade of Δi*
Determination of intrinsic viscosity by single specific viscosity measurement
Authors: Rao M. V. Ram Mohan , Yaseen M.
Published: April 2003

Single point determination of intrinsic viscosity saves considerable amount of time, effort and materials. Quite a few equations are available in the literature which require relative viscosity of the polymer solution at a single concentration for calculation of [η]. A comparative assessment of the applicability of two such equations and that of a proposed one has been made by using reported data as well as the practical data on viscosity of alkyd solutions in different solvents. It is inferred from the findings that, for good results from single point methods, the concentration should not be the sole criterion, as suggested by earlier workers; ηsp may also be considered as one of the criteria. The single point technique is found to be applicable to alkyd solutions in different solvents.
Residual stresses and birefringences in large, quenched samples
Authors: Lee Sangmoon , De La Vega Javier , Bogue Donald C.
Published: April 2003

As large polymer samples are quenched rapidly, residual stresses (and birefringence) are frozen into the final part due to the different thermal/contraction histories of the surface and center portions. The present work on polystyrene, a continuation of earlier studies, deals with the effects of sample size and initial temperature; these results are treated with the genral theory of Lee, Rogers, and Woo. Finally, data for two other amorphous polymers, poly(methyl methacrylate) and polycarbonate, are presented; in these cases the simpler theory of Aggarwala and Saibel is used. The theories help explain the relative behavior of the three materials and are qualitatively useful. However, the compexity of the rheooptical response precludes doing a completely rigorous treatment.
Studies on NBR/PVC blends
Authors: George K. E. , Joseph Rani , Francis D. Joseph
Published: April 2003

Studies conducted on butadiene–acrylonitrile copolymer (NBR)/poly(vinyl chloride) (PVC) blends at different temperatures indicate that an optimum temperature exists for the formation of a particular blend. The mechanical properties of the blends confirm this observation. PVC stabilizer based on magnesium oxide, zinc oxide, and stearic acid was found to be very useful in NBR/PVC blends.
Time‐dependent changes in morphology of neat and reinforced epoxy resins part I. Neat epoxies
Authors: Mijovic Jovan , Lin King‐Fu
Published: April 2003

An investigation was conducted of the morphological changes in neat epoxy resins after cure, that is, during cooling and subsequent “annealing” at a temperature below the glass transition. A series of bifunctional and tetrafunctional epoxy formulations were prepared and studied. A simultaneous drive toward thermodynamic equilibrium (homogeneity) and morphological inhomogeneity was found to take place in the glassy network. A conceptual model was advanced to explain the time‐dependent development of inhomogeneous morphology in the glassy state. After a certain sub‐Tg annealing time, “morphological equilibrium” is reached while physical aging of the glassy network (decrease in enthalpy and/or free volume) continues to occur. The proposed model, based upon the variation of contractive forces throughout the epoxy network, was corroborated by experimental evidence obtained from calorimetric and viscoelastic measurements and electron microscopy.