bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of thermal aging on chemical–physical and electrical properties of poly(propylene terephthalate)
Authors: Saccani Andrea , Motori Antonio , Sisti Laura , Lotti Nadia 
Published: January 2004

AbstractPoly(propylene terephthalate) (PPT) was subjected to aging at high temperatures (150–190°C) in air and some mechanical (impact strength), physical (weight loss), and electrical (dc conductivity and ac electrical strength) properties were determined as a function of aging time and temperature. Some chemical–physical characteristics (such as the average molecular weight, the carboxyl end‐group content, and crystallinity degree) were investigated during the degradation process, as well. From the collected data, the thermal endurance parameters (i.e., the temperature index and the halving interval), which are key parameters in the determination of materials reliability and design of electrical insulating system, were derived according to IEC 216 Standard, and compared with those relevant to other thermoplastic polyesters. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2848–2854, 2004
Numerical modeling of the dynamic tensile behavior of irregular fibers
Authors: He Wendy W. , Wang Xungai 
Published: January 2004

AbstractMost fibers are irregular and are often subjected to rapid straining during mechanical processing and end‐use applications. In this article, the effect of fiber dimensional irregularities on the dynamic tensile behavior of irregular fibers was examined using the finite‐element method (FEM). Fiber dimensional irregularities are simulated with sine waves of different magnitude (10, 30, and 50% level of diameter variation). The tensile behavior of irregular fibers was examined at different strain rates (333, 3333, and 30,000%/s). The breaking load and breaking extension of irregular fibers at different strain rates were then calculated from the finite‐element model. The results indicate that strain rate has a significant effect on the dynamic tensile behavior of an irregular fiber, and that the position of the thinnest segment along the fiber significantly affects the simulation results. Under dynamic conditions, an irregular fiber does not necessarily break at the thinnest segment, which is different from the quasi‐static results. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2855–2861, 2004
Electric studies on polyvinyl alcohol with additions of magnesium sulfate
Authors: Mansour A. B. 
Published: January 2004

AbstractPolyvinyl alcohol (PVA; molecular weight 17,000 g/mol) with additions of several different amounts of magnesium sulfate (molecular weight 246.945 g/mol) was prepared by the casting technique. The dc electric properties of these films were measured in different temperature ranges and the activation energy values as a function of different magnesium sulfate amounts were calculated. The dependency of dc electrical conductivity σdc at a certain temperature was found to fit the well‐known equation σdc = [(1/R) × (t/A)] (Ω−1 m−1). The temperature dependency of σdc, which suggested an electronic hopping conduction mechanism in a thermally assisted electric field, in addition to some theoretical mechanism were discussed. Also the values of activation energy as a function of different amounts of magnesium sulfate were investigated and it was found that the activation energy values for most samples increase with increased amounts of magnesium sulfate. On the other hand, the nonlinear coefficient parameter as a function of the different amounts of magnesium sulfate was investigated for all the prepared samples. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3167–3173, 2004
Predication of critical distance of wall‐slip phenomenon during extrusion of carbon black‐filled natural rubber/cis‐polybutadiene rubber compound
Authors: Liang Ji‐Zhao 
Published: January 2004

AbstractThe wall‐slip phenomenon during extrusion of polymer fluids is an important characteristic of viscoelasticity. The wall‐slip behavior and the factors affecting it for natural rubber (NR)/cis‐polybutadiene rubber (BR) filled with carbon black compound were investigated by using a Monsanto processability tester in a temperature range of 90–130°C and at shear rates that varied from 50 to 103 s−1. Under simplified supposition conditions, a mathematical model for description of the relationship between pressure variation, polymeric properties, and extrusion operation parameters when wall‐slip phenomenon occurs was established by using a tensor analysis method. On the basis of this model, an equation for estimation of critical slip distance (or position) was derived. The results showed that the measured critical pressure drop, when wall‐slip begins to occur, was consistent with the theoretical predictions. The wall‐slip phenomenon of the sample happened near the exit of the die. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3239–3243, 2004
Glass‐transition temperature in the curing process of bismaleimide modified with diallylbisphenol A
Authors: Boey F. , Xiong Y. , Rath S. K. 
Published: January 2004

AbstractThe Tg‐conversion relationship, during the thermal curing of different stoichiometric formulations of 1,1′‐(methylene‐di‐4,1‐phenylene) bismaleimide (BMI), modified with o,o′‐diallyl bisphenol A (DABA), was investigated. The DiBenedetto equation was used to model this relationship for the formulation of DABA‐1 (BMI : DABA, 1 : 1). Based on this model, the Tg‐conversion relationship of formulation DABA‐0.5 (BMI : DABA, 1 : 0.5) was modeled. The high consistency between the model curve and experimental data showed that the change of Tg, attributed to copolymerization between BMI and DABA in DABA‐0.5, in the low‐conversion regime, was the same as that in DABA‐1. This also verifies that, for the formulation DABA‐0.5, copolymerization and homopolymerization do not overlap with each other. The reactions progressed sequentially and homopolymerization occurred after completion of copolymerization. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3244–3247, 2004
Effect of bentonite on the physical properties and drug‐release behavior of poly(AA‐co‐PEGMEA)/bentonite nanocomposite hydrogels for mucoadhesive
Authors: Lee Wen‐Fu , Chen Yung‐Chu 
Published: January 2004

AbstractA series of nanocomposite hydrogels for mucoadhesive were prepared from acrylic acid, poly(ethylene glycol) methyl ether acrylate, and intercalated bentonite clay by photopolymerization. The microstructures were identified by X‐ray diffraction (XRD). Results showed that the swelling ratio for the present nanocomposite hydrogels decreased with an increase of bentonite, whereas the gel strength and Young's modulus of the present gels increased with an increase of bentonite. However, the adhesive force of the present gels did not decrease with an increase of bentonite. XRD results indicated that the exfoliation of bentonite was achieved in the xerogels and swollen gels. Finally, the drug‐release behaviors for these gels were also assessed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2934–2941, 2004
Synthesis and properties of water‐soluble sulfonated acetone–formaldehyde resin
Authors: Pei Meishan , Yang Yongqing , Zhang Xiuzhi , Zhang Jin , Li Yingbo 
Published: January 2004

AbstractWater‐soluble sulfonated acetone–formaldehyde (SAF) resins were synthesized by the reaction among acetone, formaldehyde, and sodium bisulfite. The factors affecting the properties of SAF resins and optimum conditions of preparation were investigated. The SAF resins prepared under proper conditions have good water solubility and high performance as a superplasticizer used in concrete. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3248–3250, 2004
Synthesis of new optically active poly(amide‐imide)s containing EPICLON and L‐phenylalanine in the main chain by microwave irradiation and classical heating
Authors: Mallakpour Shadpour , Reza Zamanlou Mohammad 
Published: January 2004

AbstractEPICLON [3a,4,5,7a‐Tetrahydro‐7‐methyl‐5‐(tetrahydro‐2,5‐dioxo‐3‐furanyl)‐1,3‐isobenzofurandione] or [5‐(2,5‐dioxotetrahydrofurfuryl)‐3‐methyl‐3‐cyclohexyl‐1,2‐dicarboxylic acid anhydride] (1) was reacted with L‐phenylalanine (2) in acetic acid, and the resulting amic acid was refluxed under a Dean‐Stark system with benzene, which produced diacid (3) in high yield. Compound (3) was converted to the diacid chloride (4) by reaction with oxalyl chloride in dry carbon tetrachloride. The polycondensation reaction of this diacid chloride (4) with several aromatic diamines such as 4,4′‐sulfonyldianiline (5a), 4,4′‐diaminodiphenylmethane (5b), 4,4′‐diaminodiphenylether (5c), 1,4‐phenylenediamine (5d), 1,3‐phenylenediamine (5e), 2,4‐diaminotoluene (5f), and 1,5‐diaminonaphthalene (5g) was developed by using a domestic microwave oven in the presence of a small amount of a polar organic medium such as N‐methylpyrrolidone (NMP). The polymerization reactions were also performed under two different classical heating methods: low temperature solution polycondensation in the presence of trimethylsilyl chloride, and high temperature polymerization. A series of optically active poly(amide‐imide)s with moderate yield and inherent viscosity of 0.14–0.22 dL/g were obtained. All of the above polymers were fully characterized by IR, elemental analyses, and specific rotation. Some structural characterization and physical properties of this optically active poly(amide‐imide)s are reported. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3281–3291, 2004
Selection of quaternary ammonium groups for optimizing properties of water‐soluble, photosensitive phenolic resins and study of their postcuring mechanism
Authors: Xie Hong‐Quan , Gao Yu , Zhan Xue‐Gui , Xie Dong 
Published: January 2004

AbstractThis article deals with the selection of quaternary ammonium groups for synthesis of water‐soluble, photosensitive phenolic resins, containing acrylate and different quaternary ammonium salt groups (AQSPRs), via ring‐opening reactions of epoxy phenolic resin (EPR) with acrylic acid and with different tertiary amine‐protonic acid salts. Conversion of epoxy groups, solubility, photosensitive properties, and thermal decomposition of the different AQSPRs were compared. Modification of AQSPR with methanol solution of KOH to form phenolic resin containing both quaternary ammonium hydroxide groups and acrylate groups (AQHPR) was also studied. Characterization by IR spectrum, DSC, and thermal gravimetric analysis was carried out. The results showed that in the synthesis of AQSPRs containing different quaternary ammonium salt groups, the efficiency of ring‐opening reaction of epoxy phenolic resin with tertiary amine salt in terms of conversion of epoxy groups decreases in the following order: for the tertiary amine, N,N‐dimethyl benzylamine (DMBA) > triethylamine (TEA) > trimethylamine (TMA) > N,N‐dimethyl aniline (DMA) > triethanolamine (TENA) > tri(n‐butylamine) (TBA); for the protonic acid, HCl > HBr > HCOOH > HI > NaHSO3 > Cl3CCOOH > HClO4 > HBF4. All the AQSPRs except that from HClO4 can be dissolved in water, methanol, DMF, or DMSO. The gel content formed during UV exposure decreases in the following order of acids used in forming quaternary ammonium salt groups: HCl > HCOOH > NaHSO3 > Cl3CCOOH; or decreases in the following order of tertiary amines or hydrohalic acids used in forming the quaternary ammonium groups: TMA. > TEA > DBMA; HCl > HBr > HI. During thermal decomposition of EPR with about half epoxy groups of EPR ring‐opened with tertiary amine salt at 160°C for 0.5 h, water‐insoluble product was formed. The insoluble content and the % decrease of epoxy groups or halide ions increase in the following order: TMA < TEA < DMBA; HCl < HBr < HI. The % decrease of epoxy groups for the insoluble residue is nearly equal to the % decrease of halide ions. A crosslinking reaction mechanism occurred in the thermal decomposition was thus proposed. During the modification of AQSPR with KOH, conversion of quaternary ammonium chloride groups can reach above 90%. The decomposition temperature of the quaternary ammonium groups was lowered from 204 to 120°C after modification of AQSPR with KOH. The photosensitive properties of the resin after modification became lower. It is better to react DMBA · HCl with EPR so as to obtain a product with higher conversion of epoxy groups, good water solubility, moderate photosensitivity, lower decomposition temperature, and better postcuring. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2914–2922, 2004
Gas permeation through water‐swollen polysaccharide/poly(vinyl alcohol) membranes
Authors: Kim Min‐Joung , Park You‐In , Youm Kyung‐Ho , Lee Kew‐Ho 
Published: January 2004

AbstractThe effect of Na‐alginate content on the gas permeation properties of water‐swollen membranes prepared by varying Na‐alginate and poly(vinyl alcohol) (PVA) content in membranes was investigated. The influences of water content and crystallinity of the membranes on the gas permeation performance of the water‐swollen membranes were studied. The gas permeation rate and selectivity of Na‐alginate/PVA water‐swollen membranes were compared with those of the dry membranes. The permeation rates of nitrogen and carbon dioxide through water‐swollen membranes were in the range of 0.4–7.6 × 10−7 to 3.7–8.5 × 10−6 cm3 (STP)/cm2 s−1 cmHg−1, which were 10,000 times higher than those of dry‐state membranes. The permeation rates of mixture gases through water‐swollen Na‐alginate/PVA membranes were found to increase exponentially with the increase of Na‐alginate content, whereas carbon dioxide concentration in permeates was decreased linearly. It was found that the gas permeance of the water‐swollen membranes increased with increasing the Na‐alginate content in the membrane. Gas permeation rates of the water‐swollen Na‐alginate/PVA membranes increased with increasing the water content in the membrane and decreasing the crystallinity of the membrane. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3225–3232, 2004
Fractionated crystallization of dispersed PA6 phase of PP/PP‐g‐MAH/PA6 blends
Authors: Shi Dean , Yin Jinghua , Ke Zhuo , Gao Ying , Li R. KY 
Published: January 2004

AbstractFractionated crystallization behavior of dispersed PA6 phase in PP/PA6 blends compatibilized with PP‐g‐MAH was investigated by scanning electron microscopy (SEM), differential scanning calorimeter (DSC), polarized light microscopy (PLM), and wide‐angle X‐ray diffraction (WAXD) in this work. The lack of usual active heterogeneities in the dispersed droplet was the key factor for the fractionated crystallization of PA6. The crystals formed with less efficient nuclei might contain more defects in the crystal structures than those crystallized with the usual active nuclei. The lower the crystallization temperature, the lesser the perfection of the crystals and the lower crystallinity would be. The fractionated crystallization of PP droplets encapsulated by PA6 domains was also observed. The effect of existing PP‐g‐MAH‐g‐PA6 copolymer located at the interface on the fractionated crystallization could not be detected in this work. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3742–3755, 2004
Preparation of aqueous dispersible polyurethane: Effect of acetone on the particle size and storage stability of polyurethane emulsion
Authors: Chinwanitcharoen Charoen , Kanoh Shigeyoshi , Yamada Toshiro , Hayashi Shunichi , Sugano Shunji 
Published: January 2004

AbstractAn aqueous dispersible polyurethane was prepared by the reaction of hydroxyl‐terminated poly(ethylene adipate), dimethylol propionic acid, 4,4′‐diphenylmethane diisocyanate, and ethylene glycol. Formation of the dispersion was achieved by phase inversion of an acetone solution of the polyurethane with water, utilizing carboxylate anion groups as the internal emulsifying sites. The amount of acetone added has a large effect on the particle diameter (0.08 to 8.61 μm) and particle size distribution of the polyurethane emulsion. The storage stability was evaluated in terms of particle size distribution breadth. The aqueous emulsion obtained with no use of acetone was sufficiently stable in storage for at least 6 months. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3455–3461, 2004
Tensile and impact properties of carbon filled nylon‐6,6 based resins
Authors: Heiser Jessica A. , King Julia A. , Konell Jeremiah P. , Miskioglu Ibrahim , Sutter Lawrence L. 
Published: January 2004

AbstractElectrically and thermally conductive resins can be produced by adding conductive fillers to insulating polymers. Mechanical properties such as tensile modulus, ultimate tensile stress, strain at ultimate tensile stress, and notched Izod impact strength are also important and cannot be ignored. This study focused on performing compounding runs, followed by injection molding and evaluation of tensile and impact properties of carbon filled nylon‐6,6 based resins. The three carbon fillers investigated include an electrically conductive carbon black, synthetic graphite particles, and a surface treated polyacrylonitrile (PAN) based carbon fiber. Resins containing varying amounts of these single carbon fillers were produced and tested. In addition, combinations of fillers were investigated by conducting a full 23 factorial design and a complete replicate. The addition of carbon fiber increased the composite tensile modulus, ultimate tensile stress, and impact strength. Also, in many cases, combining two or three different fillers caused a statistically significant effect at a 95% confidence level. When comparing the results of this study with prior work, it appears that increased heteroatoms present on the carbon fiber surface likely improve composite ultimate tensile stress and impact strength. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2881–2893, 2004
Interfacial behavior of epichlorohydrin–ethyleneoxide–allylglycidyl ether/fluorinated carbon black observed from mechanical and dielectrical properties
Authors: Katada A. , Shimura T. , Tominaga Y. , Asai S. , Sumita M. 
Published: January 2004

AbstractThe purpose of this work was to study the effect of carbon black (CB) surface state on the interaction between CB and polymer matrix, as well as the polymer chain mobility. The mobility of polymer chain absorbed on the CB surface was estimated by using a dynamic mechanical analyzer and an impedance analyzer. The interaction parameter (B) and immobilized polymer layer thickness (ΔR) were estimated from the dynamic mechanical analysis. It was observed that values of B and ΔR decreased with increasing fluorine content on the CB surface. On the other hand, from the dielectric measurement, the Maxwell–Wagner–Sillars (MWS) relaxation peak, accompanied by migration of the charge carriers, accumulated at the interface between polymer and CB, observed at temperatures higher than the glass‐transition temperature (Tg) of the polymer matrix. The activation energy (Ea MWS), calculated from the relaxation frequency of MWS relaxation, was decreased with increasing surface fluorine content. Good agreement was found between the B and the ΔR values estimated from the dynamic mechanical analysis and the Ea MWS calculated from the MWS relaxation frequency estimated from dielectric measurement. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2928–2933, 2004
Study of progesterone release mechanisms from a silicone matrix by a new analytical method
Authors: Taghizadeh S. Mojtaba , Mashak Arezou , Jamshidi Ahmad , Imani Mohammad 
Published: January 2004

AbstractThe release behavior of progesterone from a silicone matrix to release media containing 60% (v/v) alcohol and water was investigated and kinetically evaluated. For this purpose, samples containing 5, 10, or 15% (w/w) micronized progesterone were prepared through the mixing of two‐component silicone and the drug in a thermomixer. The discs were cured with compression molding. Then, the release from a controlled surface area was experimentally determined by a high‐performance thin‐layer chromatography technique, a new method for progesterone analysis. With Higuchi's model, the drug‐release behavior of the dispersion systems was determined by a partition‐controlled process (the relationship between the accumulated amount of the drug released and the time) and a matrix‐controlled process (the relationship between the accumulated amount of the drug released and the square root of time). The release profile determined by experimental data was in good agreement with Higuchi's model. Moreover, the product of the solubility and diffusivity of progesterone in the polymer matrix was evaluated and found to be 8.1 × 10−7 mg/cm/s. Finally, the effects of fillers on the release behavior were studied. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3040–3044, 2004
Deterioration behavior of cellulose acetate films in acidic or basic aqueous solutions
Authors: Yamashita Yoichiro , Endo Takeshi 
Published: January 2004

AbstractThe deterioration behavior of cellulose acetate (CA) films (degree of substitution = 2.5) was examined in hydrochloric acid (HCl) and sodium hydroxide (NaOH) solutions of various concentrations to determine acid and base catalytic effects in heterogeneous systems at room temperature. With concentrations of 0.5N HCl and 0.01N NaOH and higher, the physical properties of the films changed. The films, recovered after 1–10 days of immersion, were slightly opaque and rubbery from swelling in the solutions before drying. They became brittle and shrank when they dried. For HCl immersion, the weight change of a film depended on the HCl concentration and the immersion time. With 6.0N HCl, the film shape was broken, and a fine powder was deposited in the solution with a recovery of 53.8 wt %. The infrared spectrum of this deposit indicated that it was completely deacetylated cellulose. For NaOH immersion, although the weight change depended on the NaOH concentration, the weight loss reached 40–50% within the first 24 h, and it was constant with respect to the immersion time and base concentration in 0.5N NaOH or NaOH of a higher concentration. The infrared and gel permeation chromatography analyses showed that this deterioration mainly depended on the deacetylation of CA. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3354–3361, 2004
Bismaleimides and biscitraconimides: Synthesis and properties
Authors: Sava M. 
Published: January 2004

AbstractA series of bismaleimide and biscitraconimide compounds with ester units were synthesized by a condensation reaction between 3‐maleimido benzoic acid chloride or 4‐maleimido benzoic acid chloride and citraconimido benzoyl chloride with 4,4‐(hexafluoroisopropylidene)diphenol and 4,4‐hydroxyphenylsulfone. The monomers were characterized by IR, 1H‐NMR, and elemental analysis. Differential scanning calorimetry, thermogravimetric analysis, and isothermal weight loss were performed to evaluate the thermal properties. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3806–3812, 2004
Permeation of chlorinated hydrocarbons through nylon 6/ethylene–propylene rubber blends
Authors: George Soney C. , Ninan K. N. , Geuskens G. , Thomas Sabu 
Published: January 2004

AbstractVapor transport offers one the unique ability to study structure–property relationships in polymers. An analysis of the transport of chlorinated hydrocarbons through nylon/ethylene–propylene rubber (EPR) blend membranes showed us how the permeation behavior varied according to the structure and morphology of the material under study. Binary blends were subjected to solvent transport studies. The solvent uptake increased with EPR content and decreased with nylon content. The behavior varied with the blend morphology. The effects of blend ratio, compatibilization, and dynamic vulcanization on the vapor permeation behavior of nylon/EPR blends were investigated in detail. The results from the vapor permeation studies were complimentary to those of the morphology studies. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3756–3764, 2004