bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rheological and thermal properties of single‐site polyethylene blends
Authors: Chen Fei , Shanks Robert A. , Amarasinghe Gandara 
Published: January 2005

AbstractBranched polyethylenes, low‐density polyethylenes (LDPE1 and LDPE2) or long‐chain‐branched very low density polyethylenes (VLDPE2), were blended with very low density polyethylenes containing short branches (VLDPE1 and VLDPE3). The rheological and thermal measurements of the pure copolymers and their blends (VLDPE1–LDPE1, VLDPE1–LDPE2, VLDPE1–VLDPE2, and VLDPE2–VLDPE3) were taken by controlled stress rheometry and differential scanning calorimetry, respectively. The shear‐thinning effect became stronger with increasing long‐chain‐branched polymer compositions when it was correlated with the flow behavior index, and the extent of shear thinning was different for each blend set. Stronger shear thinning and a linear composition dependence of the zero‐shear viscosity were observed for the VLDPE1–LDPE1 and VLDPE1–LDPE2 blends. These blends followed the log additivity rule, and this indicated that they were miscible in the melt at all compositions. In contrast, a deviation from the log additivity rule was observed for the VLDPE1–VLDPE2 blend compositions with 50% or less VLDPE2 and for the VLDPE3–VLDPE2 blends with 50% or more VLDPE2. The thermal properties of the blends were consistent with the rheological properties. VLDPE1–LDPE1 and VLDPE1–LDPE2 showed that these blends were characteristic of a single‐component system at all compositions, whereas the phase separation (immiscibility) was detected only for VLDPE1–VLDPE2 blends with 50% or less VLDPE2 and for VLDPE3–VLDPE2 blends with 50% or more VLDPE2. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1549–1557, 2005
Morphology and mechanical properties of polyamide 12 blends with styrene/ethylene–butylene/styrene rubbers with and without maleation
Authors: Jose S. , Thomas S. , Lievana E. , Karger‐Kocsis J. 
Published: January 2005

AbstractBlends of polyamide 12 (PA12) with styrene/ethylene–butylene/styrene (SEBS) and maleic anhydride grafted SEBS (SEBS‐g‐MA) were prepared by twin‐screw extrusion and injection molding. The morphology, mechanical properties, and dynamic mechanical properties of the blends were studied. The morphology of the blends was evaluated from the etched surfaces of cryogenically fractured specimens with scanning electron microscopy. The morphological parameters showed that the PA12/SEBS‐g‐MA blends (PM series) exhibited a finer and more uniform rubber dispersion than the PA12/SEBS blends (PS series) because of the interfacial chemical reactions. SEBS functionalization via maleic anhydride grafting strongly affected the morphological parameters, such as the domain size, interfacial area per unit of volume, and critical interparticle distance, but the distribution of the rubber domains in the blends was less affected. Tensile and impact studies showed that the PS blends had worse mechanical properties than the PM blends. The tensile strength and elongation at break of the PM blends were considerably greater than those of the PS blends. The fracture toughness and energy values determined for notched Charpy specimens in high‐speed impact tests were markedly higher for the PM blends than for the PS blends. A similar observation was obtained from instrumented falling weight impact studies. Dynamic mechanical analysis confirmed the incompatibility of the blend components because the glass‐transition temperatures of PA12 and the rubber phase (SEBS and SEBS‐g‐MA) were not affected. © 2005 Wiley Periodicals, Inc. J Appl polym Sci 95: 1376–1387, 2005
Thermal switching of the actuation ability of an electroactive polymer actuator
Authors: Watanabe Masashi , Wakimoto Naoko , Hirai Toshihiro , Yokoyama Mikito 
Published: January 2005

AbstractElectroactive polymer actuators have the simple ability to be actuated by a voltage. In this study, we added a new function: the ability to be actuated by temperature. We used a bending‐electrostrictive actuator made of a polyurethane film. The polyurethane was designed to be rigid at room temperature but to be flexible at temperatures greater than 40°C because of the melting of the soft segment in the polyurethane. Therefore, the actuator showed slight bending in response to a voltage at room temperature. However, it showed significant bending at 61°C. The degree of bending at 61°C was 29 times greater than that at 13°C. Thus, the actuation ability was switched on at 61°C but switched off at 13°C. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1566–1570, 2005
Properties and structure of PVP–lignin “blend films”
Authors: Liu Changhua , Xiao Chaobo , Liang Hui 
Published: January 2005

AbstractBlend films of poly (4‐vinylpyridine) and lignin were prepared by the casting method. Their structure and properties were studied by Fourier transform infrared (FTIR), wide‐angle X‐ray diffraction (WXRD), scanning electron microscopy (SEM), thermogravimetric analysis (TG), and differential scanning calorimetry (DSC). The IR spectra of the blend films indicated that hydrogen‐bonding interaction occurred between poly (4‐vinylpyridine) and lignin. The glass transition temperature of these blends increased with the increase of lignin content, which indicated that these blends were able to form a miscible phase due to the formation of intermolecular hydrogen bonding between the hydroxyl of lignin and the pyridine ring of poly (4‐vinylpyridine). The thermostability of these blends decreased with the increase of lignin content. Initially, an appreciable increase in the measured tensile strength was achieved with a lignin content of 15%, at which the maximum value of 33.03 MPa tensile strength was reached. At a 10% lignin incorporation level, the blend film exhibited a maximum value of 9.03% strain. When the threshold in lignin content for blend films exceeded that limit of 10% lignin, the strain behavior of these blend films deteriorated. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1405–1411, 2005
Monodisperse‐porous poly(styrene‐co‐divinylbenzene) beads providing high column efficiency in reversed phase HPLC
Authors: Unsal E. , Elmas B. , Çamlı S. T. , Tuncel M. , Şenel S. , Tuncel A. 
Published: January 2005

AbstractA multistage polymerization protocol, the so‐called “modified seeded polymerization,” was developed for the production of monodisperse‐porous poly(styrene‐co‐divinylbenzene) providing high column efficiency as a packing material in reversed phase high performance liquid chromatography (RPLC). In the first stage of the multistage production, uniform polystyrene seed particles, produced by dispersion polymerization, were swollen by an organic agent (i.e., the diluent) and then by a monomer mixture containing styrene and divinylbenzene. The final porous particles were obtained in the monodisperse form by the polymerization of monomer mixture in the seed particles. By the use of a small size seed latex with low molecular weight and by the selection of the appropriate diluent, relatively small monodisperse‐porous particles with suitable pore structure could be achieved. In the reversed phase separation of alkylbenzenes, under isocratic conditions, theoretical plate numbers up to 40,000 plates/m were achieved by using 5.2 μm porous particles, obtained by a toluene‐dibutyl phthalate mixture as the diluent. No significant decrease in the resolution power was observed by the fourfold increase in the mobile phase flow rate. The column efficiency and the resolution observed with 5.2 μm monodisperse‐porous particles were significantly higher with respect to the currently available polymer based packing materials used in the reversed phase HPLC. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1430–1438, 2005
Preparation of syndiotactic polystyrene/montmorillonite nanocomposites via in situ intercalative polymerization of styrene with monotitanocene catalyst
Authors: Shen Zhigang , Zhu Fangming , Liu Dan , Zeng Xiguo , Lin Shangan 
Published: January 2005

AbstractSyndiotactic polystyrene (sPS)/montmorillonite nanocomposites were prepared via in situ intercalative coordination polymerization using mono‐(η5‐pentamethylcyclopenta‐ dienyl) tribenzyloxy titanium [Cp*Ti(OBz)3] complex activated by methylaluminoxanes (MAO) and triisobutylaluminum (TIBA). The influences of polymerization conditions, such as the weight ratio of montmorillonite and styrene, temperature, and monomer concentration, on the preparation of sPS/montmorillonite nanocomposites was investigated. The intercalation spacing in the nanocomposites, as well as the exfoliation of the montmorillonite interlayers, was characterized with wide angle X‐ray diffraction (WAXD) and transmission electron microscopy (TEM). The dispersibility of the nanoscale elements depended on the polymerization conditions and the surfactant treatment. The crystallizability and thermal properties of these nanocomposites were determined by differential scanning calorimetry (DSC) analysis and thermogravimetric analysis (TGA). Experimental results indicated that the degree of crystallinity of the sPS nanocomposite increased with increasing montmorillonite content and with higher Tg and thermal decomposition temperature than pure sPS. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1412–1417, 2005
Kinetic approach on stabilization of LDPE in the presence of carnosic acid and related compounds. I. Thermal investigation
Authors: Jipa S. , Zaharescu T. , Setnescu R. , Gorghiu L. M. , Dumitrescu C. , Santos C. , Silva A. M. , Gigante B. 
Published: January 2005

AbstractCarnosic acid and similar compounds exhibit antioxidant behavior in a polyethylene matrix. Thermal resistance of LDPE was investigated at three temperatures (190, 200, and 210°C) by isothermal chemiluminescence. The main kinetic parameters: oxidation induction period (ti), half oxidation time (t1/2), maximum oxidation time (tmax), and propagation rate of oxidation (voxmax) were calculated. The inhibition of thermal degradation is proved by the values of these parameters relative to unstabilized polymer: the induction times of stabilized low density polyethylene are of one order of magnitude greater that raw polyethylene, and half oxidation periods are three to five times longer than initial LDPE. Thermal aging of protected low density polyethylene occurs at a much slower rate in comparison with unmodified LDPE. The depletion of stabilizers was also evaluated and the kinetic characteristics (the half‐life and the rate constant of consumption for each antioxidant) at three concentrations of all tested additives (0.125, 0.25, 0.50, and 0.75% w/w) were determined. The effectiveness of stabilization was depicted by two values of activation energies calculated from oxidation induction times and maximum oxidation periods. Some considerations on stabilizing mechanism are presented. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1571–1577, 2005
Strength of materials and elasticity approach to stiffness of fibrous composites using the concept of interphase
Authors: Sideridis E. , Papadopoulos G. A. , Kyriazi E. 
Published: January 2005

AbstractA strength of materials and elasticity approach was used in this study to determine the stiffness of fiber‐reinforced composites, by taking into account the concept of boundary interphase. Theoretical expressions for longitudinal transverse and shear moduli, as well as for longitudinal Poisson's ratio, were derived by use of this model. Results derived from these expressions were compared with others, to observe the discrepancies and evaluate their validity. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1578–1588, 2005
Effect of reaction parameters on the structure and properties of acrylic rubber/silica hybrid nanocomposites prepared by sol‐gel technique
Authors: Bandyopadhyay Abhijit , Sarkar Mousumi De , Bhowmick Anil K. 
Published: January 2005

AbstractThe effects of a few reaction parameters, namely, type of solvents, tetraethoxysilane (TEOS)‐to‐water mole ratio, and temperature of gelation at constant concentration of TEOS (45 wt %) and pH of 1.5 were investigated for acrylic rubber/silica hybrid nanocomposites prepared by sol‐gel technique. Infrared spectroscopic studies indicated the maximum silica generation within the system when tetrahydrofuran was used as the solvent for the sol‐gel reaction. The distribution of the silica particles (average dimension 100 nm) forming a network type of structure within the composite was confirmed by scanning electron microscopic studies (SEM). The other solvents studied here produced a lower amount of silica because of either high polarity of the solvents (methyl ethyl ketone and dimethyl formamide) or their limited miscibility with water (for ethyl acetate). An increase in the proportion of water caused silica agglomeration. Energy dispersive X‐ray analysis (EDAX) silicon mapping also demonstrated the existence of agglomerated silica structures at high TEOS‐to‐water mole ratio (>2). Higher temperature for gelation of the composites caused the aggregation of silica particles. The uncured composites containing nanolevel (<90 nm) dispersion of silica particles demonstrated slightly higher storage modulus, lower value of tan δmax, and higher glass transition temperature compared to the composites with silica particles of a larger dimension (>2 μm). Improvement in tensile strength and modulus was observed in the uncrosslinked as well as in the crosslinked state (cured by a mixed crosslinking system of hexamethylenediamine carbamate and ammonium benzoate). However, the extent of improvement in strength and modulus for the nanocomposites was higher (247 and 57%, respectively) compared to the microcomposite (150 and 27%, respectively) in the cured state. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1418–1429, 2005
Phase‐separation mechanism and corresponding final morphologies of thermoset blends based on unsaturated polyester and low‐molar‐weight saturated polyester
Authors: Boyard N. , Vayer M. , Sinturel Ch. , Erre R. 
Published: January 2005

AbstractThe final morphology of cured blends based on unsaturated polyester, styrene, and low‐molar‐weight saturated polyester as a low profile additive (LPA) was investigated with atomic force microscopy and scanning electron microscopy. The observed structure was compared to those obtained with widely used poly(vinyl acetate) (PVAc). On the surface and in the bulk, a network of particles, ranging in size from 50 to 60 nm, was observed with saturated polyester as an LPA. The influence of the molar weight and LPA content was investigated. To determine the mechanism of formation of such a morphology, in situ experiments were carried out to elucidate the phase‐separation mechanism. Small‐angle laser light scattering and small‐angle neutron scattering experiments were performed on ternary blends containing PVAc and saturated polyester, respectively. The first stage of spinodal decomposition was observed in both cases. Within our experimental conditions, gelation froze further evolution and led to a two‐phase cocontinuous structure that imposed the final morphology characteristics. In particular, the period and amplitude of the concentration fluctuations generated during the phase separation played essential roles. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1459–1472, 2005
Spectrophotometric investigation of laser dye diffusion in styrene–acrylonitrile copolymer solutions
Authors: Rao K. Chowdoji , Rao K. S. V. Krishna , Mallikarjuna N. N. , Naidu B. Vijaya Kumar , Aminabhavi Tejraj M. 
Published: January 2005

AbstractAn ultraviolet spectrometer was used to measure the absorption kinetics of a laser dye, 1,4‐bis(5‐phenyloxazoyl‐2‐yl) benzene, at its maximum wavelength in solutions of styrene–acrylonitrile copolymer dissolved in 1,4‐dioxane. From the time‐dependent absorbance data, the dye diffusion coefficient was calculated by a combination of Fick's law of diffusion with the Beer–Lambert law of absorption. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1481–1484, 2005
Mechanical properties of copper‐clad laminate using composite naphthalene–phenyl‐based epoxy as prepreg
Authors: Duann Yeh‐Fang , Chen Bor‐Lin , Tsai Teh‐Hua 
Published: January 2005

AbstractA composite was prepared that contained diglycidyl ether of tetrabromobisphenol A (DGETBA) and 1,5‐di(2,3‐epoxypropoxy)naphthalene (A), 4,4′‐bis(2,3‐epoxypropoxy)benzylideneaniline (B), or 4,4′‐bis(2,3‐epoxypropoxy)biphenyl (C), and then was cured using different ratios of dicyandiamide (DICY). The results of DSC, TGA, coefficient of thermal expansion, dielectric constant, and dissipation factor testing of the composite epoxy resins were analyzed, and investigation of the copper‐clad laminate using the composite epoxy resins as prepreg was also performed. Additionally, moisture absorption, peel strength, arc resistance, comparative tracking index, and flammability of the copper‐clad laminate were examined. Clearly, some of the physical or mechanical properties of the composite and the copper‐clad laminate can be improved by optimal addition of naphthalene–phenyl‐based epoxy. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1485–1492, 2005
Photofabrication of biofiber‐based polymer matrix composites
Authors: Kumar R. N. , Hee Khoo Chin , Rozman H. D. 
Published: January 2005

AbstractThe novel development of a photofabrication process of biofiber composites, based on oil palm empty fruit bunch fibers, is reported. The process consists of the following steps: (1) the preparation by a wet process of nonwoven mat of biofiber, either alone or in combination with glass and nylon; (2) drying the mat; (3) preparation of photocurable resin matrix, consisting of vinyl ester and photoinitiator; (4) impregnation of the mat by photocurable resin; and (5) irradiation of the impregnated mat by UV radiation to effect the cure of the composite. The nonwoven mat was formed in a “headbox” into which was poured a slurry of fibers. A wet mat was formed by after dewatering of the slurry. Biofiber, glass, and nylon fibers were mixed in different proportions. A “mixture experimental design” was used to generate experimental compositions of the reinforcing fibers and to model dependency of the response variables on the components through mathematical relationships. These relationships were meant to (1) determine the effect of composition of the reinforcing fibers on the physical and mechanical properties, (2) predict the response for any unknown composition of fibers, and (3) determine the optimum values of any identified properties. Because the product was characterized by multiple responses, simultaneous maximization of all properties was not feasible. The product must be considered in the definition of the trade‐off or compromise of properties to obtain overall satisfactory performance. Such an optimization was carried out and the results are reported. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1493–1499, 2005
Kinetic study of the thermal decomposition of (2‐phenyl‐1,3‐dioxolane‐4‐yl) methyl methacrylate and 2‐hydroxyethyl methacrylate copolymers
Authors: Ceylan Nilgün Neşe , İlter Zülfiye , Ceylan Kadim 
Published: January 2005

AbstractThe kinetics of nonisothermal decomposition of (2‐phenyl‐1,3‐dioxolane‐4‐yl) methyl methacrylate (PDMMA), 2‐hydroxyethyl methacrylate (HEMA), and vinyl‐pyrrolidone (VPy) copolymers were investigated by thermogravimetry (TG) and differential thermal analysis (DTA). The data indicated that the major weight loss occurs in the range of 270 to 450°C. The decomposition characteristics showed essentially two regimes and varied depending on the temperature and the copolymer composition. The apparent kinetic parameters of the decompositions were estimated from both TG and DTA data by using the alternative calculation methods. The results suggest that the weight loss rates may be represented, depending on the type of sample, by a reaction model of overall order 1.0 to 1.6, with an activation energy of approximately 65–95 kJ mol−1. The DTA data estimated considerably higher values for the overall activation energies, around 198–240 kJ mol−1. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1500–1508, 2005
Thermal stability of chemically crosslinked moisture‐cured polyurethane coatings
Authors: Chattopadhyay D. K. , Sreedhar B. , Raju K. V. S. N. 
Published: January 2005

AbstractPolyurethane prepolymers are widely used in reactive hot melt adhesives and moisture‐cured coatings. The segmented moisture‐cured formulations, based on polytetramethylene glycol (PTMG‐1000)/trimethylol propane (TMP)/isophorone diisocyanate (IPDI) and PTMG/TMP/toluene diisocyanate (TDI), were prepared with NCO/OH ratio of 1.6 : 1.0. The excess isocyanate groups of the prepolymers were chain extended in the ratio of 2 : 1 (NCO/OH) with different aliphatic diols and 4 : 1 with different aromatic diamines. The surplus isocyanate groups of the formulations were completely reacted with atmospheric moisture, and the thermal stability of the postcured materials obtained as cast films were evaluated by thermogravimetric (TG) analysis. It was observed that initial degradation temperatures were above 270°C, with two‐ or three‐step degradation profiles. The degradation parameters were evaluated using the Broido and Coats–Redfern methods. The thermal resistance of moisture‐cured formulations using diisocyanates with the cycloaliphatic structures (IPDI) and the aromatic TDI, at the same NCO/OH ratio (1.6), and TMP content were compared from the isothermal TG experiments at different temperatures and dynamic TG experiments at different heating rates in nitrogen and oxygen environments. The observation suggests that polyurethane‐containing sulfone groups and straight‐chain diol chain extenders were more stable. It was also observed that at lower temperature polyurethane, prepared from aliphatic diisocyanates (IPDI), was more stable than the aromatic diisocyanate (TDI) containing polyurethanes. At high temperature, the stability order follows the reverse trend. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1509–1518, 2005