bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dissolution enhancement of flavonoids by solid dispersion in PVP and PEG matrixes: A comparative study
Authors: Kanaze F. I. , Kokkalou E. , Niopas I. , Georgarakis M. , Stergiou A. , Bikiaris D. 
Published: July 2006

AbstractPolyvinylpyrrolidone (PVP) and poly(ethylene glycol) (PEG) solid dispersion systems with flavanone glycosides, naringin and hesperidin, and their aglycones, naringenin and hesperetin, were prepared, using solvent evaporation method, to enhance their dissolution rates that may affect their bioavailability. Drug release of both flavanone glycosides and their aglycones was directly affected by the physical state of solid dispersions. Powder‐XRD technique in combination with scanning and transmission electron microscopy revealed that PVP polymer formed amorphous nanodispersion systems with flavanone aglycones, while such systems could not be formed with their glycosides, which are bulkier molecules. Fourier transform infrared spectra suggest the presence of hydrogen bonds between PVP carbonyl groups and hydroxyl groups of both flavanone aglycones. These interactions prevent the crystallization of naringenin and hesperetin aglycones in PVP matrix. On the other hand, the ability of PEG carrier to form hydrogen bonds with flavanone glycosides or aglycones was limited, and as a result both flavanone glycosides and their aglycones remain in the crystalline form. For this reason, the solubility enhancement of PEG solid dispersions was lower than when PVP was used as drug carrier. At pH 6.8, the % release of naringenin and hesperetin from PVP/naringenin–hesperetin (80/20 w/w) solid dispersion was 100% while in PEG solid dispersions, it was not higher than 60–70%. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 460–471, 2006
Colored rubber vulcanizates with some magnetic properties
Authors: El‐Sabbagh S. H. , Ahmed N. M. , Daoush W. M. 
Published: July 2006

AbstractA new composite based on natural rubber vulcanizates loaded with the newly prepared iron oxide–aluminum oxide (Fe2O3·Al2O3) fillers were prepared and their physical and magnetic studies were investigated. The prepared fillers were evaluated as reinforcing fillers with some magnetic properties; these properties were dependent on the ratio of iron oxide to aluminum oxide in each prepared ratio of these fillers. Rheological properties of rubber mixes containing (1Fe2O3:3Al2O3) and (1Fe2O3:1Al2O3) fillers exhibited better properties than mixes containing (3Fe2O3:1Al2O3) and (α‐Fe2O3), which showed almost the same behavior. Physical properties such as tensile strength, stress at 100 and 200% strain, Young's modulus, and hardness were increased by increasing the volume fraction of the investigated fillers concentration in the mixed vulcanizates. Measured rheological and physical results were inversely related to the magnetic properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:494–505, 2006
Investigating polypropylene–green coconut fiber composites in the molten and solid states through various techniques
Authors: Leblanc Jean L. , Furtado Cristina R. G. , Leite Marcia C. A. M. , Visconte Leila L. Y. , Ishizaki Marina H. 
Published: July 2006

AbstractA series of polypropylene (PP)–green coconut fiber (GCF) composites were prepared by melt mixing and their properties studied in the molten state using an advanced nonlinear harmonic testing technique, and in the solid state using standard mechanical testing and scanning electron microscopy (SEM). The effect of fiber loading as well as the role of maleated polypropylene as compatibilizing agent was investigated. PP–GCF composites are heterogeneous materials that, in the molten state, are found to exhibit essentially a nonlinear viscoelastic character, in contrast with the pure PP, which has a linear viscoelastic region up to 50–60% strain. Complex modulus increases with GCF content but in such a manner that the observed reinforcement is at best of hydrodynamic origin, without any specific chemical interaction occurring between the polymer matrix and the fibers. The addition of maleated polypropylene improves the wetting of fibers by the molten polymer but the effect is so small that specific chemical reactions could hardly be considered as occurring. Flexural modulus data confirm the reinforcing effects of the fiber and an improvement is noted when some maleated polypropylene is used, with an optimum level of around 1% (or the PP content). SEM microphotographs clearly show that maleated polypropylene imparts a better wetting of GC fibers by PP, but chemical interactions are unlikely to occur between the polymer and GCF. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1922–1936, 2006
Comparison between microwave and thermal curing of glass fiber–epoxy composites: Effect of microwave‐heating cycle on mechanical properties
Authors: Tanrattanakul Varaporn , Jaroendee Dumrong 
Published: July 2006

AbstractThe objective of this study was to compare the mechanical properties between epoxy composites cured by thermal heating and microwave heating. Epoxy‐anhydride resins reinforced with glass fiber were cured in a domestic microwave oven and in a thermal oven. Hardening agents included methyl tetrahydrophthalic anhydride and methyl hexahydrophthalic anhydride. Microwave curing was carried out at various conditions, including 1‐, 2‐, and 3‐step heating cycle, whereby each cycle employed different power level and time. Mechanical properties were tested according to ASTM standards. It is found that the microwave‐cured composites produced mechanical properties as good as the thermally cured composites. The 2‐ and 3‐step heating cycle used in the microwave curing process produced better mechanical properties higher than those obtained from the microwaved 1‐step and thermally curing process. This is attributed to the slow increase in temperature during the beginning of the microwave curing process whereby the very low power level was applied in the first cycle of the multistep heating process. This affected the slower rate of viscosity increment, resulting in better wettability of the glass fiber with enhanced interfacial adhesion between the fibers and the resins. The viscosity of resins affected the homogeneity of the crosslinked structure. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1059–1070, 2006
Electrical behavior of high impact polystyrene/liquid crystalline polymer blends containing low content of carbon black
Authors: Shemesh R. , Siegmann A. , Tchoudakov R. , Narkis M. 
Published: July 2006

AbstractThis article presents a study of the structure and electrical behavior of carbon black (CB) containing immiscible polymer blends. A series of electrically conductive blends of high impact polystyrene (HIPS), liquid crystalline polymer (LCP), and CB was compounded and followed by a capillary rheometer extrusion process or by injection molding. In these immiscible blends, HIPS serves as a low surface tension matrix and LCP as a polar dispersed phase. Shear and elongational flow result in blend morphology consisting of highly elongated and oriented LCP particles dispersed in the HIPS matrix. The enhancement of conductivity in these blends is due to the affinity of CB to LCP and the formation of cocontinuous phase morphology, giving rise to conductive networks. Blends of various compositions were prepared using various processing conditions, emphasizing the relationship between morphology, rheology, and electrical properties. The presence of at least 20 wt % LCP and 2 phr CB under certain processing conditions (mixing sequence and temperature) is necessary to obtain stable resistivity, independent of the studied extrusion shear rate, and low resistivity values. In addition, the processing mode significantly affects the blends' structure and the resultant electrical properties. Hence, injection molding due to high shear rates, elongational flow, and fast cooling results in high structural and electrical anisotropy. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1688–1696, 2006
Synthesis of asymmetric star‐branched block copolymers based on PS, PTHF, and PMMA by combination of cationic ring opening polymerization and redox polymerization methods
Authors: Arslan Hülya , Hazer Baki , Higashihara Tomoya , Hirao Akira 
Published: July 2006

AbstractAsymmetric star‐branched block copolymers based on polystyrene (PS), polytetrahydrofuran (PTHF), and poly(methyl methacrylate) (PMMA) were synthesized by a combination of cationic ring opening polymerization and redox polymerization methods in two steps. At first, cationic ring opening polymerization of THF was initiated by using chain‐end‐multifunctionalized polystyrenes with 2, 4, and 8 benzyl bromide moieties as initiators in the presence of AgSbF6 at 30°C to obtain 3‐, 5‐, and 9‐arm AB2, AB4, and AB8 type asymmetric star‐branched polymers consisting of PS (A) and PTHF‐OH (B) segments. Polymers obtained in this way were characterized by gel permeation chromatography, FTIR, 1H NMR, and thermal analysis (DSC and TGA). At second step, redox polymerization of methyl methacrylate was initiated by using these characterized asymmetric star‐branched polymers as macroinitiators in the presence of Ce(IV) salt at 40°C to obtain PS‐s‐(PTHF‐b‐PMMA)n (n = 2, 4, and 8) asymmetric star‐branched block copolymers. PS‐s‐(PTHF‐b‐PMMA)n (n = 2, 4, and 8) asymmetric star‐branched block copolymers obtained were purified by fractional precipitation method before characterization. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 516–522, 2006
Mechanical and tribological properties of PA66/PPS blend. III. Reinforced with GF
Authors: Chen Zhaobin , Liu Xujun , Lü Renguo , Li Tongsheng 
Published: July 2006

AbstractBased on previous work, 70 vol % PA66/30 vol % PPS blend was selected as a matrix, and the PA66/PPS blend reinforced with different content of glass fiber (GF) was prepared in this study. The mechanical properties of PA66/PPS/GF composites were studied, and the tribological behaviors were tested on block‐on‐ring sliding wear tester. The results showed that 20–30 vol % GF greatly increases the mechanical properties of PA66/PPS blend. When GF content is 20 vol %, the friction coefficient of composite is the lowest (0.35), which is decreased by 47% in comparison with the unfilled blend. The wear volume of the GF‐reinforced PA66/PPS blend composite decreases with the increase of GF content. However, the wear‐resistance is not apparently improved by the addition of GF in the experimental range for comparison with unfilled PA66/PPS blend. The worn surface and the transfer film on the counterface were examined by scanning electron microscopy (SEM). The observations revealed that the friction coefficient of composite depends on the formation and development of a transfer film. The wear mechanism involves polymer matrix wear and fiber wear. The former consists of melting wear and plastic deformation of the matrix, while the latter includes fiber sliding wear, cracking, rupturing, and pulverizing. The contributions of the matrix wear and the fiber wear determine the ultimate wear volume of PA66/PPS/GF composite. In addition, the abrasive action caused by the ruptured glass fiber is also a very important factor. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 523–529, 2006
Effect of physical aging on the microstructure and dynamic mechanical properties of poly(ether sulfone) copolymer
Authors: Zhou Xiao‐Ming , Jiang Zhen‐Hua 
Published: July 2006

AbstractEffects of physical aging on the submicroscopic structure and dynamic mechanical properties of amorphous poly(ether sulfone) copolymer film were studied by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and electron‐microscopy measurements. Heat flow responses were measured after annealing the amorphous samples obtained, by quenching the melt into an ice‐water bath close to but below the glass transition temperature. The extent of aging is related to the supercooling from the glass transition temperature and to the aging time. The activation energy of the aging process was estimated by the Williams–Watt expression (Williams and Watts, Trans Faraday Soc 1970, 66, 80). A systematic study of the influence of aging on the dynamic mechanical properties of poly(ether sulfone) copolymer has also been made. During isothermal annealing, the increase of the temperature of tan δ peak for the α and β′ relaxation with aging time has been observed. The aging in the zone of the β peak has also been investigated and an interpretation of the results was proposed on the basis of foregone theories. The result of electron‐microscopy investigation indicates that poly(ether sulfone) copolymer has formed a local order structure during the physical aging. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 530–534, 2006
The importance of interfacial design at the carbon nanotube/polymer composite interface
Authors: Gorga Russell E. , Lau Kenneth K. S. , Gleason Karen K. , Cohen Robert E. 
Published: July 2006

AbstractThis research focuses on the need for interfacial engineering at the carbon nanotube/polymer composite interface in the effort to obtain enhanced mechanical properties. The mechanical properties of multiwall carbon nanotubes (MWNTs)/poly (methyl methacrylate) (PMMA) nanocomposites were studied as a function of both nanotube concentration and surface treatment. One method, plasma enhanced chemical vapor deposition (PECVD), was successfully used to produce a PMMA conformal coating (using methyl methacrylate monomer) on multiwall carbon nanotubes. Excellent suspensions of MWNTs in organic solvents were achieved via the PMMA coating. The coated‐MWNTs were dispersed into PMMA via melt mixing and orientation was achieved by melt drawing. The overall set of mechanical properties indicates that while the conformal polymer coating had a significant effect on the mechanical properties at a 1% concentration of nanotubes as compared to the uncoated nanotube composites, suggesting improved interfacial adhesion between the nanotube and the matrix material. However, the mechanical properties of the 1% coated nanotube composite were not significantly better than those for pure PMMA. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:1413–1418, 2006
Synthesis and characterization of flame retarding UV‐curable organic–inorganic hybrid coatings
Authors: Karataş Sevim , Hoşgör Zuhal , Menceloğlu Yusuf , Kayaman‐Apohan Nilhan , Güngör Atilla 
Published: July 2006

AbstractUV‐curable, organic–inorganic hybrid materials were synthesized via sol–gel reactions for tetraethylorthosilicate, and methacryloxypropyl trimethoxysilane in the presence of the acrylated phenylphosphine oxide resin (APPO) and a bisphenol‐A‐based epoxy acrylate resin. The sol–gel precursor content in the hybrid coatings was varied from 0 to 30 wt %. The adhesion, flexibility, and hardness of the coatings were characterized. The influences of the amounts of inorganic component incorporated into the coatings were studied. Results from the mechanical measurements show that the properties of hybrid coatings improve with the increase in sol–gel precursor content. In addition, thermal properties of the hybrids were studied by thermogravimetric analysis in air atmosphere. The char yield of pure organic coating was 32% and that of 30 wt % silicate containing hybrid coating was 30% at 500°C in air atmosphere. This result demonstrates the pronounced effect of APPO on the flame retardance of coatings. Gas chromatography/mass spectrometry analyses showed that the initial weight loss obtained in thermogravimetric analysis is due to the degradation products of the photoinitator and the reactive diluent. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1906–1914, 2006
Analysis of spinning process parameters on development of spun‐dyed PET yarn using the Taguchi method
Authors: Cho Dae Hwan , Jeong Youngjin 
Published: July 2006

AbstractThe yarn tenacity of a spun‐dyed yarn is predicted from the spinning conditions and other properties of the yarn are analyzed through the defined parameters using the Taguchi method. To develop a spun‐dyed yarn using the Taguchi method, four factors that can largely influence the yarn properties are selected. From the experimental design based on four factors, the processes are executed to produce the specific yarns whose properties are measured to analyze the relationship between the process conditions and their results. The target properties of a spun‐dyed yarn may be obtained through adjusting the spinning parameters that are related to the yarn properties by the Taguchi tool. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:1419–1427, 2006
In situ polymerization of aniline in the presence of carbon black
Authors: Souza Fernando G. , Sirelli Lys , Michel Ricardo C. , Soares Bluma G. , Herbst Marcelo H. 
Published: July 2006

AbstractA hybrid material of polyaniline doped with dodecylbenzenesulfonic acid and conductive carbon black (PaniDBSA/CB) was prepared by in situ polymerization. The presence of low amount of CB (up to 25 wt %) resulted in a decrease in resistivity as compared to pure PaniDBSA. Composite with 25 wt % of CB presented the lowest resistivity and a tubular morphology characterized by microtubules with high aspect ratio evidenced by SEM examination. Higher amount of CB give rise to materials with higher resistivity values and a granular morphology, similar to pure carbon black. Ultraviolet–visible and electron paramagnetic resonance analyses were employed to evaluate the polaron concentration. X‐ray diffraction was used to characterize the molecular structure of these composites. It was observed a decrease in the crystallinity degree and a shift of the polaron band transition toward lower wavelength as the amount of CB in the composite increases. From the EPR measurements, one can suggest that the higher chain order and polaron mobility is observed in hybrid with 25% of CB. This behavior is in agreement to the electrical resistivity values and SEM microscopy. The effect of CB on thermal stability of the composites was also investigated. The effect of the PaniDBSA/CB hybrid material on the processability and resistivity of the composites based on styrene‐butadiene‐styrene (SBS) block copolymer as the insulating matrix have been also evaluated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 535–541, 2006
Evaluation of dynamic elastic properties of wood‐filled polypropylene composites
Authors: Chauhan Shakti S. , Karmarkar Ajay , Aggarwal Pankaj 
Published: July 2006

AbstractDynamic modulus of elasticity (MoE) and shear modulus of wood‐filled polypropylene composite at various filler contents ranging from 10% to 50% was determined from the vibration frequencies of disc‐shaped specimens. Wood filler was used in both fiber form (pulp) and powder form (wood flour). A novel compatibilizer, m‐isopropenyl‐α,α‐dimethylbenzyl‐isocyanate(m‐TMI) grafted polypropylene with isocyanate functional group was used to prepare the composites. A linear increase in dynamic MoE, shear modulus, and density of the composite was observed with the increasing filler content. Between the two fillers, wood fiber filled composites exhibited slightly better properties. At 50% filler loading, dynamic MoE of the wood fiber filled composite was 97% higher than that of unfilled polypropylene. Halpin‐Tsai model equation was used to describe the changes in the composite modulus with the increasing filler content. The continuous improvement in elastic properties of the composites with the increasing wood filler is attributed to the effective reinforcement of low‐modulus polypropylene matrix with the high‐modulus wood filler. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1706–1711, 2006
Surface modification of PBO fibers by argon plasma and argon plasma combined with coupling agents
Authors: Liu Dandan , Hu Jian , Zhao Yaoming , Zhou Xuesong , Ning Ping , Wang Yi 
Published: July 2006

AbstractThe methods of argon plasma and argon plasma combined with coupling agents were employed to modify the poly[1,4‐phenylene‐cis‐benzobisoxazole] (PBO) fiber surface. The interfacial shearing strength (IFSS) of PBO fibers/epoxy resin was measured by the single fiber pull‐out test. The surface chemical structure and surface composition of PBO fibers were determined by FTIR and X‐ray photoelectron spectroscopy respectively. The morphology of the fiber surface was investigated by scanning electron microscopy and the specific surface area of the fibers was calculated by B.E.T. equation. Furthermore, the wettability of PBO fibers was confirmed by the droplet profile analysis method. The results showed that the elemental composition ratio of the fiber surface changed after the modification. The IFSS increased by 42 and 78% when the fibers were treated by argon plasma and argon plasma combined with the coupling agents, respectively. Meanwhile, the specific surface areas of the treated fibers were improved. In addition, compared with the modification of argon plasma, the modification of argon plasma combined with the coupling agents inhibited the attenuation phenomena of the IFSS and the wettability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1428–1435, 2006
Flammability and thermal degradation behaviors of phosphorus‐containing copolyester/BaSO4 nanocomposites
Authors: Qu Ming‐Hai , Wang Yu‐Zhong , Liu Ya , Ge Xin‐Guo , Wang De‐Yi , Wang Chuan 
Published: July 2006

AbstractA novel phosphorus‐containing copolyester (PET‐co‐DDP)/barium sulfate (BaSO4) nanocomposite was synthesized by in situ polymerization. The oxygen index values of the resulting nanocomposites decreased with increasing the content of BaSO4 nanoparticles, but their antidripping behaviors were improved obviously through the UL‐94 test. The flammability tests based on the cone calorimetry showed that the introduction of nano‐BaSO4 to the copolyester decreased remarkably the heat release rate and effective heat of combustion. The thermal oxidative decomposition behaviors of PET‐co‐DDP/BaSO4 nanocomposites were studied by a conventional dynamic thermogravimetric analysis in a flowing air atmosphere with a heating rate of 20°C/min. The activation energies determined from Kissinger method, Flynn‐Wall‐Ozawa method, and Friedman method had a same variation trend. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 564–570, 2006
Low molecular weight water‐soluble chitosans: Preparation with the aid of cellulase, characterization, and solubility
Authors: Li Jin , Du Yumin , Liang Hongbo 
Published: July 2006

AbstractPreparation of water‐soluble chitosan (WSC) was made by treating partially N‐deacetylated chitosan with acetic anhydride in aqueous acetic acid. The optimal conditions of preparing WSC were determined on the basis of orthogonal tests. Low molecular weight WSC with broad molecular weight (600–1.5 kDa) were obtained by the depolymerization of WSC using cellulase at optimum condition of pH 4.5 and 60°C. The solubility of WSC in water and aqueous organic solvents was investigated in detail. Weight–average molecular weight (Mw) and molecular weight distribution (Mw/Mn) of samples were measured by gel permeation chromatography. The structure of WSC and its degraded products were characterized by XRD, FTIR, and MALDI‐TOF MS. The decrease of molecular weight led to transformation of crystal structure and the increase of solubility, but the chemical structures of residues were not modified compared to WSC, which was not hydrolyzed. The solubility of the WSC in water and aqueous organic solvents increased with the decrease of molecular weight. The solubility of the WSC with low molecular weight was rather high even in aqueous dimethylacetamide and dimethylsulfoxide. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1098–1105, 2006