bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrospinning of polyacrylonitrile nanofibers
Authors: Wang Tong , Kumar Satish 
Published: July 2006

AbstractPolyacrylonitrile (PAN) was electrospun in dimethylformamide as a function of electric field, solution flow rate, and polymer concentration (C). The fiber diameter increased with C and ranged from 30 nm to 3.0 μm. The fiber diameter increased with the flow rate and decreased when the electric field was increased by a change in the working distance; however, it did not change significantly when the electric field was varied by a change in the voltage at a given working distance. The fibers below about 350 nm diameter contained beads, whereas above this diameter, bead‐free fibers were obtained. For PAN with a molecular weight of 100,000 g/mol, the fiber diameter scaled as C1.2 and C7.5 at low (5.1–16.1 wt %) and high (17.5–22.1 wt %) C values, respectively. Both concentrations were in the semidilute entangled regime, where the specific viscosity scaled as C4.4, consistent with De Gennes's scaling concepts. In the semidilute unentangled regime (0.5–3.1 wt %), where the viscosity scaled as C1.3, microscopic or nanoscopic particles rather than fibers were obtained. Concentration‐ dependent electrospinning studies were also carried out for higher molecular weight PAN (250,000 and 700,00 g/mol). The results of these studies are also presented and discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1023–1029, 2006
Adsorption of fibrinogen onto macroporous, biocompatible sponges based on poly(2‐hydroxyethyl methacrylate)
Authors: Bajpai A. K. , Mishra D. D. 
Published: July 2006

AbstractHydrophilic, spongy matrices of poly (2‐hydroxyethyl methacrylate) were synthesized by a redox polymerization method, and the adsorption of fibrinogen was carried out on their surfaces. The prepared sponges were characterized with Fourier transform infrared and environmental scanning electron microscopy and were assayed for their water‐sorption potential. The chemical architecture of the sponges had a pronounced impact on both the water sorption and the protein adsorption affinity of the sponge surface. The adsorption kinetics were investigated, and kinetic parameters such as the rate constants for adsorption and desorption and the penetrate rate constant were evaluated. The influence of experimental conditions such as the pH and temperature were observed on the adsorption profiles of fibrinogen. The prepared sponges were also judged for in vitro blood compatibility by methods such as blood‐clot‐formation and hemolysis‐percentage tests. An attempt was also made to correlate the fibrinogen adsorption capacity of the sponge to its antithrombogenic response to static blood. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1341–1355, 2006
Evaluation of the effects of biobased plasticizers on the thermal and mechanical properties of poly(vinyl chloride)
Authors: Gil N. , Saska M. , Negulescu I. 
Published: July 2006

AbstractBlends were prepared of poly(vinyl chloride) (PVC) with four different plasticizers; esters of aconitic, citric, and phthalic acids; and other ingredients used in commercial flexible PVC products. The thermal and mechanical properties of the fresh products and of the products after 6 months of aging were measured. Young's modulus of the PVC blends was reduced about 10‐fold by an increase in the plasticizer level from 15 to 30 phr from the semirigid to the flexible range according to the ASTM classification, but a 40‐phr level was required for PVC to retain its flexibility beyond 6 months. At the 40‐phr level, tributyl aconitate performed better than diisononyl phthalate (DINP) or tributyl citrate, in terms of lowering Young's modulus, both in the fresh materials and those aged for 6 months. The effects of the four plasticizers on the glass‐transition temperature (Tg) were similar, with Tg close to ambient temperature at the 30‐ and 40‐phr levels in freshly prepared samples and at 40–60°C in those aged for 6 months. The thermal stability of the PVC plasticized with DINP was superior among the group. Overall, tributyl aconitate appeared to be a good candidate for use in consumer products where the alleged toxicity of DINP may be an issue. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1366–1373, 2006
Kinetics of the curing reaction of unsaturated polyester resins catalyzed with new initiators and a promoter
Authors: Worzakowska Marta 
Published: July 2006

AbstractIn this article, the curing of unsaturated polyester resins catalyzed with a promoter [cobalt(II) octoate] and free‐radical initiators is presented. The new initiators were formed by the oxidation process of ethyl methyl ketone or cyclohexanone with hydrogen peroxide and the mixture of solvents containing hydroxyl groups. As a reference, a typical curing system containing ethyl methyl ketone hydroperoxide (Luperox) and the promoter was used. The differential scanning calorimetry runs were performed at different heating rates. The experimental data were fitted with the empirical kinetic model. First, the kinetic parameters (activation energy, frequency factor, and reaction order) were obtained with a single reactive process and with the nth‐order reaction f(α), the nth‐order reaction f(α) with autocatalysis, and the first‐order reaction f(α) with autocatalysis. Second, two or three different reactive processes with the nth‐order reaction f(α) for each step were used. The obtained values of the activation energies for the curing of the unsaturated polyester resins with the free radical initiator–cobalt(II) salt catalytic system were in the range 40–60 kJ/mol for the polymerization initiated by the redox decomposition of the initiators and 80–90 kJ/mol for the polymerization initiated by the thermal decomposition of the initiators at high temperatures. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1870–1876, 2006
Experimental analysis of temperature and crystallinity profiles of wood sawdust/polypropylene composites during cooling
Authors: Sombatsompop N. , Kositchaiyong A. , Wimolmala E. 
Published: July 2006

AbstractThe temperature profiles of wood sawdust/polypropylene (PP) composite melts during cooling were experimentally investigated with a cooling jacket apparatus connected to the end of an injection‐molding machine. Real‐time melting temperature was measured with an unsheathed thermocouple array coupled with a high‐speed data‐acquisition unit. The crystallinity level of the solidified composites was evaluated with an X‐ray diffractometer. Before the crystallization temperature (Tc) was reached, the cooling rate of the melt layer near the wall was greater than that near the center. After Tc was reached, the opposite behavior was observed. Wood sawdust content did not affect the general temperature and crystallinity profiles across the duct diameter but led to more nonuniform temperature profiles across the duct diameter. The sawdust particles could act as a nucleating agent during the nucleation stage to increase Tc of the PP and as an interfering agent during the crystal growth stage to decrease the overall crystallinity level of the PP. The temperature and crystallinity profiles were not affected by the coolant flow rate. The normalized induction time changed with reduced radius (r/R, where r is the distance between the central duct to any point along the cross‐section of the duct and R is the duct radius) positions and coolant flow rate, especially for neat PP and PP composites with a low sawdust content (10 wt %). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1896–1905, 2006
Homogeneous graft copolymerization of chitosan with butyl acrylate by γ‐irradiation via a 6‐O‐maleoyl‐N‐phthaloyl‐chitosan intermediate
Authors: Huang Meifang , Xia Xu , Zhang Zhongcheng , Liu Li , Fang Yue'e 
Published: July 2006

AbstractThe graft copolymerization of butyl acrylate (BA) onto chitosan was tried via a new protection‐graft‐deprotection procedure. About 6‐O‐maleoyl‐N‐phthaloyl‐chitosan was synthesized and characterized by Fourier transform infrared spectra analysis (FT‐IR) and 1H‐NMR. Because the intermediate 6‐O‐maleoyl‐N‐phthaloyl‐chitosan was soluble in organic solvents, the graft copolymerization was carried out in a homogeneous system. Grafting was initiated by γ‐irradiation. The graft extent was dependent on the irradiation dose and the concentration of BA monomer, and copolymers with grafting above 100% were readily prepared. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 489–493, 2006
Photoregulated complexation, redox behavior, and photoluminescence of a supramolecular polymer solution
Authors: Dahmane Smail , Zhao Yue 
Published: July 2006

AbstractReported in this paper is a new finding based on a spectroscopic and electrochemical study of a supramolecular polymer in dilute solution. Dissolved in a mixture of dichloromethane and acetonitrile, zinc‐tetraphenylporphyrin (ZnTPP) can complex with a polymethacrylate bearing an azopyridine moiety (AzPy) through the axial coordination between the metal and pyridyl group. The self‐assembled polymer (PAzPy–ZnTPP) displays different photoluminescence and redox behaviors compared with those of noncomplexed ZnTPP. Moreover, the reversible trans–cis‐photoisomerization of azopyridine upon UV and visible light irradiation was found to alter the equilibrium of the axial coordination between azopyridine and ZnTPP in solution, resulting in photoregulable redox potentials and fluorescence emission of the metalloporphyrin. The results suggest that supramolecular polymer solutions could enhance the mechanism of photoinduced change in the degree of complexation, which gives rise to a phenomenon of photoregulation of the electrochemical and optical properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 744–750, 2006
Capillary effect of hydrophobic polyester fiber bundles with noncircular cross section
Authors: Zhang Y. , Wang H. P. , Chen Y. H. 
Published: July 2006

AbstractMoisture transport in fiber assembly is one of the critical factors affecting physiological comfort. It is useful to model bundle structure for understanding capillary flow in complex geometries representative of the void spaces formed between fibers. A new mathematical model MFB has been used to simulate alignment representative of void spaces formed between fibers in noncircular cross section fiber bundles. Fiber morphological character and their random packing pattern are emphasized to discuss the mechanism of capillary flow in fiber assembly in this work. Capillary equivalent radius distribution, flux of saturated fiber bundle, capillary generating ability, and wicking velocity are computed to predict which kind of shape is predominant for hydrophobic polyester fiber wicking. Vertical wicking model of polyester filaments bundle predicts that as the nonroundness of filaments increase, the maximum liquid height, flux of saturated bundle, and capillary forming ability will increase, while instantaneous wicking velocity increases not stably. Concave polygon shape of fiber bundle has much more small capillary tubes than convex shape of fiber bundle. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1405–1412 2006
The preparation of core‐shell CaCO3 particles and its effect on mechanical property of PVC composites
Authors: Xiong Ying , Chen Guangshun , Guo Shaoyun 
Published: July 2006

AbstractIn this study, a novel mechanochemical route to prepare core‐shell structured particles was introduced. XPS, TEM, and dissolving experimental results indicate the formation of [(inorganic particle)/(elastomer)] core‐shell structured particles, and several kinds of calcium carbonate (nano‐CaCO3) particles with various interfaces were obtained. The mechanical properties and morphological results indicate that the surface treatment of nano‐CaCO3 particles and the existence of outer elastic layer will strengthen the interfacial interaction between nano‐CaCO3 particles and PVC matrix, which results in improvement of mechanical properties of PVC/CaCO3 composites. The theoretical calculations of the interfacial interaction and DMA results confirm these especially when the surface of nano‐CaCO3 particles was treated by MMA and coated in succession by ACR through vibro‐milling. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1084–1091, 2006
Preparation and characterization of poly(2‐chloroaniline)/SiO2 nanocomposite via oxidative polymerization: Comparative UV–vis studies into different solvents of poly(2‐chloroaniline) and poly(2‐chloroaniline)/SiO2
Authors: Gök Ayşegül , Şen Songül 
Published: July 2006

AbstractPoly(2‐chloroaniline)/silica (P2ClAn)/SiO2 nanocomposites have been chemically prepared by oxidative polymerization of 2‐chloroaniline in acidic medium containing SiO2. The prepared composites were characterized by FTIR, UV–vis, TGA, XRD, SEM, ESEM, conductivity, and magnetic susceptibility. The incorporation of P2ClAn in composites was endorsed by FTIR studies. The effect of the solution concentration of P2ClAn and P2ClAn/SiO2 prepared in protonated, deprotonated, and reprotonated structures on the UV–vis spectra was investigated into three different solvents (DMF, NMP, and H2SO4). In all forms, the oxidation state of P2ClAn and P2ClAn/SiO2 composite increased with increasing concentration of the testing solution into H2SO4. Thermogravimetric study exhibited that the composite has a higher thermal stability than P2ClAn. XRD measurement of the composite revealed that the crystal structure of incorporated SiO2 undergone a distortion and converted into amorphous. Thus, the XRD pattern of P2ClAn was predominant. SEM analysis results revealed interesting morphological features for the composites converted to different forms and confirmed the formation of monodispersed composite particles. ESEM image of P2ClAn/SiO2 has particle diameter of less than 1 μm. The conductivity of P2ClAn and P2ClAn/SiO2 was measured by four‐probe technique. Magnetic susceptibility measurements revealed that the composite has a paramagnetic properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:935–943, 2006
Morphology and melt rheology of nylon 11/clay nanocomposites
Authors: He Xiaofeng , Yang Jun , Zhu Lianchao , Wang Biao , Sun Guangping , Lv Pengfei , Phang In Yee , Liu Tianxi 
Published: July 2006

AbstractNylon 11 (PA11)/clay nanocomposites have been prepared by melt‐blending, followed by melt‐extrusion through a capillary. Transmission electron microscopy shows that the exfoliated clay morphology is dominant for low nanofiller content, while the intercalated one is prevailing for high filler loading. Melt rheological properties of PA11 nanocomposites have been studied in both linear and nonlinear viscoelastic response regions. In the linear regime, the nanocomposites exhibit much higher storage modulus (G′) and loss modulus (G″) values than neat PA11. The values of G′ and G″ increase steadily with clay loading at low concentrations, while the G′ and G″ for the sample with 5 wt % clay show an inverse dependence and lie between the modulus values of the samples with 1 and 2 wt % of clay. This is attributed to the alignment/orientation of nanoclay platelets in the intercalated nanocomposite induced by capillary extrusion. In the nonlinear regime, the nanocomposites show increased shear viscosities when compared with the neat resin. The dependence of the shear viscosity on clay loading has analogous trend to that of G′ and G″. Finally, a comparison has been made between the complex and steady viscosities to verify the applicability of the empirical Cox‐Merz rule. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 542–549, 2006
Synthesis and characterization of superabsorbent hydrogels composites based on polysuccinimide
Authors: Yang Jun , Fang Li , Tan Tianwei 
Published: July 2006

AbstractA kind of novel superabsorbent hydrogel with high swelling ratio property that could be used for the development of water absorbing resin, soil water retention agent, and chemical sand‐fixing material was synthesized in this study. The hydrogels were prepared by the crosslinking reaction of polysuccinimide (PSI). The relationships between swelling ratio and volume of solvent as well as the concentration of crosslinking agent were investigated in detail. Several composites, such as starch, carrageenan, and polyacrylamide, were added into hydrogels to enhance the swelling ratio. It was found that the swelling ratio was significantly increased, which the maximum water absorbency was enhanced 2.46 times when the composite polyacrylamide (PAM) was added compared to the control. The effects of ionic strength and sensitivity of pH on hydrogels were also studied. The modified hydrogels products with swelling ratio less sensitivity to the salinity as well as relative high swelling ration in salinity system were also obtained by adding PAM. Through the Fourier transform infrared spectroscopy (FTIR) characterizations, the crosslinking reaction mechanism and the structure of composite were proposed. In addition, the transmission electron microscopy (TEM) examinations showed that some composite materials elevated the physical crosslinked and connected channels density substantially. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 550–557, 2006
Vitrification, devitrification, and dielectric relaxations during the non‐isothermal curing of diepoxy‐cycloaliphatic diamine
Authors: Montserrat S. , Roman F. , Colomer P. 
Published: July 2006

AbstractThe curing of an epoxy resin based on diglycidyl ether of bisphenol A (DGEBA) with a diamine based on 4,4′‐diamino‐3,3′‐dimethyldicyclohexylmethane (3DCM) was analyzed by dielectric relaxation spectroscopy (DRS) between −100 and 220°C, at heating rates ranging from 0.1 to 2 K min−1. The permittivity, ε′, and the loss factor, ε″, were measured by DRS in the frequency range between 1 and 100 kHz. The dielectric relaxations were correlated with the relaxations observed previously by temperature modulated differential scanning calorimetry (TMDSC) at the same heating rates and in modulation conditions of amplitude 0.2 K and a period of 60 s, which is equivalent to a measuring frequency of 16.7 mHz. The dielectric measurements showed three frequency‐dependent dipolar relaxations and one ionic relaxation, which was independent of the frequency. The dipolar relaxations were associated with the glass transition of the unreacted system and the vitrification and the devitrification processes of the system during the crosslinking reaction, and the ionic relaxation was associated with the beginning of the crosslinking reaction. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 558–563, 2006
Synthesis of a side chain liquid crystalline polycarbonate with a chiral backbone
Authors: Sahin Y. Muge Calik , Serhatli I. Ersin , Menceloglu Yusuf Z. 
Published: July 2006

AbstractWe report the experimental demonstration of a novel and environmentally benign supercritical carbon dioxide (ScCO2) technique that yields an optically active, side chain liquid crystalline polycarbonate in a single‐step reaction. The obtained polymer is worthwhile, since it is highly stereoregular and can find applications in an enlarged mesomorphic temperature range compared to its acrylic analogues. The synthesized materials were characterized by IR, 1H‐NMR, and 13C‐NMR, while the thermal properties were measured by DSC. Polarized optical micrograph and wide angle X‐ray diffraction were used for the mesogenic property characterization of the copolymer. The transfer chirality from the backbone to the mesophase is demonstrated on the optical microscopy textures. Being consistent with the 13C‐NMR, X‐ray implies an ordered polymeric structure. The DSC analysis of the copolymer indicates that the Ti (the clearing point temperature) value does not change dramatically, whereas a pronounced decrease in Tg (the glass transition temperature) value is observed from that of its acrylic analogues. Hence, the obtained polymer exhibits another practical benefit by widening the mesomorphic temperature range. This study is the insightful combination of material processing and chemical design that elucidates the advantages of ScCO2 application, in terms of liquid crystallinity and the tacticity of the obtained polymer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1915–1921, 2006
Contact angle determination on plasma‐treated poly(ethylene terephthalate) fabrics and foils
Authors: Hossain M. M. , Hegemann D. , Herrmann A. S. , Chabrecek P. 
Published: July 2006

AbstractThe surfaces of polyester (PET) fabrics and foils were modified by low‐pressure RF plasmas with air, CO2, water vapor as well as Ar/O2 and He/O2 mixtures. To increase the wettability of the fabrics, the plasma processing parameters were optimized by means of a suction test with water. It was found that low pressure (10–16 Pa) and medium power (10–16 W) yielded a good penetration of plasma species in the textile structure for all oxygen‐containing gases and gaseous mixtures used. While the wettability of the PET fabric was increased in all cases, the Ar/O2 plasma revealed the best hydrophilization effect with respect to water suction and aging. The hydrophilization of PET fabrics was closely related to the surface oxidation and was characterized by XPS analysis. Static and advancing contact angles were determined from the capillary rise with water. Both wetting and aging demonstrated a good comparability between plasma‐treated PET fabrics and foils, thus indicating a uniform treatment. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1452–1458, 2006
Polyacrylate‐core/TiO2‐shell nanocomposite particles prepared by in situ emulsion polymerization
Authors: Ai Zhaoquan , Sun Guilin , Zhou Qilong , Xie Changsheng 
Published: July 2006

AbstractWe report the preparation of polyacrylate‐core/TiO2‐shell nanocomposite particles through in situ emulsion polymerization in the presence of nano‐TiO2 colloid obtained by the hydrolysis of titanium tetrachloride. The resultant colloidal system can be stable for months without any precipitation. In a typical sample, the diameter of nanocomposite particles was about 150 nm, and the thickness of TiO2‐shell was 4–10 nm. Only cetyltrimethylammonium bromide was employed to provide the latex particles with positive charge, which was enough for the formation of fine TiO2 coatings. Three initiators were tested. Ammonia persulfate was the most suitable one, because the cooperative effect was formed by the negatively charged TiO2 particles and the terminal anionic group (SO42−, the fraction of Ammonia persulfate) of the polymer chain on the surface of latex particles to maintain the stability of nanocomposite system. The pH value played a vital role in obtaining a tight TiO2 coating. Transmission electron microscopy, X‐ray diffraction and Atomic force microscopy were used to characterize this nanocomposite material. It was found that rutile and anatase coexisted in the nanocomposite film. This may suggest a potential application in the field of photocatalytic coating. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1466–1470, 2006