bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonlinear surface electrical resistivity of graphite–polyurethane composite films
Authors: Kannarpady Ganesh K. , Mohan Bharath , Bhattacharyya Abhijit 
Published: June 2007

AbstractIn this article, we study the surface resistivity of graphite–polyurethane composites using voltage–current characteristics. The evolution of the percolation network of graphite in polyurethane is qualitatively studied using optical micrographs. As expected, the surface resistivity decreases as a function of graphite concentration. In particular, the surface resistivity of the 69% graphite–polyurethane composite is about four orders of magnitude lower than the surface resistivity of the 27% graphite–polyurethane composite. The electrical resistivity of the composite is found to be highly nonlinear with respect to an increasing voltage at a low graphite weight fraction. On the other hand, the nonlinearity is significantly milder at higher weight fractions. The reasons behind the nonlinearity are discussed. Very preliminary studies indicate that very low weight fractions of single wall carbon nanotubes (e.g. 2.5%) are sufficient to generate electrical conductivities comparable to much higher loading fractions (∼ 60% and higher) of the heavier graphite particles. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Dielectric studies of conductive carbon black reinforced microcellular ethylene–propylene–diene monomer vulcanizates
Authors: Mahapatra S. P. , Sridhar V. , Tripathy D. K. 
Published: June 2007

AbstractThe alternating‐current and electrical conductivity of conductive, carbon black reinforced, microcellular ethylene–propylene–diene monomer vulcanizates was measured in the frequency range of 100 Hz to 1 MHz. The effects of variations in the filler and blowing‐agent loadings on the dielectric constant and percolation behavior were studied. The phenomenon of percolation was examined on the basis of measured changes in the electrical conductivity and morphology of composites with different concentrations of the filler. Scanning electron microphotographs showed the agglomeration of the filler above these concentrations and the formation of a continuous network structure. The experimental results were not in agreement with the predictions of the statistical percolation theory; this deviation was explained in light of the formation of an interphase or mesostructure in the composites. The variation of the dielectric constant with the filler and blowing‐agent loadings was explained on the basis of polarization of the filler in the polymer matrix. Additionally, the use of dielectric mixture laws in describing the dielectric constants of both solid and microcellular composites was investigated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Optical and conductivity studies of Pseudo‐doped chitin‐polyaniline blend
Authors: Rao Vijayalakshmi , Ramaprasad A. T. 
Published: June 2007

AbstractIn this article, we report the preparation and characterization of self‐doped conducting chitin, polyaniline blends by solution blending method. The characterization of the blends was done by UV–vis absorption spectrum, FTIR, and conductivity studies. Conductivity of the self doped blends increases from less than ∼10−7 S/cm to 2.15 × 10−5 S/cm, depending on the percentage of polyaniline in the blend. Spectroscopic analysis shows interaction between chitin and polyaniline and the electronic states are similar to those of the emeraldine and protonically doped forms of polyaniline. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Dielectric properties of thermosetting material nanocomposites
Authors: Luiz Dias Filho Newton , Adolfo de Aquino Hermes , Souza Pereira Denise , Rosa André H. 
Published: June 2007

AbstractThe dieletric relaxation properties of thermosetting material nanocomposites based on spherosilicate nanoplatforms were studied from room temperature to 170°C, varying the frequency from 10 to 1000 KHz. Permittivity (ε′), dielectric loss (ε″), and activation energy (Ea) were calculated. The results of dielectric relaxation were confirmed by those of the final properties. The dielectric loss amplitude decreases with increasing ODPG content until about 70–73 wt % and slightly increases at higher ODPG content. This means that the increasing of the ODPG content in the composite samples decreases the number of pendants groups and/or increases crosslink density, causing decreased motion of organic tethers, and subsequently decreasing of the dipolar mobility. The results of apparent activation energy, fracture toughness and tensile modulus mechanical properties show the same profile with respect to ODPG content, in the sense that they exhibit maxima around 70 wt % ODPG. For the ODPG/MDA composites, this formulation of 70 wt % ODPG containing excess of amine is not composition where the highest crosslinked density is reached. This implies that the best mechanical properties and Ea are provided by some degree of chain flexibility. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Recognition properties of poly(vinylidene fluoride) hollow‐fiber membranes modified by levofloxacin‐imprinted polymers
Authors: Bing Nai‐Ci , Xu Zhen‐Liang , Wang Xue‐Jun , Yang Zuo‐Guo , Yang Hu 
Published: June 2007

AbstractThrough the use of thermal polymerization, poly(vinylidene fluoride) (PVDF) hollow‐fiber membranes modified by a thin layer of molecularly imprinted polymers (MIPs) were developed for the selective separation of levofloxacin. To demonstrate the changes induced by thermal polymerization, PVDF hollow‐fiber membranes with different modification degrees by repeated polymerization were weighed. The total weight of the imprinted membranes increased by 14 μg/cm2 after a five‐cycle polymerization. An increase in the membrane weight indicated the deposition of an MIP layer on the external surface of PVDF hollow‐fiber membranes during each polymerization cycle, which was also characterized by scanning electron microscopy. MIP membranes with different degrees of surface modification provided highly selective binding of levofloxacin. Both hollow‐fiber MIP membranes and nonimprinted membranes showed enhanced adsorption of levofloxacin and ofloxacin gradually with an increase in the modification degrees of PVDF hollow‐fiber membranes to a maximum value followed by a decrease. These results indicate that thermal polymerization indeed produces an MIP layer on the external surface of PVDF hollow‐fiber membranes and that it is feasible to control the permeability by repeated polymerization cycles. Different solvent systems in the permeation experiments were used to understand the hydrophobic interaction as one of the results of the binding specificity of MIP membranes. Selective separation was obtained by multisite binding to the template via ionic, hydrogen‐bond, and hydrophobic interactions. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Use of poly(o‐toluidine)/ZrO2 nanocomposite coatings for the corrosion protection of mild steel
Authors: Chaudhari Sudeshna , Patil P. P. , Mandale A. B. , Patil K. R. , Sainkar S. R. 
Published: June 2007

AbstractThis study explored the possibility of using poly(o‐toluidine) (POT)/ZrO2 nanocomposite coatings for the corrosion protection of mild steel in a chloride environment. POT/ZrO2 nanocomposite coatings were synthesized on steel substrates through an electrochemical route. These coatings were characterized with cyclic voltammetry, ultraviolet–visible absorption spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and X‐ray photoelectron spectroscopy. The performance of POT/ZrO2 nanocomposites as protective coatings against the corrosion of mild steel in aqueous 3 wt % NaCl was evaluated with the potentiodynamic polarization technique and electrochemical impedance spectroscopy. The results of this study demonstrate that POT/ZrO2 nanocomposite coatings provide better protection for mild steel against corrosion than pure POT coatings. The corrosion potential was about 0.312 V versus a saturated calomel electrode, more positive in aqueous 3 wt % NaCl for the nanocomposite‐coated steel than the uncoated steel, and the corrosion rate of steel was reduced by a factor of almost 51. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Phase morphology and mechanical properties of a poly(ether sulfone)‐modified bismaleimide resin
Authors: Liu Xiao Yun , Zhan Guo Zhu , Han Zhe Wen , Li Shan Jun , Yu Ying Feng 
Published: June 2007

AbstractThe polymerization‐induced phase‐separation behavior of a thermoplastic [poly(ether sulfone) (PES)]‐ modified thermosetting bismaleimide resin during isothermal curing was investigated with differential scanning calorimetry, time‐resolved light scattering, and scanning electron microscopy with various contents and molecular weights of PES. The results suggested that the phase structure changed from a dispersed structure to a bicontinuous structure to phase inversion with an increase in the PES content. Three kinds of PES with different molecular weights were used to study the effects of the molecular weight on the phase structure and mechanical properties of modified systems. With higher molecular weight PES, a phase‐inversion morphology could be obtained at lower PES contents. The curing conversion of bismaleimide was affected by the composition of the blend. The curing rate decreased with an increase in the PES content. A blend with 15 wt % PES of a suitable molecular weight had a higher tensile strength and elongation at break than that without PES. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Acid‐dye‐dyeable polyacrylonitrile/ poly(N,N‐dilkylaminoethylacrylate) acrylic blend fiber
Authors: Wang Ya‐Zhen , Du Shu‐Ping , Shen Xin‐Yuan , Zhu Li‐Wu , Gong Zhen‐Ping 
Published: June 2007

AbstractAn acid‐dye‐dyeable polyacrylonitrile/poly (N,N‐dilkylaminoethylacrylate) blend fiber was prepared. On the basis of research for the dye uptake, color strength, tensile strength, and breaking elongation of the polyacrylonitrile/poly (N,N‐dilkylaminoethylacrylate) blend fiber, it was found that the blend fiber and its fabrics for acid dyes possessed favorable dyeability and mechanical properties. The effect of the polyacrylonitrile ratio on the blend fiber was examined. The optimum dyeing‐process parameters were determined. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Cationic water‐soluble polymers with the ability to remove arsenate through an ultrafiltration technique
Authors: Rivas Bernabé L. , del Carmen Aguirre María , Pereira Eduardo 
Published: June 2007

AbstractDifferent cationic water‐soluble polymers with (R)4N+X− groups and pyridinium groups were prepared, and their arsenate retention performance was investigated with the liquid‐phase polymer‐based retention technique. Poly[3‐(methacryloylamino)propyl]trimethylammonium chloride, poly[2‐(acryloyloxy)ethyl]trimethylammonium chloride, poly(ar‐vinylbenzyl)trimethylammonium chloride, poly[2‐(acryloyloxy)ethyl]trimethylammonium methyl sulfate, poly(4‐vinyl‐1‐methyl pyridinium)bromide, and poly[3‐(methacryloylamino)propyl]dimethyl(3‐sulfopropyl)ammonium hydroxide were prepared. The synthesis of the polymers by solution radical polymerization produced a yield higher than 77%. Structural analyses were performed with Fourier transform infrared and 1H‐NMR spectroscopy and thermogravimetry/differential scanning calorimetry. Commercial poly(4‐vinyl‐1‐methyl pyridinium)bromide and poly(ar‐vinylbenzyl)trimethylammonium chloride were also used. The liquid‐phase polymer‐based retention technique was employed to study the retention of arsenate species. The polymer structure and exchange groups, such as methyl sulfate, chloride, bromide, and hydroxide, presented different properties for removing arsenate anions from aqueous solutions. The type of voluminous quaternary ammonium group present influenced arsenic retention. All the polymers could bind HAsO42− species from an aqueous solution more selectively at pHs 8 and 6 than at pH 4. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Hyperbranched aromatic polyamines with s‐triazine rings
Authors: Mahapatra Sibdas Singha , Karak Niranjan 
Published: June 2007

AbstractTwo aromatic hyperbranched polyamines with s‐triazine rings were synthesized from A2 (4,4′‐sulfonyl dianiline or 4,4′‐methylene dianiline) and B3 (2,4,6‐trichloro‐s‐triazine) types of monomers by a single‐step nucleophilic displacement polymerization technique in the presence of diisopropyl ethyl amine as the base. The hyperbranched polyamines were obtained in high yields (∼ 82–90%) with this technique. The polymers were characterized through solubility testing, measurements of the inherent viscosity, Fourier transform infrared, ultraviolet, 1H‐NMR, and 13C‐NMR spectroscopy, and X‐ray diffraction studies. The inherent viscosities of the polymers were in the range of 0.23–0.42 dL/g in 0.5% (w/v) N,N′‐dimethylacetamide at 27 ± 0.1°C. They were soluble only in highly polar solvents such as N,N′‐dimethylacetamide, dimethylformamide, dimethyl sulfoxide, and N‐methylpyrrolidone. The thermal behavior of the polymers was investigated with thermogravimetric analysis and differential scanning calorimetry studies. The flame‐retardant characteristics of the polymers were tested through the measurement of the limiting oxygen index. In the thermogravimetric analysis of these hyperbranched polyamines, no weight loss was observed below 250°C under a nitrogen atmosphere, whereas differential scanning calorimetry showed that the glass‐transition temperatures were about 240 and 230°C for the polymers with sulfonyl and methylene groups, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Styrene–butadiene block copolymer with high cis‐1,4 microstructure
Authors: Zhu Han , Wu Yi‐Xian , Zhao Jiang‐Wei , Guo Qing‐Lei , Huang Qi‐gu , Wu Guan‐Ying 
Published: June 2007

AbstractThe sequential block copolymerization of styrene (St) and butadiene (Bd) was carried out with an activated rare earth catalyst composed of catalyst neodymium tricarboxylate (Nd), cocatalyst Al(i‐Bu)3 (Al), and chlorinating agent (Cl). The microstructure, composition, and morphology of the copolymer were characterized by FTIR, 1H NMR, 13C NMR, and TEM. The results show that styrene–butadiene diblock copolymer with high cis‐1,4 microstructure of butadiene units (∼ 97 mol %) was synthesized. The cis‐selectivity for Bd units was almost independent on the content of styrene units in the copolymer ranging from 18.1 mol % to 29.8 mol %. The phase‐separated morphology of polystyrene (PS) domains of about 40 nm tethered by the elastomeric polybutadiene (PB) segments is observed. The PS‐b‐cis‐PB copolymer could be used as an effective compatilizer for noncompatilized binary PS/cis‐PB blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Synthesis, characterization, and acoustic properties of new soluble polyurethanes based on 2,2′‐[1,4‐phenylenebis(nitrilomethylylidene)diphenol and 2,2′‐[4,4′‐methylene‐di‐2‐methylphenylene‐1,1′‐bis(nitrilomethylylidene)]diphenol
Authors: Raghu A. V. , Gadaginamath G. S. , Mathew N. , Halligudi S. B. , Aminabhavi T. M. 
Published: June 2007

AbstractEight novel polyurethanes based on 2,2′‐[1,4‐phenylenebis(nitrilomethylylidene)]diphenol and 2,2′‐[4,4′‐methylene‐di‐2‐methylphenylene‐1,1′‐bis(nitrilomethylylidene)]diphenol acting as hard segments with two aromatic and two aliphatic diisocyanates (4,4′‐diphenylmethane diisocyanate, toluene 2,4‐diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate) were prepared and characterized with Fourier transform infrared, UV spectrophotometry, fluorescence spectroscopy, 1H‐NMR and 13C‐NMR spectroscopy, thermogravimetric analysis, and differential thermal analysis. All the polyurethanes contained domains of semicrystalline and amorphous structures, as indicated by X‐ray diffraction. The acoustic properties and solubility parameters were calculated with the group contribution method. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Electrical behavior of polyurethane composites with acid treatment‐induced damage to multiwalled carbon nanotubes
Authors: Jang Pill Gyu , Suh Kwang S. , Park Min , Kim Jun Kyung , Kim Woo Nyon , Gyu Yoon Ho 
Published: June 2007

AbstractWe have studied the electrical conductivity and percolation threshold of polyurethane (PU) composites filled with multiwalled carbon nanotubes (MWCNT) purified by increasing immersion time in aqueous solutions of either nitric acid or a mixture of nitric and sulfuric acids at 80°C. The MWCNT crystallinity peaks after 2 h of treatment, which enables the PU composites to enhance the percolation threshold and electrical conductivity in the conductive network formation region. MWCNT treated under either a milder or severer acidic condition deteriorate the electrical behavior of the composites, since MWCNT are poorly dispersed in the PU matrix in the former condition, but lost their intrinsic electrical conductivity due to the partial destruction of their crystalline structure in the latter. Therefore, the acid treatment needs to be carefully controlled to effectively purify the MWCNT, maintain the crystalline structure without further damage, and thereby improve the electrical behavior of PU/MWCNT composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Kinetics for chlorination of maleic anhydride grafted polypropylene
Authors: Fu He‐Qing , Huang Hong , Zhang Xin‐Ya , Ye Dai‐Yong , Chen Huan‐Qin 
Published: June 2007

AbstractPreparation of Chlorinated maleic anhydride grafted polypropylene (Cl‐PP‐g‐MAH) by free radical process was carried out using carbon tetrachloride (CCl4) as the solvent and benzoperoxide (BPO) as the initiator. Effects of reaction temperature, concentrations of PP‐g‐MAH and BPO on the rate of chlorination were studied. The experimental results showed the actual rate constant for chlorination of maleic anhydride grafted polypropylene followed the Arrhenius law and the total apparent activation energy was 19.7 kJ mol−1. The kinetic model for chlorination of maleic anhydride grafted polypropylene was found to be R = K[BPO]0.53[C]0.93. The properties of chlorination of maleic anhydride grafted polypropylene were better than those of maleic anhydride grafted polypropylene. The products were characterized by Fourier transform infrared spectroscopy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Preparation and properties of EPDM/TiO2 composites
Authors: Haitao Shan , Juqing Cui , Qiang Zhang , Wei Zhuang , Qihui He , Baixing Hu , Jian Shen 
Published: June 2007

AbstractComposites of EPDM/TiO2 in which TiO2 particles were surface modified with γ‐methacryloxypropyl trimethoxysilane (MPS) and preultrasonically dispersed, and EPDM was grafted with maleic anhydride (MA) were successfully prepared. FTIR analysis showed that the modification of TiO2 and the grafting of EPDM had taken place. The uniform dispersion of TiO2 particles in EPDM matrix as well as good interfacial compatibility was observed from scanning electron microscopy (SEM) images. The tensile strength and elongation at break were greatly improved and reached the maximum as the content of TiO2 in the composite reached 7.5% wt. The result of swell and solution test indicated that the composites were evidently crosslinked. Thermogravimetric analysis (TGA) indicated that the decomposition temperature of the composite was increased about 20°C. This work provides a potential way for crosslinking EPDM matrix with inorganic filler in a convenient method. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Effect of the structure on sorption and diffusion processes in polyamide 6, part 1: Activation energy and thermodynamic parameters of water desorption in oriented and unoriented polyamide 6
Authors: Avramova Nadka 
Published: June 2007

AbstractEffect of the structure on desorption of water in polyamide 6 is studied by differential scanning calorimetry and thermogravimetry. Oriented and unoriented polyamide 6 fibers annealed in water at 100°C for different times (2 s up to 1 h) are characterized by their structure and transport properties. It is found that water treatment leads to substantial change in the polymer structure (including phase transition even at room temperature). Activation energy and enthalpy of water desorption are determined, and their high values (Ea = 60–130 kJ/mol; ΔHd = 950–1360 J/g) are attributed to the formation of strong sorbent–sorbat bonds. Both parameters are influensed substantially by the polymer structure (degree of crystallinity and orientation). Besides, it is found that the temperature of water desorption (Td) is also very sensitive to the structure. The Td‐values increase sharply with rise of degree of crystallinity, being always considerably lower for oriented fibers. This quite unexpected result is also confirmed and further interpreted in the next parts of the article. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Preparation and thermal property of hybrid nanocomposites by free radical copolymerization of styrene with octavinyl polyhedral oligomeric silsesquioxane
Authors: Yang Benhong , Xu Hongyao , Wang Jiafeng , Gang Shanyi , Li Cun 
Published: June 2007

AbstractThe poly(styrene‐co‐octavinyl‐polyhedral oligomeric silsesquioxane) (PS–POSS) organic–inorganic hybrid nanocomposites containing various percent of POSS were prepared via one‐step free radical polymerization and characterized by FTIR, high‐resolution 1H NMR, 29Si NMR, GPC, DSC, and TGA technologies. The POSS contents in these nanocomposites were determined using FTIR calibration curve. The result shows that the POSS contents in nanocomposites can be tailored by varying the POSS feed ratios. On the basis of the POSS contents in the nanocomposites and the 1H NMR spectra, the number of reacted vinyl groups of each octavinyl‐POSS macromonomer were calculated to be 6–8. DSC and TGA measurements indicate that the incorporation of POSS into PS homopolymer can apparently improve the thermal properties of the polymeric materials. The dramatic Tg and Tdec increases are mainly due to the formation of star and low cross‐linking structure of the nanocomposites, where POSS cores behave as the joint points and hinder the motion and degradation of the polymeric chains. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Influence of different amides as plasticizer on the properties of soy protein plastics
Authors: Liu Dagang , Tian Huafeng , Zhang Lina 
Published: June 2007

AbstractA series of amide‐plasticized soy protein isolate materials were prepared by hot compression‐molding techniques at 140°C and 20 MPa. The plasticizing efficiency of amides was in the order of formamide > acetamide > acrylamide resulting from scanning electron microscopy, optical transmittance and differential scanning calorimetry. The results from torque rheology indicated that flowability and processability could be improved by adding amide as plasticizers. All of the sheets showed single glass transition temperature obtained by differential scanning calorimetry, indicating good compatibility between amide and soy protein. The water uptake of the plastics sheets and effects of moisture content on the thermal and mechanical properties were also investigated. The glass transition temperature and tensile strength decreased with an increase of moisture content in sheets. Formamide was considered as the best plasticizer of three amides because of the higher plasticizing efficiency and water resistance of SFm sheets. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007