bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of new conducting polymeric membrane based on sulfonation of compatibilized NR/EPDM blend
Authors: El Sayed A. Mounir 
Published: March 2007

AbstractIn this study, research was undertaken to obtain new conducting polymer blend membrane based on compatibilized natural rubber/ethylene–propylene–diene monomer (NR/EPDM) by using different compatibilizers. To utilize them as membranes in polymer electrolyte membrane fuel cells, the blend membranes become conducting by sulfonation reaction, which inserts SO3H groups into the macromolecular chain. The polymer blend membrane ratio (50/50), which was compatibilized by polyacrylonitrile compound was selected among the entire blend studied (A6), with the aim of determining its conductivity and water and methanol permeabilities. The degree of compatibility of NR/EPDM blend was improved by the use of polyacrylonitrile compounds as compatibilizers. The effect of these compounds on the compatibility of blend was evaluated by ultrasonic spectroscopy and differential scanning calorimetry, DSC. It was found that a good compatibility has been achieved by using polyacrylonitrile because of the nitrile groups. When the polymer blend membrane (A6) was sulfonated with SO3H groups good perspectives were shown regarding the methanol and water permeabilities and physical properties comparing to the commercial Nafion one. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3804–3812, 2007
Thermal and crystallization behaviors of polyethylene blends synthesized by binary late transition metal catalysts combinations
Authors: Pan L. , Zhang Kun Y. , Li Yan G. , Bo Shu Q. , Li Yue S. 
Published: March 2007

AbstractA series of reactor blends of linear and branched polyethylenes have been prepared, in the presence of modified methylaluminoxane, using a combination of 2,6‐bis[1‐(2,6‐dimethyphenylimino) pyridyl]‐cobalt(II) dichloride (1), known as an active catalyst for producing linear polyethylene, and [1,4‐bis(2,6‐diidopropylphenyl)] acenaphthene diimine nickel(II) dibromide (2), which is active for the production of branched polyethylene. The polymerizations were performed at various levels of catalyst feed ratio at 10 bar. The linear correlation between catalyst activity and concentration of catalyst 2 suggested that the catalysts performed independently from each other. The weight‐average molecular weights
$ {({\overline{M}}_{w})} $, crystalline structures, and phase structures of the blends were investigated, using a combination of gel permeation chromatography, differential scanning calorimetry, wide‐angle X‐ray diffraction, and small angle X‐ray scattering techniques. It was found that the polymerization activities and MWs and crystallization rate of the polymers took decreasing tendency with the increase of the catalyst 2 ratios, while melting temperatures (Tm), crystalline temperatures (Tc), and crystalline degrees took decreasing tendency. Long period was distinctly influenced by the amorphous component concentration. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4188–4198, 2007
Uptake of aromatic solvents by polyethylene films
Authors: Igwe Isaac O. 
Published: March 2007

AbstractThe sorption properties of the solvents benzene, toluene, and xylene in polyethylene films at 40, 60, and 80°C were investigated. The diffusion coefficient increased with an increase in the sorption temperature for the solvents and was highest for xylene and least for benzene. The inability of xylene to show a definite order of the diffusion coefficients at the investigated temperatures was attributed to the presence of two methyl side groups in the molecule. The solubilities of the solvents in polyethylene increased with an increase in the sorption temperature, and the following order of the solubilities could be observed: xylene > toluene > benzene. The permeabilities of the solvents in polyethylene depended on the sorption temperature, and the following order of the permeabilities was observed: xylene > toluene > benzene. The calculated activation energies of sorption in polyethylene films were all positive; benzene had the highest energy of sorption, and xylene had the lowest. The calculated enthalpies of sorption (ΔHS) were also positive for the three solvents and were in the following order: xylene > toluene > benzene. The calculated entropies of sorption (ΔS) were negative for the solvents and showed trends similar to the variation of ΔHS among the solvents. The change in the Gibbs free energies of sorption (ΔGS), evaluated with the expression ΔGS = ΔHS − TΔS (where T is the Kelvin temperature), were all positive, and this was an indication of the nonspontaneity of the solubility of polyethylene in the aromatic solvents at 313 K. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3849–3854, 2007
Synthesis of formaldehyde polymers from benzene‐1,2‐diol, phenolic alkane‐1,2‐diol, and phenolic alkane‐1,3‐diol as immobilized chelatants for borate anion
Authors: Tyman John H. P. , Payne Peter B. 
Published: March 2007

AbstractA variety of phenolic aryl‐1,2‐ and 1,3‐diols have been condensed with formaldehyde to form polymers serving as immobilized chelatants for borate anions. In this way, polymers from 1,2‐dihydroxybenzene, 2‐hydroxymethylphenol, and a 3‐methyl derivative (saligenins) and 2‐(4‐hydroxyphenyl)‐propane‐1,3‐diol have been converted into formaldehyde polymers with an increasing level of conformational mobility in the diol moiety of the polymer. The extraction of borate from alkaline solutions with three types of polymers has been examined, and the polymer containing planar 1,2‐dihydroxybenzene has been found to be superior to a saligenin‐ and 2‐(4‐hydroxyphenyl)‐ propane‐1,3‐diol‐derived polymer. This suggests that conformational mobility is not an important structural feature. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Crystallization behaviors of linear and long chain branched polypropylene
Authors: Tian Jinghua , Yu Wei , Zhou Chixing 
Published: March 2007

AbstractThe nonisothermal crystallization kinetics of linear and long chain branched polypropylene (LCB PP) were investigated by differential scanning calorimetry (DSC) at various cooling rates. Several methods such as Avrami, Ozawa, and Jeziorny were applied to describe the crystallization process of linear PP and LCB PPs with different LCB level under nonisothermal conditions. The values of t1/2, Zc, and F(T) show that LCB has the role of heterogeneous nucleating agent and accelerates the crystallization process of PP. Moreover, the Kissinger method was used to evaluate the activation energy of linear PP and LCB PPs. The result shows that the activation energy of LCB PPs are higher than that of linear PP, indicating that the presence of LCB baffles the transfer of macromolecular segments from PP melt to the crystal growth surface. Furthermore, the crystal morphology of linear PP and LCB PPs was observed through polarized optical microscopy (POM), and fine spherulites were observed for LCB PPs. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3592–3600, 2007
Effects of polymethylvinylsilicone oil with side tetraphenylphenyl groups on the radiation resistance of addition‐type silicone rubber
Authors: Jiang Zhigang , Zhang Jie , Feng Shengyu 
Published: March 2007

AbstractPolymethylvinylsilicone oil with side tetraphenylphenyl groups (called C2 gum for short) as a low molecular additive was used in two kinds of addition‐type silicone rubber, polymethylvinyl silicone rubber and poly (dimethyl‐diphenyl) silicone rubber, and the radiation resistance of silicone rubbers obtained was investigated by γ‐rays radiation with the dose rate of 117 Gy/min at doses up to 350, 500, and 850 kGy, respectively. Moreover, the average molecular weight between crosslinks and mechanical properties of silicone rubbers after irradiated in air and N2 were determined by toluene‐swelling method and on a XLS‐A rubber test instrument, respectively. The results show that C2 gum can effectively improve the radiation resistance of silicone rubber. When C2 gum is used in poly(dimethyl‐diphenyl) silicone rubber, phenyl groups and tetraphenylphenyl groups may have synergistic effect, and the radiation resistance is improved greatly. The suitable amount of C2 gum used in silicone rubber is 10– 14 phr. The crosslinking density of vulcanizates irradiated in N2 is higher than that of vulcanizates irradiated in air because of the oxidative degradation. The radiation protection mechanism of C2 gum was also discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4144–4148, 2007
Synthesis of functionalized double‐cylinder‐type copolymer brushes and crosslinking of internal cylindrical domains
Authors: Ishizu Koji , Takano Satoshi , Ochi Koichiro 
Published: March 2007

AbstractPhotoinduced atom transfer radical polymerization (ATRP) was applied to the synthesis of double‐cylinder‐type copolymer brushes. The procedure included the following steps: (1) photoinduced ATRP of multifunctional polystyrene (PSDC) having N,N‐diethyldithiocarbamate (DC) pendant groups with t‐butyl acrylate (BA) and (2) subsequent photoinduced ATRP of methyl methacrylate (MMA) with this PBA brush polyinitiator provided double‐cylinder‐type brushes [PSDC‐graft‐(PBA‐block‐PMMA)]. Solution properties of such double‐cylinder‐type brushes were investigated by dynamic light scattering. As a result, these copolymer brushes exhibited an isotropic conformation in solution. After hydrolysis of PBA blocks, we obtained amphiphilic copolymer brushes: PSDC‐graft‐[poly(acrylic acid) (PAA)‐block‐PMMA]. Crosslinking of PAA internal cylindrical domains was performed by the reaction of PAA blocks with ethylenediamine. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3994–4000, 2007
Investigation of styrene/1‐hexene copolymerization by homogeneous and heterogeneous bisindenyl ethane zirconium dichloride catalyst system
Authors: Rahmani Sohrab , Abbasian Mojtaba , N. Moghadam Peyman , A. Entezami Ali 
Published: March 2007

AbstractHomogeneous copolymerization of styrene and 1‐hexene was carried out in toluene at room temperature using bisindenyl ethane zirconium dichloride/methylaluminoxane (MAO). The supported catalyst was prepared with immobilization of Et(Ind)2ZrCl2/MAO on silica (calcinated at 500°C) with premixed method. Heterogeneous copolymerization of styrene/1‐hexene with different mole ratios was carried out in the presence of supported catalyst system. The copolymers obtained from homogeneous and heterogeneous catalyst system were characterized by 1H NMR and 13C NMR. Composition of the resulting copolymers was determined by 1H NMR data. Analysis of 13C NMR spectra of obtained copolymers by homogeneous and heterogeneous catalyst systems present isotactic olefin‐enriched copolymers. Molecular weight and thermal behavior of resulting copolymers was investigated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4008–4014, 2007
Platinum and palladium ions adsorption at the trace amounts by radiation crosslinked carboxymethylchitin and carboxymethylchitosan hydrogels
Authors: Wasikiewicz Jaroslaw M. , Mitomo Hiroshi , Seko Noriaki , Tamada Masao , Yoshii Fumio 
Published: March 2007

AbstractAdsorption of palladium and platinum ions at the trace amounts onto radiation crosslinked carboxymethylchitin (CMCht) and carboxymethylchitosan (CMChts) has been investigated. Maximum adsorption capacities for palladium were 2.679 and 1.053 mg/g dry gel, whereas for platinum they were 2.513 and 1.155 mg/dry gel for CMCht and CMChts, respectively. Retention capacity values for palladium were 0.45 and 0.06; for platinum 0.25 and 0.11 mEquiv./g for CMCht and CMChts, correspondingly. It has been shown that adsorption of Pd and Pt ions onto both hydrogels were dependent on the chloric and nitric ions concentration. Desorption experiments in HCl and HNO3 solutions proved that adsorption is governed by chelating mechanism rather than ion‐exchange one. SEM‐EDX spectroscopy showed that palladium and platinum ions were homogeneously distributed in all sections of hydrogel matrix. DSC experiments demonstrated decreasing in the decomposition temperature of polymers after inclusion of palladium and platinum ions, suggesting that metals are causing lowering of stability in polymer structural integrity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4015–4023, 2007
Properties of pH‐dependent tertiary amine‐based gels as potential drug delivery matrices
Authors: Pardini O. R. , Amalvy J. I. , François N. , Daraio M. E. 
Published: March 2007

AbstractThe rheological and morphological properties and in vitro theophylline release of tertiary amine‐based microgels were evaluated. The testing of such a formulation through in vitro diffusion experiments revealed that the release of theophylline from the microgels was pH‐dependent and differs significantly with respect to a nonresponsive gel like scleroglucan (Scl). The microgels were obtained from 2‐(diethyl amino) ethylmethacrylate (DEA) in the presence of a bifunctional crosslinker at pH 8–9. As the resulting microgels are pH‐responsive and an increase in viscosity from high to low pH range is exhibited, the in vitro release of theophylline as model drug was studied at different pHs of both the matrix and the receptor medium. The release behaviors of PDEA‐based microgels were compared to nonresponsive natural gel Scl, studied previously. For microgels, diverse release patterns were found at different acidity conditions. This observation seems to be related to complex diffusion phenomena and the different gel structure obtained for samples prepared at dissimilar pH. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4035–4040, 2007
Polyimide‐silica nanocomposites exhibiting low thermal expansion coefficient and water absorption from surface‐modified silica
Authors: Tang J. C. , Lin G. L. , Yang H. C. , Jiang G. J. , Chen‐Yang Y. W. 
Published: March 2007

AbstractIn this study, a commercially available nano‐sized silica (SiO2) was surface‐modified via esterification with oleic acid (OA), a relatively inexpensive and hydrophobic modifier, and characterized by FTIR, NMR, SEM, EDS, and TGA measurements. Various amounts of the surface‐modified silica nanoparticles (SiO2‐OA) were dispersed in a poly(amic acid), which were then cyclized at high temperatures to form a series of PI/SiO2‐OA nanocomposite films (PISA). The effect of the addition of the SiO2‐OA nanoparticles on the properties of the as‐prepared polyimide nanocomposite was studied. The results indicated that, comparing with pure PI and PI/pristine‐SiO2 composite film (PISI), the as‐prepared PISA films had enhanced dynamic mechanical properties and thermal stability, as well as reduced water absorption and thermal expansion. The as‐prepared PI/SiO2‐OA nanocomposites have potential for applications in high performance microelectronic devices. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104, 4096–4105, 2007
Carbon nanofibre‐reinforced ultrahigh molecular weight polyethylene for tribological applications
Authors: Galetz M. C. , Blaβ T. , Ruckdäschel H. , Sandler J. K. W. , Altstädt V. , Glatzel U. 
Published: March 2007

AbstractCarbon nanofibre (CNF)‐reinforced ultrahigh molecular weight polyethylene (UHMWPE) nanocomposites containing up to 10 wt % of nanofibres were prepared by a novel solvent‐assisted extrusion process using short chain oligomers to tailor the melt viscosity of the UHMWPE matrix. A detailed investigation of the resulting nanocomposite microstructure and of the static mechanical properties revealed that the carbon nanofibres lead to improved mechanical properties of the UHMWPE related to the wear performance of such systems. Unidirectional sliding tests against a 100Cr6 steel under dry conditions verified the significant potential of dispersed carbon nanofibres to reduce the wear rate of this polymer. In light of the promising results, a further optimization of the processing conditions of such UHMWPE nanocomposites is expected to yield interesting future nanocomposite materials even for demanding applications such as artificial knee implants. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4173–4181, 2007
Synthesis and properties of poly(aryl ether ketone ketone)/poly(aryl ether ether ketone ketone) copolymers with pendant cyano groups
Authors: Yu Yikai , Xiao Fen , Cai Mingzhong 
Published: March 2007

Abstract2,6‐Diphenoxybenzonitrile (DPOBN) was synthesized by reaction of phenol with 2,6‐difluorobenzonitrile in N‐methyl‐2‐pyrrolidone in the presence of KOH and K2CO3. Poly(aryl ether ketone ketone)/poly(aryl ether ether ketone ketone) copolymers with pendant cyano groups were prepared by the Friedel–Crafts electrophilic substitution reaction of terephthaloyl chloride with varying mole proportions of diphenyl ether and DPOBN using 1,2‐dichloroethane as solvent and N‐methyl‐2‐pyrrolidone as Lewis base in the presence of anhydrous AlCl3. The resulting polymers were characterized by various analytical techniques, such as FT‐IR, differential scanning calorimeter, thermal gravimetric analysis, and wide‐angle X‐ray diffraction. The crystallinity and melting temperature of the polymers were found to decrease with increase in concentration of the DPOBN units in the polymer. Thermogravimetric studies showed that all the polymers were stable up to 514°C in N2 atmosphere. The glass transition temperature was found to increase with increase in concentration of the DPOBN units in the polymer when the molar ratios of DPOBN to DPE ranged from 10/90 to 30/70. The copolymers containing 30–40 mol % of the DPOBN units exhibit excellent thermostability at (350 ± 10)°C and have good resistance to acidity, alkali, and organic solvents. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3601–3606, 2007
Synthesis of high molecular weight polyoxyethylene with a quaternary catalyst and study of its conductive blends with poly(2‐vinyl pyridine)
Authors: Xie Hong‐Quan , Zhang Ji‐Hong , Cui Min‐Hui , Xie Dong 
Published: March 2007

AbstractHigh molecular weight polyoxyethylene (PEO) was synthesized by using a quaternary catalyst composed of triisobutyl aluminum, phosphoric acid, water, and N,N‐dimethylaniline (DMA). Optimum synthesis conditions and some properties of the product were studied. This catalyst showed high activity and the molecular weight of the polyoxyethylene obtained can approach one million. The activity of polymerization mainly depends upon the composition of catalyst. The optimum composition is as follows: i‐Bu3Al:H3PO4:H2O:DMA = 1 : 0.17 : 0.17 : 0.10–0.15 (molar ratio).The active centers of the catalyst was thus proposed. The high molecular weight PEO synthesized by this catalyst was blended with poly(2‐vinyl pyridine) (PVP) and then doped with LiClO4 and TCNQ to obtain a conductive elastomeric material. Ionic, electronic, and mixed (ionic–electronic) conductivities of blends were investigated. At a Li/EO molar ratio of 0.1 and a TCNQ/VP molar ratio of 0.5, the mixed conductivity of the blend of PEO/PVP/LiCIO4/TCNQ is higher than the sum of ionic conductivity of PEO/PVP/LiCIO4 and electronic conductivity of PEO/PVP/TCNQ, when the weight ratio of PEO to PVP is 6/4 or 5/5. It can reach 4 × 10−6 S/cm at room temperature. Differential scanning calorimetry, thermal gravimetric analysis, and the appearance of the blend showed that both TCNQ and LiClO4 can complex with PEO and PVP, thus enhancing the compatibility between PEO and PVP. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Preparation and characterization of aqueous polyurethane dispersions containing ionic centers
Authors: Barikani M. , Valipour Ebrahimi M. , Seyed Mohaghegh S. M. 
Published: March 2007

AbstractAqueous polyurethane dispersions were prepared from toluene di‐isocyanate, polytetramethylene glycol, and 1,4‐butanediol, with different weight percent of dimethylol propionic acid (DMPA) as anionic center. IR Spectroscopy was used to follow the polymerization reaction as well as the polymer characterization. The effect of DMPA content on the state of dispersion, particle size distribution, mechanical, and thermal properties of the emulsion‐cast films were studied. Average particle size of the prepared emulsion polyurethanes decreased with increasing DMPA content. Tensile strength and hardness increase and elongation at break and contact angle decrease by increasing the ionic content. Glass transition temperature (Tg) shifted toward higher temperature and thermal stability decreased by increasing the DMPA content. The increased Tg and tensile properties are interpreted in terms of the increased hard segments and coulombic forces between ionic centers. The decreased contact angle is ascribed to the increase in the hydrophilicity of the polyurethanes because of the incorporation of more hydrophilic moiety in polymer backbone. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3931–3937, 2007
Effect of cellulase pretreatment of raw and bleached cotton fibers on properties of hydroentangled nonwoven fabrics
Authors: Verenich S. , Arumugam K. , Shim E. , Pourdeyhimi B. 
Published: March 2007

AbstractThis study was undertaken to investigate the effect of enzymatic pretreatment of cotton (polysaccharides) fibers on the properties of resulting nonwoven fabric. Enzymatic treatment is known to improve the esthetical properties of fabrics but will likely lead to a reduction in strength. In the case of nonwovens the strength loss can be even more drastic as cellulase may attack bonded areas of the fabric. In this work, raw and bleached cotton fibers were treated with enzyme solutions prior to fabric formation to avoid possible damage to the bonded areas and improve strength retention. These fibers were first modified with commercially available whole cellulases and monocomponent endoglucanase enzyme solutions. Then they were formed into a fabric and bonded via hydroentangling. Parameters such as bending modulus, fabric tenacity, fiber strength, length and reducing power were measured for each sample. The pretreatment of cotton fibers prior to fabric formation showed that the resulting nonwovens could be stronger and more drapeable than the same fabric composed of untreated fibers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Application of polypyrrole to flexible substrates
Authors: Winther‐Jensen Bjørn , Clark Noel , Subramanian Priya , Helmer Richard , Ashraf Syed , Wallace Gordon , Spiccia Leone , MacFarlane Douglas 
Published: March 2007

AbstractConducting polymers such as polypyrrole may be useful in smart packaging products, provided application methods can be developed that circumvent the insolubility and infusibility of these materials. Experiments were conducted in five research areas relevant to the application of polypyrrole to nonrigid substrates. The studies reveal that application of polypyrrole from the liquid phase, either by deposition from depleted bulk solution or inkjet printing dispersions, is unlikely to give films as regular as those produced by vapor phase polymerization. Using the latter approach, two potential methods of applying patterned polypyrrole films to nonrigid substrates were developed. The first used hypochlorite to pattern a continuous film of polypyrrole, previously applied by vapor phase polymerization. The second used inkjet printing to apply an oxidant solution, whose pH had been raised with a volatile base, to nonrigid substrates. The higher pH reduced corrosion of the print head, increasing the lifetime of printers exposed to oxidative compounds. The base was subsequently evaporated by heating, and the dried oxidant used as a template for vapor phase polymerization of polypyrrole. This method gave smooth, shiny and adherent polypyrrole films on papers and polyester transparency, with high resolution. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3938–3947, 2007