bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of 3′,4′‐disubstituted terthiophenes. Characterization and electropolymerization. I. 3′,4′‐dibromo‐2,2′:5′,2″‐terthiophene in photovoltaic display
Authors: Vélez J. H. , Díaz F. R. , del Valle M. A. , Bernède J. C. , East G. A.
Published: September 2006

Recent studies on conducting polymers have demonstrated that polymers of 3‐substituted thiophene produce very stable compounds. Although this kind of substitution improves the regularity, structural defects still exist. To overcome this drawback, the polymerization of 3,4‐disubstituted thiophene is proposed as a convenient way of synthesizing regular, highly conjugated conductive polymers. Our interest is thus focused on the synthesis of tetra‐substituted thiophene derivatives, their polymerization, electrochemical properties, spectral characteristics, oxidizing potential, and the feasibility of photocells development. In this article, we report the synthesis and characterization of 3′,4′‐dibromo‐2,2′:5′,2″‐terthiophene which, as such or modified, may be a good starting product for obtaining new monomers of 3′,4′‐disubstituted terthiophenes, that would allow the effect of the substituents on the properties of the respective polymers to be studied. In addition, the monomer was electropolymerized and the resulting deposit was electrochemically and morphologically characterized. Two conclusions were drawn: first, more uniform and homogeneous layers than those of polythiophene are obtained; second, the thin layers of the polymer, electron acceptors, absorb in the visible. Finally, photocells were assembled to investigate their photovoltaic effect. Although the so prepared solar cells showed some photovoltaic effect, the yield was low.© 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5314–5321, 2006
A novel flame retardant of spirocyclic pentaerythritol bisphosphorate for epoxy resins
Authors: Chen Gui‐Hong , Yang Bing , Wang Yu‐Zhong
Published: September 2006

A novel flame retardant for epoxy resins, bisdiglycol spirocyclic pentaerythritol bisphosphorate (BDSPBP) was synthesized from the reaction of diglycol with spirocyclic pentaerythritol bisphosphorate diphosphoryl chloride, which was obtained from the reaction of phosphoryl chloride with pentaerythritol. Flammability of the cured epoxy resin systems consisted of diglycidyl ether of bisphenol A (DGEBA), low‐molecular‐weight polyamide and BDSPBP are investigated by vertical burning test (UL‐94) and limiting oxygen index test (LOI). The results indicate that BDSPBP has good flame retardance on epoxy. The thermogravimetric analysis (TGA) shows that the epoxy resin containing BDSPBP has a high yield of residual char at high temperatures, indicating that BDSPBP is an effective charring agent. From the SEM observations of the residues of the flame retardant systems burned, the compact charred layers can be seen, which form protective shields to protect effectively internal structure, and inhibit the transmission of heat and heat diffusion during contacting fire. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4978–4982, 2006
Nanocomposites from phenolic resin and various organo‐modified montmorillonites: Preparation and thermal stability
Authors: Jiang Wei , Chen Shinn‐Horng , Chen Yun
Published: September 2006

Phenolic resin (PF)/montmorillonite (MMT) nanocomposites have been successfully prepared using intercalative polymerization of resole‐type phenolic resins in montmorillonites modified by octadecylamine (C18), benzyldimethylhexadecylammonium chloride (B2MH), benzyltriethylammonium chloride (B3E), and benzyldimethylphenylammonium chloride (B2MP). X‐ray diffraction measurements and transmission electron microscope observations showed that clay platelets were partially exfoliated or intercalated after complete curing of the phenolic resins. The cured nanocomposites were named as modifier‐MP (MP means montmorillonite‐phenolic resin), for example, B3E‐MP. Thermogravimetric analysis showed that thermal decomposition temperatures (Tds) of the cured nanocomposites B2MP‐MP (826 K), B3E‐MP (794 K), and B2MH‐MP (783 K) were much higher than those of C18‐MP (768 K) and cured phenolic resin (737 K). Therefore, thermal stability of the nanocomposites depends mainly on the chemical structure of the organic modifiers. B2MP‐MP possesses the highest Td since B2MP contains both benzyl and phenyl groups, followed with B3E‐MP and B2MH‐MP whose modifiers contain only one benzyl group. This is attributable to favorable interaction between phenolic resin and organic modifiers containing benzene rings. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5336–5343, 2006
Preparation and photophysical properties of organic fluorescent polymers and their nanoparticles
Authors: Uthirakumar Periyayya , Hong Chang‐Hee , Suh Eun‐Kyung , Lee Youn‐Sik
Published: September 2006

New classes of stable organic florescent polymer nanoparticles were prepared from the corresponding tetrahydrofuran (THF) solutions, upon slow evaporation of solvent under a mild vacuum. Uniform spherical nanospheres having mean diameter of ˜ 500–700 nm, showed enhanced fluorescence emission in solution, but it diminished when it is destroyed using an organic base. These end‐capped fluorescent polymers are highly stabilized in the excited states at higher concentration in solution, leads no more intra‐ and intermolecular interactions among the excited molecules, because of the absence of free functional groups. The significant enhancement in fluorescence emission was attributed to the high level of molecular stacking in the fluorescent nanoparticles, when compared with micron‐sized isolated powder sample. In addition, these fluorescent polymers exhibited significant thermal properties, along with better solubility in most of common organic solvents for their future application. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5344–5350, 2006
Structural investigations of (9‐ethyl‐carbazol‐6‐yl) methyl methacrylate/methyl acrylate copolymers using two‐dimensional NMR spectroscopy
Authors: Brar Ajaib Singh , Gandhi Sonia
Published: September 2006

(9‐Ethyl‐carbazol‐6‐yl) methyl methacrylate/methyl acrylate (E/A) copolymers of different compositions were prepared by solution polymerization by varying the molar infeed ratio, using AIBN as initiator at 60°C. The reactivity ratios calculated by Kelen–Tudos (KT) method were found to be rE = 1.16 ± 0.02 and rA = 0.69 ± 0.01 whereas those calculated from RREVM method were found to be rE = 1.18 and rA = 0.68. The molecular weights (Mw) and polydispersity index (PDI, Mw/Mn) were determined using gel permeation chromatography (GPC). Glass transition temperatures (Tg) for different compositions of E/A copolymers were determined using differential scanning calorimetry (DSC). Copolymer molar outfeed ratio (FE) was calculated from 1H NMR spectra. The α‐methyl, methine, backbone methylene, and quaternary carbon resonance signals of the copolymers were distinguished using 13C{1H}, DEPT‐45, ‐90, and ‐135 NMR techniques. The α‐methyl and β‐methylene showed compositional and configurational sensitivity up to pentad and tetrad level, respectively, whereas methine showed only compositional sensitivity up to pentad level. Unambiguous assignments for 1H and 13C{1H} NMR spectra were done by correlating 1D (1H, 13C{1H}, DEPT) and 2D (HSQC, TOCSY) NMR data. The spectral assignments for carbonyl region were done by studying higher bond order couplings by heteronuclear multibond correlation (HMBC) spectra. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5595–5606, 2006
Properties and morphology of poly(L‐lactide)/clay composites according to the clay modification
Authors: Hun Shim Jae , Soo Kim Eung , Hiuk Joo Jung , Yoon Jin San
Published: September 2006

Montmorillonite (MMT) was modified with dodecylamine, 1,12‐diaminododecane, and 1,11‐aminoundecanoic acid to prepare CHMMT, NHMMT, and COMMT, respectively. The three clays were mixed with poly(L‐lactide) (PLLA) with the aid of chloroform. Depending on the modifiers, PLLA/MMT composites exhibited different mechanical properties and morphology. A completely exfoliated morphology was observed in the PLLA/COMMT composite (PLACO). The PLACO exhibited the best tensile properties among the tested composites because of the finest dispersion of the clay layers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:4983–4988, 2006
Preparation and properties of polyethylene–clay nanocomposites by an in situ graft method
Authors: Qi Rongrong , Jin Xing , Zhou Chixing
Published: September 2006

The polyethylene–clay nanocomposites were prepared by the in situ graft copolymerization of styrene containing twin‐benzyldimethyldioctadecylammonium bromine modified montmorillonite (TBDO‐MMT) in polyethylene with dicumyl peroxide (DCP) as an initiator in molten state. XRD and TEM analysis indicated that intercalated polyethylene/MMT nanocomposites are obtained. The mechanics performance, crystal behavior, thermal properties, and the effect of MMT contents on PE/MMT nanocomposite were also studied. As comparison, polyethylene/montmorillonite composites prepared by a simply melt compounding without styrene were studied as well. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4921–4927, 2006
Characterization of the biocide polyhexamethylene biguanide by matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry
Authors: O'Malley Leon P. , Hassan Kaneez Z. , Brittan Helen , Johnson Neil , Collins Andrew N.
Published: September 2006

The biocide polyhexamethylene biguanide (PHMB) has been characterized by matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS). Previously, no method has been able to provide a detailed structural characterization of PHMB. MALDI‐TOF MS was able to detect PHMB oligomers with n ≤ 6. Six different PHMB product types were identified, which possess combinations of amine, cyanoamine, guanidine, or cyanoguanidine end‐groups. Postsource decay (PSD) fragmentation was used to confirm the correct assignment of PHMB structure for the dominant PHMB molecular ion. MALDI‐TOF MS analysis of a 15N‐labeled PHMB confirmed the correct assignment of PHMB molecular ions, and also indicated the existence of a polymerization–depolymerization equilibrium during melt polymerization of the polymer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4928–4936, 2006
Application of Taguchi method in determining optimum level of curing system of NBR/PVC blend
Authors: Hafezi Mahshid , Khorasani Saied Nouri , Ziaei Farhood
Published: September 2006

Taguchi method is applied in this study to determine the optimum level of curing system (sulfur, MBTS, and CBS) in a NBR/PVC blend. By considering physicomechanical properties of cured NBR/PVC blend, optimum level of curing system is determined. A fixed master batch formulation of NBR/PVC is used, and the effect of curing system is studied on the physicomechanical properties of NBR/PVC blend, such as tensile strength (TS) and elongation‐at‐break (EB) before and after aging and also hardness and abrasion. The L9 orthogonal array that includes nine rows and four columns is applied. In this matrix, rows show the experiments and three columns show the amount of three factors (sulfur, MBTS, and CBS) and one column is left arbitrarily as an empty column. In this array, the columns are mutually orthogonal. The optimum physicomechanical properties of cured NBR/PVC blend are at 2 phr sulfur, 2 phr MBTS, and 0.5 phr CBS of curing system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5358–5362, 2006
Structure–properties relationship in toughening of poly(butylene terephthalate) with core–shell modifier
Authors: Sun S. L. , Xu X. Y. , Tan Z. Y. , Zhou C. , Ao Y. H. , Zhang M. Y. , Zhang H. X.
Published: September 2006

The performance of acrylonitrile–butadiene–styrene (ABS) core–shell modifier with different grafting degree, acrylonitrile (AN) content, and core–shell ratio in toughening of poly(butylene terephthalate) (PBT) matrix was investigated. Results show PBT/ABS blends fracture in ductile mode when the grafting degree is high, and with the decrease of grafting degree PBT/ABS blends fracture in a brittle way. The surface of rubber particles cannot be covered perfectly for ABS with low grafting degree and agglomeration will take place; on the other hand, the entanglement density between SAN and PBT matrix decreases because of the low grafting degree, inducing poor interfacial adhesion. The compatibility between PBT and ABS results from the strong interaction between PBT and SAN copolymer and the interaction is influenced by AN content. Results show ABS cannot disperse in PBT matrix uniformly when AN content is zero and PBT/ABS fractures in a brittle way. With the addition of AN in ABS, PBT/ABS blends fracture in ductile mode. The core–shell ratio of ABS copolymers has important effect on PBT/ABS blends. When the core–shell ratio is higher than 60/40 or lower than 50/50, agglomeration or cocontinuous structure occurs and PBT/ABS blends display lower impact strength. © 2006 Wiley Periodicals, Inc. J Appl PolymSci 102: 5363–5371, 2006
Thermal stability and chemical durability of PVC‐based biomedical devices
Authors: Manfredini Matteo , Bodecchi Lidia M. , Marchetti Andrea
Published: September 2006

Poly(vinyl chloride) (PVC)‐based blood circuits for extracorporeal hemodialysis were investigated for the assessment of their thermal stability as well as their chemical durability towards ionizing radiation sterilization and environmental conditions of storage and transportation. Thermal degradation was monitored by measuring the amount of hydrochloric acid (HCl) evolved as a function of different thermal stresses. HCl was extracted from the internal lumen of the blood circuits, and then quantitatively evaluated under the corresponding form of chloride ions by chromatographic technique (HPLC‐IC). Behavior of PVC heat stabilizers was evaluated as well, determining also the concentration of calcium and zinc released by the investigated materials, by flame atomic absorption spectroscopy (FAAS) technique. Electron beam irradiation revealed an impact on blood tubing higher than that of environmental storage conditions. Nevertheless, real operative cases of sterilization and storage conditions turned out to be quite safe, and all blood circuits displayed good performances in terms of thermal stability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:5378–5387, 2006
Morphology and characterization of conductive films based on polyaniline‐coated polystyrene latexes
Authors: Liau Wen‐Bin , Sun Yu‐Ting , Yang Ling‐Yueh , Wang Lee‐Yih , Chiu Wen‐Yen , Hsieh Kuo‐Huang , Tseng Sheng‐Mao
Published: September 2006

The polyaniline (PANI)‐coated polystyrene (PS) latexes were synthesized, and the electrically conductive films were prepared thereafter. The weight ratio of PANI was 5%. Thermal analysis of the latices was performed using DSC and TGA. In this study, the electrically conductive films were prepared above the PS glass transition temperature (Tg). During the film formation, the effects of the annealing temperature and atmosphere (air or N2) on the film resistance were investigated. In addition, the film morphology was observed utilizing scanning electron microscopy. The film resistance decreased in the initial heating stage due to the increasing temperature and the compaction of film. Then the film resistance increased with further annealing due to the aging of PANI. Typically, the film resistance was about 6000 Ω/sq, and the conductivity was 0.3 S/cm. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5406–5413, 2006
High thermal conductivity epoxy molding compound filled with a combustion synthesized AlN powder
Authors: Hsieh Cheng‐Yu , Chung Shyan‐Lung
Published: September 2006

A combustion synthesized AlN powder was studied for its feasibility as a filler for epoxy molding compound (EMC) and effects of various experimental parameters on the thermal conductivity and moisture resistance of the EMC were investigated. The AlN powder was coated with silane both to increase the moisture resistance of the EMC and to enhance the bonding between the filler AlN and the matrix resin. The thermal conductivity could be significantly increased by using AlN powders with large particle sizes and this was considered to be due to a reduction in interface area between the AlN particles and the matrix resin. A thermal conductivity of 14 W/mK was obtained when the EMC was fabricated by a process involving no use of a solvent and a AlN powder with a particle size of 35.3 μm and a filler content of 67 vol % were used. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4734–4740, 2006
Rigidity of heat‐treated oriented isotactic polypropylene
Authors: Tsobkallo Katherina , Tikhomirov A. , Bozdogan A. , Tshmel A.
Published: September 2006

Uniaxially oriented commercial films of isotactic polypropylene were strained with ends keeping fixed and subjected to the heat treatment at temperatures from 50 to 200°C. The rigidity of annealed samples was characterized by the value of tangent modulus, Et, determined graphically at the initial portions of stress–strain curves. The structural changes in the samples were studied with the help of the IR and low‐frequency Raman spectroscopies. The smallest Et values were obtained for the low‐strained films, while the tangent moduli measured for highly strained samples exceeded the value for the original (untreated) film. The most prominent positive effect was achieved after annealing the samples at 90°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 6074–6080, 2006
Naphthoic acid derivatives as hydrogen bond donors in supramolecular materials
Authors: Riedel Paul J. , Kumpfer Justin R. , Rogness Donald C. , Wiegel Kurt N.
Published: September 2006

The synthesis of a series of 6‐hydroxy‐2‐naphthoic acid derivatives is described. These have been used to form supramolecular main‐chain liquid crystalline polymers. These hydrogen bond donors are complexed with a series of bisfunctionalized rigid pyridine species. These associative chain structures were analyzed through differential scanning calorimetry and polarizing light thermal optical microscopy. The liquid crystalline phases formed displayed mainly enantiotropic nematic phases that display an increase in clearing temperature as the rigid portions of the supramolecular system increased in length. A decrease in the clearing temperature was observed as the length of the flexible spacer group increased. Both of these observations follow established trends in liquid crystalline behavior. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5890–5894, 2006
Synthesis of poly(vinyl propionate) from poly(vinyl alcohol) in nonaqueous medium using ethyl nitrate dimethyl sulfoxide as a catalyst
Authors: Chetri Prafulla , Dass Narendra N. , Sarma Neelotpal Sen
Published: September 2006

Poly(vinyl alcohol) (PVA) can be dissolved in a nonaqueous medium in the presence of catalytic concentration of ethyl nitrate dimethyl sulfoxide, C2H5ONO2·DMSO. From the PVA solution, poly(vinyl propionate), PVPR was prepared by the homogeneous esterification of PVA with propionic acid. The ester thus formed contained some unconverted hydroxyl group. The formation of the ester was confirmed by the IR and 1H‐NMR spectra. The molecular weight of the ester was determined by GPC and intrinsic viscosity (η) was determined by viscometric method. Glass transition temperature, Tg, was obtained from differential scanning calorimetric (DSC) analysis. Thermal stabilities of the ester were checked by thermogravimetric analysis (TGA) and differential thermogravimetric (DTG) analysis. The efficiency of the ester as a flow improver of crude oil was also examined. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5675–5679, 2006
Synthesis and photopolymerization of ethylene glycol 3‐morpholine‐propionate methacrylate for potential dental composite application
Authors: Wu G. Q. , Shi S. Q. , Xiao P. , Nie J.
Published: September 2006

2,2‐Bis[4‐(2‐hydroxy‐3‐methacryloxypropoxy) phenyl]‐propane (bis‐GMA), triethylene glycol dimethylacrylate (TEGDMA), camphorquinone (CQ), ethyl‐4‐dimethylaminobenzoate (EDMAB), or 2‐(dimethylamine)ethyl methacrylate (DMEM) were composed of the modern dental composite system and acted as resin, diluent, photoinitiator, and coinitiator, respectively. In this study, ethylene glycol 3‐morpholine‐propionate methacrylate (EGMPM) was synthesized via Michael addition reaction to replace both the TEGDMA as a diluent and the nonpolymerizable amine EDMAB as a coinitiator. Mixtures of bis‐GMA/TEGDMA/CQ/EGMPM and bis‐GMA/TEGDMA/CQ/DMEM were found to have almost the same rate of polymerization and reach final double bond conversion at 58%, slightly lower than that of the bis‐GMA/TEGDMA/CQ/EDMAB (63%) and bis‐GMA/EGMPM/CQ (60%) under comparable visible light irradiation conditions. In addition, the results of dynamic mechanical analysis showed that all of the four samples had approximately the same modulus and the glass transition temperature. The water sorption and solubility of bis‐GMA/TEGDMA/CQ with different amines (EDMAB, DMEM, and EGMPM) had almost the same value except that the water sorption of bis‐GMA/EGMPM/CQ was out of the range of the ISO 4049 (2000) standards. The results indicated that EGMPM was potentially a coinitiator for dental composite, because there are no significant differences in photopolymerization characteristic and physical properties when compared with traditional system (bis‐GMA/TEGDMA/CQ/EDMAB). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4589–4594, 2006
Simultaneous novel synthesis of conducting, nonconducting, and crosslinked polymers by microwave initiation
Authors: Bayraklı Çelik Güler , Kısakürek Duygu
Published: September 2006

A novel synthesis of poly(dibromophenylene oxide) (P), conducting polymer (CP), and/or crosslinked polymer (CLP), and/or radical ion polymers (RIP) was achieved simultaneously from sodium 2,4,6‐tribromophenolate by microwave energy in a very short‐time interval. The synthesized polymers were characterized via elemental analysis, FTIR, 1H NMR and 13C NMR, X‐ray diffraction spectroscopy, SEM, DSC, TGA, ESR, GPC, conductivity measurement, and light scattering. It was found that polymerization proceeds through both 1,2‐ and 1,4‐addition at equal rates. The effects of the energy and time on the % conversion and the polymer synthesis were investigated. The optimum condition for synthesis of P (the highest Mw, 2.97 × 105 g/mol) and CP was 70 W for 5 min in 5 mL water and 100 W for 1 min in 0.5 mL water, having maximum values 23.6% and 27.2%, respectively. In addition, synthesis of CLP and RIP were achieved in 5 mL water at 350 W and 700 W at the end of 1 min, respectively. The direct synthesis of highly conducting polymer, with the conductivity of 1 S cm−2 was achieved in the absence of applied doping process in a very short time sequence. P, CP, CLP, and RIP had fine granular, sponge‐like, dendrite, and coarse surface structures, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:5427–5435, 2006
Supported titanium–magnesium catalysts with different titanium content: Kinetic peculiarities at ethylene homopolymerization and copolymerization and molecular weight characteristics of polyethylene
Authors: Echevskaya Ludmila G. , Matsko Mikhail A. , Mikenas Tatiana B. , Nikitin Valentin E. , Zakharov Vladimir A.
Published: September 2006

The effect of Ti content on the activity of titanium–magnesium catalysts (TMC) and molecular weight distribution (MWD) of polyethylene (PE) produced has been studied. It was found that the activity enhances sharply as Ti content decreases from 0.6 to 0.07 wt %, and shows no significant changes in the Ti content range of 0.6–5.0 wt %. The maximum activity (36 kg PE/mmol Ti × h × bar C2H4) was observed for TMC with the lowest Ti content. The catalyst with low titanium content (∼ 0.1 wt % of Ti) produced PE with narrower MWD (Mw/Mn = 3.1–3.5) as compared to catalysts with higher titanium content (3–5 wt % of Ti; Mw/Mn = 4.8–5.0). New data on the effect of hydrogen on MWD of PE have been found. Increasing hydrogen concentration results in broadening the MWD of PE, especially in the case of TMC with high titanium content. The data presented indicate the heterogeneity of active centers of TMC in the reaction of chain transfer with hydrogen. The data on the ethylene–hexene‐1 copolymerization over TMC with different titanium content are presented. Comonomer reactivity ratios were shown to be independent of the Ti content in TMC. Presumably the difference in activity of these catalysts is mainly caused by the difference in the number of active centers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:5436–5442, 2006
Electrospinning of chitosan/poly(vinyl alcohol)/acrylic acid aqueous solutions
Authors: Zhou Yingshan , Yang Dongzhi , Nie Jun
Published: September 2006

Chitosan bicomponent fibers were prepared via the electrospinning of chitosan/poly(vinyl alcohol)/acrylic acid aqueous solutions with different concentrations. With a 4% acrylic acid aqueous solution, when the chitosan/poly(vinyl alcohol) mass ratios were lower than 80/20, electrospinning nanofibers could be obtained. With a 90% acrylic acid aqueous solution, when the chitosan/poly(vinyl alcohol) mass ratios were less than 95/5, good nanofibers could be electrospun. The average diameter of the nanofibers gradually decreased, and its distribution became narrower as the poly(vinyl alcohol) concentration increased. Chitosan/poly(vinyl alcohol)/acrylic acid aqueous solutions could be electrospun at various concentrations by the adjustment of the chitosan and poly(vinyl alcohol) concentrations. The effects of the viscosity and conductivity of the blend solution on the morphologies of the fiber mats were also investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5692–5697, 2006
Morphology and coalescence of ethylene copolymers: Influence of thermal treatments and sorbitol nucleating agents
Authors: Lin W. , Bellehumeur C. T.
Published: September 2006

Coalescence of polymer particles is a key phenomenon in many powder processing technologies. Both the extent and the rate of coalescence between particles govern the production cycle and the performance of the end‐product. It is well accepted that both processing conditions and material formulation affect the morphology of molded parts and consequently their mechanical properties. The interest of this study is to evaluate the impact that changes in morphological features caused by the imposition of different thermal treatments as well as by the addition of a nucleating agent (bis 3,4 dimethylbenzylidene sorbitol) have on the coalescing behavior of ethylene copolymers produced from Ziegler–Natta and metallocene catalyst technologies. Results showed that samples produced using slower cooling rates exhibited higher crystallinity and increased thermal stability. Variations in thermal treatments, however, only resulted in minor changes in the coalescing behavior of the resins considered in this work. However, the addition of the nucleating agent to Ziegler–Natta ethylene copolymers led to the formation of crystalline structures with increased material thermal stability, but reduced chain mobility, and consequently resulted in a slower coalescing rate. These effects, however, are dependent on the molecular structure of the copolymers. The addition of the sorbitol nucleating agent influenced the morphological structure of the metallocene copolymer used in this work but did not result in any significant changes in the coalescence behavior of the resin. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5443–5455, 2006
Thermal stability of structural one‐component polyurethane adhesives for wood—structure‐property relationship
Authors: Richter K. , Pizzi A. , Despres A.
Published: September 2006

The relationship between the chemical structure of commercial polyurethanes and temperature‐dependent creep properties was determined in full scale tests and the results were compared with thermomechanical analysis. Comparison of mechanical performance with 13C‐NMR spectroscopy studies elucidated important structure‐property relationships, which either allow the reduction or elimination of temperature‐dependent creep in one‐component polyurethanes (1C‐PUR) adhesives for wood. The combination of the relative content of still reactive, free NCO groups on the polyurethane, careful selection of the degree of resin polymerization and a slower rate of reaction are the three most significant parameters that have to be controlled to overcome the problem of temperature‐dependent creep found in 1C‐PUR adhesives. The results obtained indicate that adhesives presenting a combination of a higher content of still unreacted NCO groups, a lower degree of polymerization and slower reaction rate are capable to counteract problems of high sensitivity of polyurethane to temperature‐dependent creep. Two commercial polyurethanes that fulfil the latter requirements and exhibit almost no creep were identified and characterized. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5698–5707, 2006
Modeling the morphology development of ethylene copolymers in rotational molding
Authors: Xu H. , Bellehumeur C. T.
Published: September 2006

A model is proposed to describe the solidification and crystallization phenomena in rotational molding. To capture the morphology development with crystallization behavior, a two‐dimensional theoretical simulation was carried out, consisting of a phase‐field model emphasizing the metastability of polymer crystallization and a heat‐transfer model describing the molding cycle. The model parameters were experimentally evaluated with differential scanning calorimetry and isothermal crystallization tests. Molding trials were also conducted with bench‐scale rotational molding equipment, and the cross sections of the molded products were examined under polarized light optical microscopy. The model predictions capture the formation of transcrystalline structures near the mold surface, which is more apparent under moderate cooling conditions. Our results show that the model predictions are in general agreement with the experimental results obtained in our laboratory as well as those presented in the literature. Because morphological features are important contributing factors to product performance, the model will be useful for the formulation of new materials and process optimization. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5903–5917, 2006
Thermal conductivity of carbon fiber/liquid crystal polymer composites
Authors: Keith Jason M. , King Julia A. , Miller Michael G. , Tomson Amanda M.
Published: September 2006

Thermally conductive resins are needed for bipolar plates in fuel cells. Currently, the materials used for these bipolar plates often contain a single type of graphite in a thermosetting resin. In this study, varying amounts of two different types of polyacrylonitrile based carbon fibers, Fortafil 243 and Panex 30, were added to a thermoplastic matrix (Vectra A950RX Liquid Crystal Polymer). The resulting single filler composites were tested for thermal conductivity and a simple exponential thermal conductivity model was developed for the square root of the product of the in‐plane and through‐plane thermal conductivity
$\sqrt{k_{\rm in}k_{\rm thru}}$. The experiments showed that the through‐plane thermal conductivity was similar for composites up to 40 vol % fiber. However, at higher loadings, the Panex 30 samples exhibited higher thermal conductivity. The experiments also showed that the in‐plane thermal conductivity of composites containing Panex 30 was higher than those containing Fortafil 243 for all volume fractions studied. Finally, the model agreed very well with experimental data covering a large range of filler volume fraction (from 0 to 55 vol % for both single filler systems). The model can be used with existing through‐plane thermal conductivity models to predict in‐plane thermal conductivity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5456–5462, 2006
Curing of an epoxy resin modified with nanoclay monitored by dielectric spectroscopy and rheological measurements
Authors: Kortaberria G. , Solar L. , Jimeno A. , Arruti P. , Gómez C. , Mondragon I.
Published: September 2006

Dielectric and rheological measurements have been performed in “real‐time” to follow curing reaction on blends of a diglycidyl ether of bisphenol‐A epoxy resin with 4,4‐methylene bis(2,6‐diethylaniline) hardener and different amounts of organically modified nanoclay (Nanofil 919) as modifier. The effect of the modifier and its amount on the curing reaction, as well as that of the curing temperature has been studied. Changes in molecular mobility in the reaction mixture have been investigated by dielectric relaxation spectroscopy. Evolutions of ionic conductivity and main relaxation have been analyzed and vitrification times have been obtained and compared with those obtained by rheological measurements. The relaxational behavior has been analyzed through curing in the frequency domain, being the displacement of the main relaxation indicative of the cure reaction advancement. Gelation and vitrification times for the nanocomposite systems have been found to be lower than for the neat resins, indicating a catalytic effect of the clays on the curing reaction. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5927–5933, 2006
Synthesis and characterization of isocyanic acid, m‐phenylenediiso‐propylidene based poly(urethane‐urea) dispersions containing different amount of 2,2‐Bis(hydroxyl methyl)propionic acid
Authors: Chiu Hsien‐Tang , Huang Yi‐Chin , Hu Hsiu‐Yeh
Published: September 2006

Isocyanic acid, m‐phenylenediiso‐propylidene (m‐TMXDI)‐based anionic poly(urethane‐urea) dispersions were prepared by the prepolymer mixing process. The equivalent ratio of NCO/OH was kept constant at 1.8, while 2,2‐bis(hydroxyl methyl) propionic acid (DMPA) used was varied from 3 to 10 wt %. The colloidal stability of poly(urethane‐urea) dispersions arose entirely from the presence of ionized carboxylic acid groups. The chemical structure of poly(urethane‐urea) dispersions with various amount of DMPA were identified by FTIR and 13C NMR analysis. The test results showed that the hydrophilicity of poly(urethane‐urea) dispersions were increased with increase in DMPA content. The degree of chain extension was much lower than the values predicted theoretically due to the side reaction of a small amount of hydrophilic isocyanate‐terminated prepolymer with water. The average particle size of poly(urethane‐urea) dispersions were decreased with an increase in DMPA content, and this lead to an increase in viscosity. Also, the thermal degradation behavior were measured and was shown that the initial degradation temperature shifted to lower temperature with an increase in DMPA content. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5737–5746, 2006
Methanol permeability and properties of DMFC membranes based on sulfonated PEEK/PVDF blends
Authors: Wootthikanokkhan J. , Seeponkai N.
Published: September 2006

Proton exchange membranes for a direct methanol fuel cell were prepared by blending poly(vinylidene fluoride) [PVDF] with sulfonated poly(etheretherketone) [SPEEK]. The effects of PVDF content on methanol permeability in the blend membranes were investigated by using a diffusion cell and gas chromatography technique. The thermal resistance and proton conductivity of the membranes were also determined by using a thermal gravimetric analysis (TGA) and an impedance analysis technique, respectively. It was found that methanol permeability in the blend membranes decreased with PVDF content at the expense of proton conductivity. The methanol permeability values of the blend membranes are much lower than that of Nafion 115, whereas proton conductivities of the membranes are comparable to that of Nafion. The thermal stability of these blend membranes are above 250°C which is sufficiently high for use in DMFC. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5941–5947, 2006
Influence of high density polyethylene‐g‐maleic anhydride on compatibility and properties of poly(butylene terephthalate)/high density polyethylene blends
Authors: Qi Rongrong , Nie Jinghui , Zhou Chixing , Mao Dalian , Zhang Bian
Published: September 2006

Poly(butylene terephthalate)/high density polyethylene (PBT/HDPE) blends and PBT/HDPE‐grafted maleic anhydride (PBT/HDPE‐g‐MAH) blends were prepared by the reactive extrusion approach, and the effect of blend compositions on the morphologies and properties of PBT/HDPE blends and PBT/HDPE‐g‐MAH blends was studied in detail. The results showed that flexural strength, tensile strength, and notched impact strength of PBT/HDPE blends decreased with the addition of HDPE, and flexural strength and tensile strength of PBT/HDPE‐g‐MAH blends decreased, while the notched impact strength of PBT/HDPE‐g‐MAH increased with the addition of HDPE‐g‐MAH. Compared with PBT/HDPE blends, the dimension of the dispersed phase particles in PBT/HDPE‐g‐MAH blends was decreased and the interfacial adhesion was increased. On the other hand, the effects of HDPE and HDPE‐g‐MAH contents on the crystalline and the rheological properties of the blends were also investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 6081–6087, 2006
Evaluation of some of the properties of plasma treated wool fabric
Authors: Kan C. W. , Yuen C. W. M.
Published: September 2006

Low temperature plasma (LTP) treatment was applied to wool fabric with the use of a nonpolymerizing gas, namely oxygen. Properties of the LTP‐treated samples including low stress mechanical behavior, air permeability, and thermal characteristics were evaluated in this study. Kawabata evaluation system fabric (KES‐F) was employed to determine the tensile, shearing, bending, and compression strength properties and surface roughness of the specimens. The changes in these properties are believed to be closely related to the interfiber and interyarn frictional force induced by the LTP. The decrease in the air permeability of the LTP‐treated wool fabric was found to be probably because of the plasma action effect on increasing the fabric thickness and a change in fabric surface morphology, which was confirmed by scanning electron microscopy micrographs. The change in the thermal properties of the LTP‐treated wool fabric was in good agreement with the earlier findings and can be attributed to the amount of air trapped between the yarns and fibers. This study suggested that the LTP treatment can influence the final properties of the wool fabric, and also provide information for developing LTP‐treated wool fabric for industrial use. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5958–5964, 2006
A very simple empirical kinetic model of the acid‐catalyzed cure of urea–formaldehyde resins
Authors: Carvalho Luisa M. H. , Costa Mário Rui P. F. N. , Costa Carlos A. V.
Published: September 2006

The hot pressing operation is the final stage in MDF (medium density fiberboard) manufacture; the fiber mat is compressed and heated up to promote the cure of the resin. The aim of the investigations is to study the curing reactions of UF (Urea–Formaldehyde) resins as commonly used in the production of MDF, and to develop a simplified kinetic model. This investigation has combined Raman spectroscopy to study the reaction cure and 13C‐NMR for the quantitative and qualitative characterization of the liquid and still uncured resin. Raman spectroscopy was found very interesting for the study of the resin cure and permitted to obtain kinetic data as the basis for a simple empirical model, considering a homogeneous irreversible reaction of a single kind of methylol group and ureas with rate constants depending on their degree of substitution. Although these results can provide a better understanding of the composition and the cure of an UF resin, several issues remain open, such as the influence of the reversibility of the reactions taking place during the curing process as well as the possible formation of cyclic groups in the resin. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5977–5987, 2006
Reorganization of the chain packing between poly(ethylene isophthalate) chains via coalescence from their inclusion compound formed with γ‐cyclodextrin
Authors: Pang Kyeong , Schmidt Ben , Kotek Richard , Tonelli Alan
Published: September 2006

Amorphous poly(ethylene isophthalate) (PEI) was synthesized, and was used for preparing an inclusion compound (IC) with γ‐cyclodextrin (γ‐CD). Coalesced polymer was produced by washing the PEI‐γ‐CD‐IC with hot water. Wide angle X‐ray diffraction, Fourier transform infrared, and differential scanning calorimetry analyses were employed to verify formation of PEI‐γ‐CD‐IC and to compare the as‐synthesized and coalesced PEI samples. These observations suggested that the conformations and morphology/chain‐packing of PEI were changed via coalescence from its γ‐CD inclusion compound. The glass‐transition temperature of the amorphous coalesced PEI is 15–20°C higher than the Tg observed for the as‐synthesized sample, even when observed in the second heat after cooling from well above Tg at 260°C. The amorphous as‐synthesized PEI retains its randomly‐coiling structure, while coalesced PEI has at least partially retained, the highly extended and parallel chains from the narrow channels of the inclusion compound, resulting in better/tighter packing among the PEI chains manifested by a higher Tg. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 6049–6053, 2006
Synthesis of nanostructured large particles of polyaniline
Authors: Eftekhari Ali
Published: September 2006

Synthesis of larger particles of conductive polymers is usually favorable due to higher conductivity (as a result of lesser interfacial resistance). On the other hand, advantages of nanostructured materials are well known. Thus, it is desirable to fabricate large particles that have nanostructure, to gain double advantage. A simple method based on chemical polymerization under centrifugal forces is proposed to achieve this goal. It was typically employed for a well‐known conductive polymer, namely, polyaniline to fabricate large particles (e.g., 400 μm) with internal nanostructure of ∼100 nm. This also significantly increases the electrical conductivity of the polymer. This is indeed a simple approach, which can be easily performed using a conventional centrifuge system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 6060–6063, 2006
Synthesis and Aldose Reductase Inhibitory Activities of Novel O‐Substituted Hydroxyphenylacetic Acid Derivatives
Authors: Rakowitz Dietmar , Angerer Helga , Matuszczak Barbara
Published: September 2006

In continuation of our work aimed towards the preparation of novel aldose reductase inhibitors, several O‐substituted hydroxyphenylacetic acid derivatives were investigated. The highest inhibitory activity was found for compounds 7b and 7c bearing a cyclohexylmethyl substituent. This result demonstrates that within these series, this moiety is a useful surrogate for the 4‐bromo‐2‐fluorobenzyl residue which can be often found in potent aldose reductase inhibitors.
IKKβ inhibition protects against bone and cartilage destruction in a rat model of rheumatoid arthritis
Authors: Schopf Lisa , Savinainen Anneli , Anderson Karen , Kujawa Julie , DuPont Michelle , Silva Matthew , Siebert Elizabeth , Chandra Sudeep , Morgan Jennifer , Gangurde Pranoti , Wen Danyi , Lane Joan , Xu Yajun , Hepperle Michael , Harriman Geraldine , Ocain Timothy , Jaffee Bruce
Published: September 2006

Objective

The IKK complex regulates NF‐κB activation, an important pathway implicated in the rheumatoid arthritis (RA) disease process. This study was undertaken to assess the efficacy of N‐(6‐chloro‐7‐methoxy‐9H‐β‐carbolin‐8‐yl)‐2‐methylnicotinamide (ML120B), a potent and selective small molecule inhibitor of IKKβ.

Methods

Polyarthritis was induced in rats by injection of Freund's complete adjuvant into the hind footpad. ML120B was administered orally twice daily, either prophylactically or therapeutically. Paw volumes and body weights were measured every 2–3 days throughout the study. We assessed bone erosions by several methods: histologic evaluation, quantitative micro–computed tomography (micro‐CT) imaging analysis, and measurement of type I collagen fragments in the serum. Quantitative polymerase chain reaction was used to evaluate expression of messenger RNA for genes related to inflammation and to bone and cartilage integrity.

Results

Oral administration of ML120B inhibited paw swelling in a dose‐dependent manner (median effective dosage 12 mg/kg twice daily) and offered significant protection against arthritis‐induced weight loss as well as cartilage and bone erosion. We were able to directly demonstrate that NF‐κB activity in arthritic joints was reduced after ML120B administration. Also, we observed that down‐regulation of the NF‐κB pathway via IKKβ inhibition dampened the chronic inflammatory process associated with rat adjuvant‐induced arthritis.

Conclusion

The results of the present study suggest that IKKβ inhibition is an effective therapeutic approach to treat both the inflammation and the bone/cartilage destruction observed in RA. Methods for the determination of serum markers for bone and cartilage destruction, as well as micro‐CT analysis, may aid in predicting and evaluating the therapeutic efficacy of IKKβ inhibition therapy in humans.
Clinical assessment of the long‐term risk of fracture in patients with rheumatoid arthritis
Authors: Staa T. P. Van , Geusens P. , Bijlsma J. W. J. , Leufkens H. G. M. , Cooper C.
Published: September 2006

Objective

To determine whether patients with rheumatoid arthritis (RA) have an increased risk of fracture, and to estimate their long‐term absolute fracture risk.

Methods

We studied patients with RA ages ≥40 years in the British General Practice Research Database, each matched by age, sex, calendar time, and practice to 3 control patients. Incident fractures, as recorded in the computerized medical records, were ascertained over a median followup of 7.6 years. The fracture rate in RA patients compared with controls was adjusted for smoking, body mass index (BMI), and several clinical risk factors, and Cox proportional hazards models were used to calculate the relative risk (RR) of fracture in RA. A risk score was then developed to provide an estimate of the 5‐ and 10‐year fracture risk among RA patients.

Results

There were 30,262 patients with RA, of whom 2,460 experienced a fracture during followup. Compared with controls, patients with RA had an increased risk of fracture, which was most marked at the hip (RR 2.0, 95% confidence interval [95% CI] 1.8–2.3) and spine (RR 2.4, 95% CI 2.0–2.8). Indicators of a substantially elevated risk of fracture (at the hip) included >10 years' duration of RA (RR 3.4, 95% CI 3.0–3.9), low BMI (RR 3.9, 95% CI 3.1–4.9), and use of oral glucocorticoids (RR 3.4, 95% CI 3.0–4.0). Modeling of the long‐term risk profiles revealed that, for example, in a woman age 65 years with longstanding RA whose risk factors also included low BMI, a history of fracture, and frequent use of oral glucocorticoids, the 5‐year risk of hip fracture was 5.7% (95% CI 5.3–6.1%).

Conclusion

Patients with RA are at increased risk of osteoporotic fractures. This increased risk is attributable to a combination of disease activity and use of oral glucocorticoids.