bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of molecular parameters and processing conditions on degradation of hydrogenated nitrile butadiene rubbers
Authors: Chaudhry R. A. , Hussein I. A. , Amin M. B. , Abu Sharkh B. F.
Published: May 2005

The thermomechanical modification of hydrogenated nitrile butadiene rubbers (HNBR) of different molecular parameters was investigated by rheological and light scattering techniques. The influences of acrylonitrile content, degrees of hydrogenation, and Mooney viscosity were examined. A melt blender with Banbury‐type mixing blades was used to condition the rubber samples in the temperature range from 190 to 260°C. Light scattering was used to determine the effect of conditioning on MW and hydrodynamic radius of the rubber molecules. Dynamic viscosity (η′) and storage modulus (G′) were measured for the as‐received and conditioned samples. Experimental results showed that degradation in these rubbers occurred through chain scission and crosslinking. Depending on the molecular parameter, it was found that one of these two mechanisms dominated the degradation process in most brands. Addition of adequate amounts of antioxidants (Irganox 1010 and Irgafos 168) was successful only in preventing degradation by crosslinking. Compared to thermal degradation, thermomechanical degradation was found to be much more severe and progressed at much higher rates. Rheology was found to be a very sensitive technique to structural parameters of the polymers and could be used to detect and identify the mechanism of degradation. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1432–1441, 2005
Comparison of microwave and thermal cure of epoxy–anhydride resins: Mechanical properties and dynamic characteristics
Authors: Tanrattanakul Varaporn , SaeTiaw Kaew
Published: May 2005

The objective of this work was to compare the mechanical properties of epoxy resins cured by thermal heating and microwave heating. Epoxy–anhydride (100:80) resins were cured in a domestic microwave oven and in a thermal oven. The hardening agents included methyl tetrahydrophthalic anhydride and methyl hexahydrophthalic anhydride. Three types of accelerators were employed. Thermal curing was performed at 150°C for 20 and 14 min for resins containing 1 and 4% accelerator, respectively. Microwave curing was carried out at a low power (207 or 276 W) for 10, 14, and 20 min. All cured resins were investigated with respect to their tensile properties, notched Izod impact resistance, and flexural properties (three‐point bending) according to ASTM standards. The tan δ and activation energy values were investigated with dynamic mechanical thermal analysis, and the extent of conversion was determined with differential scanning calorimetry. The differences in the mechanical properties of the thermally cured and microwave‐cured samples depended on the resin formulation and properties. Equivalent or better mechanical properties were obtained by microwave curing, in comparison with those obtained by thermal curing. Microwave curing also provided a shorter cure time and an equivalent degree of conversion. The glass‐transition temperatures (tan δ) of the thermally and microwave‐cured resins were comparable, and their activation energies were in the range of 327–521 kJ/mol. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1442–1461, 2005
Spectrophotometric measurement of swelling of polymer films by very poor solvents
Authors: Stevens F.
Published: May 2005

Solvent swelling of polymers is important for many applications, but can be difficult to measure when thin films or very poor solvents are involved. A novel spectrophotometric method is presented that is well suited for measuring swelling of thick or thin polymer films by very poor solvents. In this method, the solvent is stained with iodine, and solvent uptake is measured by observing the change in visible light absorption of the polymer using a spectrophotometer. Using this method, swelling can be accurately measured in thin (< 2 μm) polymer films and with poor solvents that cause little swelling, even water. Results are presented for PMMA films of varying molecular weights swelled by water, by water–alcohol mixtures, and by undiluted alcohols. Swelling of these films is more rapid and more Fickian than has been reported for bulk samples, probably due to differences in PMMA molecular weight and processing. The properties of the iodine–PMMA complex are also explored. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1082–1089, 2005
Effects of the chemical foaming agents, injection parameters, and melt‐flow index on the microstructure and mechanical properties of microcellular injection‐molded wood‐fiber/polypropylene composites
Authors: Bledzki Andrzej K. , Faruk Omar
Published: May 2005

Wood‐fiber‐reinforced plastic profiles are growing rapidly in nonstructural wood‐replacement applications. Most manufacturers are evaluating new alternative foamed composites, which are lighter and more like wood. Foamed wood composites accept screws and nails better than their nonfoamed counterparts, and they have other advantages as well. For example, internal pressures created by foaming give better surface definition and sharper contours and corners than nonfoamed profiles have. In this study, the microfoaming of polypropylene (PP) containing hardwood fiber was performed with an injection‐molding process. The effects of different chemical foaming agents (endothermic, exothermic, and endothermic/exothermic), injection parameters (the mold temperature, front flow speed, and filling quantity), and different types of PP (different melt‐flow indices) on the density, microvoid content, physicomechanical properties, surface roughness, and microcell classification of microfoamed PP/wood‐fiber composites were studied. A maleic anhydride/polypropylene copolymer (MAH‐PP) compatibilizer was used with the intention of improving the mechanical properties of microfoamed composites. The microcell classification (from light microscopy) and scanning electron micrographs showed that an exothermic chemical foaming agent produced the best performance with respect to the cell size, diameter, and distance. The polymer melt‐flow index and the variation of the injection parameters affected the properties and microstructure of the microfoamed composites. The density of the microfoamed hardwood‐fiber/PP (with a high melt‐flow index) composites was reduced by approximately 30% and decreased to 0.718 g/cm3 with an exothermic chemical foaming agent. Tensile and flexural tests were performed on the foamed composites to determine the dependence of the mechanical properties on the density and microvoid content of the foamed specimens, and these properties were compared with those of nonfoamed composites. MAH‐PP improved the physicomechanical properties up to 80%. With an increase in the mold temperature (80–110°C), the surface roughness was reduced by nearly 70% for the foamed composites. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1090–1096, 2005
Lamination of high‐density polyethylene by bulk photografting and the mechanism of adhesion
Authors: Wang Huiliang , Brown Hugh R.
Published: May 2005

The photolamination of high‐density polyethylene (HDPE) by bulk photografting is described, along with a discussion of the adhesion mechanism. HDPE can be photolaminated very easily with a thin poly(acrylic acid) layer, photopolymerized from acrylic acid, with very strong adhesion obtained after a short time of UV irradiation; the adhesion failure mode is polyethylene breakage. Thicker HDPE sheets require longer irradiation times for strong adhesion. Methacrylic acid or hydroxyethyl methacrylate provides no adhesion of HDPE at all after irradiation. When glycidyl acrylate is used alone between HDPE sheets, the peel strength of the photolaminated polyethylene is only approximately 320 N/m, but when glycidyl acrylate or hydroxyethyl methacrylate is grafted with acrylic acid, very good adhesion can be obtained. It is proposed that stronger adhesion is produced by a less branched grafted chain structure, which permits much more chain entanglement. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1097–1106, 2005
Crystallization behavior of poly(butylene succinate)/corn starch biodegradable composite
Authors: Ohkita Tsutomu , Lee Seung‐Hwan
Published: May 2005

The effects of corn starch (CS) filler and lysine diisocyanate (LDI) as a coupling agent on the crystallization behavior of a poly(butylene succinate) (PBS)/CS ecocomposite were investigated using differential scanning calorimetry. In isothermal crystallization, n values for pure PBS were from 2.33 to 2.82. On the other hand, both composites showed values of 3 < n < 4. In nonisothermal crystallization, the Avrami exponent varied from 2.12 to 2.55 for pure PBS, from 1.58 to 1.96 for the composite without LDI, and from 1.79 to 1.91 for the composite with LDI, depending on the cooling rate. There was not a large difference of the crystallization rate constant (k) as adjusted by the Jeziornay suggestion. The activation energy for nonisothermal crystallization was also calculated on the basis of three different equations (Augis–Bennett, Kissinger, and Takhor equations). However, the values of the activation energy were in contradiction with the results of the kinetics. The addition of the filler (CS) and coupling agent (LDI) affected the morphological structure of PBS spherulites. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1107–1114, 2005
Preparation, characterization, and drug‐release properties of poly(N‐isopropylacrylamide) microspheres having poly(itaconic acid) graft chains
Authors: Taşdelen Betül , Kayaman‐Apohan Nilhan , MISIrlI Zülal , Güven Olgun , Baysal Bahattin M.
Published: May 2005

An inverse suspension polymerization method for the preparation of thermoresponsive hydrogel microspheres based on N‐isopropylacrylamide was described in this article. The polymerization reaction was carried out at 200 rpm stirring rate and the microspheres obtained were in the size range of 71–500 μm in the swollen states. The particles were sieved by using ASTM sieves. The selected fraction (180–250 μm) of poly(N‐isopropylacrylamide) (PNIPAAm) microspheres was used for radiation‐induced modification with itaconic acid (IA) to obtain PNIPAAm/poly(itaconic acid) graft copolymer. Viagra and lidocaine were used as model drugs for the investigation of controlled‐release behavior of the microspheres. Incorporation of IA graft chains onto microspheres enhanced significantly the uptake of both drugs and further controlled release at specific pH values. The release studies showed that some of the basic parameters affecting the drug‐loading and ‐release behavior of the microspheres were pH, temperature, particle size, and chemical nature of drug. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1115–1124, 2005
Mechanical properties of deproteinized natural rubber in comparison with synthetic cis‐1, 4 polyisoprene vulcanizates: Gum and black‐filled vulcanizates
Authors: Rattanasom N. , Thammasiripong U. , Suchiva K.
Published: May 2005

Gum and black‐filled vulcanizates having various crosslink densities were prepared from 2 types of rubber, namely, deproteinized natural rubber (DPNR) and synthetic cis‐1, 4 polyisoprene vulcanizates (IR). Their mechanical properties, such as tensile strength, tear strength, abrasion loss, and heat buildup resistance, at various crosslink densities as well as at similar optimum crosslink density were compared. For both gum and black‐filled systems, IR possessed a higher crosslink density than that of DPNR at a fixed curative content. Tensile and tear strength of all vulcanizates passed through a maximum with increasing crosslink density. For gum vulcanizates, tensile and tear strengths of DPNR and IR below the maximum were not much different. However, IR had a narrower tear strength peak relative to DPNR. At a comparable optimum crosslink density, DPNR exhibited higher tensile strength and crack growth resistance than IR. For black‐filled vulcanizates, tensile and tear strengths, and heat buildup resistance of DPNR and IR at a given crosslink density were similar. The results revealed that the properties of gum samples were more dependent upon crosslink density than the black‐filled ones because the reinforcement by carbon black overshadowed the intrinsic properties of the rubbers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1139–1144, 2005
An improved prediction result of entropic‐FV model for vapor–liquid equilibria of solvent–polymer systems
Authors: Wibawa Gede , Takishima Shigeki , Sato Yoshiyuki , Masuoka Hirokatsu
Published: May 2005

In this work, entropic expressions of UNIFAC‐FV and Entropic‐FV models were evaluated by using an extensive database of infinite dilution vapor–liquid equilibrium (VLE) data of athermal systems containing polypropylene, polyethylene, and polyisobutylene. For the infinite dilution athermal systems, performance of the Entropic‐FV model was better than that of the UNIFAC‐FV model. Then, finite concentration VLE data of non‐athermal systems that consisted of 16 polymers and 36 solvents containing a large variety of solvent–polymer systems ranging from nonpolar to polar substances were considered to optimized 46 pairs of group interaction parameters of the Entropic‐FV model. For systems containing polar solvents of three types of solvents studied, revised group interaction parameters gave significant improvements from 17.9 to 13.0% average absolute deviation (AAD) of solvent activities. For overall results, improvements were achieved from 15.1 to 12.4% AAD. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1145–1153, 2005
Morphology and activity of nanosized NdCl3 catalyst for 1,3‐butadiene polymerization
Authors: Kwag Gwanghoon , Kim Donghwan , Lee Seunghwa , Bae Cheolbeom
Published: May 2005

The binary lanthanide catalyst for 1,3‐butadiene was invented for 40 years ago. However, it has not been employed in commercial application due to its poor solubility and low activity. Nanosized neodymium chloride (NdCl3) was prepared in tetrahydrofuran (THF) medium through dissolution, chelation, and colloidal formation steps. Anhydrous NdCl3 was dissolved in THF, and ca. 1.5 THF molecules were coordinated. In the colloidal formation step, THF was slowly replaced with the addition of cyclohexane, and pale blue nuclei, nanosize below 200 nm, were formed. The structural studies for NdCl3 · xTHF using X‐ray powder diffraction (XRD) and scanning electron microscope (SEM) indicate that high ordered crystallinity is decreased with reduced particle size from trigonal prismatic to porous sphere structure. Nano NdCl3, obtained as colloidal state in cyclohexane, was activated with Al(iBu)3 and Al(iBu)2H at room temperature and employed for 1,3‐butadiene solution polymerization. The nanosized Nd catalysts showed high activity (1.0 ∼ 1.3 × 105 g/Nd mol · h), which is comparable to that of the ternary neodymium catalyst Nd(neodecanoate)3/AlEt2Cl/Al(iBu)3. The microstructures of polybutadiene, cis, trans, and vinyl, are about 96.0, 3.5, and 0.5%, respectively. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1279–1283, 2005
Kinetics studies on copolymerization of acrylonitrile vinyl acids by solvent–water suspension polymerization
Authors: Sharifnejad Farshid , Bahrami S. Hajir , Noorpanah Parviz
Published: May 2005

Polyacrylonitrile is an important polymer that is widely used in the manufacture of synthetic fibers, particularly for applications in apparel. Although a vast amount of literature is available on the polymerization process of acrylonitrile (AN) with other monomers, there are few reports of studies on polymerization in a mixed solvent of water with an organic solvent. It is conceivable that this method could combine the advantages of the solution and suspension polymerization methods. Synthesis of AN copolymers with two vinyl acids, methacrylic acid (MAA) and itaconic acid (IA), is carried out by solvent–water suspension polymerization. The polymerizations are performed with an equal ratio mixture of dimethylformamide as a solvent and water as a nonsolvent at 60°C using α,α‐azobisisobutyronitrile as an initiator. The kinetics of polymerization are studied by plotting the conversion versus reaction time for different mole ratios of AN with vinyl acids. Copolymers are characterized by FTIR and capillary viscometery. The results show that IA depresses the rate of polymerization more than MAA in this reaction medium, and this effect becomes more significant at higher vinyl acid mole ratios. High conversion in a short reaction time is obtainable for copolymers with a low vinyl acid mole fraction. However, for mole ratios of more than 93:7, the rate of the reaction is drastically reduced and low conversion (<60%) results, even after 8 h. The intrinsic viscosities of all cases are surprisingly high. Although they are reduced with increasing acidic comonomer mole fraction, this reduction is more significant for IA compared to MAA. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1284–1291, 2005
Analysis of the kinetics and current efficiency of pyrrole galvanostatic electropolymerization
Authors: Tyr'yan Yakov I. , Gorenbein Pavel , Domb Abraham J.
Published: May 2005

We propose a modified kinetic equation for the galvanostatic electropolymerization of pyrrole based on equal rates of monomer disappearance and its galvanostatic electropolymerization associated with applied current (I). The equation is distinguished by a zero‐order kinetic plot and takes into account the effects of the pyrrole initial concentration ([M]0) and current efficiency (η). We propose a mechanism for obtaining a η of less than 100% and increasing η with increasing [M]0 and I on the basis of the diffusion of radical cations (M•+) from the anode surface to the bulk solution after the electroreduction of M•+ to monomer molecules at the cathode. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1167–1169, 2005
Metal ion retention properties of poly(acrylic acid) and poly[N‐3‐(dimethylamino)propyl acrylamide‐co‐acrylic acid]
Authors: Rivas Bernabé L. , Quilodrán Benita , Quiroz Eduardo
Published: May 2005

The crosslinked resins poly(acrylic acid) (PAA) and poly[N‐3‐(dimethylamino)propyl acrylamide‐co‐acrylic acid] [P(NDAPA‐co‐AA)] are obtained by radical polymerization and characterized by FTIR spectroscopy. PAA at basic pH exists basically as an acrylate anion that may contain end carboxylate groups or form bridges acting as mono‐ or bidentate ligands. P(NDAPA‐co‐AA) presents three potential ligand groups in its structure: carboxylic acid, amide, and amine. The trace metal ion retention properties of these two resins is compared by using the batch equilibrium procedure. The metal ions are contained in saline aqueous solutions and are found in natural seawater. The retention of Cu(II), Pb(II), Cd(II), and Ni(II) metal ions is studied under competitive and noncompetitive conditions. The effects on the pH, contact time, amount of adsorbent, temperature, and salinity are investigated. The PAA resin presents a high affinity (>80%) for Cu(II) and Cd(II) ions. The P(NDAPA‐co‐AA) resin shows a high affinity for Pb(II) and Cd(II) ions. With 4M HNO3 it is possible to completely recover the PAA resin charged with Cu(II) ions and the P(NDAPA‐co‐AA) resin charged with Pb(II) ions. The two resins show a high affinity for Cd(II) ions from the seawater containing Cu(II) and Cd(II) ions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1385–1394, 2005
Barrier resistance of polyethylene, polyethylene/modified polyamide, and polyethylene/blends of modified polyamide and ethylene vinyl alcohol bottles against permeation of polar and nonpolar mixed solvents
Authors: Yeh Jen‐Taut , Huang Shyh‐Shiuan , Chen Heng‐Yi
Published: May 2005

The main objective of this study is to investigate the barrier properties and mechanisms of polyethylene (PE), PE/modified polyamide (MPA), and PE/blends of MPA and ethylene vinyl alcohol copolymer (MPAEVOH) bottles against permeation of polar/nonpolar (acetone/white spirit) mixed solvents. The mixed solvent permeation resistance improves dramatically after blending MPA and MPAEVOH barrier resins in PE matrices during blow molding. By using the proper MPAEVOH compositions, the white spirit permeation rate of PE/MPAEVOH bottles at 40°C can be about 145 times slower than that of the PE bottle specimen; however, it is still 2.5 times faster than that of the PE/MPA bottles. In contrast, the rate of polar acetone solvent permeation through the PE bottle is much slower than that of white spirit and only slightly faster than that through the PE/MPA and PE/MPAEVOH bottle specimens. In contrast, the permeation rates of acetone/white spirit mixed solvents into PE/MPA bottles are at least 20–60 times faster than the summation permeation rates calculated using the simple mixing rule when the acetone contents in the mixed solvents are between 10 and 70 wt %. It is somewhat interesting that, after blending the proper amounts of EVOH in MPA, the mixed solvent permeation rates of PE/MPAEVOH bottles are dramatically reduced and are very close to the summation permeation rates calculated using the simple mixing rule when the acetone contents are in the particular “window” range. These interesting barrier properties of PE/MPA and PE/MPAEVOH bottle specimens were investigated in terms of the free volumes, barrier properties, molecular interactions in the amorphous phases of the barrier resins, and their resulting morphological structures that present in their corresponding bottles. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1333–1344, 2005
Effect of compatibilization on the oxygen‐barrier properties of poly(ethylene terephthalate)/poly(m‐xylylene adipamide) blends
Authors: Prattipati V. , Hu Y. S. , Bandi S. , Schiraldi D. A. , Hiltner A. , Baer E. , Mehta S.
Published: May 2005

The improvement of the oxygen‐barrier properties of poly(ethylene terephthalate) (PET) via blending with an aromatic polyamide [poly(m‐xylylene adipamide) (MXD6)] was studied. The compatibilization of the blends was attempted through the incorporation of small amounts of sodium 5‐sulfoisophthalate (SIPE) into the PET matrix. The possibility of a transamidation reaction between PET and MXD6 was eliminated by 13C‐NMR analysis of melt blends with 20 wt % MXD6. An examination of the blend morphology by atomic force microscopy revealed that SIPE effectively compatibilized the blends by reducing the MXD6 particle size. Thermal analysis showed that MXD6 had a nucleating effect on the crystallization of PET, whereas the crystallization of MXD6 was inhibited, especially in compatibilized blends. Blending 10 wt % MXD6 with PET had only a small effect on the oxygen permeability of the unoriented blend when it was measured at 43% relative humidity, as predicted by the Maxwell model. However, biaxially oriented films with 10 wt % MXD6 had significantly reduced oxygen permeability in comparison with PET. The permeability at 43% relative humidity was reduced by a factor of 3 in compatibilized blends. Biaxial orientation transformed spherical MXD6 domains into platelets oriented in the plane of the film. An enhanced barrier arose from the increased tortuosity of the diffusion pathway due to the high aspect ratio of MXD6 platelets. The aspect ratio was calculated from the macroscopic draw ratio and confirmed by atomic force microscopy. The reduction in permeability was satisfactorily described by the Nielsen model. The decrease in the oxygen permeability of biaxially oriented films was also achieved in bottle walls blown from blends of PET with MXD6. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1361–1370, 2005
New theory on the physical properties of polymers from cured resins to linear polymers: Melting temperature, glass‐transition temperature, and strength
Authors: Matsushita Yahachiro
Published: May 2005

Here it is shown how a property is acquired with a new segment. This means that when a polymer is produced without a melting temperature by heating (Tm) or solvent and mechanical stress, new physical properties will not occur. A new segment starts from crosslinking, which takes the three steps of initiation, propagation, and termination, such as the polymerization of a vinyl monomer. An excess of crosslinking causes a crack in the resin. The boiling water absorption expresses the magnitude, which consists of a closed and open cell. The limit of the thermal elongation of the CC‐bond‐composed main chain is 1% from 0°C, which is a common value making possible a comparison for the general polymer, extending the CC bond of the organic compound. An equation of the glass‐transition temperature (Tg) is obtained from summation inversely to the linear coefficient of thermal expansion of each molecular unit. DNA is given as a perfect form composed of all new segments without waste; the molecular unit responds to an individual function as a condition of a living thing. Tg is a signal to change direction to the thermal elongation of the main chain for Tm; Tm − Tg indicates a similar process in the original direction of Tg. There is no Tm without Tg. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1467–1475, 2005
Preparation and properties of layered silicate/polyimide hybrid films
Authors: Wu Juntao , Yang Shiyong , Gao Shengqiang , Hu Aijun , Fan Lin
Published: May 2005

Layered silicate/polyimide (PI) hybrid films were prepared from 4,4′‐oxydianiline, 3,3′,4,4′‐oxydiphthalic anhydride, and chemically modified montmorillonite via an in situ intercalation polymerization pathway. The X‐ray diffraction and transmission electron microscopy results indicated that the silicates were homogeneously dispersed as exfoliated layers in the PI hybrid film with 2% silicate. The mechanical properties and thermal stabilities of the PI hybrid films changed with the content of the layered silicates. The coefficient of thermal expansion and water uptake of the PI hybrid films decreased with increasing silicate contents because of the barrier effect of platelike silicate layers, which prevented the diffusion and penetration of water. The dielectric strength and electrical aging performance of the PI hybrid films could also be improved as the silicate layer highly dispersed in the films. For the hybrid PI film with 5% layered silicate, the time to failure during electrical aging exceeded 280 h, which was 2.5 times as long as that of pure PI film. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1176–1183, 2005
Aromatic polyimides from m‐phenylene diamines containing pendant groups: Synthesis and characterization
Authors: Pal Ravindra R. , Patil Prashant S. , Dere Ravindra T. , Salunkhe Manikrao M. , Maldar Noormahamad N. , Wadgaonkar Prakash P.
Published: May 2005

Two diamine monomers, 4‐[4‐(1‐methyl‐1‐phenylethyl)phenoxy]‐1,3‐diamino benzene and 4‐{4‐[(4‐methylphenyl)sulfonyl]phenoxy}‐1,3‐diamino benzene, were synthesized, and both diamines were polycondensed with three commercial dianhydrides to obtain aromatic polyimides containing pendant groups. The polyimides were characterized by solubility tests, viscosity measurements, IR, 1H‐NMR, and 13C‐NMR spectroscopy, X‐ray diffraction studies, and thermogravimetric analysis. The polyimides had inherent viscosities of 0.33–0.58 dL/g in m‐cresol at 30 ± 0.1°C. All the polyimides were amorphous and were soluble in solvents such as N,N‐dimethylacetamide, N‐methyl‐2‐pyrrolidone, N,N‐dimethylformamide, and m‐cresol. Thermogravimetric analysis of the polyimides indicated no weight loss below 410°C under a nitrogen atmosphere. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1377–1384, 2005
Metal‐chelating properties of poly(2‐hydroxyethyl methacrylate–methacryloylamidohistidine) membranes
Authors: Denizli Adil , Bektaş Sema , Arıca Yakup , Genç Ömer
Published: May 2005

Metal‐chelating membranes have advantages as adsorbents in comparison with conventional beads because they are not compressible and they eliminate internal diffusion limitations. The aim of this study was to explore in detail the performance of poly(2‐hydroxyethyl methacrylate–methacryloylamidohistidine) [poly(HEMA–MAH)] membranes for the removal of three toxic heavy‐metal ions—Cd(II), Pb(II), and Hg(II)—from aquatic systems. The poly(HEMA–MAH) membranes were characterized with scanning electron microscopy and 1H‐NMR spectroscopy. The adsorption capacity of the poly(HEMA–MAH) membranes for the selected heavy‐metal ions from aqueous media containing different amounts of these ions (30–500 mg/L) and at different pH values (3.0–7.0) was investigated. The adsorption capacity of the membranes increased with time during the first 60 min and then leveled off toward the equilibrium adsorption. The maximum amounts of the heavy‐metal ions adsorbed were 8.2, 31.5, and 23.2 mg/g for Cd(II), Pb(II), and Hg(II), respectively. The competitive adsorption of the metal ions was also studied. When the metal ions competed, the adsorbed amounts were 2.9 mg of Cd(II)/g, 14.8 mg of Pb(II)/g, and 9.4 mg of Hg(II)/g. The poly(HEMA–MAH) membranes could be regenerated via washing with a solution of nitric acid (0.01M). The desorption ratio was as high as 97%. These membranes were suitable for repeated use for more than three adsorption/desorption cycles with negligible loss in the adsorption capacity. The stability constants for the metal‐ion/2‐methacryloylamidohistidine complexes were calculated to be 3.47 × 106, 7.75 × 107, and 2.01 × 107 L/mol for Cd(II), Pb(II), and Hg(II) ions, respectively, with the Ruzic method. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1213–1219, 2005
Dynamic–mechanical properties of modified poly(ethylene‐co‐vinyl acetate)
Authors: Barbosa Ronilson V. , Neto Ricardo B. , Mauler Raquel S. , Gorga Carlos J. Perez , Schneider Cláudia G. , Simanke Adriane G.
Published: May 2005

To study the relationship among relaxation peaks observed in dynamic mechanical experiments and the structure of poly(ethylene‐co‐vinyl acetate) (EVA), EVA copolymers with different substitution in the carbonyl group were synthesized. EVA was hydrolyzed to obtain poly (ethylene‐co‐vinyl alcohol) and was subsequently reacted with formic, hexanoic, and octanoic acids. The copolymers synthesized were characterized by infrared spectroscopy. Analysis of the DMA spectra of the copolymers showed that their relaxation behavior depends on the vinyl acetate concentration. The α‐ and β‐transitions were observed in EVA copolymers with 8 and 18 wt % of functional groups, and the relationship among relaxation process with the structure of polymer was investigated. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1371–1376, 2005
Synthesis and characterization of alternate copolymers constructed by 1,3‐bis(diphenylsilyl)‐2,2,4,4‐tetraphenylcyclodisilazane units with oligo‐dimethylsiloxane segments
Authors: Jing‐Bo Zhao , Ze‐Min Xie
Published: May 2005

1,3‐Dichloro‐1,1,3,3‐tetraphenyldisilazane (DCTPS) with 71.6% yield was synthesized by the reaction of hexaphenylcyclotrisilazane (HPCT) with Ph2SiCl2 catalyzed by dibutyltin dilaurate. A ring‐closure reaction of DCTPS was carried out with BuLi in xylene–hexane mixture solvent; 1,3‐bis(chlorodiphenylsilyl)‐2,2,4,4‐tetraphenyl‐cyclodisilazane (BcPTPC) with 73.2% yield was obtained. Hydrolysis of BcPTPC in ether–triethylamine solvent resulted in 71.9% yield of 1,3‐bis(diphenylhydroxysilyl)‐2,2,4,4‐tetraphenylcyclodisilazane (BHPTPC). By condensation polymerization of BHPTPC with α,ω‐bis(diethylamino)‐oligo‐dimethylsiloxane, a kind of alternate copolymer constructed by 1,3‐bis(diphenylsilyl)‐2,2,4,4‐tetraphenylcyclodisilazane units with oligo‐dimethylsiloxane segments [P(BPTPC‐alt‐ODMS)] was synthesized. BcPTPC, BHPTPC as well as P(BPTPC‐alt‐ODMS) were characterized by 29Si‐NMR spectra, FT‐IR spectra, and elemental analysis. DGA study shows that P(BPTPC‐alt‐ODMS)s are thermally stable. The thermal decomposition onsets of P(BPTPC‐alt‐ODMS)s are all above 520°C. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1484–1490, 2005
Cationic polymerization of hydrogenated bisphenol‐A glycidyl ether with cycloaliphatic epoxy resin and its thermal discoloration
Authors: Morita Yasumasa
Published: May 2005

One of the key issues associated with epoxy resin–based LED encapsulant is discoloration under operating conditions that caused a decrease in light output. In this article, thermal cationic polymerization of hydrogenated bisphenol‐A glycidyl ether using 3‐methyl‐2‐butenyltetramethylenesulfonium hexafluoroantimonate and its discoloration are reported. Polymerization was followed by thermal analysis, FT‐IR spectrum, and hardness measurements. Thermal discoloration was measured by yellowness index based on transmittance spectrum. Increased catalyst concentration causes acceleration in polymerization rates, but this also increased discoloration after thermal aging. In low catalyst concentration under 0.3 wt %, the hardness of plaque was low and required a high temperature to complete polymerization and this resulted in a highly colored plaque. Formulation with cycloaliphatic epoxy (3′‐4′‐epoxycyclohexane)methyl 3′‐4′‐epoxycyclohexyl‐carboxylate (CEL2021P) enhanced the polymerization even at low catalyst concentration and reduced thermal discoloration. With addition of di‐t‐butylphenol (BHT) as the oxidation inhibitor, the thermal discoloration was extremely improved but this also caused inhibition of polymerization as seen by thermal analysis. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1395–1400, 2005
Dependence of the electrical conductivity and elastomeric properties on sample preparation of blends of polyaniline and natural rubber
Authors: Camillo E. C. , Constantino C. J. L. , Teruya M. Y. , Alves N. , Mattoso L. H. C. , Job A. E.
Published: May 2005

Blend films (free‐standing) containing 20% in volume of polyaniline (PANI) in 80% of natural rubber (NR) were fabricated by casting in three different ways: (1) adding PANI‐EB (emeraldine base) dissolved in N‐methyl‐2‐pyrrolidone (NMP) to the latex (NRL), (2) adding PANI‐EB dissolved in m‐cresol to NR dissolved in xylol (NRD), (3) overlaying the surface of a pure NR cast film with a PANI layer grown by in situ polymerization (NRO). All the films were immersed into HCl solution to achieve the primary doping (protonation) of PANI before the characterization. The main goal here was to investigate the elastomeric and electrical conductivity properties for each blend, which may be applied as pressure and deformation sensors in the future. The characterization was carried out by optical microscopy, dc conductivity, vibrational spectroscopy (infrared absorption and Raman scattering), thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and tensile stress–strain curves. The results suggest that the NRL blend is the most suitable in terms of mechanical and electrical properties required for applications in pressure and deformation sensors: a gain of conductivity without losing the elastomeric property of the rubber. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1498–1503, 2005
Effect of peroxide crosslinking on the dynamic modulus of silicone rubber
Authors: Warley R. L. , Feke D. L. , Manas‐Zloczower I.
Published: May 2005

The effect of peroxide crosslinking on the dynamic modulus of a silica‐reinforced silicone [poly(dimethylsiloxane)] elastomer was investigated. Three different peroxides (t‐butyl peroxide, t‐butyl perbenzoate, and benzoyl peroxide) were employed at various practical loadings and differences in the nonlinear behavior of the dynamic modulus were found. Results are discussed with respect to changes in crosslinking density and the identity of the peroxide. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1504–1512, 2005
Biodegradability and mechanical properties of agro‐flour–filled polybutylene succinate biocomposites
Authors: Kim Hee‐Soo , Yang Han‐Seung , Kim Hyun‐Joong
Published: May 2005

The objective of this study was the production of rice husk flour (RHF) and wood flour (WF) filled polybutylene succinate (PBS) biocomposites as alternatives to cellulosic material filled conventional plastic (polyolefins) composites. PBS is one of the biodegradable polymers, made from the condensation reaction of 1,4‐butanediol and succinic acid that can be naturally degraded in the natural environment. We compared the mechanical properties between conventional plastics and agro‐flour–filled PBS biocomposites. We evaluated the biodegradability and mechanical properties of agro‐flour–filled PBS biocomposites according to the content and filler particle size of agro‐flour. As the agro‐flour loading was increased, the tensile and impact strength of the biocomposites decreased. As the filler particle size decreased, the tensile strength of the biocomposites increased but the impact strength decreased. The addition of agro‐flour to PBS produced a more rapid decrease in the tensile strength, notched Izod impact strength, and percentage weight loss of the biocomposites during the natural soil burial test. These results support the application of biocomposites as environmentally friendly materials. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1513–1521, 2005
Dielectric studies of hyperbranched aromatic polyamide and polyamide‐6,6 blends
Authors: Hakme C. , Stevenson I. , Fulchiron R. , Seytre G. , Clement F. , Odoni L. , Rochat S. , Varlet J.
Published: May 2005

The objective of this work was to study the interactions between polyamide‐6,6 (PA‐6,6) and hyperbranched (HB) polyamide with different functional end groups. The investigation focused on the thermal, dielectric, and viscoelastic properties of two kinds of HB polyamides, with amine and alkyl end groups, prepared by a one‐pot process, in a polyamide‐6,6 matrix. Thermal analysis (by TGA and DSC) allowed us to observe decomposition and glass‐transition temperatures of these polymers. The melting point, crystallization temperature, and crystallinity ratio remained practically independent of HB content. Dielectric relaxation spectroscopy (DRS) showed two secondary relaxation (γ and β) and one primary (α) relaxation in the HB polymers and in the blends similar to those observed in polyamide‐6,6 with comparable activation energies and distribution parameters. An increase of the glass‐transition temperature was observed, showing a reinforcement of the polymer matrix and a decrease of the molecular mobility of the polyamide chains when the percentage of amine‐terminated HB polyamide increased in the matrix. DRS results found on the alkyl‐terminated HB polymer blend were indistinct from those of the polyamide‐6,6 matrix. Viscoelastic experiments confirmed the results observed in DRS. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1522–1537, 2005
Systematic review of dressings and topical agents for surgical wounds healing by secondary intention
Authors: Vermeulen H , Ubbink D T , Goossens A , de Vos R , Legemate D A
Published: May 2005

Background

The best dressing for postoperative wounds healing by secondary intention is unknown.

Methods

A systematic review was conducted to assess the effectiveness of dressings and topical agents on such wounds. Main endpoints were wound healing, pain, patient satisfaction, costs and hospital stay. Systematic methodological appraisal and data extraction were performed by independent reviewers.

Results

Fourteen reports of 13 randomized clinical trials on dressings or topical agents (gauze, foam, bead, alginate and hydrocolloid dressing) for postoperative wounds healing by secondary intention were identified; they were of weak methodological quality. In general, no statistically significant differences in wound healing were found for various dressing comparisons (11 of 13 trials). Patients experienced significantly more pain (four of six trials) and were less satisfied when gauze was used (three of six trials). Gauze was inexpensive, but its use was associated with significantly more nursing time than dressing with foam (two of three trials). No substantial differences in hospital stay were found (four of five trials).

Conclusions

Only small, poor-quality trials exist, rendering the evidence insufficient. Foam is best studied as an alternative to gauze and appears to be preferable in terms of pain reduction, patient satisfaction and nursing time.
Chimerism in transplant allografts
Authors: Ng I O L
Published: May 2005

Continuing the Journal's 2005 series of leading articles highlighting where laboratory science meets clinical practice, Professor Ng of Hong Kong outlines the importance of stem cell plasticity and chimerism.
Structure and Redox Properties of the Haem Centre in the C357M Mutant of Cytochrome P450cam
Authors: Murugan Rajamanickam , Mazumdar Shyamalava
Published: May 2005

The effects of site‐specific mutation of the axial cysteine (C357M) to a methionine residue in cytochrome P450cam on the enzyme’s coordination geometry and redox potential have been investigated. The absorption spectra of the haem centre in the C357M mutant of the enzyme showed close similarity to those of cytochrome c both in the oxidised and reduced forms. A well‐defined absorption peak at 695 nm, similar to that seen in the case of cytochrome c and characteristic of methionine ligation to the ferric haem, was observed. The results indicated that the haem of C357M cytochrome P450cam is possibly axially coordinated to a methionine and a histidine, analogously to cytochrome c. The circular dichroism spectra in the visible and the far‐UV regions suggested that the tertiary structure of the haem cavity in the C357M mutant cytochrome P450cam was distinctly different from that in the wild‐type enzyme or in cytochrome c, although the secondary structure of the mutant remained identical to that of the wild‐type cytochrome P450cam. Comparison of the natures of the CD spectra in the 400 nm and 695 nm regions of the C357M mutant of cytochrome P450cam with those of horse cytochrome c suggested (R) chirality at the sulfur atom of the iron‐bound methionine residue in the mutant. The redox potential of the haem centre, estimated by redox titration of the C357M mutant, was found to be +260 mV, which is much higher than that in the wild‐type enzyme and similar to the redox potential of cytochrome c. This supported the concept that axial ligation of the haem plays the major role in tuning the redox potential of the haem centre in haem proteins.
Highly Stable DNA Triplexes Formed with Cationic Phosphoramidate Pyrimidine α‐Oligonucleotides
Authors: Michel Thibaut , Debart Françoise , Heitz Frédéric , Vasseur Jean‐Jacques
Published: May 2005

The ability of cationic phosphoramidate pyrimidine α‐oligonucleotides (ONs) to form triplexes with DNA duplexes was investigated by UV melting experiments, circular dichroism spectroscopy and gel mobility shift experiments. Replacement of the phosphodiester linkages in α‐ONs with positively charged phosphoramidate linkages results in more efficient triplex formation, the triplex stability increasing with the number of positive charges. At a neutral pH and in the absence of magnesium ions, it was found that a fully cationic phosphoramidate α‐TFO (triplex‐forming oligonucleotide) forms a highly stable triplex that melts at a higher temperature than the duplex target. No hysteresis between the annealing and melting curves was noticed; this indicates fast association. Moreover, the recognition of a DNA duplex with a cationic α‐TFO through Hoogsteen base pairing is highly sequence‐specific. To the best of our knowledge, this is the first report of stable triplexes in the pyrimidine motif formed by cationic α‐oligonucleotides and duplex targets.
Evidence for d Orbital Aromaticity in Square Planar Coinage Metal Clusters.
Authors: Wannere Chaitanya S. , Corminboeuf Clemence , Wang Zhi‐Xiang , Wodrich Matthew D. , King R. Bruce , von Rague Schleyer Paul
Published: May 2005

For Abstract see ChemInform Abstract in Full Text.
Crystal and Magnetic Structures of the Mn3+ Orbital Ordered Manganite YBaMn2O5.5.
Authors: Perca Cristian , Pinsard‐Gaudart Loreynne , Daoud‐Aladine Aziz , Fernandez‐Diaz Maria Teresa , Rodriguez‐Carvajal Juan
Published: May 2005

For Abstract see ChemInform Abstract in Full Text.
Synthesis and Structural Studies of the A‐Site Substituted Bismuth Double Perovskites, Ba2‐xSrxLuBiO6.
Authors: Macquart Rene B. , Kennedy Brendan J.
Published: May 2005

For Abstract see ChemInform Abstract in Full Text.
Electronic Structure of Ag2Cu2O4. Evidence of Oxidized Silver and Copper and Internal Charge Delocalization
Authors: Munoz‐Rojas D. , Subias G. , Fraxedas J. , Gomez‐Romero P. , Casan‐Pastor N.
Published: May 2005

For Abstract see ChemInform Abstract in Full Text.
Synthesis, Thermal Evolution, and Luminescence Properties of Yttrium Disilicate Host Matrix.
Authors: Diaz M. , Pecharroman C. , del Monte F. , Sanz J. , Iglesias J. E. , Moya Jose S. , Yamagata C. , Mello‐Castanho S.
Published: May 2005

For Abstract see ChemInform Abstract in Full Text.
Effect of Li Addition on Structural, Electrical and Electrochemical Properties of Lanthanum Manganite.
Authors: Shih Fu‐Yun , Fung Kuan‐Zong
Published: May 2005

For Abstract see ChemInform Abstract in Full Text.
Role of Hybridization in Magnetic Properties of DyPdAl Single Crystals.
Authors: Talik E. , Skutecka M. , Mydlarz T. , Kusz J. , Boehm H.
Published: May 2005

For Abstract see ChemInform Abstract in Full Text.
Synthesis, Structure, and Properties of Two New Ruddlesden—Popper Phase Analogues of SFMO (Sr2FeMoO6).
Authors: Sher Falak , Williams A. J. , Venimadhev A. , Blamire Mark G. , Attfield J. Paul
Published: May 2005

For Abstract see ChemInform Abstract in Full Text.
Ferromagnetic Nitrides with the Filled β‐Mn Structure: Fe2‐xMxMo3N (M: Ni, Pd, Pt).
Authors: Prior Timothy J. , Oldham Sophie E. , Couper Victoria J. , Battle Peter D.
Published: May 2005

For Abstract see ChemInform Abstract in Full Text.
Biomimetic Hydrogen Evolution: MoS2 Nanoparticles as Catalyst for Hydrogen Evolution
Authors: Hinnemann Berit , Moses Poul Georg , Bonde Jacob , Joergensen Kristina P. , Nielsen Jane H. , Horch Sebastian , Chorkendorff Ib , Noerskov Jens K.
Published: May 2005

For Abstract see ChemInform Abstract in Full Text.
Selective Formation of MSi16 (M: Sc, Ti, and V).
Authors: Koyasu Kiichirou , Akutsu Minoru , Mitsui Masaaki , Nakajima Atsushi
Published: May 2005

For Abstract see ChemInform Abstract in Full Text.
Synthesis and Structure of a Novel Three‐Dimensional Organo‐zincophosphite with Three Intersecting Channels.
Authors: Chen Wen‐Bin , Li Niu , Xiang Shou‐He
Published: May 2005

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A Ladderlike Chain Aluminum Fluoride ([Al2F8]2‐)n with Edge‐Sharing AlF6 Octahedra.
Authors: Loiseau Thierry , Muguerra Herve , Marrot Jerome , Ferey Gerard , Haouas Mohamed , Taulelle Francis
Published: May 2005

For Abstract see ChemInform Abstract in Full Text.
Synthesis, Crystal Structure and Characterization of a New Layered Lanthanum(III) Diselenite Hydrogenselenite: La(Se2O5)(HSeO3) (H2O)×H2O.
Authors: Feng Mei‐Ling , Mao Jiang‐Gao
Published: May 2005

For Abstract see ChemInform Abstract in Full Text.
Ln5Co4Si14 (Ln: Ho Er, Tm, Yb): Silicides Grown from Ga Flux Showing Exceptional Resistance to Chemical and Thermal Attack.
Authors: Salvador James R. , Malliakas Christos , Gour Jeff R. , Kanatzidis Mercouri G.
Published: May 2005

For Abstract see ChemInform Abstract in Full Text.
Evidences for Intermediate Valence Behavior in CeNi5In.
Authors: Rojas D. P. , Pereira L. C. J. , Salamakha P. , Lopes E. B. , Waerenborgh J. C. , da Silva L. M. , Gandra F. G.
Published: May 2005

For Abstract see ChemInform Abstract in Full Text.
Crystal Growth and Magnetic Properties of Lanthanide‐Containing Osmium Double Perovskites, Ln2NaOsO6 (Ln: La, Pr, Nd).
Authors: Gemmill William R. , Smith Mark D. , Prozorov Ruslan , zur Loye Hans‐Conrad
Published: May 2005

For Abstract see ChemInform Abstract in Full Text.
Ru‐Catalyzed Asymmetric Hydrogenation of α‐Phthalimide Ketones and 1,3‐Diaryl Diketones Using 4,4′‐Substituted BINAPs.
Authors: Hu Aiguo , Lin Wenbin
Published: May 2005

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Polymer‐Supported Phosphinooxathiane as Ligands for Palladium‐Catalyzed Asymmetric Allylations.
Authors: Nakano Hiroto , Takahashi Kouichi , Fujita Reiko
Published: May 2005

For Abstract see ChemInform Abstract in Full Text.