bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization and electrical properties of methyl‐2‐hydroxyethyl cellulose doped with erbium nitrate salt
Authors: Abd‐El Kader F. H. , Said G. , El‐Naggar M. M. , Anees B. A.
Published: August 2006

X‐ray diffraction, infrared (IR), and electrical properties for pure and Er (NO3)3‐doped methyl‐2‐hydroxyethyl cellulose (MHEC) with concentrations of 0.5, 1, 2, 5, 7, and 10 wt % were studied. X‐ray analysis indicates that the addition of Er (NO3)3, which is a crystalline material, to MHEC at concentrations 10 and 13 wt % leads to the formation of crystalline phases in the amorphous polymeric matrix. The appearance of the bending mode ν2 and the combination mode (ν1 + ν4) of Er (NO3)3 in the IR spectra of composite samples indicates the coordination of nitro group in the chains of MHEC. From the I–V characteristics, it was found that the charge transport mechanism in MHEC appears to be essentially space charge limited conduction, while the predominant mechanism in the composite samples is Poole–Frenkel. Values of both drift mobility (μ) and the charge carrier density (n) has been reported. The temperature dependence conductivity data has been analyzed in terms of the Arrhenius and Mott's variable range hopping models. Different Mott's parameters such as the density of states, N(EF), hopping distance (R), and average hopping energy (W) have been evaluated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:2352–2361, 2006
Preparation and modification of macroporous epoxy‐triethylenetetramine resin for preconcentration and removal of Hg(II) in aqueous solution
Authors: Pan Junyan , Wang Sui , Zhang Ruifeng
Published: August 2006

A novel macroporous resin was prepared from epoxy resin and triethylenetetramine through a polymerization with phase separation. In this experiment, the polyethylene glycol (PEG‐1000) plays a very important part. It was used as solvent, as phase‐separation reagent in the preparation processes, and as the pore‐forming reagent through removing PEG‐1000 from polymer by water‐cleaning process after completing polymerization. The prepared resin was modified by carbon bisulfide and soaked in 1 mol L−1 NaOH. Its structure was characterized by Fourier transform‐infrared spectra, scanning electron microscopy, and elemental analysis. The adsorption characteristic of the chelating resin was studied by series of experiments. The results show that the chelating resin possesses excellent adsorption characteristic toward trace Hg(II). The recovery can come to 100% when the concentration of Hg(II) is only 0.05 ppm, and the average maximum adsorption capacity of the chelating resin for Hg(II) is 122 mg g−1. The precision (relative standard deviation) for six replicate adsorbent extraction of 0.01 μg mL−1 Hg(II) was 1.1%. The accuracy of the proposed procedure was verified by analyzing a standard reference material. Moreover, the chelating resin was applied to two natural samples and also got satisfactory results. That is to say, the chelating resin modified by carbon bisulfide exhibits a high chelating ability toward Hg(II) and can be used as adsorbent for preconcentration and removal of trace Hg(II) in aqueous solution. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:2372–2378, 2006
Optimal policies for BMA polymerization in nonisothermal batch reactor
Authors: Sundaram B. S. , Upreti S. R. , Lohi A.
Published: August 2006

In this paper, the optimal policies for bulk polymerization of n‐butyl methacrylate (BMA) are determined in a nonisothermal batch reactor. Four objectives are realized for BMA polymerization based on a detailed process model. The objectives are: (i) maximization of monomer conversion in a specified operation time, (ii) minimization of operation time for a specified, final monomer conversion, (iii) maximization of monomer conversion for a specified, final number average polymer molecular weight, and (iv) maximization of monomer conversion for a specified, final weight average polymer molecular weight. For each objective, the optimal temperature policy of heat‐exchange fluid inside reactor jacket is determined. The temperature of the heat‐exchange fluid is considered as a function of a specified variable. Necessary equations are provided to suitably transform the process model in terms of a specified variable other than time, and to evaluate the elements of Jacobian to help in the accurate solution of the process model. A genetic algorithm‐based optimal control method is applied to realize the objectives. The resulting optimal policies of this application reveal considerable improvements in the batch production of poly(BMA). © 2006 Wiley Periodicals, Inc. J Appl PolymSci 102: 2799–2809, 2006
Synergistic efficiency of combined HALS–UV absorber polymerizable stabilizers
Authors: Bojinov Vladimir
Published: August 2006

The influence of combined 2,2,6,6‐tetra methylpiperidine  2‐hydroxyphenyl‐benzotriazole [1,3,5]triazine polymerizable stabilizers on the photostability of their copolymers with methyl methacrylate as well as the interaction of the photoreactive HALS and UV absorber fragments in the combined molecules have been studied. Chemical bonding of the stabilizers in the polymer was confirmed spectrophotometrically. The participation of the combined stabilizers in the polymerization did not affect considerably the molecular weight and the molecular weight distribution of the copolymers. A significant stabilizing effect against photodegradation was determined. Strong synergistic interaction between different HALS and UV absorber fragment in the combined stabilizers was established. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2408–2415, 2006
Characterization of conducting poly(3‐methylthiophene) films prepared under sono‐electrochemical conditions
Authors: Galal A.
Published: August 2006

Poly(3‐methlthiophene) films were prepared under “silent” and “sono‐electrochemical” potentiostatic (SEP) conditions. A three‐electrode one‐compartment sono‐cell was used with a working platinum disc electrode. The sono‐electrochemically formed polymer films were deposited with different working electrode‐to‐horn distances. The composition, electrochemical, spectroscopic, and morphological characteristics of the resulting polymer films were determined. Elemental analysis, FTIR‐spectra, and X‐ray photoelectron spectroscopy (XPS) data proved that the polymer films prepared under SEP conditions have predominant α‐α′‐couplings between the 3MT units, and the aromatic ring integrity is maintained in the film. Scanning electron microscopy showed that those films are more compact and less porous compared to the films prepared under silent conditions. The use of sono‐irradiation during electropolymerization enhanced the diffusion of the monomer units towards the electrode surface and resulted in relatively less doped polymers with less conductivity. Electrochemical impedance spectroscopy (EIS) data for films prepared under silent and SEP conditions were collected in a monomer‐free solution. The results show that the impedance of SEP films is relatively higher than those prepared under silent conditions, and a combination of charge transfer kinetics with diffusion‐controlled conduction mechanism within the films. The diffusion was found to be a function of the porosity of the film. Conductivity measurements are in good agreement with EIS, elemental analysis, and XPS data. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2416–2425, 2006
Soybean and castor oil based monomers: Synthesis and copolymerization with styrene
Authors: Can E. , Wool R. P. , Küsefoğlu S.
Published: August 2006

In this study, castor oil was alcoholyzed with both aliphatic alcohols, such as glycerol and pentaerythritol, and an aromatic alcohol, bisphenol A propoxylate. The resulting alcoholysis products were then malinated and cured in the presence of styrene. Soybean oil pentaerythritol glyceride maleates were also prepared for a direct comparison of the properties of the castor oil and soybean oil based resins. Castor oil was directly malinated as well to see the effect of the alcoholysis step on the properties of the castor oil based resins. The monomers synthesized were characterized by 1H‐NMR spectroscopy, and the styrenated resin liquid properties, such as viscosity and surface energy values, were determined. The conversion of polymerization was determined using time resolved FTIR analysis for the styrenated soybean oil pentaerythritol glyceride maleates, castor oil maleates, and castor oil pentaerythritol glyceride maleates. The effect of monomer identity and styrene content on the conversion of polymerization was explored. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2433–2447, 2006
Moisture diffusion properties of HFPE‐II‐52 polyimide
Authors: Bhargava Peeyush , Chuang Kathy C. , Chen Kenway , Zehnder Alan
Published: August 2006

Moisture diffusion properties of the polyimide HFPE‐II‐52 were determined using weight gain, weight loss, and swelling experiments over a temperature range of 25–200°C. Below 100°C, diffusivity was measured using standard weight loss and weight gain methods. Above 100°C, diffusivity is found by weight loss experiments performed by placing moisture saturated samples in an oven and recording weight loss dynamically. The diffusivity of the polyimide was found to obey the Arrhenius relation over the entire range of temperature. Weight gain experiments were performed to determine the equilibrium level of moisture absorbed by the polyimide as a function of relative humidity. Swelling experiments were performed to measure swelling strain as a function of moisture absorption. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3471‐3479, 2006
Development of dispersed phase size and its dependence on processing parameters
Authors: Chen Xi , Xu Jun , Guo Bao‐Hua
Published: August 2006

Through measurement of phase dimension via laser scattering, phase morphology development in immiscible blends of polyamide 12/poly(ethylene glycol) (PEG) with an extremely high viscosity ratio was investigated. The blends were prepared by melt blending in a batch mixer. The objective was to examine the influence of mixing time, rotor speed, as well as blending temperature on the size distribution of the minor phase. It is of interest that the breakup process of the dispersed PA 12 phase was observed for the blend systems even for extremely high viscosity ratios of ≤ 102–103. Mixing time had a significant effect on the development of dispersed phase size distribution. It was found that the bulk of particle size reduction took place very early in the mixing process, and very small droplets with a diameter of 0.1–10 μm were produced. The number of small particles then decreased, resulting in a larger average particle size. With further prolonged mixing, the particle size levels off. The particle size and its distribution were also found to be sensitive to the rotor speed. The average particle size decreased with increased rotor speed. The effect of blending temperature on size and size distribution, which has seldom been studied, was also examined in this work. When the blending temperature altered from 190°C to 220°C, the size and its distribution of the dispersed phase varied considerably, and the change of viscosity ratio was found to be the key factor affecting the dispersed phase size. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3201–3211, 2006
Free‐volume hole properties of two kinds thermoplastic nanocomposites based on polymer blends probed by positron annihilation lifetime spectroscopy
Authors: Fang Zhengping , Xu Yuzhen , Tong Lifang
Published: August 2006

Two type of nanocomposites—an immiscible blend, high density polyethylene/polyamide 6 (HDPE/PA‐6) with organomodified clay, and a compatibilized blend, high density polyethylene grafted with acrylic acid/PA‐6 (PEAA/PA‐6) with organomodified clay—were prepared via melt compounding. X‐ray diffraction and transmission electron microscopy results revealed that the clay was intercalated and partially exfoliated. Positron annihilation lifetime spectroscopy has been utilized to investigate the free‐volume hole properties of two type of nanocomposites. The results show a negative deviation of free‐volume size in PEAA/PA‐6 blend, and a positive deviation in HDPE/PA‐6 blend, and I3 has a greater negative deviation in compatibilized blend than in immiscible blend due to interaction between dissimilar chains. For nanocomposites based on polymer blends, in immiscible HDPE/PA‐6/organomodified clay system, the variation of free‐volume size with clay content is not obvious and the free‐volume concentration and fraction decreased. While in the case of compatibilized PEAA/PA‐6/organomodified clay nanocomposites, complicated variation of free‐volume properties due to interactions between two phases and organomodified clay was observed. And the interaction parameter β shows the interactions between polymers and organomodified clay. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2463–2469, 2006
Poly(dimethylaminoethylmethacryloylpropanesulfonate)‐suitable polymer additive for pulsed electrodeposition of nanocrystalline nickel
Authors: Georgiev George , Kamenova Irena , Georgieva Ventsislava , Kamenska Elena , Hempelmann Rolf , Natter Harald
Published: August 2006

Nano‐nickel (n‐Ni) is deposited by a pulsed electrodeposition (PED) in the presence of nonionogenic (poly(ethylene glycol), poly(N‐vinylpyrrolidone), starch), anionogenic (gum arabic, sodium alginate), cationic (quaternized guar gum), and polyampholytic (polyzwitterionic) poly(dimethylaminoethylmethacryloylpropanesulfonate) (PDMAEMPS) polymers. It is established that, by PED (40 mA/cm2, ton = 1 ms, toff = 50 ms, 323 K), the size of the nanocrystalline particles produced in the presence of PDMAEMPS is far less (by a factor of 6–10) than those obtained in the presence of other polymer additives. These comparative results emphasize a new possibility of controlling the nanograin size of the electrodeposited metals by PED. The dramatic difference in the size of the nickel particles and the unique ability of the polyzwitterionic (PZI) additives are connected by the specific for the polyzwitterionic macromolecular conformation response to the pulsatile electric potential. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2967–2971, 2006
Structure and characterization for conterminously linked polymer of short‐chain epoxy resin with triallyl isocyanurate and bismaleimide
Authors: Leu Tsu‐Shang
Published: August 2006

The short‐chain epoxy resin (SCER) was prepared direct from epichlorohydrin/bisphenol A (ECH/BPA). The resulted SCER and 4,4′‐diaminodiphenyl sulfone (DDS) with various weight percent of triallyl isocyanurate/4,4′‐bismaleimidophenylmethane (TAIC/BMI) were subsequently thermally coreacted to the corresponding high performance materials for high frequency application. They were characterized using potentiometry, Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), thermogravimetric analyses (TGA), dielectric analyzer, and scanning electron microscope (SEM). Dynamic mechanical analysis (DMA) of polymers showed only a Tg indicating a low entropy, amorphous state and formed a conterminously linked polymer. The morphology of polymers revealed no phase separation. The formation of polymer was in good agreement with the proposed molecular structure, and has enhanced good thermal, mechanical, and electric properties. Furthermore, with lower nitrogen content was achieved UL‐94 V‐0 rating. No fume and toxic gas emission were observed during burning test for this system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2470–2480, 2006
Nanocomposites from fluoro‐oxygenated polyethylene: A novel route to organoclay exfoliation
Authors: Shah Rhutesh K. , Cui Lili , Williams Kelly L. , Bauman Bernard , Paul D. R.
Published: August 2006

We present a novel approach to improving organoclay exfoliation in a nonpolar matrix, polyethylene. High‐density polyethylene (HDPE) particles were modified by exposure to a reactive gas atmosphere containing F2 and O2. This treatment was aimed at increasing the polarity of the polymer with the formation of carboxyl, hydroxy, and ketone functionalities on the particle surface. The surface‐treated high‐density polyethylene (ST‐HDPE) particles were then melt‐mixed with an appropriate organoclay to form nanocomposites. Transmission electron microscopy (TEM), wide‐angle X‐ray scattering, stress–strain analysis, and Izod impact measurements were used to evaluate the nanocomposite morphology and physical properties. These data were compared to those of equivalent nanocomposites prepared from unmodified HDPE and high‐density polyethylene grafted with maleic anhydride (HDPE‐g‐MA). The nanocomposites prepared from the ST‐HDPE particles exhibited much better properties and organoclay dispersion than those prepared from unmodified HDPE. The level of reinforcement observed in ST‐HDPE‐based nanocomposites was comparable to, if not better than, that seen in HDPE‐g‐MA‐based nanocomposites. However, a comparison of the TEM micrographs suggested better organoclay exfoliation in HDPE‐g‐MA than the current version of ST‐HDPE. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2980–2989, 2006
Influence of copolymerization conditions on the structure and properties of polyethylene/polypropylene/poly(ethylene‐co‐propylene) in‐reactor alloys synthesized in gas‐phase with spherical ziegler‐natta catalyst
Authors: Fan Zhiqiang , Deng Jian , Zuo Yan‐Mei , Fu Zhi‐Sheng
Published: August 2006

A spherical TiCl4/MgCl2‐based catalyst was used in the synthesis of polyethylene/polypropylene/poly (ethylene‐co‐propylene) in‐reactor alloys by sequential homopolymerization of ethylene, homopolymerization of propylene, and copolymerization of ethylene and propylene in gas‐phase. Different conditions in the third stage, such as the pressure of ethylene–propylene mixture and the feed ratio of ethylene, were investigated, and their influences on the compositions, structural distribution and properties of the in‐reactor alloys were studied. Increasing the feed ratio of ethylene is favorable for forming random ethylene–propylene copolymer and segmented ethylene–propylene copolymer, however, slightly influences the formation of ethylene‐b‐propylene block copolymer and homopolyethylene. Raising the pressure of ethylene–propylene mixture results in the increment of segmented ethylene–propylene copolymer, ethylene‐b‐propylene block copolymer, and PE fractions, but exerts a slight influence on both the random copolymer and PP fractions. The impact strength of PE/PP/EPR in‐reactor alloys can be markedly improved by increasing the feed ratio of ethylene in the ethylene–propylene mixture or increasing the pressure of ethylene–propylene mixture. However, the flexural modulus decreases as the feed ratio of ethylene in the ethylene–propylene mixture or the pressure of ethylene–propylene mixture increases. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2481–2487, 2006
Swift heavy ion irradiated polymeric membranes for gas permeation
Authors: Kulshrestha V. , Awasthi K. , Acharya N. K. , Singh M. , Avasthi D. K. , Vijay Y. K.
Published: August 2006

Polycarbonate membranes of thickness 18 μm were irradiated by Ni7+ ion of 100 MeV at fluences 106–108 ions/cm2. The permeability for hydrogen and carbon dioxide has been measured from the membrane with increasing etching time. Permeability of both the gases increases with etching time, but for hydrogen the permeability was higher than for carbon dioxide for all membranes. The selectivity of hydrogen increases as ion fluence of membrane increases, for 108 ions/cm2 membrane was higher than the lower fluence membranes. The irradiated membranes were also etched by monitoring the current, which shows change in the etching time for membrane of different doses. Ion permeation measurements show that pores in polymeric membrane are charged or neutralized, which depends upon the variation in concentration of the solvent. The etched tracks of membranes were characterized by the scanning electron microscopy. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:2386–2390, 2006
Novel heat resistant methyl‐tri(phenylethynyl)silane resin: Synthesis, characterization and thermal properties
Authors: Zhou Quan , Feng Xia , Ni Lizhong , Chen Jianding
Published: August 2006

Methyl‐tri(phenylethynyl)silane (MTPES) was successfully synthesized by the reaction of lithium phenylacetylide with methyltrichlorosilane. The structure was characterized by HRMS, FTIR, 1H‐NMR, 13C‐NMR, 29Si‐NMR, and elementary analysis. Thermal cure process was monitored by DSC, DMA, and FTIR. MTPES was heated to free flowing liquid around 130°C and thermally polymerized at 327–377°C to form thermoset. Thermal and oxidative properties were evaluated by TGA analysis. Thermoset exhibits extremely high heat‐resistance and TGA curve in nitrogen shows the temperature of 5% weight loss (Td5) of 695°C and total weight loss at 800°C of 7.1%. TGA shows a high Td5 of 565°C even in air, although the total weight loss at 800°C was 56.1% of the initial weight, much higher than that in nitrogen. The high heat resistance of MTPES was ascribed to crosslinking reaction concerning ethynyl groups. Aging studies performed at elevated temperatures in air on a thermoset showed that MTPES is oxidatively stable to 300°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2488–2492, 2006
Crystallization kinetics for simulation of processing of various polyesters
Authors: Kim Kyuk Hyun , Isayev Avraam I. , Kwon Keehae
Published: August 2006

The approach to determine crystallization kinetic parameters based on the DSC nonisothermal crystallization experiments is applied to poly(butylene terephthalate) (PBT) and poly(ethylene‐2,6‐naphthalate) (PEN). The differential form of the Nakamura equation and master curve approach are used. The isothermal induction times are obtained from nonisothermal induction times according to the concept of induction time index. The correction of temperature lag between the DSC furnace and the sample is incorporated. The corrected nonisothermal crystallization kinetic data is shifted with respect to an arbitrarily chosen reference temperature to obtain the master curve. By fitting the obtained master curve with the Hoffman‐Lauritzen equation, the model parameters for the crystallization rate constant are obtained. The relative crystallinity measured at different cooling and heating rates is described by these model parameters. © 2006 Wiley Periodicals, Inc. J Appl PolymSci 102: 2847–2855, 2006
Effect of ultrasonic oscillations on weld line strength of PS, PMMA, and their blends
Authors: Yu Xiaofeng , Lu Chang , Wu Hong , Guo Shaoyun
Published: August 2006

The effect of ultrasonic oscillations on the weld line strength of amorphous polystyrene (PS), polymethyl methacrylate (PMMA), and PS/PMMA (20/80, 50/50, 80/20) blends at various temperatures was investigated. By facilitating the molecular diffusion across the weld line, the introduction of ultrasonic oscillations could evidently improve the weld line strength of PS, PMMA, and their blends. The different effects on the weld line strength of PS/PMMA (20/80, 50/50, 80/20) blends were investigated. The ultrasonic oscillations could greatly increase the weld line strength of PS/PMMA (80/20) by ∼ 70%, but was less efficient to PS/PMMA (50/50, 20/80) blends, due to the great difference of weld line morphologies of these blends. The dispersed phase of PS/PMMA (80/20) in the weld line was spherical while two different morphologies in the weld line of PS/PMMA (50/50) were observed. And the stripe‐like morphology of PS perpendicular to the flow direction in the weld line of PS/PMMA (20/80) is responsible for the little effect of ultrasonic oscillations. The fractured surfaces of PS, PMMA, and PS/PMMA (80/20) with weld line became much rougher due to the introduction of ultrasonic oscillations. The morphology study of PS/PMMA (80/20) showed that the spherical dispersed phase of PS/PMMA at the skin turned smaller under ultrasonic oscillations. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2990–2997, 2006
Incorporation of metallic POSS, POSS copolymers, and new functionalized POSS compounds into commercial dental resins
Authors: Wheeler Paul A. , Fu Bruce X. , Lichtenhan Joseph D. , Weitao Jia , Mathias Lon J.
Published: August 2006

An array of polyhedral oligomeric silsesquioxane (POSS) compounds, including metal, methacrylate, and amine functional POSS, and POSS copolymers were incorporated into aromatic and aliphatic dental resins. Heptaphenyl‐propylamine POSS and methacrylate derivatives were synthesized by corner‐capping and Michael addition reactions, respectively. The POSS compounds were tested for solubility in commercial resins at concentrations of 1, 5, 10, and 15 wt %, followed by UV polymerization of all soluble combinations. The POSS compounds generally increased modulus and had an unpredictable effect on Tg. The modulus of the aliphatic resin increased 83% by incorporation of 15 wt % aluminum‐phenyl POSS, while aromatic resins saw a maximum modulus improvement of 18% at 30°C and 72% at 160°C by incorporating 1 wt % of heptaphenyl‐methacrylate POSS. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2856–2862, 2006
Efficient light emitting diodes from ternary blends of PPV‐based copolymers
Authors: Cirpan Ali , Aroguz Z. Ayse , Karasz Frank E.
Published: August 2006

Light emitting diodes (LEDs) were prepared using ternary blends of block copolymers emitting in the blue (I and II) and green (III) regime. These blends were studied in terms of their absorbance, photoluminescence (PL), and electroluminescence (EL) spectra. The PL spectra in dilute solution and in the solid state were compared. Förster energy transfer from I and II to III was studied in the solid state. The EL device made using a ternary blend with the ratio (1 : 1 : 1) showed the highest EL quantum efficiency. Differential scanning calorimetry (DSC) measurements have been made to investigate the phase separation in these copolymer blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2509–2511, 2006
Blends containing amphiphilic polymers. V. Compatibilization of N‐alkylitaconamic acid‐co‐styrene copolymers with interacting polymers
Authors: Urzúa Marcela , Sandoval Claudia , González‐Nilo Fernando , Leiva Angel , Gargallo Ligia , Radić Deodato
Published: August 2006

The phase behavior of blends containing N‐alkylitaconamic acid‐co‐styrene copolymers (NAIA‐co‐S) with poly(N‐vinyl‐2‐pyrrolidone) (PVP) of two different weight average molecular weights (Mw), poly(2‐vinylpyridine) (P2VPy) and poly(4‐vinylpyridine) (P4VPy), was analyzed by differential scanning calorimetry and Fourier transform infrared spectroscopy. Copolymers containing 80% S are miscible with PVP10, PVP24, and P4VPy over the whole range of composition. In the case of blends with P2VPy, miscibility is observed only for the first three members of the series, i.e., NEIA‐co‐S, NPIA‐co‐S, and NBIA‐co‐S. For copolymers containing hexyl to dodecyl moieties, phase separation is observed in blends with P2VPy. Copolymers containing 50% S are miscible over the whole range of composition irrespective of the homopolymer and the length of the side chain of the itaconamic moiety of the copolymer. This behavior is interpreted in terms of steric hindrance, in the sense that the copolymers with long side chains are not able to interact with the nitrogen of P2VPy because of the position in the aromatic ring. The interactions between copolymers and homopolymers are discussed in terms of specific interactions like hydrogen bonds between the itaconamic moiety and the different functional groups of the homopolymers, together with the hydrophobic interaction, which cannot be disregarded. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2512–2519, 2006
Effect of composite preparation techniques on electrical and mechanical properties and morphology of nylon 6 based conductive polymer composites
Authors: Koysuren Ozcan , Yesil Sertan , Bayram Goknur
Published: August 2006

Nylon 6/carbon black conductive composites were prepared using two different methods, masterbatch dilution and melt mixing. Their effect on the size and distribution of carbon black agglomerates in the matrix was studied in terms of electrical and mechanical properties and morphology. The electrical resistivity of composites prepared by both methods decreased with increasing filler composition. The electrical resistivity of the diluted masterbatch composites and the melt mixed composites was reduced from the resistivity of pure nylon 6, 1015 “ohm, cm”, to 107 “ohm, cm” at 1 and 6 wt % of carbon black, respectively. As the filler content increased, elongation at break and impact strength decreased, but tensile modulus increased. Masterbatch dilution method provided smaller carbon black clusters in composites compared to melt mixing method. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2520–2526, 2006
Dependence of solids conveying on screw axial vibration in single screw extruders
Authors: Jinping Qu , Baoshan Shi , Yanhong Feng , Hezhi He
Published: August 2006

In the single‐screw extruder, the vibration force field is applied to the solids conveying process by the axial vibration of the screw and the novel concept on the solids conveying process being strengthened with the vibration force field has been brought forward in this study. We establish the mathematical model that describes the solids conveying process with the vibration force field and obtain the approximative analytical solutions of the pressure and velocity of the solids conveying in the down‐channel. In the new theory, if the screw has no axial vibration the solids conveying pressure is the same as that of the Darnell and Mol theory, but the density and velocity of solids conveying along the screw channel is variable, which has modified the Darnell and Mol theory in which the density and velocity of the solids conveying along the screw channel was considered invariable. The results reveal that the axial vibration of the screw can increase the average pressure of solids conveying, decrease the channel length of the solids conveying section and increase the solids conveying angle. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2998–3007, 2006
Highly wettable polyethylene films generated by spontaneous surface enrichment of perfluoroalkylated phosphorylcholines
Authors: Iwasaki Yasuhiko , Akiyoshi Kazunari
Published: August 2006

We report here a new feature for highly wettable polyethylene films prepared by spontaneous surface enrichment of perfluoroalkylated phosphorylcholine (PC) additives via a simple heat‐press technique. Perfluoroalkylated PCs were newly synthesized from monohydroxyethyl ether compounds with hexafluoromethylene (C6F13PC), octafluoromethylene (C8F17PC), and decafluoromethylene (C10F21PC) chains. Hexadecyl phosphorylcholine (C16PC) was synthesized as a control. These PC additives were mixed well with low‐density polyethylene (LDPE) microparticles (ϕ = 6 μm), placed between stainless plates, and pressed at 120°C. Perfluoroalkylated PCs effectively improved the surface wettability of the composite film compared with that of the alkylated PC. C8F17PC is extremely surface active in the LDPE matrix and occupies ∼ 95% of the outermost ∼ 10 Å. The water contact angle data for the LDPE film was decreased from 94°/81° (θA/θR) to 28°/8° by the addition of an approximately low concentration of C8F17PC (3.3% w/w) because of spontaneous enrichment on the surface. When the elongation to break value of the films was slightly reduced with the PC additives, Young's modulus and the tensile strength of the composite films were similar to those of pure LDPE film. In conclusion, fluoroalkylated PCs have good potential as additives to improve the wettablility of thermoplastic polymers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2868–2874, 2006
Influence of fiber wettability on the interfacial adhesion of continuous fiber‐reinforced PPESK composite
Authors: Chen Ping , Lu Chun , Yu Qi , Gao Yu , Li Jianfeng , Li Xinglin
Published: August 2006

Interfacial adhesion between fiber and matrix has a strong influence on composite mechanical performance: better interfacial adhesion can enhance composite transverse properties, flexural properties, and interlaminar shear strength, and so on. To exploit the reinforcement potential of the fibers in advanced composite, it is necessary to reach a deeper understanding on the relation between fiber wettability and interfacial adhesion. In our experiment, we study the influence of fiber wettability on interfacial properties of fiber/PPESK composites by choosing three kinds of fibers with different wettabilities. The relation between fiber wettability and surface free energy was discussed, and the influence of fiber wettability on the interfacial property of fiber/PPESK composites was analyzed. Results indicate that higher surface free energy can enhance the wettability between fiber and matrix, and the humid resistance and interfacial adhesion can be improved at the same time. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2544–2551, 2006
Synthesis and characterization of biodegradable and charged salen‐based polymers
Authors: Nadeau Véronique , Rabanel Jean‐Michel , Sant Shilpa , Chahwan Roula , Clas Sophie‐Dorothée , Hildgen Patrice
Published: August 2006

The goal of this study was to synthesize novel biodegradable charged polymers for medical applications. The polymers synthesized were metal‐coordinated salicylidene‐based copolymers. The linear copolymers were prepared by polycondensation of the metal‐coordinated salicylidene monomer with acyl or aryl dichloride. Structure analysis was carried out by 1H and 13C NMR, FTIR, and elemental analysis. Physicochemical evaluation was carried out using DSC and thermogravimetry. The surface properties were analyzed by contact angle measurements and the crystallinity was determined by polarizing microscopy and AFM. Finally, polymer electrical conductivity and biocompatibility were examined. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2568–2577, 2006
Aggregate formation in poly(ethylene oxide) solutions
Authors: Khan Mohammad Saleem
Published: August 2006

Static light scattering and viscosity measurements were performed on different molecular weight poly (ethylene oxide) to see the formation of aggregates in its dilute solutions. Viscosity measurements were carried out for PEO samples in water and methanol at 20–45°C and in chloroform at 20–30°C. Using Huggin's equation, the viscosity plots showed distinct upward curvature indicating the presence of aggregates in both PEO/H2O and PEO/CH3OH solutions The [η] values for PEO/H2O and PEO/CH3OH system were 2–4 times as large as observed for other linear flexible polymers in good solvents thus showing extensive coil swelling/aggregation. This is also apparent from the exponent a values of the Mark–Houwink–Sakurada equation. Light Scattering results using Zimm method showed that aggregation occurred in low molecular weight samples; however, in higher molecular weight samples there was a little evidence for aggregation both in water and methanol. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2578–2583, 2006
Isotactic polypropylene hollow microfibers prepared by CO2 laser‐thinning
Authors: Suzuki Akihiro , Ohnishi Hiroshi
Published: August 2006

An isotactic polypropylene hollow microfiber was continuously produced by using a carbon dioxide (CO2) laser‐thinning method. To prepare the hollow microfiber continuously, the apparatus used for the thinning of the solid fiber was improved so that the laser can circularly irradiate to the hollow fiber. Original hollow fiber with an outside diameter (OD) of 450 μm and an internal diameter (ID) of 250 μm was spun by using a melt spinning machine with a specially designed spinneret to produce the hollow fiber. An as‐spun hollow fiber was laser‐heated under various conditions, and the OD and the ID decreased with increasing the winding speed. For example, when the hollow microfiber obtained by irradiating the CO2 laser to the original hollow fiber supplied at 0.30 m min−1 was wound up at 800 m min−1, the obtained hollow microfiber had an OD of 6.3 μm and an ID of 2.2 μm. The draw ratio calculated from the supplying and the winding speeds was 2667‐fold. The hollow microfibers obtained under various conditions had the hollowness in the range of 20–30%. The wide‐angle X‐ray diffraction patterns of the hollow microfibers showed the existence of the highly oriented crystallites. Further, the OD and ID decreased, and the hollowness increased by drawing hollow microfiber obtained with the laser‐thinning. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2600–2607, 2006
Ultraviolet preirradiation of high‐density polyethylene for the grafting of maleic anhydride during reactive extrusion
Authors: Martinez J. G. , Benavides R. , Guerrero C.
Published: August 2006

High‐density polyethylene was irradiated with ultraviolet light for various exposure times, as a prestep for hydroperoxide production, before a bulk grafting reaction with maleic anhydride in the melt phase by reactive extrusion. This method was compared with a traditional grafting procedure using peroxides optimized by an evaluation of the grafting level versus the screw speed; the highest speed showed the greatest grafting value. The reaction was followed by Fourier transform infrared, the gel percentage, and the grafting degree, which was evaluated by titration. The effect of grafting for both methods under the established processing conditions on the thermal properties was observed with differential scanning calorimetry via their heating and cooling thermograms; there were notorious changes in the fusion peak temperatures, indicating differences in the crystallization process after the grafting reaction. The latter was confirmed by NMR spectroscopy, which showed succinic anhydride rings attached to the polyethylene chains. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2882–2888, 2006
Synthesis and characterization of in situ polymerized segmented thermoplastic elastomeric polyurethane/layered silicate clay nanocomposites
Authors: Choi Mi Young , Anandhan S. , Youk Ji Ho , Baik Du Hyun , Seo Seung Won , Lee Han Sup
Published: August 2006

Nanocomposites based on thermoplastic elastomeric polyurethane (TPU) and layered silicate clay were prepared by in situ synthesis. The properties of nanocomposites of TPU with unmodified clay were compared with that of organically modified clay. The nanocomposites of the TPU and organomodified clay showed better dispersion and exhibited superior properties. Exfoliation of the clay layers was observed at low organoclay contents, whereas an intercalated morphology was observed at higher clay contents. As one of major purposes of this study, the effect of the silicate layers in the nanocomposites on the order–disorder transition temperature (TODT) of the TPU was evaluated from the intensity change of the hydrogen‐bonded and free carbonyl stretching peaks and from the peak position change of the NH bending peak. The presence of the organoclay increased TODT by approximately 10°C, which indicated improved stability in the phase‐separated domain structure. The layered silicate clay caused a tremendous improvement in the stiffness of the TPU; meanwhile, a reduction in the ultimate elongation was observed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3048–3055, 2006
Blending and characterizations of microbial poly(3‐hydroxybutyrate) with dendrimers
Authors: Xu Songling , Luo Rongcong , Wu Linping , Xu Kaitian , Chen Guo‐Qiang
Published: August 2006

Blending of microbial polyester poly(3‐hydroxybutyrate) (PHB) with various dendritic polyester oligomers or dendrimers was achieved by solution casting to improve the film forming ability of PHB. Films of the blends were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron micrograph (SEM), and Fourier transform infrared spectroscopy (FTIR). It was revealed that there were mainly two types of interactions in the blending system: the plasticizing or lubricating effect of the low melting spherical dendrimers molecules improved the polymer chain mobility through the suppression of PHB crystallization in the blends; The dendrimers also functioned as crosslinking agents or antiplasticizing agents via weak hydrogen bonding to enhance the overall intermolecular interactions which decrease the chain mobility and thus cause the increase of glass transition temperature (Tg) of PHB. TGA results concluded that incorporating the dendrimers could retard the thermal decomposition of PHB and enhanced its thermal stability accordingly. With the above blend processes, the so‐obtained PHB possessed better film forming ability and even patterned surface structures. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3782–3790, 2006
Mechanical and dielectric relaxation phenomena of poly(ethylene‐2,6‐napthalene dicarboxylate) by fractional calculus approach
Authors: Reyes‐Melo M. E. , Martínez‐Vega J. J. , Guerrero‐Salazar C. A. , Ortiz‐Méndez U.
Published: August 2006

The mechanical and dielectric relaxation phenomena in PEN‐films have been studied using fractional models. A mechanical fractional model for the description of dynamic modulus, E* = E′ + iE″, and a dielectric fractional model for the dynamic relative permittivity, ε = ε − iε. These models takes into account three relaxation phenomena and the corresponding differential equations have derivatives of fractional order between 0 and 1. In applying the Fourier transform to fractional differential equations and in considering that each relaxation mode is associated to cooperative or noncooperative molecular movements, we calculated E*(iω,T) and ε(iω,T). The isochronal diagrams of the real and imaginary parts of either E* and ϵ obtained from fractional models have been used to study the three relaxation phenomena (α, β*, and β) of poly(ethylene‐2,6‐napthalene dicarboxylate). An agreement between experiments and fractional models has been achieved for both mechanical and dielectric relaxation phenomena, and the effect of morphology samples on the fractional order parameters of the Fractional Models are related to molecular motions associated to α, β*, and β relaxations. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3354–3368, 2006
New anion exchanger organic–inorganic hybrid materials and membranes from a copolymerof glycidylmethacrylate and γ‐methacryloxypropyl trimethoxy silane
Authors: Wu Yonghui , Wu Cuiming , Gong Ming , Xu Tongwen
Published: August 2006

Organic–inorganic hybrid materials and mem branes were prepared through coating on Teflon plate or dip‐coating on microporous alumina substrates with the solution of glycidylmethacrylate (GMA) and γ‐methacryloxypropyl trimethoxy silane (γ‐MPS) copolymer, followed by ring‐opening of the GMA moiety with trimethylamine hydrochloric and sol–gel reaction of the γ‐MPS moiety. Composition of the GMA and γ‐MPS copolymer was varied by changing the feed ratio of GMA to γ‐MPS during the copolymerization. So the thermal stability, hydrophilicity, electrical properties, etc. of the hybrid materials and membranes were varied. Results showed that as the γ‐MPS amount increased in the copolymer, Td (the temperature on thermogram at 5% weight loss) value of the hybrid materials and water contact angle of the hybrid membrane generally increased, while the anion exchange capacity, water uptake (WR) and pure water flux decreased. The charge transition point of the hybrid membranes deduced from their streaming potential behavior decreased from pH > 12 to pH = 7–8 as the γ‐MPS amount increased. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3580–3589, 2006
Optimal combinational quota‐share and excess‐of‐loss reinsurance policies in a dynamic setting
Authors: Zhang Xin , Zhou Ming , Guo Junyi
Published: August 2006

In this paper, we describe a large insurance company's surplus by a Brownian motion with positive drift, which is the approximation of a classical risk process. The problem of minimizing the probability of ruin by controlling the combinational quota‐share and excess‐of‐loss reinsurance strategy is considered. We show that the optimal combinational reinsurance strategy must be the pure excess‐of‐loss reinsurance strategy. Moreover, we give an explicit solution for the optimal reinsurance strategy. Copyright © 2006 John Wiley & Sons, Ltd.
20S proteasomes and protein degradation “by default”
Authors: Asher Gad , Reuven Nina , Shaul Yosef
Published: August 2006

The degradation of the majority of cellular proteins is mediated by the proteasomes. Ubiquitin‐dependent proteasomal protein degradation is executed by a number of enzymes that interact to modify the substrates prior to their engagement with the 26S proteasomes. Alternatively, certain proteins are inherently unstable and undergo “default” degradation by the 20S proteasomes. Puzzlingly, proteins are by large subjected to both degradation pathways. Proteins with unstructured regions have been found to be substrates of the 20S proteasomes in vitro and, therefore, unstructured regions may serve as signals for protein degradation “by default” in the cell. The literature is loaded with examples where engagement of a protein into larger complexes increases protein stability, possibly by escaping degradation “by default”. Our model suggests that formation of protein complexes masks the unstructured regions, making them inaccessible to the 20S proteasomes. This model not only provides molecular explanations for a recent theoretical “cooperative stability” principle, but also provokes new predictions and explanations in the field of protein regulation and functionality. BioEssays 28: 844–849, 2006. © 2006 Wiley Periodicals, Inc.
Shugoshin and PP2A, shared duties at the centromere
Authors: Rivera Teresa , Losada Ana
Published: August 2006

Sister chromatid cohesion mediated by the ring‐shaped cohesin complex is essential for faithful chromosome segregation. A tight spatial and temporal control of cohesin release is observed in mitosis and meiosis, and a family of proteins known as shugoshins play a major role in this process. Shugoshin (Sgo) protects centromeric cohesin from dissociation in early mitosis and from cleavage by separase in meiosis I. Three exciting new reports indicate that this is accomplished by recruiting the serine/threonine protein phosphatase 2A (PP2A) to centromeres.(1–3) The proposed targets of PP2A activity include cohesin and Sgo, both of which would otherwise dissociate from chromosomes upon phosphorylation by Polo kinase. Thus, a balance of kinase and phosphatase activities seems to be the key to the conserved mechanism that regulates the stepwise release of cohesin from mitotic and meiotic chromosomes. Additional evidence, however, suggests that this is only part of the story, and that Sgo has also a role independent of PP2A. BioEssays 28: 775–779, 2006. © 2006 Wiley Periodicals, Inc.