bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biodegradable shape‐memory polymer—polylactide‐co‐poly(glycolide‐co‐caprolactone) multiblock copolymer
Authors: Min Changchun , Cui Wenjin , Bei Jianzhong , Wang Shenguo 
Published: June 2005

AbstractIn this study, biodegradable shape‐memory polymers—polylactide‐co‐poly(glycolide‐co‐caprolactone) multiblock (PLAGC) copolymers—were synthesized by the coupling reaction of both macrodiols of polylactide (PLLA‐diol) and poly(glycolide‐co‐caprolactone) (PGC‐diol) in the presence of 1,6‐hexanediisocyanate as coupling agent. The copolymers formed were found to be thermoplastic and easily soluble in common solvents. The compositions of the copolymers were determined by 1H‐NMR and the influences of segment lengths and contents of both macrodiols on the properties of the PLAGC copolymers were investigated. It was found that the copolymers had adjustable mechanical properties which depended on contents and segment lengths of both macrodiols. The copolymers showed such good shape‐memory properties that the strain fixity rate (Rf) and the strain recovery rate (Rr) exceed 90%. By means of adjusting the compositions of the copolymers, PLAGC copolymers with transition temperatures around 45°C could be obtained. The degradation rate determination showed that the PLAGC copolymers have fast degradation rates, the mechanical strengths of the PLAGC copolymers would be completely lost within 1–2 months depending on molecular weights and contents of the both segments of PLLA and PGC. Copyright © 2005 John Wiley & Sons, Ltd.
The preparation of nano‐scope chitosan‐oligomer copper complexes and their interaction with DNA
Authors: Wang Rong‐Min , He Nai‐Pu , He Yu‐Feng , Xie Yun‐Tao , Wang Yun‐Pu , Tsuchida Eishun 
Published: June 2005

AbstractWater‐soluble low molecular weight chitosan of nanometer level and its copper complexes were prepared, and characterized by IR spectra, elemental analysis and gel permeation chromatography (GPC). The modes and mechanism of these copper complexes interaction with DNA were studied by a fluorescent probe method and electrophoresis analysis. It is suggested that there are electrostatic and intercalation modes of copper complexes interacting with DNA. At first, the cationic complex electrostaticly binds to the negatively charged phosphate backbone of DNA, and then a portion of the complex intercalates between the base pairs on the DNA duplex strand. Copyright © 2005 John Wiley & Sons, Ltd.
Preparation of porous polylactide microspheres by emulsion‐solvent evaporation based on solution induced phase separation
Authors: Hong Yi , Gao Changyou , Shi Yanchao , Shen Jiacong 
Published: June 2005

AbstractPorous polylactide (PLA) microspheres were fabricated by an emulsion‐solvent evaporation method based on solution induced phase separation. Scanning electron microscopy (SEM) observations confirmed the porous structure of the microspheres with good connectivity. The pore size was in the range of decade micrometers. Besides large cavities as similarly existed on non‐porous microspheres, small pores were found on surfaces of the porous microspheres. The apparent density of the porous microspheres was much smaller than that of non‐porous microspheres. Fabrication conditions such as stirring rate, good solvent/non‐solvent ratio, PLA concentration and dispersant (polyvinyl alcohol, PVA) concentration had an important influence on both the particle size and size distribution and the pore size within the microspheres. A larger pore size was achieved at a slower stirring rate, lower good solvent/non‐solvent ratio or lower PLA concentration due to longer coalescence time. Copyright © 2005 John Wiley & Sons, Ltd.
The preparation and characterization of silver‐loading cellulose acetate hollow fiber membrane for water treatment
Authors: Chou Wen‐Li , Yu Da‐Guang , Yang Ming‐Chien 
Published: June 2005

AbstractSilver‐loading asymmetric cellulose acetate (CA) hollow fiber membrane was spun via the dry jet‐wet spinning technique. The spinning solution was prepared by dissolving AgNO3 and CA in N,N‐dimethylformamide (DMF). The silver ions were reduced in the spinning dope into silver nano‐particles. The morphology of the resulting hollow fibers was examined using a scanning electron microscope and the silver content in the fiber was measured using an inductively coupled plasma atomic emission spectrometer. The antibacterial activities were evaluated. These hollow fibers had a sponge‐like structure and dense inner and outer surfaces. At a 50 k magnification, the pore on the skin layer was not observable, while the nodule size was smaller than 10 nm. The residual silver content of as‐spun hollow fiber was about 60% of the original silver added in the polymer solution. After immersing in water bath for 180 days, the silver content in the bulk of the hollow fibers decreased to 60% and the silver content on the surface reduced to 10%, yet still showed antibacterial activity against Escherichia coli and Staphylococcus aureus. After permeating with water for 5 days, the silver content in the hollow fibers decreased, and did not show antibacterial activity against E. coli and S. aureus. Thus, silver content must be periodically replenished after permeation. The proper range of AgNO3 in the spinning solution for CA hollow fiber should be about 100–1000 ppm. Copyright © 2005 John Wiley & Sons, Ltd.
Solvent‐induced reversible color changes in block copolymer films and new locking method of structural colors
Authors: Ishizu Koji , Yasuda Michio , Sato Yumi , Tamura Toru 
Published: June 2005

AbstractThe well‐defined polystyrene‐block‐poly(4‐vinylpyridine) [PS‐block‐P4VP (SV1); lamellar morphology] and polyisoprene‐block‐poly(α‐methyl styrene) [PI‐block‐PMS (IMS1); PI spherical morphology] diblock copolymers were prepared by sequential anionic polymerization techniques. The segregated chains in the P4VP lamellar layers of the SV1 film (PS lamellae: 41 nm; P4VP lamellae: 51 nm) were crosslinked with 1,4‐dibromobutane. This crosslinked film was insoluble in organic solvents such as benzene and chloroform (CHCl3) and exhibited various structural colors under the swollen state. The IMS1 film (body‐centered cubic lattice, diameter of PI spheres: 53 nm) was soaked in the mixture of CHCl3/hexane (1 : 10, v/v). This solvent system resulted in the swelling of PI spherical domains. The transmitted and reflected light color through the swollen film changed to a deep blue. Such color changes were reversible upon swelling in solvent and evaporation of the solvent. Subsequently, photofunctional diethyldithiocarbamate (DC) groups were introduced into the PS block of the parent block copolymer IMS1 by means of polymer reactions. The locking of the cubic lattice was performed with living radical graft copolymerization from DC groups of swollen as‐cast film in methyl methacrylate (MMA) under UV irradiation. The locking of structural colors such as blue and green was also achieved, varying the content of poly(methyl methacrylate) (PMMA) grafted chains. Copyright © 2005 John Wiley & Sons, Ltd.
Structure and redox properties of electropolymerized film obtained from iron meso‐tetrakis(3‐thienyl)porphyrin
Authors: Yuasa Makoto , Oyaizu Kenichi , Yamaguchi Aritomo , Ishikawa Masuhide , Eguchi Katsuya , Kobayashi Tomohiro , Toyoda Yuujiro , Tsutsui Satoshi 
Published: June 2005

AbstractOxidative polymerization of bromoiron(III) meso‐tetrakis(3‐thienyl)porphyrin gave a novel polymeric porphyrin complex randomly crosslinked at the 2,5‐positions of the peripheral thienyl groups. The electrical semiconductivity of ca. 10−5 S/cm after I2 doping indicated that the polymer had a π‐conjugated structure with a moderate delocalization of π electrons over the thienylporphyrin units. PM3 calculations for free‐base models revealed that HOCO (the highest occupied crystal orbital) band width was reduced by introduction of the porphyrin moieties into the thienylene backbone and yet low HOCO‐LUCO (the lowest unoccupied crystal orbital) gap was maintained, which accounted for the relatively low electrical conductivity of the porphyrin polymer. The modified electrode prepared by electropolymerization was redox‐active due to the presence of iron(II/III) couple and the semiconductivity of the film, which served as a novel non‐enzymatic electrochemical sensor for superoxide anion radical based on the facile electrocatalytic oxidation of the superoxide. Copyright © 2005 John Wiley & Sons, Ltd.
Electrospinning of methacrylate‐based copolymers: Effects of solution concentration and applied electrical potential on morphological appearance of as‐spun fibers
Authors: Pornsopone Varaporn , Supaphol Pitt , Rangkupan Ratthapol , Tantayanon Supawan 
Published: June 2005

AbstractThree methacrylate‐based copolymers [i.e., poly(methacrylic acid‐co‐methyl methacrylate), poly(ethyl acrylate‐co‐methyl methacrylate‐co‐trimethyl‐ammonioethyl methacrylate chloride), and poly(butyl methacrylate–co‐(2‐dimethylaminoethyl) methacrylate‐co‐methyl methacrylate)] were successfully electrospun into fibers using ethanol as the solvent. For a given applied electrical potential, increasing the concentration of the spinning solutions caused the morphology of the as‐spun products to change from discrete droplets to a combination of beaded and smooth fibers and finally to completely smooth fibers. For a given spinning solution having a low concentration, increasing the applied electrical potential increased the electro‐spinnability of the spinning solution. The average diameters for all of the as‐spun fibers were found to range between about 0.2 and 5.5 μm. Generally, for a given applied potential, the average fiber diameter increased with increasing concentration of the spinning solutions, and for a given solution concentration the average fiber diameter increased with increasing applied electrical potential. POLYM. ENG. SCI., 45:1073–1080, 2005. © 2005 Society of Plastics Engineers
Sulfonated poly(ether ketone ketone) ionomers as proton exchange membranes
Authors: Swier Steven , Chun Yong Sung , Gasa Jeffrey , Shaw Montgomery T. , Weiss R.A. 
Published: June 2005

AbstractSulfonated poly(ether ketone ketone) ionomers (SPEKK) with ion‐exchange capacities (IEC) between 0.2 and 3.4 meq/g were prepared by sulfonating PEKK with a mixture of concentrated and fuming sulfuric acids. Sulfonation occurs only on the phenyl rings attached to ether and ketone groups. The glass transition temperature of the dry SPEKK ionomers increased linearly with increasing IEC, and the ionomers were thermally stable to ∼250°C, above which desulfonation occurred. Water‐swollen ionomers exhibited microphase separated morphologies, and the average correlation length determined by small angle X‐ray scattering increased with increasing IEC. The proton conductivity of hydrated SPEKK membranes measured by impedance spectroscopy ranged from ∼10–3 to 10–1 S/cm as the IEC increased from ∼1.0 to 2.4 meq/g. Single cell performance curves on membrane‐electrode assemblies (MEA) indicated that the SPEKK membranes approached the performance of Nafion™ for an IEC of 2 meq/g. POLYM. ENG. SCI., 45:1081–1091, 2005. © 2005 Society of Plastics Engineers
Rheology studies of polyethylene/chemical blowing agent solutions within an injection molding machine
Authors: Qin X. , Thompson M.R. , Hrymak A.N. , Torres A. 
Published: June 2005

AbstractAn in‐line capillary rheometer nozzle equipped to a conventional reciprocating 55‐ton injection molding machine was used to study the viscosity of single phase low density polyethylene (LDPE)/chemical blowing agent (CBA) solutions under high shear rate in the concentration range of 0 to 5 wt%. The steady shear viscosity of LDPE with endothermic and exothermic chemical blowing agents was measured for shear rates ranging from 170 to 200,000 s−1 and under pressure conditions up to 36 MPa. Pressure‐volume‐temperature (pvT) measurements were determined to account for the pressure effects and the changes of the free volume during processing. The viscosity reduction of the polymer‐CBA solution was found to be dependent on the concentration of the chemical blowing agent and melt pressure. A model based on a simplified Cross‐Carreau model, incorporating the pvT behavior of LDPE, and the free volume concept was proposed to estimate the viscosity reduction resulting from the addition of a chemical blowing agent. The model employs a scaling method based on concentration‐dependent and pressure‐dependent shift factors to collapse the viscosity measurement to a master curve at each temperature. POLYM. ENG. SCI., 45:1108–1118, 2005. © 2005 Society of Plastics Engineers
Empirical formulas for distributions of air velocity/temperature along the spinline of a dual slot die
Authors: Wang Xiaomei , Ke Qinfei 
Published: June 2005

AbstractEmpirical formulas, which describe the air velocity and air temperature decays along the spinline of a dual slot die, are improved by introducing the influence of the ratio of die end width to air slot width. The thus‐improved empirical formulas include more die geometry parameters and are more accurate than the existing ones. The fiber diameters of nonwoven web are predicted by incorporating these new empirical formulas into a one‐dimensional theoretical model for melt‐blowing process. The agreement between the predicted results and the experimental data cited from literature is very good, which confirms the reliability and the accuracy of these new formulas. POLYM. ENG. SCI., 45:1092–1097, 2005. © 2005 Society of Plastics Engineers
Prediction of residual stresses in cross‐linked polyethylene cable insulation
Authors: Olasz L. , Gudmundson P. 
Published: June 2005

AbstractModeling of the manufacturing process of high‐voltage power cables was performed with the aim of predicting residual stresses in the cable insulation. A viscoelastic power law‐type constitutive model was used which incorporates temperature and crystallinity dependence of the parameters. In this way the mechanical problem is coupled to the heat transfer and crystallization problems. In order to illustrate the effects of relaxation, a comparison to a thermoelastic material model is made. POLYM. ENG. SCI., 45:1132–1139, 2005. © 2005 Society of Plastics Engineers
Nucleation effect of polyamide on polyoxymethylene
Authors: Hu Youliang , Ye Lin 
Published: June 2005

AbstractThe crystallization behavior and morphology of polyoxymethylene (POM) and POM with polyamide (PA) were studied by polarized light microscopy (PLM), isothermal and nonisothermal differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The isothermal crystallization kinetics were analyzed with the Avrami equation. Compared with the virgin POM, the addition of PA can reduce the spherulites size and improve the crystallization growth rate and crystallinity (Xc) of POM, which demonstrates that the nucleation effect of PA as the high‐molecular nucleus is favorable to the mechanical properties and dimension stability of POLYM. ENG. SCI., 45:1174–1179, 2005. © 2005 Society of Plastics Engineers
Increased flow property of polycarbonate by adding hollow glass beads
Authors: Chen Peng , Zhang Jun , He Jiasong 
Published: June 2005

AbstractThe steady shear viscosity and dynamic viscoelastic properties of glass beads (GB) filled polycarbonate (PC) melts were studied at varying filler diameters and concentrations. The PC/GB composites containing small amounts of GB bore lower melt viscosity and dynamic modulus than those of pure PC at studied frequencies and shear rates, showing a “ball‐bearings” effect. For highly filled systems, the viscosity and dynamic modulus were decreased further at higher frequencies and shear rates. This ball‐bearings effect was enhanced by changing the GB from larger to smaller one. The oscillatory experiments with modified shear stress showed a stress‐dependent decrease of the viscoelastic properties, and revealed an interfacial slip mechanism, combined with the polymer chains disentanglement at melt/solid interfaces. The scaling relationship between the relative viscosity and the mean interparticle gap confirmed that the interfacial slip and polymer chains disentanglement were induced by the extremely high local shear developed in the narrow gaps between the nearby rotating spheres. POLYM. ENG. SCI., 45:1119–1131, 2005. © 2005 Society of Plastics Engineers
Evaluation of mechanical properties of adjacent flow weldline
Authors: Yamada Koji , Tomari Kiyotaka , Ishiaku Umaru Semo , Hamada Hiroyuki 
Published: June 2005

AbstractWeldlines occur at the interface of two adjacent flows of material behind an obstructive pin in a cavity in injection molding (meldline or hot weldline). Tensile strength of such “adjacent flow weldline” in injection molded polystyrene plates was evaluated by a mechanical step‐by‐step milling technique. The strength when the milling depth was 1/5 of the thickness from each surface was about the same and independent of the distance from the pin. In contrast, the strength without milling decreased once and then increased along the flow direction. This demonstrates that the strength of a weldline is predominantly dependent on the properties of the surface layer of the weldline. The depth of the surface layer was defined as the depth of the weld, Dw. Dw reduced monotonously along the flow direction and faded away with the V‐notch, resulting in an increase of strength along the direction. On the other hand, it was considered that the farther from the pin, the flow‐induced molecular orientation in the surface layer is greater. It caused a decrease of the strength along the flow direction. The sequence of decrease and increase in tensile strength of adjacent flow weldline is due to the complex effect of these two contradictory factors. POLYM. ENG. SCI., 45:1180–1186, 2005. © 2005 Society of Plastics Engineers
Thermal and rheological properties of maleated polypropylene modified asphalt
Authors: Yeh Pei‐Hung , Nien Yu‐Hsun , Chen Jean‐Hong , Chen Wei‐Chyum , Chen Jian‐Shiuh 
Published: June 2005

AbstractModified asphalts using polymeric additives, such as isotactic polypropylene (iPP) and maleated polypropylene (MPP), for asphalt binders were prepared and characterized for potential usages in pavement construction. The differential scanning calorimetry (DSC) studies show that most of the crystallinity of iPP remains intact in the asphalt binders, but MPP exhibits more interaction with the asphalt due to the increase of the amorphous region of MPP. The phase distributions and rheological properties of the modified asphalts were examined by scanning electron microscope (SEM) and dynamic shear rheometer (DSR), respectively. The images of SEM show that the MPP‐rich phase is larger than the iPP‐rich phase in asphalt blends, which contributes to more dispersion of the polymer into the asphalt phase in the asphalt/MPP blend. From the rheological studies, the asphalt blends containing iPP exhibit higher viscosity in terms of higher temperature to get Newtonian behavior and have a higher performance grade for rutting resistance at high temperature and frequency. POLYM. ENG. SCI., 45:1152–1158, 2005. © 2005 Society of Plastics Engineers
The effect of nanoclays on the processibility of polyolefins
Authors: Hatzikiriakos Savvas G. , Rathod Nimish , Muliawan Edward B. 
Published: June 2005

AbstractThe influence of a new processing additive (particles of organically modified nanoclays) on the processibility of polyolefins in extrusion is studied. The equipment used includes an Instron capillary rheometer with two types of dies, namely capillary dies and special annular dies (Nokia Maillefer wire coating crosshead) attached to the rheometer. Ziegler Natta and metallocene polyethylenes and one polypropylene were tested using these two pieces of equipment. It was found that the nanoclay additive had a significant effect on the extrudate appearance of polyethylene. It eliminates surface melt fracture and postpones the critical shear rate for the onset of gross melt fracture to significantly higher values depending on resin type, temperature, and additive concentration (typically 0.05 to 0.5 wt%). To explain the possible mechanism for the effect of the additive on the processibility of the resins, shear and extensional rheological measurements were carried out for the pure resins as well those loaded with the nanoclay additives. It seems that the presence of nanoclays suppresses the development of extensional stresses to such high levels that can cause melt fracture phenomena. Finally, it was found that the combination of nanoclays with traditional processing aids such as fluoropolymers produce an enhanced processing aid that can increase the critical shear rates for the onset of melt fracture to levels much higher than the individual constituents when they are used independently. POLYM. ENG. SCI., 45:1098–1107, 2005. © 2005 Society of Plastics Engineers
Crystallization and melting behavior of homogeneous and heterogeneous linear low‐density polyethylene resins
Authors: Feng Lijun , Kamal Musa R. 
Published: June 2005

AbstractThe crystallization behavior of homogeneous and heterogeneous linear low‐density polyethylenes (LLDPE) was investigated by evaluating the characteristics of melting traces obtained by differential scanning calorimetry (DSC). Based on the isothermal experimental results, the concept of the effective nucleation induction time is suggested. In the initial crystallization stage, the Avrami equation in conjunction with the effective induction time can be used to successfully describe the overall crystallization kinetics. Avrami exponents 2, 1.5, and 1 were found to apply in regimes III, II, and IM, respectively, as identified by the modified Hoffman‐Lauritzen (MHL) equation. The kinetic parameters estimated from evaluating the linear crystallization behavior during spherulitic growth experiments using polarized light microscopy (PLM) are in agreement with the overall crystallization kinetic parameters obtained from DSC experiments. POLYM. ENG. SCI., 45:1140–1151, 2005. © 2005 Society of Plastics Engineers
Defining the configuration of co‐rotating twin‐screw extruders with multiobjective evolutionary algorithms
Authors: Gaspar‐Cunha A. , Covas J.A. , Vergnes B. 
Published: June 2005

AbstractMultiobjective evolutionary algorithms have already been used for the optimization of the processing conditions of a co‐rotating twin screw extruder. In the present paper, we develop this approach for the optimization of the screw geometry, in terms of the most adequate location of a pre‐selected set of screw elements, in order to maximize a prescribed performance. Experimental validation shows the pertinence of this approach, which is computationally more rapid and less expensive than the classical trial and error procedure. An application to the complex case of reactive extrusion is also presented. POLYM. ENG. SCI., 45:1159–1173, 2005. © 2005 Society of Plastics Engineers
Die Dunkle Energie: Kosmologie
Authors: Börner Gerhard 
Published: June 2005

AbstractBeobachtungen der Ausdehnung des Weltalls und der Temperaturschwankungen der kosmischen Hintergrundstrahlung führen zu einer präzisen Bestimmung aller kosmischen Parameter. Das überraschende Ergebnis ist, dass die kosmische Expansion gegenwärtig beschleunigt verläuft, angetrieben von einer rätselhaften Dunklen Energie. Diese macht etwa 70% der gesamten Materie und Energiekomponenten im Kosmos aus und wirkt wie eine abstoßende Gravitation. Man vermutet, dass diese Größe mit der Vakuumenergie der Quantenfeldtheorie zusammenhängt. Theoretische Deutungsversuche sind aber bisher nicht sehr erfolgreich.