bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of the porous morphology on the in vitro degradation and mechanical properties of poly(L‐lactide) disks
Authors: Sarazin Pierre , Virgilio Nick , Favis Basil D. 
Published: January 2006

AbstractPoly(L‐lactide) (PLLA) materials having an interconnected porosity are proposed as an alternative to nonporous biomaterials. Such materials allow for the potential of modulating the degradation behavior and the mechanical properties. In this article, the preparation of porous PLLA disks or cylinders with 50 and 65% void volume is presented. It is demonstrated that both a symmetric and asymmetric porosity can be generated within the disk itself. In addition, open‐ and closed‐cell structures can also be prepared. The accelerated in vitro degradation on symmetric open‐cell porous PLLA disks and on the nonporous control indicate a similar behavior in terms of melting temperature and inherent viscosity of the remaining pieces of the specimens, but the crystallinity and the mass of the remaining fragments are much smaller for the porous specimens. The mechanical properties under compression are determined for open and closed‐cell porous cylinders, porous tubes, and for the nonporous PLLA. The results highlight the excellent mechanical integrity of the prepared porous structures and demonstrate that such materials could have potential for use as biomedical implants. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1039–1047, 2006
Ultraviolet radiation curable epoxy resin encapsulant for light emitting diodes
Authors: Kumar R. N. , Keem Lim Yoke , Mang Ng Chee , Abubakar Abusamah 
Published: January 2006

AbstractLight‐emitting diodes are currently encapsulated by thermally curable epoxy resins. Thermal curing systems require long curing cycles at high temperatures. Further, because of viscoelastic behavior of the resin, the resin tends to “creep” along the connecting wires (Weisenberg effect), which causes solderability problem. The cured resin should be removed manually, which is time consuming and labor intensive. These problems are solved by the ultraviolet radiation curable systems. UV curing is an ultrafast reaction and takes place at room temperature. No creep behavior occurs due to the rapidity of the curing. The UV curing technique can result in higher productivity and energy saving than the thermal process. This article presents results on the development of UV curable formulations based on cycloaliphatic diepoxide, diglycidyl ether of bisphenol A, and epoxidized novolac induced by cationic photoinitiators. “Mixture experimental design” was employed to arrive at the optimum composition, which meets the stringent demands of performance characteristics and durability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1048–1056, 2006
Nonisothermal crystallization of poly(ethylene‐co‐glycidyl methacrylate)/clay nanocomposites
Authors: Huang Jiann‐Wen , Hung Hui‐Chuan , Tseng Kuo‐Shu , Kang Chiun‐Chia 
Published: January 2006

AbstractThe nonisothermal crystallization of poly(ethylene‐co‐glycidyl methacrylate) (PEGMA) and PEGMA/clay were studied by differential scanning calorimeter, at various cooling rates. Avrami model modified by Jeziorny, Ozawa mode and Liu model could successfully describe the nonisothermal crystallization process. Augis–Bennett model, Kissinger model, Takhor model, and Ziabicki model were used to evaluate the activation energy of both samples. It was found that the activation energy of PEGMA/clay nanocomposite was higher than that of neat PEGMA. Experimental results also indicated that the addition of modified clay might retard the overall nonisothermal crystallization process of PEGMA. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1335–1343, 2006
Chitosan: Aspects of fiber spinnability
Authors: El‐Tahlawy Khaled , Hudson Samuel M. 
Published: January 2006

AbstractThe preparation of useful fibers from chitosan remains an interesting challenge. Chitosan is easily solubilized in aqueous acids, but these solutions generally have high solution viscosities because of the polyelectrolyte effect. The high viscosity affects the processibility of chitosan during extrusion by wet‐spinning techniques. The coagulation rate, which also includes the regeneration of the free amine form of chitosan is also expected to be influenced by viscosity. In this study, the solution rheology of chitosan solutions was examined; our aim was to find the optimum compositions, in terms of chitosan, acid, and added salts, for spinnability. The diffusion of coagulants into chitosan spinning solutions is also reported. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1162–1168, 2006
A high‐resolution solid‐state NMR investigation of molecular mobility of poly(methyl methacrylate)/poly(vinyl pyrrolidone)/poly(ethylene oxide) ternary blends
Authors: Diniz Teresinha M. F. F. , Tavares Maria I. B. 
Published: January 2006

AbstractThe ternary blends of poly(methyl methacrylate)/poly(vinyl pyrrolidone)/poly(ethylene oxide), PMMA/PVP/PEO, were prepared by melting process, using a Haake plastograph, and nuclear magnetic resonance spectroscopy (NMR) was used as a methodology to characterize the molecular mobility of blend components, because NMR has several techniques that allow us to evaluate polymeric materials in different time scales. The NMR results showed that the blends were miscible on a molecular level. The values of proton lattice relaxation time in the rotating frame (T1ρH) indicate that the ternary blend interaction did not reduce the intermolecular distance, because it is dipole–dipole. The molecular motion of each component, even in the miscible amorphous phase and the addition of PEO, has a definitive effect on the PMMA molecular mobility. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1492–1495, 2006
Colloidal aggregation of aminoplastic polycondensation resins: Urea–formaldehyde versus melamine–formaldehyde and melamine–urea–formaldehyde resins
Authors: Despres A. , Pizzi A. 
Published: January 2006

AbstractColloidal particles formation followed by their clustering have been shown to be the normal way of ageing of aminoplastic resins, namely urea–formaldehyde (UF) resins, melamine–formaldehyde (MF) resins, and melamine–urea–formaldehyde (MUF) resins. Ageing or further advancement of the resin by other means such as longer condensation times causes whitening of the resin. This is a macroscopic indication of both the formation of colloidal particles and of their clustering. It eventually progresses to resins, which are mostly in colloidal, clustered state, followed much later on by a supercluster formation starting to involve the whole resin. The initial, filament‐like colloidal aggregates formed by UF resins have different appearance than the globular ones formed by MF resins. MUF resins present a short rod‐like appearance hybrid between the two. GPC has been shown to detect the existence of colloidal superaggregates in a UF resin, while smaller aggregates might not be detected at all. The star‐like structures visible in the colloidal globules of MF resins are likely to be light interference patterns of the early colloidal structures in the resins. These star‐like interference patterns become more complex with resin ageing or advancement due to the advancement of the resin to more complex aggregates, to eventually reach the stage in which filament‐like and rod‐like structures start to appear. The next step is formation of globular masses that are representative of the true start of physical gelation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1406–1412, 2006
Optimization of the properties of chitosan lactate/hyaluronan film
Authors: Kukolikova L. , Bakos D. , Alexy P. , Hanzelova S. , Zhong W. 
Published: January 2006

AbstractPolyelectrolyte complexes represent attractive class of polymer‐based materials, finding an irreplaceable role in biomaterial preparation for tissue engineering or drug delivery beads. Mechanical properties, physical properties, and enzymatic degradation of the film prepared from chitosan lactate/hyaluronan polyelectrolyte complex, crosslinked with starch dialdehyde derivatives, were studied to optimize its composition. This work represents an example demonstrating how a minor modification of the modified complex composition changes final properties of the prepared film and emphasizes enormous variations in complex formation by crosslinking. To obtain sufficiently useful information, experimental design was employed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1413–1419, 2006
Fibrillation tendency of cellulosic fibers. VII. Combined effects of treatments with an alkali, crosslinking agent, and reactive dye
Authors: Zhang Wangsun , Okubayashi Satoko , Badura Wolfram , Bechtold Thomas 
Published: January 2006

AbstractLyocell woven fabrics were treated with crosslinking agents [1,3‐dimethyl‐4,5‐dihydroxyethylene urea (X1) and 1,3‐dimethylol‐4,5‐dihydroxyethylene urea (X2)], binders [polyacrylate (B1), anionic polyacrylate (B2), anionic polyurethane (B3), and aliphatic polyisocyanate (B4)], and polyfunctional reactive dyes in combination with alkali treatments. The effects of the treatment conditions, including the reagent types, the reagent concentrations, the process types (pretreatments or posttreatments with alkali), and the treatment combinations, on the fibrillation tendency and dyeing behavior in treated samples were investigated. Generally, the fibril number decreased with an increasing concentration of additives and decreased further with reactive dyeing. Fabrics treated with 45 g/L X1 (34 g/kg of fiber) or with 28 g/L X2 (21 g/kg of fiber) and dyed thereafter exhibited no fibrillation. Posttreatments with alkalis caused no changes in either the color shade or fibrillation tendency of crosslinked fabrics, although they enhanced the water retention capacity. The use of mixtures of binders B3 and B4 minimized the fibrillation, but the use of B4 led to changes in the color shade. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:1176–1183, 2006
Pressure drop estimation for polyamide 6 flow through spinnerets and filters
Authors: Guštin A. , Zupančič A. , Mitsoulis E. 
Published: January 2006

AbstractThe pressure drop resulting from polyamide 6 flow through industrial spinnerets and wire‐mesh filters was examined as a possible parameter for improving spinning process constancy with experimental techniques and a numerical approach. The rheological characterization of the polymer melt was performed with a capillary rheometer and a controlled‐stress rotational rheometer equipped with a high‐temperature oven cell. Measurements in a nitrogen atmosphere were carried out at different temperatures and at various moisture contents to determine the effect of the postcondensation process on the rheological properties of the polymer melt. These experiments were used to collect all basic material information necessary to fit the data with the purely viscous Cross model and the viscoelastic Kaye, Bernstein, Kearsley, Zappas (K‐BKZ) model. A spinning pilot plant (consisting of an extruder, a gear pump, a pressure sensor, and a spin beam with several spin packs installed) was used to measure pressure drop values through industrial spinnerets and through two types of filters: (1) Dutch twilled weave filters and (2) sintered filters. Pilot plant tests on filters showed that in the examined range of melt throughputs, the pressure drop increased linearly with an increase in the melt flow rate for all the filters considered. The results with respect to the spinneret geometry led to the conclusion that the numerical simulations gave satisfactory predictions even for experimental data coming from complex systems such as spinning plants, as long as extensional properties were accounted for by the model. On the contrary, pressure drop predictions obtained from the Cross model underestimated the pilot plant values by approximately 20% because of the inability of the model to consider the extensional component of the flow. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1577–1587, 2006
Study of the preparation and properties of UV‐blocking fabrics of a PET/TiO2 nanocomposite prepared by in situ polycondensation
Authors: Han Keqing , Yu Muhuo 
Published: January 2006

AbstractPoly(ethylene phthalate) (PET)/nano‐TiO2 composites prepared via in situ polymerization were spun into fiber by the melt‐spinning process. The dispersion of nanosized rutile TiO2 in the PET was studied using transmission electron microscopy (TEM) and scanning probe microscopy (SPM) techniques. The mechanical properties and the properties of ultraviolet (UV) protection were investigated. The results showed that rutile TiO2 can be dispersed uniformly by the in situ polycondensation process. The mechanical properties of PET/TiO2 fiber were slightly affected by adding nano‐TiO2. The UV‐ray transmittance of PET/nano‐TiO2 fabrics was below 10% in the UV‐A band and below 1% in the UV‐B band. And the ultraviolet protection factor (UPF) of PET/nano‐TiO2 fabrics was greater than 50. All these PET/TiO2 nanocomposite fabrics exhibited excellent UV‐blocking properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1588–1593, 2006
Study on in situ synthesis of konjac glucomannan/silver nanocomposites via photochemical reduction
Authors: Tian Dating , Hu Weibing , Zheng Zhen , Liu Hangbao , Xie Hong‐Quan 
Published: January 2006

AbstractKonjac glucomannan (KGM)/Silver nanocomposites have been prepared directly in the dilute hydrosol of KGM using photochemical reduction of Ag+. The KGM/Ag nanocomposites have been characterized by means of Fourier transform infrared (FTIR) spectra, transmission electron microscopy (TEM), and thermalgravimetry (TG). The results of FTIR showed that the wavenumbers and the strengths of some characteristic peaks of KGM treated by silver nanoparticles were changed obviously, the characteristic peaks of the OH stretching and the CO (H) stretching became wider with increasing concentrations of the reactants, and the characteristic peaks of the OH stretching and the CO (H) stretching shifted to high wavenumbers with increasing time of photochemical reduction. The images of TEM indicated that Ag nanoparticles were finely dispersed inside the KGM films with different shapes, such as sphere‐like (average diameters of 9 ± 4 nm) and star‐like (edge lengths of about 20 nm), respectively. These suggested that the morphology and the agglomerated state of Ag nanoparticles in the composites changed with the conditions of the preparation, especially with the concentrations of Ag+ and KGM as well as the time of photochemical reduction. The KGM and KGM/Ag films had remarkably different thermal properties from the TG curves. The mechanism of interaction between the polysaccharide and the silver nanoparticles has also been generally discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1323–1327, 2006
Structural characterization of sulfur vulcanized deproteinized natural rubber by solid‐state 13C NMR spectroscopy
Authors: Sakdapipanich Jitladda T. , Kowitteerawut Tippawan , Tuampoemsab Surakit , Kawahara Seiichi 
Published: January 2006

AbstractThe structural changes in unfilled and filled vulcanized deproteinized natural rubber (DPNR), which is a highly purified natural rubber (NR), were investigated by solid‐state 13C NMR spectroscopy. The chemical shifts of new signal were assigned by calculation and compared with those observed by Koenig et al. for conventional vulcanized NR. The crosslink structure of sulfur vulcanized DPNR were similar to that of sulfur‐vulcanized NR for CV system assigned by Koenig et al. The increase in the relative intensities of signals between 45 and 58 ppm, which was assigned to monosulfidic and polysulfidic bonds, was concerned with the increase in crosslink density. In this case, the crosslink density was increased after aging, which might be due to incomplete curing. Furthermore, the solid‐state 13C NMR spectrum of the aged sulfur vulcanizate DPNR showed new signals at around 73 ppm, which is assignable to carbon attached to hydroxyl group because of thermal oxidation. It can provide more complete understanding of the final vulcanizate crosslink structure of DPNR vulcanizates. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1875–1880, 2006
Preparation, morphology, and mechanical properties of elastomers based on α,ω‐dihydroxy‐polydimethylsiloxane/poly(methyl methacrylate) blends
Authors: Dong Jian , Liu Zonglin , Feng Yongbin , Zheng Chao 
Published: January 2006

Abstractα,ω‐Dihydroxy‐polydimethylsiloxane (PDMS)/poly(methyl methacrylate) (PMMA) blends were prepared by the radical polymerization of methyl methacrylate in the presence of PDMS, with benzoyl peroxide as the initiator. The PDMS/PMMA blends obtained by this method were a series of stable, white gums, which were vulcanized into elastomers at room temperature with methyl triethoxysilicane (MTES). The MTES dosage was much larger than the amount necessary for end‐linking the hydroxy‐terminated chains of PDMS, with the excess being hydrolyzed into crosslinked networks, which were similar to SiO2 and acted as fillers. Investigations were carried out on the elastomeric materials by extraction measurements, swelling measurements, and scanning electron microscopy. The extraction data showed that at each composition, the sol fraction was less than expected. The extracted materials were further studied with swelling measurements, which revealed that the material obtained from an elastomer with a higher PMMA content had an apparently larger equilibrium swelling degree. Scanning electron microscopy demonstrated that the elastomer system had a microphase‐separated structure consisting of PMMA domains within a continuous PDMS matrix. Moreover, the mechanical properties of the elastomeric materials were studied in detail. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1547–1553, 2006
New melamine–formaldehyde–ketone polymers. IV. Dissolution of melamine in reactive solvents prepared from methyl ethyl ketone
Authors: Głowacz‐Czerwonka Dorota , Kucharski Mieczysław 
Published: January 2006

AbstractReactive solvents of melamine were prepared from methyl ethyl ketone and formaldehyde in the presence of the catalyst triethylamine. The solubility of melamine in the resulting solvents was determined, and the mechanism of dissolution was explained with 1H‐NMR and IR spectroscopy. Preliminary experiments aimed at curing the melamine solutions in reactive solvents into melamine–formaldehyde–butanone resins are reported. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1496–1505, 2006
Preparation of a poly(3‐hexylthiophene)‐grafted indium tin oxide/poly(3‐hexylthiopene) composite and its conductivity–temperature characteristics
Authors: Liu Chuanjun , Oshima Kenji , Shimomura Masato , Miyauchi Shinnosuke 
Published: January 2006

AbstractThe temperature–conductivity characteristics of poly(3‐hexylthiophene) (P3HT) composites filled with P3HT‐grafted indium tin oxide (ITO) particles were investigated in this work. The ITO particles were first treated with a silane coupling reagent of 3‐aminopropyltriethoxysilane (APS), and then thiophene rings were introduced through a condensation reaction between the ending amino groups of APS and the carboxylic groups of thiophene‐3‐acetic acid. The composites were prepared by the polymerization filling of the 3‐hexylthiophene (3HT) monomer with the thiophene‐ring‐introduced ITO particles. Elemental analysis, Fourier transform infrared, and X‐ray photoelectron spectroscopy were used to confirm the grafting reaction on the ITO surface. The longer the polymerization time was or the higher the 3HT/ITO feeding ratio was, the more P3HT was grafted. The influence of the grafted amount on the electrical properties of ITO particles was attributed to the wrapping effect formed by the grafted P3HT on the surface of the ITO particles. The conductivity change of the P3HT‐grafted ITO/P3HT composites was proved to be subject to the change in the average gap width of ITO interparticles, which was determined by the filling ratio of P3HT to ITO in the polymerization and the volume expansion effect of a P3HT thin film between neighboring ITO particles during the heating process. In comparison with the ungrafted ITO/P3HT composites, the grafting treatment enhanced the interaction between the particles and polymer matrix, and this was helpful for obtaining a more homogeneous dispersion structure for the composites and thus afforded a higher positive temperature coefficient intensity and better reproducibility. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1881–1888, 2006
Modification of polyolefin films surface with sodium hypochlorite
Authors: Iguerb O. , Demoustier‐Champagne S. , Marchand‐Brynaert J. , Daoust D. , Sclavons M. , Devaux J. 
Published: January 2006

AbstractSurface modification of high‐density‐polyethylene (HDPE) and linear‐low‐density polyethylene (LLDPE) films is promoted by sodium hypochlorite solutions using two different processes (I and II). Such an oxidation system introduces limited amounts of carbonyl–carboxyl and hydroxyl groups onto the surface of hydrocarbon polymers. FTIR, XPS, and SEM were used to assess the efficiency of the oxidation. The hydrophilicity of the studied surfaces was investigated by the sessile drop technique and the Wilhelmy plate and a plausible oxidation mechanism is proposed.

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© 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1184–1197, 2006
Evaluation of the microstructure and melting behavior of drawn polypropylene fibers with a microthermal analyzer
Authors: Ye Jiping , Hasegawa T. , Suzuki A. 
Published: January 2006

AbstractThe strong correlation of melting behavior with the microstructure of original and zone‐drawn isotactic polypropylene fibers was evaluated by microthermal analysis (micro‐TA) combined with wide‐angle X‐ray diffraction analysis. The crystal structure of both the original and zone‐drawn fibers was a monoclinic α‐form with a ∼ 0.64 nm, b ∼ 2.03 nm, and c ∼ 0.65 nm. In contrast to the absence of any oriented polymer molecules in the original fiber, the polymer molecules in the zone‐drawn fiber were extended and highly oriented in at least two different states; one arranged along the drawn axis and the other at 40° to the drawn axis. The micro‐TA‐derived melting points corresponded to these microstructural changes caused by the zone‐drawing process and differed from the melting points obtained by differential scanning calorimetery. The micro‐TA melting point of 140°C corresponded to the z‐e‐p melting point of the original fiber, being much lower than the conventional differential scanning calorimetery melting point of 163°C. As for the zone‐drawn fiber, an increase of 19°C in the melting temperature revealed its high orientation level, and the appearance of three elevated melting peaks (161, 167, and 178°C) at the highest heating rate (1500°C/min) coincided with its several oriented states. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1306–1311, 2006