bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluations of an aramid fiber in nonwoven processes for honeycomb applications
Authors: Wu Yi‐Jui , Seferis James C. , Lorentz Vincent 
Published: August 2002

AbstractAromatic polyamide paper has been used as the primary honeycomb core material in aircraft interior applications because of its flame‐resistant properties. This study investigated the relationships between material requirements in making sheets for honeycomb core applications by characterizing and processing a model aramid fiber into nonwoven samples, which were further characterized and whose adaptability in honeycomb application was evaluated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1149–1156, 2002
Ionomeric polyurethanes of pyridinium type with side azobenzene groups
Authors: Buruiana Tinca , Buruiana Emil C. 
Published: August 2002

AbstractNew polyurethane cationomers synthesized by a two‐step substitution postreaction of urethane hydrogen atoms with nitroazobenzene groups were studied. As a starting polymer, a polyurethane based on poly(tetramethylene oxide)diol, isophorone diisocyanate, and 2,6‐bis(hydroximethyl)pyridine was used. After a preliminary metalation of the above polymer with natrium hydride, by reaction of polyurethane N‐sodate with 4‐nitro‐4′(β–iodoethylurethane)azobenzene, chromophoric groups between 2.85 and 10.53 wt % could be incorporated instead of hydrogen. Such polymers partially functionalized with azobenzene and further quaternized with methyl iodide led to the formation of pyridinium polyurethane cationomers N‐modified with nitroazo groups. The photosensible properties of the azobenzene chromophore in a polymer solution and film state indicated important differences in their photoresponse. In the polymer solution, the trans–cis photoisomerization of the chromophore is accompanied by an irreversible photobleaching effect, while under the same UV irradiation conditions, the ionomeric films exhibited an enhanced photostability. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1240–1247, 2002
The effects of plasticizers on the dynamic mechanical and thermal properties of poly(lactic acid)
Authors: Ljungberg Nadia , Wesslén Bengt 
Published: August 2002

AbstractPoly(lactic acid) (PLA) was blended with five plasticizers in a batchwise mixer and pressed into films. The films were analyzed by means of dynamic mechanical analysis and differential scanning calorimetry to investigate the properties of the blends. Triacetine and tributyl citrate proved to be effective as plasticizers when blended with PLA. The glass transition temperature of PLA decreased linearly as the plasticizer content was increased. Both plasticizers were miscible with PLA to an extent of ∼ 25 wt %. At this point, the PLA seemed to be saturated with plasticizer and the blends tended to phase separate when more plasticizer was added. There were also signs of phase separation occurring in samples heated at 35, 50, and 80°C, most likely because of the material undergoing crystallization. The presence of the plasticizers induced an increased crystallinity by enhancing the molecular mobility. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1227–1234, 2002
Surface morphology of adsorbed sulfur‐functionalized polystyrene thin film on gold on the basis of atomic force microscopic observation
Authors: El Sayed A. Mounir 
Published: August 2002

AbstractPolystyrene thin film containing one‐terminal thiol (PS–SH) was spin‐coated and adsorbed from 0.1 to 0.001 wt % of polymer solution in toluene onto evaporated gold (Au) film supported on Si‐wafer substrate. The effect of polymer solution concentration on the aggregation structure of PS–SH thin films was determined on the basis of atomic force microscopic (AFM) observation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1248–1252, 2002
Miscibility and morphology of chiral semicrystalline poly‐(R)‐(3‐hydroxybutyrate)/chitosan and poly‐(R)‐(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)/chitosan blends studied with DSC, 1H T1 and T1ρ CRAMPS
Authors: Cheung Man Ken , Wan Kris P.Y. , Yu Peter H. 
Published: August 2002

AbstractThe phase structure of poly‐(R)‐(3‐hydroxybutyrate) (PHB)/chitosan and poly‐(R)‐(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (P(HB‐co‐HV))/chitosan blends were studied with 1H CRAMPS (combined rotation and multiple pulse spectroscopy). 1H T1 was measured with a modified BR24 sequence that yielded an intensity decay to zero mode rather than the traditional inversion‐recovery mode. 1H T1ρ was measured with a 40‐kHz spin‐lock pulse inserted between the initial 90° pulse and the BR24 pulse train. The chemical shift scale is referenced to the methyl group of PHB as 1.27 ppm relative to tetramethylsilane (TMS) based on 1H liquid NMR of PHB. Single exponential T1 decay is observed for the β‐hydrogen of PHB or P(HB‐co‐HV) at 5.4 ppm and for the chitosan at 3.7 ppm. T1 values of the blends are either faster than or intermediate to those of the plain polymers. The T1ρ decay of β‐hydrogen is bi‐exponential. The slow T1ρ decay component is interpreted as the crystalline phase of PHB or P(HB‐co‐HV). The degree of crystallinity decreases with increasing wt % of chitosan in the blend. The fast T1ρ of β‐hydrogen and the T1ρ of chitosan in the blends either follow the same trend as or faster than the weight‐averaged values based on the T1ρ of the plain polymers. Together with the observation by differential scanning calorimeter (DSC) of a melting point depression and one effective glass transition temperature in the blends, the experimental evidence strongly suggests that chitosan is miscible with either PHB or P(HB‐co‐HV) at all compositions. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1253–1258, 2002
New conductive thermoplastic elastomers. Part II. Physical and chemical‐physical characterization
Authors: Carone E. , D'Ilario L. , Martinelli A. 
Published: August 2002

AbstractTo overcome the problems relevant to the low processbility and scarce mechanical properties of polyaniline, in a previous work we have proposed the synthesis of elastomeric conducting copolymers prepared by grafting polyaniline (EB) or sulfonated polyaniline (SPAN) chains to the backbone of a carboxylated segmented polyurethane (PEUA). In the present work the physical and chemical‐physical properties of the copolymers are investigated. As evidenced by thermal (DSC) and dynamo‐mechanical (DMTA) characterization, the introduction of EB or SPAN in the matrix enhances the hard‐soft phase segregation effect, because of the strong tendency of the conductive polymer chains to aggregate. Moreover, the EB and SPAN chains, grafted to the polyurethane backbone, acting as reinforcing filler, give rise, compared with the mechanical properties of the insulating matrix, to an increase of the Young modulus and a decrease of the tensile set. When the copolymers are HCl doped their electrical conductivity increases many orders of magnitude, reaching values of about 10−3 Ω−1 cm−1. The conductivity, measured along the deformation direction, may be further increased by stretching the copolymer films. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1259–1264, 2002
Acetyl‐capped paraformaldehyde as crosslinking agent for BMI‐modified novolac resin for resin transfer molding
Authors: Yan Yehai , Zhi Linjie , Wang Hongsheng , Liu Jinge , Zhao Tong , Yu Yunzhao 
Published: August 2002

AbstractParaformaldehyde was end‐capped with acetyl groups and was applied as a crosslinking agent for a bismaleimide (BMI)‐modified novolac resin system. The processibility of the resin system containing 5 wt % crosslinking agent still met the need for resin transfer molding (RTM), whereas the thermomechanical properties of crosslinked resin improved significantly. The composites based on the resin system and woven glass fabric showed better flexural strength, modulus, and higher retention rates at 200 and 300°C than that based on a resin system without acetyl‐capped paraformaldehyde. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1265–1271, 2002
Radiation effects on LDPE/EVA blends
Authors: Dalai Siqin , Wenxiu Chen 
Published: August 2002

AbstractRadiation effects of low‐density polyethylene/ethylene‐vinyl acetate copolymer (LDPE/EVA) blends were discussed. EVA content in the LDPE/EVA blends was an enhancement effect on radiation crosslinking of LDPE/EVA blends, and the highest radiation crosslinking was obtained when the EVA content was reached at 30% when irradiated by γ‐ray in air. The phenomenon was discussed with the compatibility, morphology, and thermal properties of LDPE/EVA blends and found that the enhanced radiation crosslinking of the LDPE/EVA blends was proportional to the good compatibility, the increasing degree of the amorphous region's content of the LDPE/EVA blends, and the vinyl acetate content of EVA. We also found that the vinyl acetate of EVA in the blends is easily oxidized by γ‐ray irradiation in air. The possible radiation crosslinking and degradation mechanism of LDPE/EVA blends was discussed quantitatively with a novel method “step‐analysis” process of irradiated LDPE/EVA blends in the thermal gravimetric analysis (TGA) technique. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1296–1302, 2002
Relations between molecular mixing state and conductive property in blends composed of polyaniline and aliphatic copolymer having acid groups
Authors: Yamada Kenji , Yamane Hirokazu , Haishi Teruki , Yamamoto Katsuhiro , Haraguchi Toshihide , Kajiyama Tisato 
Published: August 2002

AbstractBlend films composed of polyaniline and aliphatic copolymer having carboxylic acid groups were prepared by vaporizing a solvent from a solution of both polymers. Poly(methyl methacrylate‐co‐methacrylic acid) and poly(1‐vinylpyrrolidone‐co‐acrylic acid) were used as the copolymers in this work. Conductivity of the blend film increased with decreasing concentration of polyaniline and then decreased in the region of low concentration. The N1s peak in the ESCA spectrum of the blend film was shifted to higher binding energy with decreasing concentration of polyaniline and then was done to lower the binding energy in the region of low concentration. Polyaniline chains in the blend films become conductive by being oxidized with the carboxylic acid groups, which are the constituents of the copolymers. Through strong intermolecular interactions such as ionic bonding and hydrogen bonding between polyaniline and the copolymer, densities of the blend films are always higher than those predicted on the basis of the additive law. Blend films with higher density and higher conductivity are able to be prepared with a higher vaporizing rate, given that phase separation occurring during vaporizing process can be depressed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1113–1117, 2002
Surface structure of radiation‐grafted polyethylene‐g‐polyacrylamide films
Authors: Gupta Bhuvanesh , Anjum Nishat 
Published: August 2002

AbstractModification of polyethylene films was carried out by radiation‐induced graft polymerization of acrylamide using a preirradiation method. The surface behavior of grafted films as a function of the degree of grafting was determined using contact angle measurements, attenuated total reflectance (ATR), and scanning electron microscopy (SEM). In spite of the presence of hydrophilic polyacrylamide chains, grafted films still showed high hydrophobicity on the surface. ATR results revealed the presence of a polyacrylamide moiety in the surface layer of the films. Interestingly, the contact angle of grafted films did not change much for the entire range of degree of grafting. SEM results showed that the roughness is introduced on the film surface irrespective of the nature of the additive. However, the addition of acetone to the grafting medium was the most effective in increasing the surface roughness. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1118–1122, 2002
Relations between the molecular aggregation state and ionic conductivity in photopolymerized crosslinking polymers with oligo(oxyethylene) chains
Authors: Yamada Kenji , Iwamoto Naoya , Yamane Hirokazu , Haraguchi Toshihide , Kajiyama Tisato 
Published: August 2002

AbstractA mixture of a vinyl monomer and a crosslinking agent was photopolymerized to form a crosslinked polymer film. Methacrylate with pendant oligo(oxyethylene) chain and poly(ethylene glycol) dimethacrylate were used as the vinyl monomer and crosslinking agent, respectively. The ionic conductivity of the film increased with an increasing concentration of LiClO4 and then decreased. The size of the quasicrystalline aggregation phase composed of pendant and crosslinking chains in the film decreased with an increasing concentration of LiClO4. The amorphous pendant and crosslinking oxyethylene chains gave rise to increased segmental motion and conductivity. The dissolution was depressed for a decrease in the ionic conductivity at a high LiClO4 concentration at which the interactions among ions became stronger and the crystal phase of LiClO4 was formed. The amount of the dissolution of the aggregation phase increased with an increasing crosslinking agent concentration. The quasicrystalline aggregation phase became larger with an increasing length of the pendant chains, and an increase in the size of the aggregation phase resulted in a decrease in the ionic conductivity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1272–1277, 2002
Synthesis, characterization, and thermal properties of phosphorus‐containing, wholly aromatic thermotropic copolyesters
Authors: Wang Yu‐Zhang , Chen Xiao‐Ting , Tang Xu‐Dong 
Published: August 2002

AbstractA series of phosphorus‐containing, wholly aromatic thermotropic copolyesters from acetylated 2‐(6‐oxide‐6H‐dibenz〈c,e〉〈1,2〉oxa phosphorin‐6‐yl)‐1,4‐dihydroxy phenylene, p‐acetoxybenzoic acid, terephthalic acid, and isophthalic acid were prepared by melting polycondensation. The structure and basic properties of the polymers, such as the glass‐transition temperature (Tg), melting temperature (Tm), thermal stability, crystallinity, and liquid crystallinity, were investigated with Fourier transform infrared, elemental analysis, differential scanning calorimetry (DSC), thermogravimetric analysis, wide‐angle X‐ray diffraction, and hot‐stage polarizing optical microscopy. The copolyesters had relatively high Tg values ranging from 183 to 192°C. The Tm values obtained from DSC curves for samples P‐20 and P‐25 were 290 and 287°C, respectively (where the number in the sample name indicates the molar fraction of the phosphorus‐containing monomer in the reactants). The initial flow temperatures of other samples observed with hot‐stage polarizing microscopy were 271–290°C. The 5% degradation temperatures in nitrogen ranged from 431 to 462°C, and the char yields at 640°C were 41–52%. All the copolyesters, except P‐40, were thermotropic and nematic. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1278–1284, 2002
Development of polylactide microspheres for protein encapsulation and delivery
Authors: Chandy Thomas , Das Gladwin S. , Wilson Robert F. , Rao Gundu H. R. 
Published: August 2002

AbstractThe development of injectable microparticles for protein delivery is a major challenge. We demonstrated the possibility of entrapping human serum albumin (HSA) and thrombin (Thr) in poly(ethylene glycol) (PEG)‐coated, monodisperse, biodegradable microspheres with a mean diameter of about 10 μm. In our earlier studies, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis was used to characterize the surface of PEG‐coated, taxol‐loaded poly(lactic acid) (PLA) microspheres. An analysis by DRIFTS revealed that PEG was incorporated well on the PLA microsphere surface. An emulsion of protein (in water) and PLA dissolved in an acetone–dichloromethane (or acetone–chloroform) mixture were poured into an aqueous solution of PEG [or poly(vinyl alcohol) (PVA)] with stirring with a high‐speed homogenizer for the formation of microparticles. HSA recovery in microspheres ranged from 13 to 40%, depending on the solvent and emulsification systems used for the preparation. PLA dissolved in a dichloromethane/acetone system and albumin loaded via a PEG emulsification solution (PLA–PEG–HSA) showed maximum drug recovery (39.5%) and drug content (9.9%). Scanning electron microscopy revealed that PEG‐coated microspheres had less surface micropores than PVA‐based preparations. The drug‐release behavior of microspheres suspended in phosphate‐buffered saline exhibited a biphasic pattern. An initial burst release (30%) followed by a constant slow release for 20 days was observed for HSA and Thr from PLA–PEG microspheres. PEG‐coated PLA microspheres show great potential for protein‐based drug delivery. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1285–1295, 2002
Impact resistance of fibrous glass reinforced plastics using polycarbonate‐polydimethylsiloxane block copolymer
Authors: Okamoto Masaya 
Published: August 2002

AbstractBy using reactive polydimethylsiloxanes that have phenolic hydroxyl groups at the ends of the chain, a polycarbonate‐polydimethylsiloxane (PC‐PDMS) block copolymer was prepared, and the properties of fibrous glass reinforced plastics (GF‐PC) using this copolymer were examined. The Izod impact value of the PC‐PDMS/GF composite increases with an increase in the degree of polymerization of reactive PDMS (n) between 40 and 160. When n is 40, the Izod impact value of the PC‐PDMS/GF composite is equal to that of the PC/GF composite. The Izod impact value is independent of the PDMS content of the copolymer when it is between 2 and 4 wt %. The PC‐PDMS/GF composite is superior, in the balance between fluidity and impact resistance, to the PC/GF composite. From the results of SEM, adhesion between the polymer and GF of the PC‐PDMS/GF composite is superior to that of the PC/GF composite. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1123–1127, 2002
Study of the I–V characteristics of organic light‐emitting diodes based on thiophene vynilic derivatives
Authors: Brovelli F. , Bernède J. C. , Marsillac S. , Díaz F. R. , Del Valle M. A. , Beaudouin C. 
Published: August 2002

AbstractOrganic light‐emitting diodes were obtained using a thiophene vynilic derivative polymer electrochemically synthesized. The electrochemistry of the thiophene vynilic derivative, 1,5‐bis(2‐thienyl)‐1,4‐pentadien‐3 one (CDV), was conducted in a nonaqueous media. The polymer was deposited on tin oxide (SnO2)‐coated glass substrates. The films obtained were physicochemically characterized by infrared absorption, a scanning microscope, microprobe X‐ray photoelectron analysis, and photoluminescence measurements. It was shown that the coverage efficiency of the films is very high. There is some oxygen contamination, not only at the surface, but also in the bulk of the polymers. The films are photoluminescent with emission between 660 and 720 nm. The current–voltage (I–V) characteristics exhibit a turn‐on voltage at about 2–4 V depending on the film thickness (120–250 nm). The electroluminescence–voltage (EL–V) curve has a similar shape but a shift of 1–2 V toward higher voltage. In the conducting state, there is no significant dependence of the temperature upon the current. All these facts cannot be explained easily by a simple thermionic model; a thermally activated tunneling effect appears more adequate. The current in the small potential domains has a behavior more or less erratic with a differential negative resistance and a switching effect. This behavior, arising from localized pathways, has a nature different from the injection processes, allowing electroluminescence. These pathways are related to surface heterogeneities (SnO2/polymer films) and aluminum diffusion. By not being directly related to electroluminescence, these pathways could induce a heating effect and an irreversible short‐circuit effect. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1128–1137, 2002
Remote detection and identification of organic remains: an assessment of archaeological potential
Authors: Ruffell Alastair 
Published: August 2002

AbstractThis paper reviews the various methods of using natural or induced light spectra as analytical tools in forensic archaeology. Chemical identification can be made at long range and wide scale (tens of metres) down to short range and very small scale (nanometres). The identification of organic gases and materials has used either chemical capture and chromatography, induced (laser or ultraviolet) light sources or laser Raman microscope spectroscopy. The remote gas detection method relies on the identification of atmospheric gases by their characteristic light spectra. Modern spectroscopes can detect gases down to a few parts per million of an atmosphere. When the light source (wavelength) and direction is controlled, so laser‐induced spectroscopy may be used to monitor the emission of gases such methane from buried organic remains. In order to identify the location of buried organic remains, a grid of sample points must be established using a base line or global positioning system. When matched to base line or ground‐positioning systems, such data can be manipulated by geographical information system packages. This would enable pinpointing of anomalies for excavation or avoidance. Microscope‐based laser Raman spectroscopy can be used to directly analyse captured gases, swabs and surfaces without the problems of long‐path detection. Copyright © 2002 John Wiley & Sons, Ltd.
The geophysical evaluation of British lead and copper working sites. Comparisons with iron working
Authors: Vernon R. W. , McDonnell G. , Schmidt A. 
Published: August 2002

AbstractRecent research at the University of Bradford has been very effective in evaluating early iron‐working sites using geophysical techniques. In addition, lead and copper smelting sites have been surveyed with a fluxgate gradiometer. Although the fluxgate gradiometer readings from these sites are lower than those from iron‐smelting sites it is possible to identify anomalies related to the different smelting methods. The paper provides details of some of the surveys and the different features that may be identified. Magnetic susceptibility measurements of selected slag samples provided additional information. Copyright © 2002 John Wiley & Sons, Ltd.
Georadar in the Roman civil town Carnuntum, Austria: an approach for archaeological interpretation of GPR data
Authors: Neubauer W. , Eder‐Hinterleitner A. , Seren S. , Melichar P. 
Published: August 2002

AbstractThe case study presented is a prime example of integrated geophysical–archaeological prospection. The aerial photographs available are complemented by non‐destructive geomagnetic and geoelectric surveys with a reading distance of 0.5 m or less. To gain depth information and provide higher resolution, ground‐penetrating radar (GPR) data are integrated. The GPR data were collected in a 0.5 × 0.05 m raster and visualized as black‐and‐white time or depth slices. The developments presented allow us to incorporate GPR into the standardized interpretation process of archaeological prospection based on a geographical information system (Grs). Using GPR and all the other prospection data available as a basis, a detailed three‐dimensional interpretation model of the monument detected, the southern part of the forum of the civil town of Roman Carnuntum, is created. Copyright © 2002 John Wiley & Sons, Ltd.