bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study on mobility of water and polymer chain in epoxy and its influence on adhesion
Authors: Luo Shijian , Leisen Johannes , Wong C. P. 
Published: August 2002

AbstractThis paper presents a study on the mobility of water and polymer chains in epoxy materials and its influence on the rate of adhesion degradation in a humid environment. Solid state nuclear magnetic resonance (NMR) techniques (both 1H NMR and 2H NMR) were used to study the binding states of water within two epoxy formulations along with the possible plasticizing effects of moisture affecting the mobility of polymer chains. Absorbed water reduces the glass transition temperature of polymeric materials. However, the presence of moisture has no significant effect on the polymer chain mobility at temperatures below the reduced glass transition temperature. Water in an epoxy in its rubbery state above the glass transition has a much higher mobility than in a polymer in its glassy state. The mobility of water absorbed by a polymer in its rubbery state is similar to that of pure water. The translational mobility of water within epoxies was studied by measuring the diffusion coefficient of water in epoxies through the water uptake. Higher rotational mobilities of water and polymer chains in the rubbery state lead to a significant increase of the water diffusion coefficient in the rubbery state polymer matrix as compared to a polymer in its glassy state. The higher mobility of absorbed water and the higher mobility of polymer chains in epoxy lead to faster adhesion degradation during aging in a humid environment. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1–8, 2002
Poly(sulfobetaine)s and corresponding cationic polymers. VIII. Synthesis and aqueous solution properties of a cationic poly(methyl iodide quaternized styrene–n,n‐dimethylaminopropyl maleamidic acid) copolymer
Authors: Lee Wen‐Fu , Chen Yan‐Ming 
Published: August 2002

AbstractA cationic poly(methyl iodide quaternized styrene–N,N‐dimethylaminopropylmaleamidic acid) copolymer was synthesized through amidoacidification reaction of styrene‐maleic anhydride copolymer with N,N‐dimethylaminopropylamine (ring‐opening reaction). Its properties in various aqueous salt solutions and pH solutions were studied by measurements of reduced viscosity and intrinsic viscosity. The results indicated that the reduced viscosity and intrinsic viscosity of this cationic polyelectrolyte were related to the type and concentration of the added salts and the results also showed a contrary tendency in some salts with monovalent acid groups to polyelectrolyte. At the same time, some salt ions were observed to strongly attract the quaternary ammonium group of the cationic polymeric side chain and resulted in agglomeration of the polymers. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1619–1626, 2001
Modeling of fractionation in CRYSTAF using Monte Carlo simulation of crystallizable sequence lengths: Ethylene/1‐octene copolymers synthesized with single‐site–type catalysts
Authors: Beigzadeh D. , Soares J. B. P. , Duever T. A. 
Published: August 2002

AbstractMonte Carlo simulation was used to model the fractionation process in crystallization analysis fractionation (CRYSTAF). Five poly(ethylene/1‐octene) samples synthesized with a single‐site–type catalyst were used to verify the simulation results. It was proposed that the fractionation mechanism be controlled by the crystallization of the longest ethylene sequence in each chain. Good agreement between experimental and simulation results verified the validity of the proposed fractionation mechanism. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2200–2206, 2001
Production of a high‐functionality RBD palm kernel oil‐based polyester polyol
Authors: Badri K. H. , Ahmad S. H. , Zakaria S. 
Published: August 2002

AbstractA diol‐based refined, bleached, and deodorized (RBD) palm kernel oil polyol was prepared. It was found that the polyurethane foam produced only gives a good compressive strength property at a 45 kg/m3 molded density. The combination of sorbitol into the polyol system resulted in a better dimensional stability and improved thermal conductivity as well as enhanced compressive strength. These were obtained by increasing the functionality of the polyol (functionality of 4.5) through introduction of a high molecular weight and branching polyhidric compound. Direct polycondensation and transesterification methods were used for the syntheses. The hydroxyl value, TLC, and FTIR were used to study the completion of the reaction. A comparative study of the mechanical properties and morphological behavior was carried out with a diol‐based polyol. From the water‐blown molded foam (zero ODP) with a density of about 44.2 kg/m3 and a closed‐cell content of 93%, a compressive strength of 222 kPa and a dimensional stability of 0.09, 0.10, and 0.12% at the length, width, and thickness of the foam, respectively, conditioned at −15°C for 24 h, were obtained. The thermal conductivity improved to an initial value of 0.00198 W/mK, tested at 0°C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 384–389, 2001
Synthesis and properties of elastomer‐modified epoxy–methacrylate sequential interpenetrating networks
Authors: Sands J. M. , Jensen R. E. , Fink B. K. , McKnight S. H. 
Published: August 2002

AbstractThe structure and properties of copolymerized sequential‐interpenetrating networks (SeqIPNs) synthesized from amine‐cured epoxies and free‐radical polymerized dimethacrylates were examined. Materials were synthesized with and without the incorporation of an epoxy‐terminated butadiene–nitrile reactive elastomer. Synthesis proceeded through full thermal cure of the epoxy–amine network, followed by polymerization of the methacrylate network. The methacrylate reactions were free‐radically induced using thermal (peroxide‐initiated) or photochemical [electron‐beam (e‐beam)] techniques. Fourier transform infrared spectroscopy was used to monitor epoxy–amine step‐growth polymerization in situ and to measure final cure conversion of methacrylates. Structural examination of the IPNs using atomic force microscopy and scanning electron microscopy revealed microphase separation in the neat–SeqIPN materials and macroscopic phase separation of rubber‐rich domains for elastomer‐modified networks. Dynamic mechanical analysis of the SeqIPN determined that the properties of the network are strongly dependent on the cure conditions. Furthermore, the viscoelastic behavior of the e‐beam–cured SeqIPN could be adequately described by the Williams–Landel–Ferry and Kohrausch–Willams–Watts equations, presumably because of a strong coupling between the epoxy–amine and methacrylate networks. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 530–545, 2001
Effect of a styrene–butadiene copolymer on the phase structure and impact strength of polyethylene/high‐impact polystyrene blends
Authors: Fortelný I. , Michálková D. , Hromádková J. , Lednický F. 
Published: August 2002

AbstractThe effect of a styrene–butadiene block copolymer on the phase structure and impact strength of high‐density and low‐density polyethylene/high‐impact polystyrene blends with various compositions was studied. For both the blends, the type of the phase structure was not affected by addition of a styrene–butadiene compatibilizer. The localization and structure of the compatibilizer in the blends were dependent on their composition. Addition of the compatibilizer improved impact strength of the blends in the whole concentration range. The improvement was the largest for blends with a low amount of the minor phase. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 570–580, 2001
Efficiency of some dinitrodiamines and dinitrodiamides in improving dynamic properties of vulcanized rubber
Authors: Klásek A. , Filipovičová E. , Špaček J. 
Published: August 2002

AbstractThe effect of some dinitrodiamines and dinitrodiamides on dynamic properties of vulcanized rubber have been investigated. Rubber compounds based on NR/BR were used for these experiments. It has been established that only the use of dinitrodiamines contribute to the increase of impact resilience in comparison with the unmodified compound. The results of carbon gel content assessment suggest that, under given conditions, dinitrodiamides do not form bonds between rubber and carbon black and, therefore, do not influence the dynamic properties of vulcanized rubber. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1439–1443, 2001
High‐performance bismaleimide resin film for resin film infusion
Authors: Liang Guozheng , Wang Dong 
Published: August 2002

AbstractA novel high‐performance resin film, coded 4508B, suitable for the resin film infusion (RFI) process, was developed. It was prepared from 4,4′‐bismaleimidodiphenylmethane (BDM), o,o′‐diallylbisphenol A (BA), polyethersulfone (PES), and polyimide (PI). The resin and its composite, reinforced by glass fiber cloth, were prepared and characterized in detail. The results showed that the resin film was stable at room temperature, its infusion temperature was 120°C, and the pot life was more than 60 min. In addition, the cured resin and the composite prepared by the RFI process had good thermal and mechanical properties and hot‐wet resistance. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2918–2922, 2001
Temperature and atmosphere influences on smoke composition during thermal degradation of poly(ethylene terephthalate)
Authors: Dziȩcioł Małgorzata , Trzeszczyński Jerzy 
Published: August 2002

AbstractThe less‐volatile compounds forming a smoke emitted during the thermal degradation of poly(ethylene terephthalate) (PET) in different conditions were studied. Thermal degradation of PET was carried out within the temperature range of 200–700°C in both a nitrogen and an air atmosphere. The less‐volatile thermal degradation products were trapped on a glass‐fiber filter and analyzed by capillary gas chromatography with mass selective detector (GC‐MS) and high performance liquid chromatography (HPLC). The results are collected in tables and presented on plots as a function of the degradation temperature. The temperature and atmosphere effects on the emission and composition of the smoke during PET thermal degradation were considered. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3064–3068, 2001
Synthesis of starch‐graft‐polyacrylonitrile hydrolyzate and its characterization
Authors: Sugahara Yasusato , Ohta Takahisa 
Published: August 2002

AbstractThe graft copolymerization of three vinyl monomer species, acrylonitrile (AN), acrylamide (AAm), and acrylic acid (AA), onto starch was carried out with ceric salt (Ce salt) as an initiator. With 3 mmol/L Ce salt, the monomer activity onto starch decreased in the following order: AN > AAm > AA. Grafting efficiency with AN as the grafting monomer was greater than 90%, but with AA and AAm, it was less than 50%. Starch‐graft‐polyacrylonitrile was hydrolyzed to introduce amide and carboxyl groups into starch. The hydrolyzates were analyzed with infrared spectroscopy. The hydrolysis reaction was accelerated with increasing alkali concentration, reaction temperature, and time. The water absorbancy of the hydrolyzate increased with an increasing carboxyl molar fraction in the polymer, and it dissolved in water above a 0.6 molar fraction. The absorbancy of water was 2 times higher than that of a NaCl aqueous solution. The copper‐ion‐exchange capacity of the sample was greater in graft copolymers with higher carboxyl group contents. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1437–1443, 2001
Surface chemical modification of natural cellulose fibers
Authors: Baiardo Massimo , Frisoni Giovanna , Scandola Mariastella , Licciardello Antonino 
Published: August 2002

AbstractSimple esterification and etherification reactions were applied to steam‐exploded Flax (Linum usitatissimum) with the aim of changing the surface properties through modification of fiber surface chemistry. Native and chemically modified cellulose fibers were characterized in terms of thermal stability, surface chemistry, morphology, and crystal structure. Independent of the substituent nature, chemically modified fibers exhibited a thermal stability comparable to that of native cellulose. Introduction of the desired chemical groups at the fiber surface was demonstrated by TOF‐SIMS analysis, whereas FTIR showed that the substitution reaction involved only a small fraction of the cellulose hydroxyls. No change of the native crystalline structure of cellulose fibers was caused by chemical modification, except in the case where ether substitution was carried out in water‐isopropanol medium. Cellulose fibers with unchanged structure and morphology and carrying at the surface the desired chemical groups were obtained for reinforcing applications in polymer composites. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 38–45, 2002
Correlation of blend and pure component viscosities
Authors: Couchman P. R. 
Published: August 2002

AbstractAn equation for the viscosity of single‐phase blends is derived by considering the fractions of the various kinds of bonds. For binary blends a quadratic term in viscosity is associated with unlike interactions in the melt. Both negative and positive deviations from the logarithmic rule of mixtures are possible. These deviations need not be connected to specific interactions. An extremum can occur and conditions for this are examined. In principle either an absolute maximum or an absolute minimum can occur. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 455–456, 2002
Finishing of textile materials
Authors: Bajaj Pushpa 
Published: August 2002

AbstractWith increasing awareness of environmental concerns, various chemical finishes for processing of textiles have been discussed. In this paper major changes which have occured to satisfy the consumer's demand in terms of comfort, easy care, health, and hygiene are reviewed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 631–659, 2002
Lymphocytes in the bronchoalveolar space reenter the lung tissue by means of the alveolar epithelium, migrate to regional lymph nodes, and subsequently rejoin the systemic immune system
Authors: Lehmann Christine , Wilkening Anja , Leiber Daniela , Markus Astrid , Krug Norbert , Pabst Reinhard , Tschernig Thomas 
Published: August 2002

AbstractLymphocytes in the bronchoalveolar space are routinely obtained and examined in lung diseases such as asthma or sarcoidosis. In a pig model, labeled lymphocytes were found in regional lymph nodes after intrabronchial instillation, indicating that reentry of lymphocytes from the bronchoalveaolar space into the body is possible. In the present study, the route and kinetics of the reentry of bronchoalveolar lymphocytes were investigated in a congenic rat model using immunohistochemistry on cryostat and semithin sections and confocal laser scanning microscopy. As early as 15 min after intratracheal instillation lymphocytes were found to leave the bronchoalveolar space by transmigration through alveolar but not bronchial epithelium and were observed in interstitial alveolar tissue. At 6 hr after intratracheal instillation, T and B lymphocytes appeared in the draining lymph nodes of the lung with an increase after 24 and 48 hr. The kinetic pattern clearly differed in nondraining lymph nodes and other organs. After 6 hr, only single cells were found in nondraining lymph nodes, spleen, and blood with a slight increase after 24 hr, and only occasionally were single cells seen in the liver, thymus, or Peyer's patches 24 and 48 hr after instillation. In conclusion, T and B lymphocytes can leave the alveolar space by reentry into the lung tissue through alveolar epithelium. They reach regional lymph nodes by means of lymphatic vessels and are then distributed all over the body to rejoin the systemic immune system. Coming into contact with environmental antigens, these lymphocytes could perform an important function in the lung immune system and might be a target for inhalative therapy. Anat Rec 264:229–236, 2001. © 2001 Wiley‐Liss, Inc.
Effect of culture medium on the in vitro secretion activity of prothoracic glands from Pseudaletia separata
Authors: Komiya Kazuyo , Agui Noriaki , Mitsuhashi Jun 
Published: August 2002

AbstractThe prothoracic glands (PGs) taken from the last instar of the common armyworm, Pseudaletia separata, were cultured in various media for the purpose of finding a suitable medium for relatively long‐term culture of PGs. Among the tested culture media, MGM‐450 medium without serum was the best to maintain PG cells viable for relatively long periods, and to continue to secrete ecdysteroids. Secretion of ecdysteroid by the PG in vitro became marked when the PG was taken from last instar larvae older than 2 days after the last molt. PGs cultured in any of the media secreted ecdysteroid only within the first 2 h after placing them in culture, however, in the MGM‐450 medium, the PGs secreted ecdysteroid even after 5 days of culture. Arch. Insect Biochem. Physiol. 38:147–154, 1998. © 1998 Wiley‐Liss, Inc.
Nitric oxide–mediated chondrocyte cell death requires the generation of additional reactive oxygen species
Authors: Del Carlo Marcello , Loeser Richard F. 
Published: August 2002

AbstractObjectiveChondrocyte cell death, possibly related to increased production of endogenous nitric oxide (NO), has been observed during the pathogenesis of osteoarthritis and rheumatoid arthritis. The purpose of this study was to investigate the potential role of NO in causing chondrocyte cell death and to determine the contribution of other reactive oxygen species (ROS).MethodsCell death and cytotoxicity were evaluated in human articular chondrocytes in response to various NO donor compounds with and without agents that stimulate or inhibit the production of additional ROS using both the alginate bead and the monolayer culture systems. Cell death was quantified by a total cell count with fluorescent labels, and cytotoxicity was measured as a function of cellular NADH‐ and NADPH‐dependent dehydrogenase activity. To determine if the redox status of the chondrocyte could influence the observed effect of NO, cells were preincubated for 24 hours in L‐cystine– and glutathione (GSH)–depleted media to reduce intracellular GSH levels, a major defense mechanism against oxidative stress. Apoptosis was analyzed with the quantification of histone‐associated DNA fragments.ResultsTreatment of chondrocytes with peroxynitrite (ONOO−), 3‐morpholinosydnonimine (SIN‐1), and sodium nitroprusside (SNP) resulted in apoptotic cell death at concentrations of 0.5 mM, 1.0 mM, and 0.5 mM, respectively. In contrast, treatment of chondrocytes with diazeniumdiolates (or the “NOC” compounds, NOC‐5 and NOC‐12) at concentrations as high as 2.0 mM did not cause cell death. Furthermore, NOC‐5 and NOC‐12, at all concentrations tested (0.125–2.0 mM), could prevent cell death caused by oxidative stress. Selective ROS scavengers protected against cell death caused by either SIN‐1 or ONOO−; however, no protection could be afforded against the cytotoxicity of SNP with any of the ROS scavengers tested.ConclusionThese results show that NO by itself is not cytotoxic to cultured chondrocytes and can even be protective under certain conditions of oxidative stress. Chondrocyte cell death from NO occurs under conditions where other ROS are also generated.
Cognitive styles and hypermedia navigation: Development of a learning model
Authors: Chen Sherry Y. , Macredie Robert D. 
Published: August 2002

AbstractThere has been an increased growth in the use of hypermedia to deliver learning and teaching material. However, much remains to be learned about how different learners perceive such systems. Therefore, it is essential to build robust learning models to illustrate how hypermedia features are experienced by different learners. Research into individual differences suggests cognitive styles have a significant effect on student learning in hypermedia systems. In particular, Witkin's Field Dependence has been extensively examined in previous studies. This article reviews the published findings from empirical studies of hypermedia learning. Specifically, the review classifies the research into five themes: nonlinear learning, learner control, navigation in hyperspace, matching and mismatching, and learning effectiveness. A learning model, developed from an analysis of findings of the previous studies, is presented. Finally, implications for the design of hypermedia learning systems are discussed.
Digital reference: Reference librarians' experiences and attitudes
Authors: Janes Joseph 
Published: August 2002

AbstractThis article reports the results of a survey of reference librarians in public and academic libraries of various sizes in the United States, asking them about their experiences with and attitudes towards the use of digital and networked technologies and resources in reference work. A total of 648 responded. In general, respondents were positive and optimistic in their outlook, but not unreservedly so. Among the strongest findings was a correlation between recent experience at doing digital reference and positive attitudes towards it, a clear set of opinions about what such services would be best and worst at, and differing perspectives and patterns of responses between academic and public librarians. In addition, questions asking about characteristics of librarians, their current and planned reference services, and some of their professional choices in doing reference work are reported.
Bayesian data mining, with application to benchmarking and credit scoring
Authors: Giudici Paolo 
Published: August 2002

AbstractThe purpose of this article is to show that Bayesian methods, coupled with Markov chain Monte Carlo computational techniques, can be successfully employed in the analysis of highly dimensional complex datasets, such as those occurring in data mining applications. Our methodology employs conditional independence graphs to localize model specification and inferences, thus allowing a considerable gain in flexibility of modelling and efficiency of the computations. Copyright © 2001 John Wiley & Sons, Ltd.
Managing uncertainty in call centres using Poisson mixtures
Authors: Jongbloed Geurt , Koole Ger 
Published: August 2002

AbstractWe model a call centre as a queueing model with Poisson arrivals having an unknown varying arrival rate. We show how to compute prediction intervals for the arrival rate, and use the Erlang formula for the waiting time to compute the consequences for the occupancy level of the call centre. We compare it to the current practice of using a point estimate of the arrival rate (assumed constant) as forecast. Copyright © 2001 John Wiley & Sons, Ltd.