bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and characterization of coordination compounds of organotin(IV) with nitrogen and sulfur donor ligands
Authors: Singh Har Lal , Varshney A. K. 
Published: September 2002

AbstractThe reactions of dimethyltin dichloride with nitrogen and sulfur donor ligands derived by condensation of S‐benzyldithiocarbazate with indol‐3‐carboxylaldehyde, thiophene‐2‐aldehyde and furfuraldehyde have been investigated in 1:1 and 1:2 molar ratios in anhydrous alcohol. These ligands act as mononegatively charged bidentate species and coordinate to the central tin(IV) atom through the thiosulfur by proton exchange with the azomethine nitrogen. The newly synthesized complexes have been characterized by elemental analysis, conductance measurements and molecular weight determinations. The mode of bonding and the geometry of the complexes have been suggested on the basis of infrared, electronic and 1H, 13C and 119Sn NMR spectroscopy, and probable structures have been assigned to these complexes. A few representative ligands and their tin(IV) complexes have also been screened for their antifungal and antibacterial activities and found to be quite active in this respect. Copyright © 2001 John Wiley & Sons, Ltd.
Arsenic concentrations and speciation in the tissues of ringed seals (Phoca hispida) from Pangnirtung, Canada
Authors: Ebisuda Ken‐ichi , Kunito Takashi , Kubota Reiji , Tanabe Shinsuke 
Published: September 2002

AbstractConcentrations of total arsenic and arsenic compounds were determined in tissues of ringed seals (Phoca hispida) using hydride generation–atomic absorption spectrometry and high‐performance liquid chromatography–inductively coupled plasma mass spectrometry. Arsenic was accumulated at high concentrations in the blubber as lipid‐soluble arsenic compounds (arsenolipids). Arsenobetaine (AB) was the most predominant arsenical in the liver, kidney, muscle and gonad, accounting for about 70% of total arsenic in these tissues. Significant positive correlations were observed for AB concentrations among liver, kidney, muscle and gonad, suggesting that the distribution of AB among these tissues was at equilibrium. Concentrations of AB in the tissues were elevated up to 1–3 years of age, and then fell to a lower level. In contrast, dimethylarsinic acid concentration was significantly increased with age in the liver and kidney. Arsenocholine was also detected in the liver, kidney and gonad, but was not detected in the muscle. Among the arsenic compounds, only AB showed a considerable decrease of the concentration in the gastrointestinal contents with their passing through the gastrointestinal tract, which might indicate that the absorption rate of AB was higher than the absorption rates of other arsenic compounds in ringed seals. To our knowledge, this is the first report of arsenic speciation in several tissues and gastrointestinal contents in marine mammals. Copyright © 2002 John Wiley & Sons, Ltd.
Urinary arsenic species in an arsenic‐affected area of West Bengal, India
Authors: Tokunaga Hiroshi , Roychowdhury Tarit , Chandraskaran N. , Uchino Tadashi , Ando Masanori 
Published: September 2002

AbstractArsenic contamination of groundwater and associated medical problems have long been reported in the Mushidabad district, one of nine arsenic‐affected districts in West Bengal, India. In order to estimate people's total exposure to arsenic, we visited 12 arsenic‐affected families in that area during 4–7 December 2000 and collected seven tubewell waters used for drinking, cooking and other household purposes and 51 urine samples from those families. The arsenic concentrations in drinking water ranged from 2.7 to 170 ppb. Those families designated A–E, G–I and J took in arsenic concentrations of 72.6 ppb, 154 ppb and 170 ppb respectively. The concentrations of arsenite, arsenate, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) in urine (corrected for creatinine level in the urine), obtained from 51 persons, ranged from 0 to 796.9 ppb (mg creatinine/ml urine)−1, from 0 to 1635.2 ppb (mg creatinine/ml urine)−1, from 2.1 to 411.0 ppb (mg creatinine/ml urine)−1 and from 8.3 to 2017.5 ppb (mg creatinine/ml urine)−1 respectively. The average concentration of total arsenic was 59.2 ppb (mg creatinine/ml urine)−1. On comparison of the ratios of (MMA + DMA) to total arsenic, the average proportion of (MMA + DMA) was 83.2%, but the proportions were 27.3% and 16.5% for two of the children (2 years old and 13 years old respectively). This result suggested that they might be damaged due to the methylating capacity. When estimating arsenic species in urine obtained from families A–E, G–I and J, these family members normally metabolized the inorganic arsenic to MMA and DMA and eliminated these as such in comparison with an intake of inorganic arsenic from the tubewell water. The arsenic species in urine from people having the same food and life habits showed the same profile in both men and women. There was a good correlation (p < 0.05) between the ages of 19 persons in families A–E and the values of (MMA + DMA) or total arsenic in urine. Copyright © 2002 John Wiley & Sons, Ltd.
Investigation on preparation and protein release of biodegradable polymer microspheres as drug‐delivery system
Authors: Zhou Shaobing , Deng Xianmo , Yuan Minglong , Li Xiaohong 
Published: September 2002

AbstractAmong the different approaches to achieve protein delivery, the use of polymers, especially biodegraded, holds great promise. This work aimed to study the preparation and protein release of a novel drug‐delivery system based on human serum albumin (HSA) encapsulated into biodegradable polymer microspheres. The microspheres containing HSA were elaborated by the solvent‐extraction method based on the formation of multiple w/o/w emulsion. The encapsulation efficiency (E.E.) of HSA was determined by the CBB method. Alginate/alginate and calcium chloride was added into an internal aqueous phase to investigate the protein loading efficiency, protein stability, and in vitro release profiles. Microspheres were characterized in terms of their morphology, size distribution, loading efficiency, and in vitro protein release. SDS–PAGE results showed that HSA kept its structural integrity during the encapsulation and release procedure. In vitro studies indicated that the microspheres with alginate added in the internal aqueous phase had a smaller extent of burst release. In conclusion, the work presents a new approach for macromolecular drugs (such as protein drugs, vaccines, and peptide drugs) delivery. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 778–784, 2002; DOI 10.1002/app.10327
Structure‐property relationships of LLDPE—highly filled with aluminum hydroxide
Authors: Wang Genlin , Jiang Pingkai , Zhu Zikang , Yin Jie 
Published: September 2002

AbstractThe mechanical performance, rheological behavior, and phase morphology of linear low‐density polyethylene (LLDPE) highly loaded with aluminum hydroxide [Al(OH)3] were investigated. It was found that titanate surface‐active agent and ethylene‐vinyl acetate copolymer (EVA) improve the processing and ductile properties of the composite remarkably but are accompanied by the deterioration of the tensile strength. Addition of vinyl triethoxy silane (VTEO) and dicumyl peroxide (DCP) improves the tensile strength of the composite because of the silane crosslinking structure introduced. A synergistic effect of interface modifying and silane crosslinking method in improving mechanical performance of the composite is presented. Phase morphology of the LLDPE/Al(OH)3 composites was studied by means of scanning electron microscopy (SEM) technique. SEM micrographs indicate that a core‐shell type with Al(OH)3 as a core and EVA as a shell is formed in the composite. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2485–2490, 2002
Synthesis, characterization, and properties of polychelates of poly(styrene sulfonic acid‐co‐maleic acid) with Co(II), Cu(II), Ni(II), and Zn(II)
Authors: Rivas B. L. , Seguel G. V. , Geckeler K. E. 
Published: September 2002

AbstractPolymer metal complexes of poly(styrene sulfonic acid‐co‐maleic acid) and Cu(II), Ni(II), Co(II), and Zn(II) were synthesized. The magnetic, spectral, and thermal properties, as well as the electrical conductivities, of the chelates were investigated, and possible structures were assigned to the polychelates. Semiempirical calculations at the AM1 level were carried out on the geometrical arrangement of the polychelates. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2546–2551, 2002
Thermal degradation of film cast from aqueous polyurethane dispersions
Authors: Lu M. G. , Lee J. Y. , Shim M. J. , Kim S. W. 
Published: September 2002

AbstractIn this paper, water‐dispersible polyurethanes based on isophorone diisocyanate and polytetramethylene glycol were synthesized, and their thermal degradation behavior under nitrogen and air was studied by thermogravimetric (TG) analysis. The influence of NCO/OH ratio and functional group concentration was discussed. The thermal decomposition kinetics under nonisothermal conditions was analyzed using Ozawa method. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2552–2558, 2002
Morphology and thermal and mechanical properties of PBT/HIPS and PBT/HIPS‐g‐GMA blends
Authors: Yang Huili , Lai Mingfang , Liu Wanjun , Sun Chunrong , Liu Jiangjiang 
Published: September 2002

AbstractThe modification of high‐impact polystyrene (HIPS) was accomplished by melt‐grafting glycidyl methacrylate (GMA) on its molecular chains. Fourier transform infrared spectroscopy and electron spectroscopy for chemical analysis were used to characterize the formation of HIPS‐g‐GMA copolymers. The content of GMA in HIPS‐g‐GMA copolymer was determined by using the titration method. The effect of the concentrations of GMA and dicumyl peroxide on the degree of grafting was studied. A total of 1.9% of GMA can be grafted on HIPS. HIPS‐g‐GMA was used to prepare binary blends with poly(buthylene terephthalate) (PBT), and the evidence of reactions between the grafting copolymer and PBT in the blends was confirmed by scanning electron microscopy (SEM), dynamic mechanical analysis, and its mechanical properties. The SEM result showed that the domain size in PBT/HIPS‐g‐GMA blends was reduced significantly compared with that in PBT/HIPS blends; moreover, the improved strength was measured in PBT/HIPS‐g‐GMA blends and results from good interfacial adhesion. The reaction between ester groups of PBT and epoxy groups of HIPS‐g‐GMA can depress crystallinity and the crystal perfection of PBT. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2600–2608, 2002
Model for thickness effect with impact testing of viscoelastic materials
Authors: Kim Ho Sung , Shafig Robert M. 
Published: September 2002

AbstractThickness effect on impact parameters is studied and a model is developed for flat‐ended drop weight impact testing of viscoelastic materials. The model represents a relationship of specimen thickness with impact force/stress and impact energy. A polymeric material, ethylene vinyl acetate (EVA), was used for experimental verification. Experimental results for a thickness range of 1–9 mm at impact energy levels of 0.42, 0.96, and 1.54 J have been found to be in reasonable agreement with predictions based on the model with some approximated parameters. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1762–1767, 2001
Formulation and mechanical characterization of PVC plastisols based on low‐toxicity additives
Authors: Jimenez A. , Lopez J. , Iannoni A. , Kenny J. M. 
Published: September 2002

AbstractNew formulations of plastisols based on low‐toxicity plasticizers were proposed and characterized. Traditional phthalate plasticizers were replaced in the plastisols studied in this research by polymeric plasticizers (i.e., saturated polyesters), produced by the reaction of a diol and a carboxylic acid. The main drawback for the use of these plasticizers in formulations of PVC plastisols is a significant increase of the paste viscosity, which decreases their processability; thus, the use of additional additives to reduce viscosity is recommended. This study also includes the optimization of the processing conditions (cure temperature and time) of the proposed plastisols: complete cure was obtained at 140°C and 10 min. It is reported that the final properties of plastisols are very sensitive with respect to the processing conditions; in fact, insufficient plasticization or degradation can affect the material when processed out of the optimum conditions. The influence of the plasticizer concentration on mechanical and optical properties, such as tensile strength, hardness, brightness, and the like, is also reported. In summary, the proposed plastisols, with low‐toxicity plasticizers, offer a valid alternative to traditional PVC plastisols based on phthalate plasticizers. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1881–1890, 2001
Junction properties of metal/polypyrrole Schottky barriers
Authors: Abthagir P. Syed , Saraswathi R. 
Published: September 2002

AbstractSchottky barriers of the type Au/polypyrrole/Al (or In) were made in sandwich configuration. The conductivity of polypyrrole was tuned to be on the order of 10−3 ohm−1 cm−1 by its electrodeposition from a novel ambient temperature ternary eutectic melt consisting of acetamide, urea, and ammonium nitrate. The rectification characteristics were obtained from the current–voltage and capacitance–voltage measurements at room temperature. The analysis of data using thermionic emission theory gave improved values for the junction parameters of ideality factor, reverse saturation current, rectification ratio, and barrier potential when compared to the previously reported values for this polymer. Between Al and In metals used for the junction formation, the diode formed with Al metal is found to show better performance. The energy gap and work function of polypyrrole were also estimated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2127–2135, 2001
Oriented crystallization in fiber formation: Inferences from the structure and properties of melt spun syndiotactic polypropylene filaments
Authors: Sura Ravi K. , Desai Prashant , Abhiraman A. S. 
Published: September 2002

AbstractIn processes, such as melt spinning, the crystallization behavior of syndiotactic polypropylene (sPP) is found to be substantially different from that of most other linear polymers. The anisotropic stress field in such processes leads invariably to extension as well as alignment (orientation) of the chains in the melt, both of which contribute usually to dramatic enhancement in the rate of crystallization. However, since the primary structure of the sPP chain in its most preferred crystal form is comprised of a “coiled helical,” (T2G2)2, sequence, stress‐induced chain extension can lead to conformational sequences that are not favorable for crystallization in this form. As a consequence, process conditions that generate higher stress levels can cause a diminution in the rate of crystallization of this polymer. Such conformation‐related aspects of oriented crystallization of sPP have been addressed through an analysis of the structure and properties of melt‐spun fibers, produced over a range of spinning speeds. The results serve to identify a refinement that is needed in current models of oriented crystallization and also a mechanism to promote the nucleation of crystallization of sPP. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2305–2317, 2001
Modification of bismaleimide resin by poly(ethylene phthalate‐co‐ethylene terephthalate), poly(ethylene phthalate‐co‐ethylene 4,4′‐biphenyl dicarboxylate), and poly(ethylene phthalate‐co‐ethylene 2,6‐naphthalene dicarboxylate)
Authors: Iijima Takao , Ono Hiroshi , Tomoi Masao 
Published: September 2002

AbstractAromatic polyesters were prepared and used to improve the brittleness of bismaleimide resin, composed of 4,4′‐bismaleimidodiphenyl methane and o,o′‐diallyl bisphenol A (Matrimid 5292 A/B resin). The aromatic polyesters included PEPT [poly(ethylene phthalate‐co‐ethylene terephthalate)], with 50 mol % of terephthalate, PEPB [poly(ethylene phthalate‐co‐ethylene 4,4′‐biphenyl dicarboxylate)], with 50 mol % of 4,4′‐biphenyl dicarboxylate, and PEPN [poly(ethylene phthalate‐co‐ethylene 2,6‐naphthalene dicarboxylate)], with 50 mol % 2,6‐naphthalene dicarboxylate unit. The polyesters were effective modifiers for improving the brittleness of the bismaleimide resin. For example, inclusion of 15 wt % PEPT (MW = 9300) led to a 75% increase in fracture toughness, with retention in flexural properties and a slight loss of the glass‐transition temperature, compared with the mechanical and thermal properties of the unmodified cured bismaleimide resin. Microstructures of the modified resins were examined by scanning electron microscopy and dynamic viscoelastic analysis. The toughening mechanism was assessed as it related to the morphological and dynamic viscoelastic behaviors of the modified bismaleimide resin system. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2352–2367, 2001
Comparative study of the tribological properties of polyamide 6 filled with molybdenum disulfide and liquid crystalline additives
Authors: Bermúdez M. D. , Carrión‐Vilches F. J. , Martínez‐Mateo I. , Martínez‐Nicolás G. 
Published: September 2002

AbstractThe effect of adding a 1 wt % proportion of thermotropic liquid crystals 4,4′‐dibutylazobenzene (LC1) and 4‐octyl, 4′‐cyanobiphenyl (LC2) on the tribological properties of polyamide 6 (PA 6) is compared with that of the addition of MoS2 in different concentrations (1 and 5 wt %). Friction and wear are determined in a pin‐on‐disk tribometer by using injection‐molded additivated nylon disks against steel or aluminum pins, below (25°C) and above (80°C) glass transition temperature. Polymeric blends are characterized by differential scanning calorimetry and by optical and scanning electron microscopy and microanalysis. Concentration of liquid crystalline additives is higher at the surface than in the bulk of PA 6 disks. Crystallinity degree of PA‐6 is not significantly changed by the presence of additives. Addition of 1 wt % LC1 improves processibility of PA 6 by increasing its melt flow rate. Cyanoderivative liquid crystal (LC2) shows the best wear‐reducing ability for PA 6/steel contacts at all temperatures. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2426–2432, 2001
Thermal, thermomechanical, and electrochemical characterization of the organic–inorganic hybrids poly(ethylene oxide) (PEO)–silica and PEO–silica–LiClO4
Authors: Kweon Jung‐Ohk , Noh Si‐Tae 
Published: September 2002

AbstractTo study the effect of the silica content on the properties of the salt‐free and salt‐added hybrids based on poly(ethylene oxide) (PEO) and silica, two series of hybrids, PEO–silica and PEO–silica–LiClO4 (O:Li, 9:1) hybrids were prepared via the in situ acid‐catalyzed sol–gel reactions of the precursors [i.e., PEO functionalized with triethoxysilane and tetraethyl orthosilicate (TEOS)]. The morphology of the hybrids was examined by scanning electron microscopy (SEM) of the fracture surfaces of the hybrid. The results indicated that the discontinuity develops with increasing the weight percent of silica in both hybrids. The differential scanning calorimetric (DSC) analysis indicated that effects of silica content on the glass transition temperatures (Tg) of the PEO phase were different in salt‐free and salt‐added hybrids. The Tg of PEO phase increased with increasing weight percent of silica in salt‐free hybrids, whereas the curve of Tg of PEO phase and silica content had a maximum at 35 wt % of silica content in salt‐added hybrids. For both salt‐free and salt‐added hybrids, peaks of the loss tangent, determined by dynamic mechanical analysis (DMA) were gradually broadened and lowered with increasing weight percent of silica. The storage modulus, E′, in the region above Tg increases with increasing silica content for both PEO–silica and PEO–silica–LiClO4 hybrids. In the conductivity and composition curves for PEO–silica–LiClO4 hybrids, the conductivity shows a maximum value of 3.7 × 10−6 S/cm, corresponding to the sample with a 35 wt % of silica. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2471–2479, 2001
Structure/rheological properties relations of crosslinked potato starch suspensions
Authors: Dubois I. , Picton L. , Muller G. , Audibert‐Hayet A. , Doublier J. L. 
Published: September 2002

AbstractSome rheological properties of aqueous suspensions of crosslinked hydroxypropylated potato starches were investigated. The crosslinking was performed at a temperature above the gelatinization temperature and the degree of crosslinking varied between 0.05 and 0.75% wt. The samples were characterized by the swelling power Q and the average particle size D and observed by light microscopy and low‐temperature SEM. The swelling power decreases with the extent of crosslinking, whereas the average particle size increases. From these observations, the starch samples can be described as suspensions of deformable particles suspended in a continuous suspending medium constituted of polymer chains plus water. The rheological properties allow us to define different concentration regimes depending on the close packing of swollen particles at a concentration C*, which is close to 1/Q. In dilute conditions, that is, for C < C*, the viscosity is little influenced by the degree of crosslinking and, hence, by the particle size. Two domains can be defined: a “true dilute” one for C < 0.6C* and a semidilute one for C > 0.6C*, in which the viscosity rapidly increases with the concentration. Moreover, an apparent yield stress and elastic properties are observed in the concentrated regime, for C > C*. Two domains can be also defined: a first one for C < 2C*, in which the rheological characteristics sharply increase with the concentration, and a second one, a quasi‐plateau domain, for C > 2C*. The variations of these rheological properties suggest that the rigidity of the swollen particles can be considered, contrary to the viscosity in the true dilute regime. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2480–2489, 2001
Dynamic mechanical properties of polyimide/poly(silsesquioxane)‐like hybrid films
Authors: Tsai Mei‐Hui , Whang Wha‐Tzong 
Published: September 2002

AbstractPolyimide/poly(silsesquioxane)‐like (PI/PSSQ‐like) films have three‐dimensional structure with linear PI blocks and a crosslinked PSSQ‐like structure. They have higher thermal stability and char yields than pure PI from 4,4′‐diaminodiphenyl ether and 3, 3′‐oxydiphthalic anhydride (ODPA). In a series of X‐PIS [PI modified with p‐aminophenyltrimethoxysilane (APTS), where X is the molecular weight of each PI block] hybrid films, decreasing the PI block chain length enhances the storage modulus, tensile modulus, and glass‐transition temperature (Tg) but reduces the α‐relaxation damping peak intensity, density, and elongation. The change in the former three properties may be caused by an increase in the crosslinking density and rigidity of the network structure. The changes in the next two properties are caused by an increase in the free volume or the PI interblock separation and decreases in the interblock PI chain interaction. The change in the last property (i.e., a decrease in elongation) is related to the increase in the rigidity of the network structure. The activation energy of the α transition depends on the chain length of the PI block. A maximum value is reached at the chain length of 10,000 because of two different factors: crosslinking density and free volume. In a series of X‐PIS‐y‐PTS [X‐PIS modified with phenyltrimethoxysilane (PTS), where y is the weight‐ratio percentage of PTS to APTS–polyamic acid] films with a constant PI block length, the storage modulus, tensile modulus, Tg, density, and α‐relaxation damping peak intensity decrease with the PTS content. This could be because of the increase of the PSSQ‐like domain size with the PTS content, which leads to the introduction of more free volume or interblock separation and to a decrease in the interblock chain interaction force. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2500–2516, 2001