bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of tacticity of poly(methyl methacrylate) on the miscibility with poly(vinyl pyrrolidone)
Authors: Hsu Wen‐Ping 
Published: August 2002

AbstractIsotactic, atactic, and syndiotactic poly(methyl methacrylates) (PMMA) (designated iPMMA, aPMMA, and sPMMA) with approximately the same molecular weight were mixed separately with poly(vinyl pyrrolidone) (PVP) primarily in chloroform to make three polymer blend systems. Differential scanning calorimetry (DSC) was used to study the miscibility of these blends. The results showed that the tacticity of PMMA has a definite impact on its miscibility with PVP. The aPMMA/PVP and sPMMA/PVP blends were found to be miscible because all the prepared films showed composition‐dependent glass‐transition temperatures (Tg). The glass‐transition temperatures of the aPMMA/PVP blends are equal to or lower than weight average and can be qualitatively described by the Gordon–Taylor equation. The glass‐transition temperatures of the other miscible blends (i.e., sPMMA/PVP blends) are mostly higher than weight average and can be approximately fitted by the simplified Kwei equation. The iPMMA/PVP blends were found to be immiscible or partially miscible based on the observation of two glass‐transition temperatures. The immiscibility is probably attributable to a stronger interaction among isotactic MMA segments because its ordination and molecular packing contribute to form a rigid domain. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3190–3197, 2001
Synthesis and characterization of novel hydroxyl‐terminated NN–bonded resins
Authors: Sridhara K. , Jain S. R. 
Published: August 2002

AbstractNovel resins containing carbonyl or thiocarbonyl moiety; NN bonds; ethereal linkage; and terminal hydroxyl groups, that is, bis(bisvanillincarbonohydrazone‐4′‐oxy)butane 1,4‐diyldiether and bis(bisvanillinthiocarbonohydrazone‐4′‐oxy)butane 1,4‐diyldiether, have been synthesized by condensing bisvanillincarbono‐ and bisvanillinthiocarbono‐hydrazone, respectively, with 1,4‐dibromobutane. The resins were characterized by elemental and hydroxyl equivalent analyses, infrared and 1H– and 13C–NMR spectra, and other properties relevant to their use as propellant binders, such as calorific value, thermal analysis, viscosity, and burning rate measurements. Both these resins have convenient viscosity, indicating their suitability as binders for processing high solid loading, at slightly above room temperature. The resins could be cured easily with toluene diisocyanate and glycerol. The DTA–TG data show that the cured samples start to decompose exothermically at relatively low temperatures, in the range around 160°C. The resins ignite immediately on coming in contact with pure nitric acid, indicating their hypergolic nature. The burning rates of the ammonium perchlorate–based propellant compositions having these resins as binders are much higher than those processed with a conventional butadiene binder. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3204–3211, 2001
CHT and TTT curing diagrams of polyflavonoid tannin resins
Authors: Garnier S. , Pizzi A. 
Published: August 2002

AbstractTTT and CHT curing diagrams for tannin‐based adhesives were built by thermomechanical analysis (TMA) by following the in situ hardening directly in a wood joint, and the curve trends observed were similar to those previously observed for synthetic polycondensation resins on lignocellulosic substrates. Of the parameters that most influence the relative position of vitrification and gel curves on the diagrams (i.e., where the influence has been quantified), chief among them is the reactivity of the tannin with formaldehyde and any factor influencing it: thus, the inherent higher reactivity of the A‐ring of the tannin (such as in procyanidins versus prorobinetinidins) and the pH of the tannin solution. The percentage formaldehyde hardener has some influence in CHT diagrams, especially for the slower‐reacting tannins, but practically no influence in TTT diagrams within the 4–10% formaldehyde range used. As in the case of synthetic polycondensation adhesive resins, regression equations relating the internal bond strength of a wood particleboard, prepared under controlled conditions, with the inverse of the minimum deflection, obtained by constant heating rate TMA of a wood joint during resin cure, have been obtained for the two types of tannins of lower reactivity (profisetinidins/prorobinetinidins) but not for the faster‐reacting procyanidin and prodelphinidin tannins. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3220–3230, 2001
Synthesis and properties of high‐performance and good water‐soluble melamine–formaldehyde resin
Authors: Su Lihong , Qiao Shengru , Xiao Jun , Tang Xuan , Zhao Guodong , Fu Shengwang 
Published: August 2002

AbstractIn this article, high‐sulfonated melamine–formaldehyde (HSMF) resins were prepared with a sulfite/melamine (S/M1.5) molar ratio. During the sulfonation process, the reaction temperature and the added velocity of sodium bisulfite affecting the properties of the resin were studied. In the condensation stage, where the pH range is 6.0 and the temperature is about 25°C, the condensation time was prolonged above 24 h. The stability and water solubility of the resin was improved greatly. It is an effective superplasticizer at small dosages of admixture. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3268–3271, 2001
Preparation of polyvinyl alcohol hydrogel through the selective complexation of amorphous phase
Authors: Hari P. R. , Sreenivasan K. 
Published: August 2002

AbstractSeveral methods for the preparation of polyvinyl alcohol (PVA) hydrogel are being reported in the literature. In this communication a new, simple, and mild complexation reaction using phenyl boronic acid, leading to a highly elastic PVA hydrogel, is addressed. It is found that the inherent crystalline property of the semicrystalline PVA is retained by the complexation reaction, which is confined to the amorphous region. An enhanced mechanical property, particularly in the wet condition, is observed after the modification resulting from the intact crystallinity. Also, the inherent nontoxic characteristic property of PVA is unaffected upon this complexation reaction. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 143–149, 2001
Water‐soluble polymers. LXXXII. Shear degradation effects on drag reduction behavior of dilute polymer solutions
Authors: Cowan Martin E. , Hester Roger D. , Mccormick Charles L. 
Published: August 2002

AbstractDrag reduction measurements were conducted on extensively characterized poly(ethylene oxide) and poly(acrylamide) utilizing a fully automated rotating disk rheometer equipped with an optical tachometer, torque transducer, and software allowing real‐time data acquisition. The instrument sensitivity allowed the study of concentrations as low as 0.1 ppm. In addition, previously immeasurable concentration‐ and time‐dependent shear degradation effects were readily observed. A power law equation was shown to adequately correlate the percentage of drag reduction and the volume fraction for each polymer. Furthermore, an empirical shift factor was utilized to superimpose data from all the systems that were studied. By conducting measurements in the proper concentration and time domains, it was possible to extract the minimal concentration for the maximum drag reduction efficiency in the absence of shear degradation. The resulting values were significantly higher than those previously reported by our laboratories for poly(ethylene oxide) and poly(acrylamide). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1211–1221, 2001
Kinetic studies on styrene–divinylbenzene copolymerization by suspension technique
Authors: Kiatkamjornwong Suda , Chientachakul Panomsak , Prasassarakich Pattarapan , Damronglerd Somsak 
Published: August 2002

AbstractKinetic studies on styrene and divinylbenzene (DVB) copolymerization by the suspension technique in a toluene diluent initiated by benzoyl peroxide are reported. Evaluation of the important reaction parameters is carried out. The crosslinked styrene–DVB copolymers can absorb toluene to a maximum swelling ratio of 17. The absorption/desorption took place instantaneously and reached the maximum value within 10 min, and it could be repeated many times, yet gave the consistent result. Rate equations evaluated by both integral and differential methods are investigated. High monomer orders of 1.5–2.3 were obtained. The activation energy for the polymerization was about 40 kcal/mol−1. Autoacceleration was found even at low conversions. The acceleration was influenced by both monomer, crosslinker, and initiator concentrations. The integral and differential methods for the rate evaluation were compared, and the relationship between the rate equation and polymerization behavior was elucidated. The kinetic orders determined for this copolymerization show considerable deviation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1521–1540, 2001
Synthesis and characterization of two polytrimellitamideimide series with different segment order by direct polycondensation
Authors: Yang Chin‐Ping , Wei Chi‐Shu 
Published: August 2002

AbstractPoly(amide–imide) (PAI) could be synthesized in regular segment order from trimellitic anhydride (TMA) and various aromatic diamines. By different processes, PAIh‐h‐t‐t containing alternating (amide–amide)–(imide–imide) sequences and PAIh‐t containing amide–imide sequences could be obtained through direct polycondensation. Comparison of PAIh‐h‐t‐t and PAIh‐t, which had different sequence orders and were prepared from TMA and 12 diamines, showed that the latter had better solubility and needed less quantity of solvent and salt (CaCl2) during polymerization, but both two series PAI using p‐substituted diamines (e.g., p‐phenylenediamine) showed poor solubility. Series PAIh‐h‐t‐t possessed larger initial modulus but smaller elongation at break than series PAIh‐t. For the thermal properties, most of series PAIh‐t had glass transition temperatures higher than corresponding series PAIh‐h‐t‐t, but these two series were similar in the 10% weight loss temperatures and the char yields at 800°C in nitrogen. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1556–1567, 2001
Effect of blending polyethersulfone on the cure kinetics and physical properties of dicyanate resin
Authors: Kim Dae Su , Lee Seok Kyu 
Published: August 2002

AbstractThe curing behavior and thermomechanical properties of dicyanate/polyethersulfone (PES) blends were investigated. Differential scanning calorimetry (DSC) was used to study the curing behavior of the dicyanate/PES blends. A second‐order autocatalytic reaction mechanism was used to describe the cure kinetics of the blends. The reaction kinetic parameters were determined by fitting DSC conversion data to the kinetic equation. The main glass‐transition temperatures of the blends decreased with increasing PES content. Two glass‐transition temperatures indicating phase‐separated morphology of the blends were observed. The thermal decomposition behavior of the blends was measured using thermogravimetric analysis. Mechanical and electrical properties of the blends were investigated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1952–1962, 2001
Sorption of chromium (VI) by spent grain under batch conditions
Authors: Low Kun‐She , Lee Chnoong Kheng , Low Choy Hoong 
Published: August 2002

AbstractBatch experiments were performed to evaluate the ability of spent grain to remove chromium (VI) from aqueous solution. Parameters investigated include pH, contact time, sorbent dosage, agitation rate, and the presence of other anions. Application of the Langmuir isotherm to the Cr(VI)–spent grain system provided a maximum sorption capacity of 18.94 mg/g. This value compares favorably with other reported values for low‐cost materials. Anions such as phosphate, arsenate, nitrate, and sulfate were antagonistic toward the uptake of Cr(VI) by spent grain. It was successful in removing Cr(VI) from a sample of electroplating waste. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2128–2134, 2001
Synthesis of calcium‐containing methacrylate resin
Authors: Abraham Elizabeth K. , Francis Anju , Ramesh P. , Joseph Roy 
Published: August 2002

AbstractThe calcium salt of p‐aminobenzoic acid [p‐ABA(Ca)] was reacted with epichlorohydrin to yield the multifunctional epoxy resin. The epoxy resin was characterized by IR spectroscopy, epoxy equivalent, calcium estimation, high performance liquid chromatography (HPLC) and refractive index. The epoxy resin was further reacted with methacrylic acid to yield the calcium containing methacrylate resin, which was characterized by IR, hydroxyl value, iodine value, HPLC and refractive index. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2342–2346, 2001
Semicontinuous emulsion polymerization of styrene–butyl acrylate–methacrylic acid with high solid content
Authors: Tang Chuanbing , Chu Fuxiang 
Published: August 2002

AbstractHigh‐solid‐content (>60 wt %) lattices of styrene (St), butyl acrylate (BA), methacrylic acid (MMA), and N‐hydroxymethacrylic amide (NMA) were prepared through semicontinuous emulsion polymerization. In order to obtain high‐solid‐content lattices with low viscosity, the intermediate emulsion (IE) of the two‐stage pathway had to have viscosity kept low, and so the amount of surfactant for the second stage was about 5–6 wt %. The relationships between IE viscosity and coagulum formation and between surfactant concentration and viscosity are discussed in this article. Particle size and particle size distribution (PSD) were investigated and are also discussed. Lattices through the two‐stage pathway were found to have a bimodal PSD and good mechanical and chemical stability. However, lattices through the one‐stage pathway had a narrow PSD and low mechanical and chemical stability. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2352–2356, 2001
Characterization of styrene/methacrylic acid copolymers by 2D‐NMR spectroscopy
Authors: Brar A. S. , Hekmatyar S. K. 
Published: August 2002

AbstractStyrene/methacrylic acid copolymers were prepared by free‐radical photopolymerization using the uranyl nitrate ion as the initiator. The copolymer composition was determined from 1H‐NMR spectroscopy. The comonomer reactivity ratios determined using Kelen Tudos and nonlinear error in variable methods (EVM) are rm = 0.61 ± 0.05 and rs = 0.14± 0.07. The broad and overlapping 1H‐NMR spectrum was assigned using the help of 2D TOCSY and NOESY experiments. These methods were used to ascertain the various geminal, vicinal, and spatial couplings between the protons. The methyl and methine protons also show configurational and compositional sensitivity. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2444–2453, 2001
Study of different types of monomer emulsion feedings to semibatch emulsion polymerization reactors
Authors: Sajjadi S. 
Published: August 2002

AbstractSemibatch emulsion polymerization processes with a monomer emulsion feed are of great importance in both academia and industry. Monomer emulsion feeds can be applied to semibatch reactors using either a stream of an emulsified monomer or two streams of a neat monomer feed and an aqueous solution of an emulsifier. The effect of the feeding policy on the rate of polymerization and on the secondary particle formation was studied for a seeded semibatch emulsion polymerization of styrene. When a single‐stream monomer emulsion feed is applied to a semibatch process, the monomer‐swollen micelles formed in the feed might become the locus of initiation upon entering the reaction vessel. Under the conditions of this study, the application of monomer emulsion feed in either one stream or two streams did not result in secondary particle formation. The incoming monomer‐swollen micelles were disintegrated to supply emulsifier molecules for the stability of growing particles, before they can capture radicals and become polymer particles. The rate of polymerization was found to be independent of the way that the monomer emulsion feed is added. In the absence of nitrogen, the rate of polymerization decreased more appreciably for the monomer emulsion feed, due to the oxygen dissolved in the emulsified monomer. The number of particles, however, was not affected by the purging policy. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2472–2477, 2001
Rheological and mechanical properties of polycarbonate–liquid‐crystalline polymer blends with controlled chemical reactions
Authors: Bum Seung , Kil  , Ok O , Park  , Yoon Kwan Han 
Published: August 2002

AbstractChemical reactions can occur during the melt blending of polymers containing an ester group because ester groups are usually unstable at high temperatures; this instability generally deteriorates the mechanical properties of blends. Here, effects of chemical reactions on the rheological and mechanical properties of polycarbonate (PC)/liquid‐crystalline polymer (LCP) blends are carefully investigated to determine a method for minimizing such undesirable impacts. For comparison, a physical blend, in which chemical reactions were minimized, was prepared at 300 °C in a twin‐screw extruder. Both shear viscosity and complex viscosities of reactive blends were lower than those of physical blends, being almost proportional to [Mw]3.4 as a result of depolymerization and transesterification. Because of the enhanced miscibility, the tensile modulus of reactive blends increased compared with that of physical blend, according to the increase in the degree of incorporation (DI). It was also possible to increase tensile modulus if triester was added to the reactive blends. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2799–2807, 2001
Kinetic interpretation of influence of sodium chloride concentration and temperature on xanthan gum dispersion flow model
Authors: Dolz M. , Hernández M. J. , Delegido J. 
Published: August 2002

AbstractThe present study derives a fixed‐concentration (0.4%) xanthan gum dispersion flow model for different molar concentrations of sodium chloride (0–0.25M) and different temperatures (20–70°C). The Ostwald–de Waele model is used in all cases. A temperature rise reduces the shear‐thinning characteristics of the systems, although the power law index is much less sensitive to changes in temperature when NaCl is added, even in very small amounts. The lowest consistency values correspond to the dispersions formulated in the absence of salt, the highest values are observed for molar values of ≥0.15, and there are decreases in consistency upon raising the temperature in all cases. The viscous behavior of the dispersions is interpreted using the Eyring equation. The activation energy and the free volume decrease when the shear rate is increased. The addition of NaCl, regardless of the molar concentration involved, provokes an important decrease of the activation energy. The free volume is independent of the molar concentration of NaCl for molar values >0.025. These results are related to the structure of the dispersions. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 332–339, 2002
Electrochromism of nickel oxide thin film with polymer gel electrolyte
Authors: Tamai Toshiyuki , Chigane Masaya , Matsukawa Kimihiro , Ishikawa Masami , Inoue Hiroshi 
Published: August 2002

AbstractPolymer gel electrolytes were investigated for an electrochromic device (ECD) using nickel oxide thin film. Poly(ethylene oxide) (PEO) derivatives were cross‐linked and swelled in KOH–aqueous solution giving a hydrogel electrolyte. The ECD containing the uniformly cross‐linked hydrogel showed good result in electrochromic switching performance. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1305–1308, 2002
Peptides that elicit midgut stem cell differentiation isolated from chymotryptic digests of hemolymph from Lymantria dispar pupae
Authors: Loeb Marcia J. , Jaffe Howard 
Published: August 2002

AbstractIsolated stem cells of Heliothis virescens, cultured in vitro, were induced to differentiate by Midgut Differentiation Factors 3 and 4. These were peptides identified from a chymotrypsin digest of hemolymph taken from newly pupated Lymantria dispar. Partial purification was obtained by filtration through size exclusion filters. The most active preparation was subsequently subjected to a series of 3 Reverse Phase‐HPLC procedures. Partial sequences of the peptides were identified via automated Edman degradation as the nanomers EEVVKNAIA‐OH (MDF 3) and ITPTSSLAT‐OH (MDF 4). These sequences were commercially synthesized. The synthetic compounds proved active in a dose‐dependent manner. Stem cells responded to synthetic MDF 3 and MDF 4 as they did to previously identified peptides MDF 1 and 2, which have quite different amino acid sequences. All of the 4 MDFs administered singly induced statistically similar differentiation responses at 2 × 10–8, 2 × 10–9, and 2 × 10–10 M. However, pairs of the 4 MDFs produced even more differentiation, the same response as one alone, no response, or were inhibitory, dependent on the MDF pair and its concentration. The data suggests complicated receptor interactions. Arch. Insect Biochem. Physiol. 50:85–96, 2002. Published 2002 Wiley‐Liss, Inc.
Captopril, a specific inhibitor of angiotensin converting enzyme, enhances both trypsin and vitellogenin titers in the grey fleshflyNeobellieria bullata
Authors: Vandingenen A. , Hens K. , Macours N. , Zhu W. , Janssen I. , Breuer M. , De Loof A. , Huybrechts R. 
Published: August 2002

AbstractA strong and constitutive angiotensin converting enzyme‐ or ACE‐like activity was demonstrated in the hemolymph of the adult grey fleshflyNeobellieria bullata. In a competition assay, theN. bullatatrypsin modulating oostatic factor (Neb‐TMOF) was confirmed to be an in vitro substrate for this circulatingNeb‐ACE. Oral uptake of captopril, a selective and specific inhibitor of ACE, resulted in a complete phenotypic knockout of circulating ACE activity. When compared with control animals, captopril‐fed female flies showed an increase in the liver meal–induced trypsin peak in the midgut and elevated levels of protein meal–induced yolk polypeptides in the hemolymph. The latter effect was not due to a slower vitellogenin uptake by the ovaries, because oocyte growth was not affected by the captopril treatment. The apparent synergism between the demonstrated ACE functionality and the previously reported effects of the oostatic peptideNeb‐TMOF are discussed in the context of our recent finding thatNeb‐TMOF represents a prime candidate for being the first known in vivo substrate for circulating insect ACE. Arch. Insect Biochem. Physiol. 47:161–167, 2001. © 2001 Wiley‐Liss, Inc.
Alluvium and geophysical prospection
Authors: Weston D. G. 
Published: August 2002

AbstractThe use of fluxgate gradiometry to investigate archaeological features under >1 m of alluvium is a known problem. However, the frequent opinion that gradiometry has no role in the alluvial environment is incorrect. It is more accurate to say that the results of geophysical surveys are highly variable, as it is often overlooked that the survey results provide other information, most notably of a palaeoenvironmental nature. Four brief case studies are used to illustrate this point. These examples are drawn from geophysical surveys in the valleys of the River Trent, River Tame and River Great Ouse in the English Midlands. Copyright © 2001 John Wiley & Sons, Ltd.