bluuebunny/crossref_metadata_2025_split huggingface dataset:
Starch urea formaldehyde matrix encapsulation of solid agrochemicals. I. Matrix synthesis and characterizations
Authors: Rajagopalan N. , Shukla P. G. , Bhaskar C. , Banker V. S. , Dharia J. R. , Khilar Kartic C. 
Published: April 2003

AbstractA starch urea formaldehyde (starch‐UF) matrix has been studied for application to the encapsulation of a solid insecticide. The pertinent parameters relating to the matrix synthesis have been identified and the influences of these parameters on release of the insecticide from the starch UF matrix have been investigated. The key parameter controlling the rate of release is the urea to starch ratio. It is shown that the release process can be described in terms of the generalized equation Mt/M∞ = ktn where k and n vary with system variables.
Epoxy resins based on aromatic glycidylamines. VI. Toughening of N,N,N′,N′‐tetraglycidyl‐4,4′‐diaminodiphenylmethane by reactive additives
Authors: Dobáš I. , Luňák S. , Zelenka J. , Horálek J. , Špaček V. , de Petris S. 
Published: April 2003

AbstractMechanical properties of N,N,N′,N′‐tetraglycidyl‐4,4′‐diaminodiphenylmethane and its mixtures with liquid bisphenol A‐type epoxy resins, bisphenol A and ε‐caprolactone have been studied. 4,4′‐Diaminodiphenylsulfone was used as hardener. Materials with improved fracture toughness and good mechanical strength in the temperature range 20–200°C have been formulated.
Synthesis and properties of cationic resins derived from urethane‐modified epoxy resins and methylethanolamine
Authors: Yang Chin‐Ping , Lee Lung‐Ta 
Published: April 2003

AbstractSix urethane‐modified cationic resins were synthesized by reacting half‐blocked polyglycoltoluene diisocyanate–urethane (half‐blocked‐PG–TDI–urethane) and 2‐ethylhexanol‐blocked toluene diisocyanate (2‐EH‐blocked‐TDI) modified epoxy resins with methylethanolamine and subsequent neutralization with acetic acid. Three different polyglycols were used to react with toluene diisocyanate to from isocyanate‐terminated urethanes (1a–c) and subsequently two different monoalcohols were added to react with 1a–c to give half‐blocked‐PG‐TDI‐urethanes (2a–f). These cationic resins were then dissolved in suitable solvents and mixed with deionized water to form emulsions. The crosslinking properties, emulsion, and electrodeposition properties of these resins were studied in some detail. The deposition yields of emulsions prepared from urethane‐modified epoxy resins were higher than those of other emulsions. The pencil hardness of the crosslinked films of urethane‐modified resins were lower than that of non‐urethane‐modified resin. The emulsion and electrodeposition properties of the cationic resins were also deeply affected by the nature of the pendant positively charged group contained in the resins.
GC/MS and PGC/MS analyses of plasma polymerization for benzaldehyde
Authors: Zhao Qiang , Zhu Yufen , Cai Minxi , Xie Mandan , Liu Xueshu 
Published: April 2003

AbstractGas chromatography/mass spectrometry studies of gas condensates in plasma and pyrolysis products of plasma polymer for benzaldehyde were made. Both products' analyses indicate the significant presence of benzyl and carbonyl groups in plasma polymer samples. Infrared measurements were also used to correlate the structures suggested by GC/MS results. A radical mechanism, which involved hydrogen abstraction, aldehyde group abstraction, and benzyl fragmentation under plasma activation, was proposed. The highly crosslinked and branched structures of the plasma polymer were attributed to the subsequent reactivity of free radicals, formed as a result of the scission of the chemical bonds in the benzaldehyde molecules.
Specific interaction of starch and polyvinyl alcohols having long alkyl groups
Authors: Okaya Takuji , Kohno Hiroji , Terada Kazutoshi , Sato Toshiaki , Maruyama Hitoshi , Yamauchi Junnosuke 
Published: April 2003

AbstractProperties of aqueous solutions of blends of starch and polyvinyl alcohols (PVAs), having alkyl groups as side chains, or at one polymer chain end, were studied in terms of viscosity stability, and transparency. In the case of corn starch, PVAs having butyl, octyl, and dodecyl end groups, as well as PVA copolymers containing small amounts of vinyl versatate, together with itaconic acid, increased the stability of the blended solution. The aqueous solutions of PVA, having dodecyl end groups and oxidized starch blend, also showed good stability in viscosities and considerable increase in transparency, whereas conventional PVA and oxidized starch blend gave turbid aqueous solutions, followed by phase separation. The phenomena were assumed to arise from the interaction of the alkyl group in PVA with starch, forming a helical structure with the alkyl group in the hydrophobic internal part.
Dielectric and viscoelastic properties of some meta‐tetramethyl xylene diisocyanate‐based polyurethanes as a function of sample composition
Authors: Capps Rodger N. , Stack Gary M. , Samuels Mary Q. , Beumel Linda L. 
Published: April 2003

AbstractA series of linear segmented polyurethanes were synthesized, based on soft segments of polycaprolactone having an average number molecular weight of 2100, or hydroxy–terminated polybutadiene having an approximate molecular weight of 2800. Hara segments were made of meta–tetramethyl xylene diisocyanate and diethyl toluene diamine. The dynamic Young's modulus and loss tangent, relative permittivity, and dielectric loss, were found to be significantly affected by soft segment polarity and hard segment content. These results are discussed in terms of polymer morphology, such as degree of phase separation and soft segment phase state.
Toughening of polystyrene and poly(phenylene oxide) matrices with elastomeric styrene‐based block copolymers: Role of molecular architecture
Authors: Park Inha , Keskkula H. , Paul D. R. 
Published: April 2003

AbstractThe effects of the molecular architecture of elastomeric styrene‐based block copolymers on efficiency of toughening a brittle (polystyrene) and a ductile [a miscible blend of 80% phenylene oxide copolymer and 20% polystyrene (80PEC)] polymer were explored experimentally. Toughening appears to be mainly controlled by the blend morphology, which is determined by the rheological characteristics of the block copolymer relative to that of the matrix. The formation of dispersed particles during melt blending in a Brabender Plasticorder is strongly influenced by the ratio of the matrix and block copolymer viscosities (estimated here by Brabender torque). The size of the dispersed particles was found to be proportional to the 1.77 power of the torque ratio when this ratio is greater than unity. Thus, to a first approximation the effect of block copolymer architecture on toughening efficiency is related to how this structure affects the rheological behavior of the copolymer. Excellent toughness of polystyrene was achieved when the particle size was larger than 1–2 μm. The 80PEC resin is best toughened by block copolymers that form a cocontinuous phase morphology. The extent of toughening of this matrix appears to be a strong function of the styrene block molecular weight, whereas this structural feature seems to have no significant effect in toughening polystyrene.
Photografting of acrylic monomers on polystyrene support
Authors: Ajayaghosh A. , Das S. 
Published: April 2003

AbstractPolystyrene xanthates, prepared through the reaction of chloromethylated polystyrene resins with potassium O‐ethyl xanthate, have been used for the photografting of acrylic monomers. Monomers such as acrylamide, acrylic acid, methacrylic acid, and methyl methacrylate were grafted onto the xanthate polymers on irradiation with a 450 W medium‐pressure mercury lamp (Hanovia). Among these monomers, the maximum graft efficiency was obtained for methyl methacrylate. The effect of cross‐link density of the xanthate polymer on the percentage graft yield was also studied. Scanning electron microscopic studies have shown that appreciable grafting has taken place on the surface of the polymer in a uniform manner. © 1992 John Wiley & Sons, Inc.
Kinetics of reaction of C36 dimeric fatty acids and ethylenediamine in solution
Authors: Vedanayagam H. Sumathi , Kale Vijay , Subbarao R. 
Published: April 2003

AbstractKinetic studies were carried out on the reaction between ethylenediamine and C36 dimeric fatty acids using benzyl alcohol as solvent. The reaction was performed at four different temperatures in the range of 160–190°C, and the products were analyzed for acid and amine values intermittently to follow the reaction. The fall in both the values was almost the same throughout the reaction. The kinetics was determined from the fall in acid value, and the reaction was found to be of overall third order and had an activation energy of 30.7 kcal mol−1 (128.5 kJ mol−1).
Influence of polymer characteristics and melt‐spinning conditions on the production of fine denier poly(ethylene terephtalate) fibers. Part III. Structure and properties of fine denier as‐spun PET fibers
Authors: Kiang Chang T. , Cuculo John A. 
Published: April 2003

AbstractThe effect of decreasing take‐up denier on the structure and mechanical properties of asspun poly(ethylene terephtalate) (PET) fibers is shown to be, in general, similar to an increase of take‐up velocity. Both can be related to increased threadline cooling rate and increased spinline stress that control the structure development in the threadline. However, important distinctions were observed in the orientation and crystallization effects due to decrease of take‐up denier or increase of take‐up velocity. These distinctions were explained on the basis of the threadline dynamics study of the fine denier PET fiber in the high‐speed spinning process, discussed in Part II of this study. Other properties, such as the dynamic mechanical properties and dye uptake, are not related to individual structure parameters, depending on the overall changes in structure, e.g., as given by the free volume.
Synthesis of chloral derivative of maleimide and its copolymerization with styrene
Authors: Sikorski Ryszard Tadeusz , Mirkiewicz Grażyna 
Published: April 2003

AbstractA new monomer N‐(1‐acetoxy‐2,2,2‐trichloroethyl)maleimide (MI) and its copolymer with styrene have been developed. It was found that MI can be synthesized from N‐(1‐hydroxy‐2,2,2‐trichloroethyl)maleamide in acetic anhydride with a yield of 65%. The radical copolymerization of MI with styrene in benzene solution occurs with a yield of 91%. The obtained copolymer has a melting point about 215°C, good thermal resistance, and is selfextinguishing. The monomer and copolymer compositions were determined by elementary, 1H‐NMR and IR analysis.
Synthesis and characterization of pH‐ and/or temperature‐sensitive hydrogels
Authors: Park Tae Gwan , Hoffman Allan S. 
Published: April 2003

AbstractA series of pH‐sensitive hydrogels that exhibit volume phase transition phenomena have been synthesized in aqueous solution and characterized with respect to their dynamic swelling behaviors. Positively charged hydrogels were prepared by copolymerizing varying ratios of N‐isopropylacrylamide and NN′‐dimethylaminopropylmethacrylamide. The hydrogels based on a temperature‐sensitive hydrogel demonstrate a large change of equilibrium swelling in response to small variations of pH and/or temperature. These hydrogels exhibit different lower critical solution temperature (LCST) ranges depending on the environmental pH values. Below their LCST, they exhibit small and broad pH sensitivities normally observed in most hydrophilic polyelectrolyte gels, but above their LCST, they exhibit sharp pH dependent phase transition behaviors. The pH‐dependent phase transition is strongly affected by temperature, while the temperature‐dependent transition is, in turn, largely influenced by the pH. As the temperature is raised, the transitional degree of gel swelling change becomes sharper and larger, and the phase transition pH value shifts to a lower pH. It was also found that swelling is faster than deswelling for these cationic hydrogels, which suggests the existence of a water diffusion barrier during the deswelling. The swelling kinetics of initially dry and glassy gels were strongly dependent on both the pH value and temperature.
Structural study of fractionated hydroxyethyl‐amylopectin in aqueous solution
Authors: Sarazin D. , Fraņois J. H. , Verwaerde C. , Fléche G. 
Published: April 2003

AbstractFractionated hydroxyethyl starch was well characterized by coupled LALLS‐SEC (lowangle laser light scattering and steric exclusion chromatography), QELLS (quasi‐elastic laser light scattering), MALLS (multiangle laser light scattering), and viscosimetry. The scaling laws of the molecular weight dependences of the following dimensions are found to exhibit low exponents consistent with a highly grafted structure:

Additional X‐ray synchrotonic scattering (SAXS) studies permit us to give a preliminary description of the internal structure of the macromolecules.
FTIR analysis of electrodeposition film from emulsion of two cationic resins
Authors: Yang Chin‐Ping , Chen Yahn‐Haur 
Published: April 2003

AbstractThe resin composition of film deposited from coemulsion of two cationic resins (epoxy–amine adduct,E, was the main resin; cationic trimethylolpropane‐toluene diisocyanate–dimethylaminoethanol/2‐ethylhexanol resin,T, was used as crosslinker) was determined by Fourier Transform Infrared (FTIR) quantitative analysis. The electrodeposition properties of cationic resins and their coemulsions were compared to study the effects of resin composition of coemulsions on the resin composition of deposited films. The optimum resin composition of coemulsions was also found to produce deposited film with the best properties after curing.
Near‐infrared probe for in situ characterization of nafion thin films
Authors: Zen Jyh‐Myng , Lipowska Malgorzata , Patonay Gabor 
Published: April 2003

AbstractA near‐infrared (NIR)‐absorbing cyanine dye was used as a probe for in situ characterization of Nafion thin films. This NIR dye was very sensitive to changes in the hydrophobicity of the environment and proved to be very suitable for probing the Nafion coatings, which involve a two‐Phase structure of hydrophobic and hydrophilic zones. Sorption phenomena of water and aqueous alkali salt solutions by Nafion were investigated. For our study systems of thin‐coating films prepared from 5% wt alcoholic solution of Nafion 117, the absorption spectrum was dominated by higher‐order aggregates when in dry form. In pure water, the absorption maximum of the monomer dye appears at 773 nm and can be used as an indication of the swelling process of the film. The water uptake reaches saturation in only a few seconds. After the swelling process, an additional absorption band with a maximum at 555 nm appears primarily at the expense of the NIR monomer dye absorption band. The peak transition process, which is a very slow process and is a strong function of the water content inside the matrix, can be used as an indication of the establishment of equilibrium between the two‐phase structure due to the water uptake. Since the absorption maximum of the study system is around 800 nm, semiconductor lasers can be used. This technique shows high potential in other applications where polymers are used as support material, e.g., in situ thin‐film thickness measurements. In the study, the feasibility of this approach was illustrated.
Poiseuille flow of a power–law fluid between coaxial cylinders
Authors: Prasanth N. , Shenoy Uday V. 
Published: April 2003

AbstractAn analytical expression is derived, which permits direct evaluation of the volumetric flow rate or the pressure gradient for the laminar flow of a power–law fluid in a concentric annulus. The derivation is valid for tangential as well as axial flow, provided a parameter q, in the problem formulation, is substituted by appropriate binary values. The final flow rate solution is in the form of an elegant algebraic equation (not a definite integral) and holds for all values of the power–law index (not merely reciprocal integers). Attention is focused on the tangential pressure flow problem, where the zero‐shear plane does not coincide with the location of the maximum velocity. © 1992 John Wiley & Sons, Inc.
The removal of carbon tetrachloride from chlorinated polyisoprene using carbon dioxide
Authors: Burgess A. N. , Jackson K. 
Published: April 2003

AbstractThis study demonstrates the use of supercritical carbon dioxide in the removal of residual carbon tetrachloride from chlorinated polyisoprene in a packed column. The effects of varying temperature and pressure on the efficiency of extraction are examined. The data indicate that there exists an optimum combination of pressure and temperature and that quite small deviations from these conditions can produce substantially poorer extraction efficiency and lead to the destruction of the polymer particle morphology.
Thermal stability of polyacrylonitrile in the melt formed by hydration
Authors: Min Byung Ghyl , Son Tae Won , Jo Won Ho , Choi Soo Ghil 
Published: April 2003

AbstractDifferential scanning calorimetry (DSC) and intrinsic viscosity measurement have been used to investigate the thermal stability of PAN‐based copolymer in the melt formed by hydration. Samples containing various water contents were annealed at temperatures between 160 and 180°C for periods up to 60 min. The melting point (Tm) and crystallization temperature (Tc) increased with annealing time, irrespective of annealing temperature and water content. The increase in Tm with annealing time was interpreted in terms of thermodynamic parameters. The decrease in the heat of fusion (ΔHf) with the increase of annealing time implies that the number of nitrile groups is reduced during annealing in the melt. The decrease in the entropy of fusion (ΔSf) calculated from Tm and ΔHf suggests that the polymer chain becomes more rigid as the annealing time (or temperature) increases; however, the intrinsic viscosity does not increase during annealing. From both thermodynamic analysis and intrinsic viscosity, it is concluded that the increase in Tm is caused by chain rigidity mainly due to the intramolecular cyclization of nitrile groups. © 1992 John Wiley & Sons, Inc.
Bending of ionic polymer gel caused by swelling under sinusoidally varying electric fields
Authors: Shiga Tohru , Hirose Yoshiharu , Okada Akane , Kurauchi Toshio 
Published: April 2003

AbstractDeformation of poly(vinyl alcohol)–poly(sodium acrylate) composite hydrogel (PVA–PAA gel) under sinusoidally varying electric fields was studied in electrolyte solutions. The PVA–PAA gel was prepared by repeatedly freezing and thawing a mixed solution of PVA and polyacrylic acid. A cyclic bending–straightening motion of the PVA–PAA gel rods of about 1 mm in diameter have been observed in Na2CO3 aqueous solutions under the fields. The PVA–PAA gel had a response time of less than several hundreds milliseconds. The bending has also been observed in organic solvents containing an electrolyte when the organic solvent is electrolyzed. It was found that the motion of the gel under electric fields of less than 1 Hz occurred mainly through swelling due to the change of the osmotic pressure based upon the difference of the ion concentration. However, it has not been determined whether the motion at higher frequencies is caused by the osmotic effect. © 1993 John Wiley & Sons, Inc.
The damage zone in microlayer composites of polycarbonate and styrene—acrylonitrile
Authors: Shin E. , Hiltner A. , Baer E. 
Published: April 2003

AbstractThe irreversible deformation behavior of coextruded microlayer composites, consisting of 49 alternating layers of polycarbonate (PC) and styrene—acrylonitrile polymer (SAN), was examined in the triaxial stress state achieved at a semicircular notch during slow tensile loading. Variations in the proportions of PC and SAN were manifest as changes in the relative thicknesses of PC and SAN layers. When the SAN layers were thicker than the PC layers (PC/SAN 25/75 v/v) or the layer thicknesses were about the same (53/47 v/v) the composites were only slightly more ductile than SAN and the deformation behavior of the layers mimicked that of the components. Examination of optical micrographs showed that the damage zone closely resembled that of SAN and consisted of internal notch crazes in the SAN layers that grew out from the notch surface in conformity with a mean stress condition. Shear processes became more evident when the PC layers were thicker than the SAN layers (PC/SAN 65/35 and 74/26 v/v). An unusual transition was observed in the SAN layers from internal notch crazing to interactive crazing and shear banding. The internal notch crazes ceased to grow when they terminated in a pair of microshear bands in the SAN layer. Subsequently a macroscopic shear‐yielding mode was observed as two sets of intersecting slip lines that grew out from the notch surface in both PC and SAN layers. Stress intensification caused by the plastic zone was responsible for the appearance of a second family of internal crazes in the SAN layers that originated in front of the notch tip. © 1993 John Wiley & Sons, Inc.
The brittle‐to‐ductile transition in microlayer composites
Authors: Shin E. , Hiltner A. , Baer E. 
Published: April 2003

AbstractThe brittle‐to‐ductile transition in continuous microlayer composites of polycarbonate (PC) and styrene–acrylonitrile copolymer (SAN) was investigated under the triaxial tensile stress state achieved at a semicircular notch. The availability of microlayer compositions with variations in the proportion of the components and also variations in the total number of alternating layers made it possible to examine the transition from SAN‐like, relatively brittle behavior, to PC‐like properties where the ductile component dominated yield and failure. Examination of the damage zone that formed at the notch root revealed that cavitational mechanisms dominated in the brittle composites that were those with the highest proportion of SAN and fewest number of layers. Shear‐yielding modes characteristic of PC dominated the damage zone of the ductile composites. Cavitational mechanisms were almost totally absent in these compositions that included those with the highest proportion of PC and the largest number of layers. A broad range of transitional behavior was observed with intermediate compositions where elements of both cavitational mechanisms and shear modes were superimposed. These compositions provided an opportunity to examine the interaction of cavitational and shear processes at the macro‐ and microscales. © 1993 John Wiley & Sons, Inc.
Sticky poly(vinyl alcohol) hydrogels
Authors: Cha Won‐Ill , Hyon Suong‐Hyu , Graiver Daniel , Ikada Yoshito 
Published: April 2003

AbstractLow‐temperature gelation of poly(vinyl alcohol) (PVA) solution was performed in the presence of CaCl2. The resulting PVA hydrogels showed high stickiness and excellent water‐holding ability. These properties became more remarkable with increasing CaCl2 concentration in solvent. Furthermore, both the peel strength on stainless steel and the degree of swelling of the PVA hydrogel drastically increased as CaCl2 concentration was increased from 20 to 30 wt %. It is concluded that the sticky and water‐holding properties of PVA hydrogels are intimately related to the state of hydration of Ca ions in aqueous environment. © 1993 John Wiley & Sons, Inc.