bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on co[poly(ethylene terephthalate‐p‐oxybenzoate)] thermotropic copolyester (IV) thermal history by differential scanning calorimetry
Authors: Shinn Ted‐Hong , Lin Chen‐Chong 
Published: April 2003

AbstractA series of co[poly(ethylene terephthalate‐p‐oxybenzoate)] thermotropic copolyesters with various compositions were prepared by the copolymerization of either poly(ethylene terephthalate) polymer (PET) or its oligomer (OET) as moiety (II) and p‐acetoxy‐benzoic acid (POB) as moiety (I). The polymeric products obtained were then subjected to solid‐state polymerization. The glass and melting transitions of the copolyesters obtained have been studied by differential scanning calorimetry (DSC). Effects of composition and solid‐state polymerization on DSC are discussed. The melting point of copolyesters possesses a higher value if the PET polymer is used as PET moiety in the copolyesters. In the DSC scan of the POB rich composition, the endothermic peak shows obscurely and enthalpy of fusion becomes small due to the change in the crystalline morphology from isotropic to anisotropic. In general, the melting point of copolyesters is increased by the solid‐state polymerization reaction. It is also found that both the melting temperature and enthalpy of fusion of the copolyesters can be increased simultaneously by the solid‐state polymerization reaction only when the composition of POB/PET is 80/20. This phenomenum at this composition may be attributed to the annealing effect caused by the randomness of two moiety units on the backbone chain of copolyesters and the increased molecular weight as well. © 1994 John Wiley & Sons, Inc.
Conversion–temperature–property diagram for a liquid dicyanate ester/high‐Tg polycyanurate thermosetting system
Authors: Simon S. L. , Gillham J. K. 
Published: April 2003

AbstractThe effects of conversion and temperature on the dynamic mechanical properties (at ≈ 1 Hz) of a dicyanate ester/polycyanurate thermosetting system are investigated after cure using torsional braid analysis (TBA). Extent of conversion is measured by Tg. The isothermal glassy‐state modulus at measurement temperatures below the glass transition temperature of the monomer (Tg0) decreases with increasing conversion. The isothermal modulus at temperatures above Tg0 passes through a maximum due to competition between increase in the isothermal glassy‐state modulus at the measurement temperature due to the vitrification process during cooling and the aforementioned decrease in the modulus with increasing conversion, which is considered to be due primarily to steric constraints in the developing network. The maximum in the isothermal modulus is associated with the boundary between the glass and glass transition regions. The experimental results are summarized in a conversion (Tg)–temperature–property diagram, the TgTP diagram, which is a framework for understanding relationships between transitions and material properties for thermosetting systems. © 1994 John Wiley & Sons, Inc.
Effect of matrix SAN in ABS/PMMA blends
Authors: Lee S. M. , Choi C. H. , Kim B. K. 
Published: April 2003

AbstractThe effect of the molecular weight and acrylonitrile (AN) content of the styrene–acrylonitrile copolymer (SAN) on the morphology, mechanical properties, and rheological properties of acrylonitrile–butadiene–styrene terpolymer/poly(methyl methacrylate) (ABS)/PMMA (60/40 by weight) blends were studied. When the AN content of matrix SAN (32%) was close to that of graft SAN (30%) AN, rubber particles existed separately. However, with matrix SAN having 35% AN, rubber particles showed tendency to agglomerate each other. With increasing molecular weight of matrix SAN, impact strength, ultimate elongation, and abrasion resistance of the blend generally increased. Yield strength increased with molecular weight at a constant AN content of matrix SAN, and it decreased with the decrease of AN content in spite of the increasing molecular weight of SAN. Melt properties, rather than the morphological and mechanical properties, were more sensitive to the AN content, rather than the molecular weight of matrix SAN. © 1994 John Wiley & Sons, Inc.
Thermoacoustical parameters of polymers at low temperatures
Authors: Kumar M. Ravi , Reddy R. R. , Rao T. V. R. , Sharma B. K. 
Published: April 2003

AbstractThe Moelwyn‐Hughes parameter has been utilized to evaluate a number of thermoacoustical parameters, viz., the Beyer nonlinear parameter; the isothermal, isobaric, and isochoric Grüneisen parameters; the repulsive exponent of intermolecular potential; the molecular constant; the fractional available volume; the Sharma thermoacoustical parameter So; and the Anderson–Grüneisen parameter for a wide variety of polymers at different low temperatures. A relationship among the isobaric, isothermal, and isochoric microscopic (lattice) Grüneisen parameters has been examined and analyzed in the case of several polymers. The results have been used to develop understanding of the significance of microscopic factors such as molecular order and intermolecular forces upon macroscopi thermoacoustic properties. The parameter S0 remains invariant with temperature over a wide range and retains, on average, a constant value of 1.10 for several polymers at low temperatures, similar to a wide variety of substances. The present treatment has the distinct advantage that several thermoacoustic parameters can be evaluated form the knowledge of volume expansivity data alone. © 1994 John Wiley & Sons, Inc.
Positive photosensitive polyimides using polyamic acid esters with phenol moieties
Authors: Hayase Rumiko , Kihara Naoko , Oyasato Naohiko , Matake Shigeru , Oba Masayuki 
Published: April 2003

AbstractPolyimide resists developable with basic aqueous solutions were realized by polyamic acid esters with phenol moieties (PPh's) and naphthoquinone diazides. The polyimide precursors (PPh's) were synthesized from diamines and dicarboxylic acids that have phenol moieties through ester linkage. A selective reaction of alcohol groups with acid dianhydride groups made the synthesis of the PPh's possible, even if the phenol groups were in the reaction mixtures. The PPh's were soluble in basic aqueous developer, but their dissolution rates were too low for use as resists. To increase the resist dissolution rate, polyamic acids were added to the PPh's. By adjusting the dissolution rates in basic aqueous developers, fine patterns could be realized. The polyimide resists had high thermal stability and reliable adhesive property to silicon substrate. © 1994 John Wiley & Sons, Inc.
Thermotropic behavior of hydroxyethyl cellulose acetate
Authors: Huang Y. 
Published: April 2003

AbstractThermotropic behavior of hydroxyethyl celloulose acetate (HECA) was studied by polarizing microscopy, DSC, and X‐ray diffraction. It was found that HECA was an anisotropic liquid between the temperature from 130 to 185°C on heating, and when the temperature was over 185°C, it became isotropic. In cooling, however, mesophase began to form at about 165°C. The transformation temperature decreased with decreasing molecular weight and the temperature region of transformation decreased with decreasing the distribution of the molecular weight for HECA. The kinetic ability of tranformation appeared the maximum with molecular weight. The HECA liquid crystal is cholesteric and the distance between layers of ordered molecular chains was enlarged when HECA was transformed from liquid crystalline glass to the liquid crystalline state. © 1994 John Wiley & Sons, Inc.
Melt viscosity of poly(diethylene glycol‐co‐succinic acid): Molar mass dependence in the nonentangled regime
Authors: Liu G. , Vancso G. J. 
Published: April 2003

AbstractExperimental and theoretical results are reported on the dependence of melt viscosity on the molar mass of poly(diethylene glycol‐co‐succinic acid) (DEG‐SA) in the nonentangled regime. A power law described the behavior with an exponent of 2.09 ± 0.10 at 30°C and of 2.59 ± 0.09 at 90°C. The modified Rouse theory was used to describe the relationship between melt viscosity and molar mass. The parameters related to the modified Rouse theory were determined by the WLF equation and the free‐volume theory. The WLF parameters of various samples were checked at their Tg, which is the reference temperature. Results confirmed that the free volume and the monomeric friction coefficient (ξ0) dominate the behavior of the melt. The agreement between the calculated and experimental melt viscosity is satisfactory. © 1994 John Wiley & Sons, Inc.
Release of tritium‐labeled estradiol steroids from fully swollen hydrogels of polyurethane networks
Authors: Zulfiqar M. , Quddos A. , Zulfiqar S. 
Published: April 2003

AbstractDiffusion of uniformly dispersed tritium‐labeled estradiol in water‐swollen poly(ethylene oxide) ‐based hydrogels was studied by assaying the release of solute from cylindrical hydrogels into a finite volume of solution at 37°C. Fractional release followed a t0.5 relationship for a range of radil between 0.20 and 0.35 cm and different polymer compositions with equilibrium water uptake of 220–750 parts per hundred dry polymer. Values of the diffusion coefficient were calculated from the fully swollen hydrogels, which represents the swelling and release profile quite accurately. © 1994 John Wiley & Sons, Inc.
Low‐stress encapsulants by vinylsiloxane modification
Authors: Ho Tzong‐Hann , Wang Chun‐Shan 
Published: April 2003

AbstractDispersed silicone rubbers were used to reduce the stress of cresol–formaldehyde novolac epoxy resin cured with phenolic novolac resin for electronic encapsulation application. The effects of structure, molecular weight, and contents of the vinylsiloxane oligomer on reducing the stress of the encapsulant were investigated. Morphology and dynamic mechanical behavior of rubber‐modified epoxy resins were also studied. The dispersed silicone rubbers effectively reduce the stress of cured epoxy resins by reducing flexural modulus and the coefficient of thermal expansion (CTE), whereas the glass transition temperature (Tg) was hardly depressed. Electronic devices encapsulated with the dispersed silicone rubber modified epoxy molding compounds have exhibited excellent resistance to the thermal shock cycling test and have resulted in an extended device use life. © 1994 John Wiley & Sons, Inc.
Hygrothermal aging studies of short carbon fiber reinforced nylon 6.6
Authors: Ishak Z. A. Mohd , Berry J. P. 
Published: April 2003

AbstractA study of hygrothermal aging, in terms of the kinetics of moisture absorption by nylon 6.6 and its carbon fiber‐reinforced composites, has been undertaken. The diffusion of water into the various materials was investigated at 100% relative humidity, by immersion of specimens in water at temperatures of between 25 and 100°C. A mathematical treatment used in analyzing the data was that of a single free phase model of diffusion, which assumed Fickian diffusion and utilized Fick's second law of diffusion. Good agreement was observed between the experimental and theoretical values. The equilibrium moisture content and the apparent diffusion coefficient of the various composites were evaluated. Hygrothermal aging has reduced the tensile properties of both unreinforced and reinforced nylon 6.6, albeit a better recoverability of the properties was achieved by the former after drying. This behavior is explained in terms of the combined action of moisture‐induced plasticization and interfacial degradation. © 1994 John Wiley & Sons, Inc.
Crazing phenomena in PC/SAN microlayer composites
Authors: Haderski D. , Sung K. , Im J. , Hiltner A. , Baer E. 
Published: April 2003

AbstractThe crazing behavior of coextruded microlayer sheets consisting of alternating layers of polycarbonate (PC) and styrene–acrylonitrile copolymer (SAN) was investigated as a function of PC and SAN layer thicknesses. In this study, the total sheet thickness remained essentially constant and the PC and SAN layer thicknesses were changed by varying both the total number of layers from 49 to 1857 and the PC/SAN volume ratio. Photographs of the deformation processes were obtained when microspecimens were deformed under an optical microscope. Three different types of crazing behavior were identified: single crazes randomly distributed in the SAN layers, doublets consisting of two aligned crazes in neighboring SAN layers, and craze arrays with many aligned crazes in neighboring SAN layers. The transition from single crazes to doublets was observed when the PC layer thickness was decreased to 6 microns. Craze array development was prevalent in composites with PC layer thickness less than 1.3 microns. It was concluded that SAN layer thickness was not a factor in formation of arrays and doublets; formation of craze doublets and craze arrays was dependent only upon PC layer thickness. © 1994 John Wiley & Sons, Inc.
Effects of cast film fabrication variables on structure development and key stretch film properties
Authors: Degroot J. A. , Doughty A. T. , Stewart K. B. , Patel R. M. 
Published: April 2003

AbstractThe properties of films produced by the cast or blown film processes can be altered by varying the fabrication parameters. An experimental design is used to determine the effect of cast film fabrication variables on the performance of LLDPE stretch films. A three‐variable Box–Behnken designed experiment was conducted to study the effects of air gap, melt temperature, and line speed on the key cast stretch film properties. In addition, the differences in molecular orientation in the films were studied using optical birefringence and shrinkage methods. The key film properties are correlated with the fabrication conditions using a statistical analysis program. The results of this study are explained in terms of web tensile stresses before solidification and the degree of molecular orientation developed in the film due to the stresses. © 1994 John Wiley & Sons, Inc.
Thermal analysis of silver coatings used for tantalum capacitors
Authors: Ulrich M. , Sarraf L. , Loucheux C. 
Published: April 2003

AbstractSilver‐filled polymer coatings are used to ensure the cathodic junction of tantalum capacitors. To polimerize new materials able to resist to the RTSH industrial test, we studied first the physical chemistry of the main commercial coatings used at the present time. Four commercial silver coatings (epoxy, polyester, polyimid, and polyacrylate binders) and one conductive epoxy adhesive were tested. We separated the silver flakes from the polymer binder by centrifugation and filtration. We analyzed the thermal degradation and stability of the two kinds of sample (with the without silver flakes) using DSC and TGA. The influence of fillers mixing is discussed. This article reports, also, the main chemical structures of the binder components, determined using 1H‐ and 13C‐NMR and elemental analysis, after HPLC or GPC fractionation. © 1994 John Wiley & Sons, Inc.
The thermo‐oxidative stability of fluorinated polyimides and polyimide/graphite composites at 371°C
Authors: Scola Daniel A. , Wai Martin 
Published: April 2003

AbstractIncreasing demands to decrease engine weight and improve engine performance has led to an investigation to develop polymer composites capable of being used at 371°C and above in 4 atmospheres of air. The results of an investigation to determine the thermo‐oxidative stability (TOS) of various fluorinated polyimides, 3F‐PDA, 36F‐PDA, Avimid‐N, AFR700B, and other PMR‐type resins and graphite composites containing these polyimides at 371°C in air at 1 and 4 atmospheres are presented. Weight losses due to aging under these conditions are presented as the criteria for measuring the TOS. The data show that 3F‐PDA and Avimid‐N which have equivalent TOS, exhibit twice the TOS than that of AFR700B and other PMR‐type resins. 36F‐PDA exhibits even better TOS than 3F‐PDA or Avimid‐N. © 1994 John Wiley & Sons, Inc.
Spreading of a droplet on a solid surface
Authors: Seaver Albert E. , Berg John C. 
Published: April 2003

AbstractThe spontaneous spreading of small liquid droplets on solid surfaces is examined with the objective of developing closed‐form expressions for the spreading dynamics, both for the case in which there is complete equilibrium spreading, that is the equilibrium contact angle is 0°, and for the case in which equilibrium spreading is incomplete. Such solutions are obtained using a simple hydrodynamic model. The results are consistent with the format of the universal Hoffman–Voinov–Tanner law (for complete spreading) and the modified Hoffman–Voinov–Tanner law for incomplete spreading. In the latter case, concurrence is found only when the dynamic contact angle is close to the equilibrium angle throughout the spreading process. © 1994 John Wiley & Sons, Inc.
Polymeric phosphonium salts as a novel class of cationic biocides. VI. Antibacterial activity of fibers surface‐treated with phosphonium salts containing trimethoxysilane groups
Authors: Kanazawa Akihiko , Ikeda Tomiki , Endo Takeshi 
Published: April 2003

AbstractAlkoxysilane with phosphonium biocides as coupling agents were covalently attached to cotton‐fiber surfaces, and the antibacterial activity of the surface‐treated fibers against Staphylococcus aureus and Escherichia coli was evaluated by the viable cell counting method in sterile distilled water. These fibers with phosphonium salts were found to exhibit high antibacterial activity against S. aureus and E. coli, particularly against S. aureus, and the activity increased as hydrophobicity of the substituents bonded directly to phosphonium ions increased. Furthermore, morphological changes of the cells of S. aureus and E. Coli in contact with the fibers were evaluated by scanning electron microscopy. It was found that the fiber with the phosphonium biocides exhibited bacteriostatic as well as bactericidal activity against both strains, which was evident from observation of normal and deformed cells of these species in contact with the fibers. © 1994 John Wiley & Sons, Inc.
Electrochromic behavior and stability of polyaniline composite films combined with prussian blue
Authors: Morita Mitsuyuki 
Published: April 2003

AbstractThe electrochromic behavior of polyaniline–poly(vinyl alcohol) composite films (CPAn–PVA) combined with electrochemically synthesized Prussian blue films (PB) was investigated in LiClO4CH3CN nonaqueous aprotic solution. The combination was achieved by chemical deposition of CPAn–PVA on PB. When the combined films (CPAn–PVA–PB) are prepared with the appropriately low quantity of PB, CPAn–PVA–PB showed various visible absorption spectra overlapped roughly with the absorption of the component materials at different applied potentials. CPAn–PVA–PB provided the color change from green to blue at much lower applied potential than did CPAn–PVA. However, the combined PB eliminates protons from the first oxidized polyaniline chains to decrease the electrochemical activity of polyaniline. Therefore, to construct multicolor electrochromic devices by the combination of polyaniline with the other electrochromic materials, it is necessary to select the materials containing no deprotonation activity. © 1994 John Wiley & Sons, Inc.
Synthesis and characterization of long‐chain fatty acid cellulose ester (FACE)
Authors: Wang Pinglang , Tao Bernard Y. 
Published: April 2003

AbstractLong‐chain fatty acid cellulose esters (FACE) were synthesized by the acid chloride‐pyridine reaction with different degrees of substitution (DS). The hydrolyzed soybean oil was used as unsaturated fatty acids, its unsaturation degree, and composition were analyzed by 1H and 13C NMR methods. The chemical structures of FACE were confirmed by solid‐state 13C NMR, and substitution reaction of fatty acid chloride on cellulose were analyzed by IR spectroscopy. FACE(s) are insoluble in common organic solvents, such as benzene, toluene, THF, etc., at refluxing temperature. As the DS increased, the tensile strength of extruded FACE films decreased, but elongation increased. © 1994 John Wiley & Sons, Inc.
Development of a poly(methyl methacrylate‐co‐n‐butyl methacrylate) copolymer binder system
Authors: Vail N. K. , Barlow J. W. , Beaman J. J. , Marcus H. L. , Bourell D. L. 
Published: April 2003

AbstractLow molecular weight poly(methylmethacrylate) and poly(methylmethacrylate‐co‐n‐butylmethacrylate) emulsion‐based polymers are developed for use as fugitive binders of high temperature powders to be used with the rapid prototyping method known as selective laser sintering. Kinetics of the homopolymerization of methylmethacrylate and n‐butyl‐methacrylate are found to deviate from Smith‐Ewart Type II predictions. Reactivity ratios for the monomer pair are determined and indicate the pair to yield random copolymers. Molecular weight was controlled by the addition of chain transfer agents. Several transfer agents were studied and one, iso‐octyl‐3‐mercaptopropionate, was selected for use with emulsion polymerizations. Glass transition temperatures of the homopolymers and copolymers were studied. © 1994 John Wiley & Sons, Inc.
Polyurethanes synthesized from polyester polyols derived from PET waste. II. Thermal properties
Authors: Lee Sen‐Chong , Sze You‐Wen , Lin Chen‐Chong 
Published: April 2003

AbstractPolyurethanes were synthesized from polyester polyols, derived from PET Waste. The PET waste was first depolymerized by glycolysis. The glycolysized products were reacted with adipic acid to yield polyester polyols, and the polyester polyols were then reacted with either MDI or TDI to obtain polyurethanes. In this article, the thermal properties of the polyurethanes obtained are discussed in detail. © 1994 John Wiley & Sons, Inc.
Development and characterization of cellulose acetate benzoate flat osmotic membranes
Authors: Vyas M. D. , Mody R. C. , Mody I. C. 
Published: April 2003

AbstractDifferent parameters of casting solutions and casting conditions were studied for the development of cellulose acetate benzoate flat osmotic membranes. Casting solutions were prepared with different concentrations of the polymer, the additive, and the solvent; viscosity of the casting solution; and the thickness of the membrane developed. The membranes were given different evaporation periods and annealing temperatures under different RH. Different annealing baths were also used. Based on these, conditions were optimized for the development of cellulose acetate benzoate flat osmotic membranes. These membranes were characterized with respect to bound water content, specific water content, transport properties by direct osmosis, salt intake by direct immersion, water permeability coefficient of the dense membrane, diffusion coefficient, salt permeability, and salt distribution by electrical conductivity. Also, cellulose acetate benzoate membranes were compared with conventionally used cellulose acetate membranes. © 1994 John Wiley & Sons, Inc.