bluuebunny/crossref_metadata_2025_split huggingface dataset:
A device for study of polymer crystallization kinetics via real‐time image analysis of small angle light scattering
Authors: Culberson Wayne T. , Tant Martin R. 
Published: April 2003

AbstractA two‐dimensional position‐sensitive detector for real‐time small‐angle light scattering (RTSALS) of polymers is described. The device performs real‐time image analysis of the evolving light‐scattering pattern during crystallization. Such an approach provides a means of simultaneously measuring the rate of spherulite growth and the overall rate of crystallization, allowing calculation of nucleation density and/or rate. Although separation of nucleation effects from growth effects typically requires the application of two different experimental techniques, this device is unique in that it allows these two effects to be easily separated using only time‐dependent light‐scattering data. The device incorporates a CCD camera, a personal computer, and an imaging board as its major hardware components. Software designed specifically for this application performs real‐time analysis of the light‐scattering pattern at a rate of 1–3 images per second, thus allowing study of even moderately rapidly crystallizing polymers. (More recent software modifications have resulted in a speed enhancement to 5 images per s and further improvement is expected.) Intensities at various scattering and azimuthal angles are plotted at each time. In addition, the average spherulite radius is calculated and plotted. Application of the device is illustrated by measuring the spherulite growth rate of poly(ethylene terephthalate) as a function of temperature. © 1993 John Wiley & Sons, Inc.
Microcellular polymeric materials from microemulsions: Control of microstructure and morphology
Authors: Raj W. R. Palani , Sasthav Mohan , Cheung H. Michael 
Published: April 2003

AbstractThe effect of a crosslinking agent on the formation of porous solids by polymerizing microemulsions formulated with monomers was investigated. Phenomenological studies were carried out to evaluate the possibility of controlling the morphology of the porous polymeric materials by using precursor microemulsions having a distinct microstructure. A microemulsion system, containing methyl methacrylate (MMA), acrylic acid (AA), the crosslinking agent ethyleneglycol dimethacrylate (EGDMA), water, and sodium dodecylsulfate (SDS) as surfactant, was studied. An identical surfactant‐free system, formed using the same monomers, crosslinking agent, and water, but without surfactant, was also studied. Microemulsion samples from both these systems, having a water in oil droplet microstructure and also samples exhibiting bicontinuous microstructural characteristics, were used as precursor systems for polymerization. The morphology of the polymeric solids obtained was examined using scanning electron microscopy and thermogravimetric analysis. The results of this study indicate the possibility of forming porous polymeric solids having specifically tailored morphology and microstructure by the polymerization of monomer containing microemulsions. © 1993 John Wiley & Sons, Inc.
Kinetic analysis of bulk polymerization of diisocyanate and polyol
Authors: Gambiroz̆a–jukić M. , Gomzi Z. , Mencer H. J. 
Published: April 2003

AbstractThe step addition polymerization between toluene diisocyanate and poly(oxypropylene) diol and triol was carried out in bulk in a closed batch reactor under vacuum and at isothermal conditions. The reactions have been examined under the influence of the catalysts N‐phenyl‐β‐naphthylamine, triethylene‐tetraamine, and ferriacetylacetonate. The disappearance of the reactants and the appearance of one of the products were observed during the reaction. The kinetic analysis was brought about on the basis of the supposed reaction scheme and proposed kinetic model. The complex reaction was considered as serial–parallel. The experimental data fit well with the computed theoretical curves. The catalysts utilized were evaluated with respect to their selective catalysis of the primary diisocyanate–polyol reaction relative to the possible secondary reaction. The computed rate constants enabled the prediction of the composition of the reaction mixture. © 1993 John Wiley & Sons, Inc.
Kinetic parameters in non‐stoichiometric epoxy‐resin/m‐xylylenediamine reactions
Authors: Abuín Senén Paz , Pellín Mercedes Pazos , Núñez Lisardo , Gándara Jesús Simal , Losada Perfecto Paseiro 
Published: April 2003

AbstractThe curing reaction of bisphenol A epoxy resin has been widely studied. We have found that when initial reactants are highly pure the reaction epoxy resin/m‐xylylenediamine follows a predominantly autocatalytic path independent of the temperature. The purpose of this study was to discern if the kinetic model is appliable at high values of amine/epoxy equivalent ratio. Because of the nature and reactivity of m‐xylylenediamine (m‐XDA), the studies were carried out at low temperatures. Also, in order to obtain information about the formation mechanism of the system, different parameters such as reaction orders, activation energies, and reaction rate variation with concentration have been studied at different (1.5 : 1, 2 : 1, and 3 : 1) amine/epoxy equivalent ratios. © 1993 John Wiley & Sons, Inc.
Characterization of PAN‐based nonburning (nonflammable) fibers
Authors: Ko Tse‐Hao 
Published: April 2003

AbstractIn this article, a continuous stabilization process is used to make nonburning (nonflammable) fibers from polyacrylonitrile (PAN) fibers. The effect of the shrinkage behavior and the stretching process of PAN fibers during the stabilization process on the physical properties, morphology, and flammability of the resultant nonourning fibers is studied for the first time. The higher shrinkage of PAN fibers during the continuous stabilization process is found to increase the diameter, the core proportion, and flammability and decrease the Al value, density, mechanical properties, and formation of oriented molecular chains in the resultant nonburning fibers. The effect of the shrinkage behavior of PAN fibers on the fracture surface of the nonburning fibers is also discussed. The nonburning fibers show a fracture structure radiating from the fiber center to the boundary. The structures are composed of small and fine radial strip‐layer–like fibrils. Nonburning fibers developed using an optimum stretch process, not only had increased preferred orientation and density, but also had improved mechanical properties. Those fibers also have sufficient nonflammability. © 1993 John Wiley & Sons, Inc.
IR spectroscopic study on the thermal degradation of plastic security cover sheets of some documents
Authors: El‐Din Nabil Mohamed Safy 
Published: April 2003

AbstractThe change in IR spectra of plastic security cover sheets of ethylene vinylacetate copolymer during thermal treatment was investigated. The results obtained revealed that the temperature reduced the concentration of the ester group; moreover, the carbonyl band disappeared at high temperatures from 200 to 220°C, as well as broading of the absorption aliphatic–CH band. The change in the mechanical properties, degree of swelling in water, and refractive index of the samples during thermal treatment were also investigated. © 1993 John Wiley & Sons, Inc.
Thermal analysis of poly(acrylic acid)/poly(oxyethylene) blends
Authors: Chu Chia‐Hsi , Berner Bret 
Published: April 2003

AbstractBlends between poly(acrylic acid) and two different poly(oxyethylenes), (1) polyethylene glycol (PEG‐1000) and (2) poly(oxyethylene) (20) sorbitan monooleate (Tween‐80), were studied by differential scanning calorimetry. The glass transition temperatures, Tg, of the various compositions of these blends were found to follow Fox's equation. At room temperature, blends containing no more than 60% PEG‐1000 were amorphous and exhibited only a single glass transition. For these blends with PEG‐1000, the glass transition temperatures for the annealed samples were higher than for the quenched samples due to the formation of a PEG crystalline phase. It was also found that addition of an amorphous polymer such as poly(acrylic acid) significantly reduced the degree of crystallinity of a semicrystalline polymer such as poly(oxyethylene). The Tween‐80 systems did not show phase separation at room temperature. The compatibility between this poly(acrylic acid) and this poly(oxyethylene) was attributed to hydrogen bonding and to the lower crystalline lattice energy of this poly(oxyethylene) through its effect on its ideal solution solubility. © 1993 John Wiley & Sons, Inc.
Effects of additions of high‐density polyethylene on the processability of linear low‐density polyethylene
Authors: Karbashewski E. , Kale L. , Rudin A. , Tchir W. J. 
Published: April 2003

AbstractIn considering the processing characteristics of typical linear low‐density polyethylenes, it is very likely that the nature and amount of the “high‐density” portion of the short chain branching distribution has a strong effect on rheological behavior. In this study, highdensity resins of varying molecular weight were blended into a linear low‐density polyethylene base resin to determine the effect on viscosity, elasticity, and onset of haze. It was determined that it is not only the high‐molecular‐weight characteristics of the high‐density portion but also the linear nature of the molecules that has a negative effect on processability. © 1993 John Wiley & Sons, Inc.
Representation of vapor–liquid and liquid–liquid equilibria for binary systems containing polymers: Applicability of an extended flory–huggins equation
Authors: Bae Y. C. , Shim J. J. , Soane D. S. , Prausnitz J. M. 
Published: April 2003

AbstractFor some binary systems, an extended Flory–Huggins equation is applicable to both vaporliquid equilibria (VLE) and liquid–liquid equilibria (LLE) using the same adjustable parameters. New LLE and VLE data are reported for polystyrene (PS) (MW = 100,000)/cyclohexane and for poly(ethylene glycol) (PEG) (MW = 8,000)/water. Experimental results for the PS/cyclohexane system agree well with the semiempirical model, whereas those for PEG/water do not, probably because, for PEG/water, the temperature range of the VLE data is about 55°C lower than that of the LLE data. Excellent fits were obtained for our previously published experimental results for PS/cyclohexane (upper critical solution temperature, UCST), PS/ethyl acetate (lower critical solution temperature, LCST), PS/tert‐butyl acetate and PS/methyl acetate (both UCST and LCST), and PEG/water (closed‐loop). The semiempirical model also fits well with new data obtained for the polymer blend PS/poly(vinyl methyl ether). © 1993 John Wiley & Sons, Inc.
Studies on co[poly(ethylene terephthalate‐p‐oxybenzoate)] thermotropic copolyester (I): Synthesis and thermogravimetric behavior
Authors: Shinn Ted‐Hong , Chen Jang‐Young , Lin Chen‐Chong 
Published: April 2003

AbstractA series of co[poly(ethylene terephthalate‐p‐oxybenzoate)] thermotropic copolyester was synthesized from various ratios of two different moieties of either poly(ethylene terephthalate) (PET) or its oligomer as moiety (II) with p‐acetoxybenzoic acid as moiety (I) through the polycondensation process. The polymeric products obtained were then ground and subjected to solid‐state polymerization under vacuum for various polymerization times. Thermogravimetric analysis (TGA) and the derivative thermogravimetric analysis (DTG) were performed with these samples obtained. Also, a commercial product, Eastman 10109, was analyzed in comparison with these samples. It was found that the copolyesters made of PET and of its oligomer in a p‐oxybenzoate (POB):PET = 80 : 20 composition ratio and subjected to 8 and 4 h solid‐state polymerization times, respectively, showed the most similar thermogravimetric behavior with Eastman 10109. © 1993 John Wiley & Sons, Inc.
Morphology development for three‐component emulsion polymers: Theory and experiments
Authors: Sundberg Eric J. , Sundberg Donald C. 
Published: April 2003

AbstractThree‐component emulsion polymer systems constitute an overall four‐component system from a morphological viewpoint. The aqueous phase is always the continuous phase within which 22 distinct and thermodynamically stable particle morphologies may exist. Six uniquely different categories of particles compose this morphological menu and may be identified as core–shell–shell, hemicore, hemishell, trisectional, “snowman,” and cored hemisphere. Extension of previously published free‐energy thermodynamic analyses of two component emulsion polymers has resulted in the ability to predict the most likely equilibrium morphology to be found for three‐component particles. Predictions have been carried out for each possible three‐component combination of poly(methyl methacrylate), polystyrene, poly(dimethyl siloxane), and polycarbonate. The results show that in nearly every instance two or three different morphologies are computed to possess nearly equivalent free energies, whereas all other possibilities would result in much higher free energies. This indicates that more precise knowledge of all interfacial tensions is required when considering three‐component systems than was found to be generally needed for two‐component systems. Experiments were carried out for each polymer combination using a very surface‐active emulsifier (sodium lauryl sulfate) and, separately, a weakly surface‐active emulsifier (natural pectin). For this choice of polymers and emulsifiers, only three of the six unique morphological categories were found experimentally. In all cases, the thermodynamic analysis predicted the experimentally determined morphology to possess the lowest or next to lowest free energy. © 1993 John Wiley & Sons, Inc.
Water transport in graphite/epoxy composites
Authors: Lee Myung Cheon , Peppas Nikolaos A. 
Published: April 2003

AbstractThe diffusive and mechanical behavior of tetraglycidyl diaminodiphenyl methane (TGDDM) resin‐based composites and diglycidyl ether of bisphenol‐A (DGEBA) resin‐based graphite/epoxy composites were investigated during water sorption at different temperatures. The water‐absorption kinetics in both systems at 50, 70, 90, and 100°C were fitted by a Fickian diffusion model. However, a Langmuir‐type, two‐step sorption behavior was observed for water transport in DGEBA‐based systems at 50 and 70°C. Using scanning electron microscopy, internal cracks due to water absorption were found in the DGEBA‐based samples after conditioning at 90 and 100°C in water, whereas no cracks were detected in TGDDM‐based samples conditioned in water at 100°C. Ultrasonic testing did not show significant modulus or density change of the TGDDM‐based samples conditioned in water at 100°C. No significant changes of dynamic modulus or damping factor were observed for the TGDDM‐based samples redried after immersion in 100°C water, whereas slight changes were observed above 120°C for the samples containing absorbed water. However, both water‐containing and redried DGEBA‐based samples showed a decrease of dynamic modulus and an ω‐transition around 120°C. A single‐fiber fragment test revealed that the absorbed water at 80°C reduced significantly the interfacial shear strength of DGEBA/DDA resin‐AS4 fiber samples and DGEBA/DDA resin‐AU4 fiber samples. © 1993 John Wiley & Sons, Inc.
Compatibility behavior in thermoplastic polymer blends containing poly(t‐butylstyrene‐co‐acrylonitrile)
Authors: Hseih D. T. , Peiffer D. G. 
Published: April 2003

AbstractThe phase behavior of a series of binary component polymer blends of poly(ε‐caprolactone) (PCL) and poly(t‐butylstyrene‐co‐acrylonitrile) (TBSAN) containing varying contents of acrylonitrile (AN) was examined to determine the influence of copolymer composition and PCL content on blend miscibility or immiscibility. Thermal measurements were extensively used to determine phase behavior, i.e., a single compositionally dependent glass transition temperature implies blend miscibility. Otherwise, immiscibility is assumed to dominant blend behavior. It was determined that TBSAN and PCL form miscible blends over a broad range of AN content, i.e., spanning from below 43.2 mol % (19.8 wt %) to about 66.4 mol % (39.6 wt %), a range considerably different from that found in poly(styrene‐co‐acrylonitrile) copolymers. TBSAN‐containing blends were found to be immiscible when the AN content is less than about 43 mol % or greater than about 67 mol %. Small‐angle light‐scattering and polarized light microscopy was used to probe the substantial morphological changes in the miscible blends. Little change was observed in the immiscible blends. These results clarify the phase separation observed in these blend systems. © 1993 John Wiley & Sons, Inc.
Transport of sodium chloride, urea, and creatinine through membranes derived from methylmethacrylate‐co‐methacrylic acid and its ionomers
Authors: Bdair Ameen , Aras Leyla , Sanli Oya 
Published: April 2003

AbstractPermeabilities of cast films of methylmethacrylate‐co‐methacrylic acid (MMA—MAA) and its 5% neutralized Na1+, CS1+, Zn2+, Ba2+, and Al3+ ionomers for urea, sodium chloride, and creatinine were determined using a double (donor and acceptor) compartment cell. Film permeability was increased as the ionic potential decreased and it was more marked with urea as compared with sodium chloride and creatinine. Tensile properties of the above samples were also tested and variations in Young's Moduli were based on the effect of type of aggregates produced by the cations in the matrix of the copolymer. © 1993 John Wiley & Sons, Inc.
On the neck‐like deformation in high‐speed spun polyamides
Authors: Haberkorn H. , Hahn K. , Breuer H. , Dorrer H.‐D. , Matthies P. 
Published: April 2003

AbstractThe neck‐like deformation process occurring in high‐speed melt spinning of polyamide 66 and polyamide 6 filaments was investigated at take‐up speeds of 4200 to 5500 m/min by on‐line laser light scattering, thermographic contrast compensation, and wide‐angle X‐ray scattering (WAXS) measurements. New information about the onset of crystallization along the spinline was obtained by measuring simultaneously diameter and temperature profiles in the neighborhood of the neck. Crystallization rates, as a function of take‐up speed, are estimated for both polyamides. Based on the present experimental results of diameter profiles, temperature profiles, and WAXS patterns, a picture of the physical mechanism responsible for the neck‐like deformation of high‐speed melt spun polyamides is proposed. © 1993 John Wiley & Sons, Inc.
Bulk anionic copolymerization of ε‐caprolactam in the presence of macroactivators derived from polypropylene glycol
Authors: Chen Yun , Chen Show‐An 
Published: April 2003

AbstractBulk anionic copolymerization of ε‐caprolactam (CPL) was conducted, under four different conditions by changing temperature (110 or 125°C) and [NCO]/[NaH] ratio (1, 2, or 3), in the presence of NCO‐terminated polypropylene glycol (P1) and its CPL‐blocked prepolymer (P2). Under the same conditions and reaction time, the conversion of CPL and reduced viscosity of the P2 system were higher than those of the P1 system. However, at the same conversion the P1 system showed higher viscosity for reactions at 125°C with [NCO]/[NaH] = 3 and at 110°C with [NCO]/[NaH] = 2. These results were attributed to cyclotrimerization of NCO groups of P1 (formation of isocyanurate) at the initial stage, which not only consumed the effective concentration of NCO but also increased the viscosity of the P1 system. Comparing IR spectra of the reaction products of model compounds, phenyl isocyanate and CPL‐blocked phenyl isocyanate, with NaH/CPL also supported this conclusion. The crystalline melting temperature (Tm = 198–208°C) and melting enthalpy of the final products depended on the conversion of CPL and the types of macroactivators. © 1993 John Wiley & Sons, Inc.
Modification of nylon‐6 with semirigid poly(p‐diphenylmethyl terephthalamide)
Authors: Shu Yao‐Chi , Lin Ming‐Fung 
Published: April 2003

AbstractIn this research, flexible nylon‐6 was reinforced by semirigid aromatic polyamide poly(p‐diphenylmethyl terephthalamide) (PMA) through physical polyblending and chemical copolymerization using p‐aminophenylacetic acid (P‐APA) as a coupling agent. From the DSC measurement, it was shown that the Tg of the polyblends was increased with the increase of PMA content. It was discovered that the Tg and Tm of multiblock copolyamides would be higher than those of polyblends and triblock copolyamides. The multiblock copolyamides exhibited a homogeneous texture rather than an aggregated one. Scanning electron microscopy revealed that the polyblends were a dispersed‐phase structure. We found that from the wide‐angle X‐ray diffraction pattern the triblock copolyamides and polyblends had two diffraction peaks, i.e., 2θ = 20° and 24°. However, the multiblock had only one at 2θ = 20°, which evidently indicates that a new crystal structure of multiblock copolyamides was formed. As for the mechanical properties, the multiblock copolyamides were found to have more significant reinforcing effects than those of polyblends and triblock copolyamides. © 1993 John Wiley & Sons, Inc.
Poly(vinyl chloride) composition. I. Mechanical properties and structure of poly(vinyl chloride) and fire‐retardant additives
Authors: Stoeva S. , Benev D. , Karaivanova M. 
Published: April 2003

AbstractNatural, activated, and modified microzeolites were studied individually and in combination with ammonium sulfamate as high‐melting dispersed additives. The strength—deformation properties of poly(vinyl chloride) were improved within the interval of 3–8 wt % additive. The strengthening effect due to the considered dispersed additives can be ascribed to the optimal adhesive interaction of the phase‐boundary surface and to the formation of a partially ordered dispersed phase. The tetrahedral configuration of the modified microzeolite that contains 3.5–4% zinc in its crystal lattice remains unchanged, but exhibits a reduced birefringence. These relationships are of exceptional importance for the use of poly(vinyl chloride). The introduction of certain amounts of the additives improves the melt flow of the polymer and facilitates the processibility of the compositions. © 1993 John Wiley & Sons, Inc.
Synergic action of aging and moisture on native and different grades of commercial gutta‐percha (trans‐polyisoprene)
Authors: Arvanitoyannis Ioannis , Kolokuris Ioannis , Robinson Colin , Blanshard John M. V. 
Published: April 2003

AbstractThe aim of this paper was to study the plasticizing effect of subjecting native/commercial gutta‐percha samples to controlled levels of different humidities. It was expected that this study would provide the practicing endodontist with invaluable insight into the mechanical properties of commercial gutta‐percha cones (i.e., retrievability, malleability, flexibility, and torsional and bending ability). The “conditioning” of the gutta‐percha samples depended greatly on the percentage of compatible/incompatible substances. The mixtures of native gutta‐percha with compatible (i.e., wax) showed greater elongation, tensile strength, and number of rotations, but lower deformation angle than the mixtures of native gutta‐percha with incompatible substances (i.e., salts, metal oxides). The observed lower values for tensile strength and torsional strain, relative energy to break, and the Young's modulus and the higher values for elongation and number of rotations for wet samples compared to the dry ones were attributed to the plasticizing effect of gutta‐percha due to the insertion of water molecules in the polymer chains. © 1993 John Wiley & Sons, Inc.