bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rheology of unsaturated polyester resins. I. Effects of filler and low‐profile additive on the rheological behavior of unsaturated polyester resin
Authors: Han Chang Dae , Lem Kwok‐Wai 
Published: April 2003

AbstractMeasurements were taken of the bulk rheological properties of concentrated suspensions of particulates in unsaturated polyester resins, using a cone‐and‐plate rheometer. The particulates used were clay, calcium carbonate, and milled glass fiber. With clay and milled glass fibers, shear‐thinning behavior of suspensions was observed at low shear rates or low shear stresses as the concentration of particulates was increased, whereas concentrated suspensions of calcium carbonate exhibited Newtonian behavior over the range of shear stresses or shear rates investigated. The cone‐and‐plate rheometer was also used for measurements of the bulk rheological properties of various mixtures of polyester resin and low‐profile additives. For low‐profile additives, solutions, in styrene, of poly(vinyl acetate) (PVAc) and poly(methyl methacrylate) (PMMA) were used. It was found that the bulk viscosities of all mixtures of polyester resin and PVAc solution lie between those of the individual components, whereas the bulk viscosities of some mixtures of polyester resin and PMMA solution go through a minimum and a maximum, depending on the composition of the mixture. While all mixtures of polyester resin and PVAc solution exhibited negligible normal stress, some mixtures of polyester resin and PMMA solution exhibited noticeable normal stresses. It should be mentioned that polyester resin follows Newtonian behavior. It turned out that all mixtures of polyester resin and PVAc solution exhibited clear, homogeneous solutions, whereas mixtures of polyester resin and PMMA solution exhibited optical heterogeneity, i.e., turbidity. When polyethylene powders were used as low‐profile additives, suspensions of polyester resin and polyethylene powders exhibited negative values of normal stress as the concentrations of suspension reached a critical value. When both filler and low‐profile additive were put together in polyester resin, the rheological behavior became quite complex, indicating that some interactions exist between the filler and the low‐profile additive.
New epoxy resins. III. Application of fourier transform IR to degradation and interaction studies of epoxy resins and their copolymers
Authors: Chen C. S. , Bulkin B. J. , Pearce E. M. 
Published: April 2003

AbstractIn the Fourier transform infrared (FT–IR) study, diglycidyl ether of bisphenol A (DGEBA) did not show aldehyde or perester absorption when it was normally cured with trimethoxyboroxine (TMB) under a nitrogen atmosphere. Neither alumina nor gold surfaces would cause oxidation of the system. In air, alumina appeared to accelerate the oxidation when compared to gold. The cure of the epoxy in oxygen appeared to cause increased Claisen rearrangement when compared with the same cure in a nitrogen atmosphere. The DGEBA cured with TMB under air or nitrogen atmospheres showed differences in their degradation patterns. The TMB‐cured DGEBA and diglycidyl ether of 9,9‐bis(4‐hydroxyphenyl) fluorene (DGEBF) copolymer had a higher degree of reaction and lower degradation than was shown by the synthetically generated spectra based on the FT–IR summation of the spectra of the respective homopolymers.
The interaction of a cationic silane coupling agent with mica
Authors: Favis B. D. , Blanchard L. P. , Leonard J. , Prud'Homme R. E. 
Published: April 2003

AbstractCarbon analysis was used as a method for measuring the quantity of a cationic vinyl benzyl silane (CVBS) adsorbed onto the surface of mica. The results obtained indicate that CVBS can be applied from aqueous solution over a wide pH range with best treatment in neutral and acidic media. The amount adsorbed depends on the concentration of the treating solution in the lower concentration range while in the higher range, the adsorption is less dependent on concentration. The relationship, silane adsorption vs. time of treatment, shows a steplike dependence. It is suggested that each step corresponds to a monolayer coverage. The data indicate that CVBS on mica is a highly ordered and closely packed multilayer phase with the silane molecules oriented normal to the surface. The multilayer adsorption of silane onto silane in this system may be compared in some respects to polymer crystal growth.
The surface orientation of polystyrene measured by liquid contact angle
Authors: Wang Li‐Hui , Porter Roger S. 
Published: April 2003

AbstractThe surface contact angle of glycerol and of water on polystyrene (PS) films has been found to depend on the extent of uniaxial draw for atactic PS. The contact angle depends on direction for the smooth films of PS drawn by solid state coextrusion. Results as a function of draw ratio to values over 4 on these noncrystalline PS samples, Mw = 6 × 105, have also been interrelated with other measures of orientation such as the anisotropy of surface and bulk properties measured, respectively, by dichroic reflectance infrared spectroscopy and by birefringence.
Main functions of iron compounds as smoke suppressant in poly(vinyl chloride) combustion
Authors: Michel A. , Bert M. , Van Hoang Tran , Bussiere P. , Guyot A. 
Published: April 2003

AbstractWhatever the state of the iron compounds as smoke suppressant during the combustion of poly(vinyl chloride), they lead rapidly to native αFe2O3 in the char residue left after dehydrochlorination. It causes incandescence of the char residue and catalyzes its oxidation into carbon monoxide and carbon dioxide that contributes to decreasing the amount of available carbon for the soot formation after self‐ignition. FeCl2 and FeCl3 are the precursors of αFe2O3, which is the true compound as smoke suppressant. Nevertheless, as intermediate, iron chlorides are able to modify the degradation processes, and they favor the formation of light tars instead of heavy tars. For that reason the iron compounds cause the formation of smoke at lower temperature than for pure PVC, but, as αFe2O3 is formed, the smoke production levels off and then decreases. The higher the ease of the iron compounds to give chlorides through reaction with HCI and further native αFe2O3, the higher the ease of the additive to cause the oxidation of the char residue sooner and in consequence to decrease the smoke level. In the PVC combustion three main steps may be distinguised: dehydrochlorination step between 200–300°C; tars aerosols formation from the char residue between 300°C and self‐ignition; at temperature higher than self‐ignition, formation of soot from the previous tars as precursors.
Simulation of nylon 6 polymerization in tubular reactors with recycle
Authors: Gupta Santosh K. , Kunzru D. , Kumar Anil , Agarwal K. K. 
Published: April 2003

AbstractIn the hydrolytic polymerization of ϵ‐caprolactam, the ring opening of the monomer is much slower than the polyaddition reaction. Hence, the mixing of aminocaproic acid to the feed results in a faster conversion of the monomer. Industrially, this fact is exploited by using a recycle stream. An isothermal plug flow reactor (PFR) with a recycle is simulated in this study, using two techniques: the method of successive substitutions and Wegstein's method. It is found that, under certain operating conditions, the use of a recycle stream gives higher monomer conversions and lower cyclic dimer concentrations than either a PFR or a homogeneous continuous‐flow stirred‐tank reactor (HCSTR), with the degree of polymerization almost the same as that obtained in an HCSTR, and thus offers a considerable advantage. However, when a recycle reactor is coupled with a subsequent flashing operation and a finishing reactor, these advantages are considerably reduced.
Poly(methyl methacrylate) as incorporation medium for spent ion‐exchange resin. II. Simulated resin
Authors: Ghattas N. K. , Ikladious N. E. , Eskander S. B. 
Published: April 2003

AbstractThe incorporation and final containment of spent ion‐exchange resins into poly(methyl methacrylate) (PMMA) was investigated in the present study. Test blocks of PMMA with 50% incorporated inactive resin were subjected to radiation doses of 105–107 rad at a dose rate of 50 rad/s. The high radiation doses impaired the mechanical properties of the final products. Both compressive strength and hardness decreased with increasing the particle size of the ion‐exchange resin. DTA diagrams showed the thermal instability of the final solidification product at about 400°C. Leaching experiments on incorporated blocks of active resins labelled with Cs‐137 and Ce‐144 showed that cesium activity was more easily released in leachant solutions than was cerium activity. Cumulative leaching rates for both Cs and Ce were lower in deionized water than in undergroud water. The mechanical, thermal, and leaching data obtained illustrate the suitability of PMMA for immobilization of spent ion‐exchange resins with low specific activity.
Melt flow crystallization of ultrahigh molecular weight polyethylene under curvilinear flow conditions
Authors: Zachariades Anagnostis E. , Logan J. A. 
Published: April 2003

AbstractMultiaxially oriented ultrahigh molecular weight polyethylene films were prepared recently under curvilinear flow conditions generated by the combined effects of compression and rotation. The films were prepared by melt flow crystallization in an optical apparatus specially designed for rheo‐optical observations. Morphological studies indicate that the films were fibrillar with the fibrils oriented along the circular flow lines. The fibrils were lamellar, and their lamellar thickness (150–450 Å) and spacing (400–2000 Å) depended on the processing conditions. The film exhibited strong birefringence (1.4 × 10−2) and had a Young modulus of 15–25 GPa along the flow lines and 3–5 GPa in the transverse direction.
Pervaporation of methanol–water mixture by poly(γ‐methyl L‐glutamate) membrane and synergetic effect of their mixture on diffusion rate
Authors: Suzuki Fumio , Onozato Kenji 
Published: April 2003

AbstractThe pervaporation behaviors of methanol–water by poly(γ‐methyl L‐glutamate) (PMLG) membrane at non‐steady‐ and steady‐state permeation were investigated. The values of t1/2 (time required to reach a half value of steady‐state permeation flux) for methanol and water changed and did not change with the component in feed, respectively. Both of the average diffusion coefficients for methanol–and water–PMLG from the mixture changed exponentially with the sorption amount of methanol by the synergetic effect on diffusion. The difference in behavior of non‐steady and steady state diffusion was explained by whether Do (diffusion coefficient at zero penetrant concentration) was influenced by the concentration distribution of penetrant in PMLG membrane.
Identification of some boron‐based curing agents in cured epoxy systems by computer‐assisted infrared spectroscopy
Authors: Davidson R. G. , Mathys G. I. 
Published: April 2003

AbstractThe use of computer‐assisted infrared spectroscopy has allowed identification of three different boroxines and a boron trifluoride complex used as curing agents in cured epoxy resins. Boroxines were distinguished from a boron trifluoride complex by the BO stretch absorption near 1400 cm−1 in the solid state. Detection of this absorption was enhanced by spectral subtraction methods in which the reference spectrum was that of the parent resin, or a suitably cured system of similar structure. Distinction between different boroxines was achieved by analysis of the gases evolved from samples heated at 300°C in nitrogen. Identification of the alcohol fraction of the original boroxine was improved by subtraction of the spectrum of water vapor. Boron trifluoride was detected in the gases evolved at 450–500°C from BF3‐cured systems, and also in the liquid pyrolyzates. Further simplification of the 300°C gas spectra by subtraction of alcohol and carbon dioxide revealed the presence of acrolein in the gases from boroxine‐cured systems while BF3‐cured systems yielded acetaldehyde. These differences may be associated with different end groups in the cured resins.
NO2‐initiated polymerization of acrylonitrile
Authors: Mishra Mahendra Kumar , Bhadani Suraj N. 
Published: April 2003

AbstractThe polymerization of acrylonitrile initiated with NO2 in dimethyl sulfoxide has been studied. The kinetics of polymerization was followed gravimetrically. The effect of monomer, initiator, and temperature on the rate of polymerization has been given. The overall activation energy was found to be 18.06 kcal.mol−1. The polymerization with NO2 appears to be initiated by a free‐radical mechanism.
Radiation crosslinking of poly(vinyl chloride) with trimethylolpropanetrimethacrylate. II. Dependence on radiation dose and blend composition
Authors: Bowmer T. N. , Hellman M. Y. , Vroom W. I. 
Published: April 2003

AbstractThe radiation crosslinking of poly(vinyl chloride) (PVC) blended with trimethylolpropanetrimethacrylate (TMPTMA) has been examined. The polyfunctional TMPTMA undergoes polymerization incorporating the PVC into a 3‐dimensional network. The kinetics and mechanisms of these crosslinking reactions were studied with particular reference to dependence on radiation dose and blend composition. The crosslinking rate was found to be proportional to the TMPTMA concentration. As the TMPTMA concentration decreased, soluble graft copolymers were produced in addition to insoluble networks. A gel permeation chromatography technique provided compositional information on the gel and sol fractions. The competition between polymerization, grafting, and degradation reactions was examined.
High performance epoxy resins cured in the presence of BF3 catalyst
Authors: Munns Thomas E. , Seferis James C. 
Published: April 2003

AbstractDynamic mechanical experiments have been conducted on an epoxy system made with tetraglycidyl 4,4′‐diaminodiphenyl methane (TGDDM) and polyglycidyl ether of Bisphenol A Novalac that were cured with 4,4′‐diaminodiphenyl sulfone (DDS) in the presence of Boron trifluoride monoethylamine catalyst (BF3:EtNH2). As the concentration of BF3:EtNH2 increased, the low temperature β‐transition magnitude increased slightly. The α1‐transition observed in the uncatalyzed system decreased significantly with the addition of BF3:EtNH2 catalyst. The α2 or glass transition temperature of this system increased with increasing catalyst concentration. Both the catalyzed and uncatalyzed epoxy formulations studied in this work are important due to their similarity to systems used commercially in epoxy matrix composites.
Processing–mechanical property relationships in injection moldings of polybutylene
Authors: Guo M. , Bowman J. 
Published: April 2003

AbstractTwo unfilled nonpigmented extrusion grades of polybutylene have been injection‐molded into a tensile bar mold under a wide range of barrel and mold temperatures. The overall structure of the moldings has been determined and correlated with processing conditions. The short term tensile mechanical properties of the moldings have been ascertained and correlated with molding structure. For low mold temperatures, the Young's modulus and tensile strength of injection moldings of polybutylene are controlled by the extent of and structure within the highly oriented skin. Low barrel temperatures can give rise to highly crystalline thick skins that treble the Young's modulus and fracture stress, when compared to high barrel temperature moldings. Increasing the mold temperature introduces a brittle response in polybutylene injection moldings. Modulus is controlled, at the high mold temperatures, by the skin thickness and by the crystallinity of the material comprising the core of the molding.
Hydraulic permeability of water in poly(vinyl alcohol) membranes as a function of the degree of hydration
Authors: Kojima Y. , Furuhata K. , Miyasaka K. 
Published: April 2003

AbstractPoly(vinyl alcohol) membranes were prepared by solution cast and subsequent annealing. The degree of crystallinity of the membranes at the dry state was not affected by the annealing, whereas the degree of hydration H was markedly changed. This made us assume a double network structure. Hydraulic permeability of water, Kw, in PVA membranes was measured to discuss the relation between H and the permeability. Kw increased with increasing H with increasing slope. The linear relation between the reduced permeability Kw/H and 1/H, expected from a free volume theory, was not obtained in the PVA membranes. This nonlinearity of the relation was confirmed also in various hydrogels reported by other authors. We found that a linear relation between H and logarithm of Kw/H, as expected from the Ogston's relation, is achieved in PVA and many other hydrogel membranes with H from 0.4 to 0.9. Under a given degree of hydration, the activation energy of permeation of PVA membrane was larger than that of cellulose, owing to the large amount of bound water in PVA membrane.
Silylation of water glass. IV. Synthesis and characterization of silylated silicic acids
Authors: Inoue Hiroshi , Kohama Shigemi 
Published: April 2003

AbstractTrimethylsilylated (TMSS) and dimethylphenylsilylated silicic acids (DMPS) were prepared via extraction with tetrahydrofuran, started from aqueous sodium silicate. Characterization of these silylates based on the 13C and 29Si NMR spectra, X‐ray diffraction, gel permeation chromatography, and solution viscosity were conducted to study their molecular structures. It was found that the GPC elution volume was significantly deviated from the calibration curve and also the exponents in solution viscosity vs. molecular weight (M̄n) relationship were very low, almost 0.3. These solution properties suggest that such silylates have compact spherical structures with a high degree of branching, also supported from the other data.
Gel permeation chromatographic analyses of resole phenolic resins
Authors: Rudin Alfred , Fyfe C. A. , Vines S. Martin 
Published: April 2003

AbstractTetrahydrofuran solutions of resole polymers were analyzed by gel permeation chromatography (GPC) on crosslinked polystyrene gel packings. The best separation was obtained with low solvent flow rates in low porosity columns. Irregular elution volumes were observed, but the effects of this erratic behavior can be eliminated by referencing retention times to that of a marker compound such as benzene or phenol. A calibration and data analysis method are presented which utilizes hydrodynamic volumes. Phenolic polymers vary in shape and ability to form hydrogen bonds with solvent; hence their molecular weights cannot be estimated from GPC data. Separation of the constituent species of resole samples is shown to be incomplete, because of aggregation between the various phenol derivatives. Particular peaks in the GPC chromatogram could generally not be assigned to individual species. Despite these limitations, GPC is a useful tool for charcterizing phenolics, and several applications are reviewed here.
Permeation characteristics of poly(vinyl alcohol)–poly(vinyl acetate) composite porous membranes
Authors: Hayashi Sadao , Hirai Toshihiro , Hayashii Fumihiko , Hojo Nobumasa 
Published: April 2003

AbstractPoly(vinyl alcohol) (PVAc) composite porous membrane has been prepared from PVAc latex film by extraction with acetone. The PVAc latex was prepared by emulsion polymerization of vinyl acetate in the presence of PVA, employing the hydrogen peroxide–tartaric acid systemm as an initiator. The extraction degree of PVAc could be controlled in a wide range by changing the addition method of the initiator, and, acoordingly, PVA–PVAc omposite porous membranes which had variosu void volumes were obtained. The maximum void volume attained was ca. 90%. Permation characteristics of organic solvents wre investigated on the membranes whose extraction degrees were 95.6% and 80.7%. Thge feeds were benzene, n‐hexane, cyclohexane, and their mixtures. neither swelling nor shrinkage in tje appearance size of the while benzene hardly permeated even at 20 kg/cm2. The grafted PVAc in the mebrane was removed or converted into grafted PVA by treatment with sodium methylate, and then the depression of benzene permeation was lost. The grafted PVAc was suggested to be localizd on the cell wall and was found to function as a valve which closes with nenzene or a good solvent for PVAc and opens with n‐haxane or a poor solvent for PVAc.
Infrared spectroscopy and conformation of alkyl vinyl ketone monomer
Authors: Kinoshita Akihiro , Naito Ikuo , Namariyama Yoichi 
Published: April 2003

AbstractThe correlation between IR spectra and conformations was examined in alkyl vinyl ketone monomer. The stretching absorption bands of double bonds shift to lower wave number with the decrease in Taft's σ* values of alkyl groups, and, conversely, the deformation band of the vinyl group shifts to the higher wave number. The inductive effect of the alkyl group is aparently three times larger in s‐cis conformation than that in the s‐trans. Absorption coefficients in the double‐bond stretchings (A CO and A CC) were measured in each conformation. Both conformations have a nearly equal value of A CO. The ratio (A s‐cis/A s‐trans) CC is 3.4 ±1.0. The ratios (A′ CO/A′ CC) are 4.5 ±0.6 for the s‐cis conformation and 15±2 for the s‐trans conformation in all alkyl vinyl ketones studied.
Application of multimethod procedure for characterization of branched polydisperse polymers
Authors: Dobkowski Zbigniew 
Published: April 2003

AbstractThe multimethod procedure for characterization of branched polydisperse polymers, including gel permeation chromatography, solution viscometry, melt viscometry, and differential scanning calorimetry, is described. An equation relating the average branching degree g¯x and the average number of branch points n̄bx has been derived and compared with the theoretical Zimm–Stockmayer equation. It has been found that both equations can be consistent for theta solvent and for the branching degree exponent b=1.5. Experimental data are given for trifunctionally branched bisphenol A polycarbonate.
Thermal stability of grafted fibers
Authors: Sundardi F. , Kadariah  , Marlianti Isni 
Published: April 2003

AbstractThis paper presents the experimental results on the study of thermal stability of grafted fibers, i.e., polypropylene‐, polyester‐, and rayon‐grafted fibers. These fibers were obtained by radiation grafting processes using hydrophylic monomers such as 1‐vinyl 2‐pyrrolidone, acrylic acid, N‐methylol acrylamide, and acrylonitrile. The thermal stability of the fibers was studied using a Shimadzu Thermal Analyzer DT‐30. It was found that the thermal stability of the fibers, which can be indicated by the value of the activation energy for thermal degradation, was not much improved by radiation grafting. The degree of improvement depends on the thermal stability of the monomers used for grafting. The thermal stability of a polypropylene fiber, either a grafted or an ungrafted one, was found to be inferior compared to the polyester of a rayon fiber, which may be due to the lack of CO and CC bonds in the polypropylene molecules. The thermal stability of a fiber grafted with acrylonitrile monomer was found to be better than that of an ungrafted one. However, no improvement was detected in the fibers grafted with 1‐vinyl 2‐pyrrolidone monomer, which may be due to the lower thermal stability of poly(1‐vinyl–2‐pyrrolidone), compared to the polypropylene or polyester fibers.