bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polyester–polycarbonate blends. I. Poly(butylene terephthalate)
Authors: Wahrmund D. C. , Paul D. R. , Barlow J. W. 
Published: April 2003

AbstractMelt blends of bisphenol A polycarbonate with poly(butylene terephthalate) were studied by DTA and dynamic mechanical behavior to determine their state of miscibility. Both techniques showed multiple glass transitions indicative of incomplete miscibility in the amorphous phase. However, these transitions in some cases did not correspond to those in the pure components and varied with overall blend composition in some instances. This indicates that there are amorphous phases containing both components, i.e., partial miscibility. This view was supported by the crystallization behavior of the polyester. Two crystallization exotherms were observed for quenched samples, which is interpreted as polyester crystallization from two separate phases, one richer in this component than the other. Other interpretations of these results are discussed.
Rheology of high solid coatings. II. Analysis of combined sagging and leveling
Authors: Wu Souheng 
Published: April 2003

AbstractThe rheology of combined sagging and leveling of high solid coatings is analyzed in terms of non‐Newtonian power‐law model. The results indicate that, in order to have good leveling, good sag control, and good sprayability at the same time, high solid coatings should have pseudoplastic rheology with power constant of about 0.5 and viscosity at sec‐1 of about 50 poises. This theoretical prediction is confirmed experimentally.
Thermal degradation of poly(2,6‐dimethyl‐1,4‐phenylene oxide). I. The mechanism of degradation
Authors: Jachowicz J. , Kryszewski M. , Kowalski P. 
Published: April 2003

AbstractAn analysis of products obtained from thermal degradation of poly(2,6‐dimethyl‐1,4‐phenylene oxide) is presented. The techniques used for identification of monomeric and dimeric degradation products were gas chromatography and mass spectrometry. On the basis of this analysis a mechanism of thermal breakdown is established. It consists of the Fries‐type rearrangement of the polymer chain in the first degradation step and statistical scission of benzyl bonds. The proposed degradation scheme accounts for the retention of ether linkage in the afterdegradation residue.
Drawing and annealing of polypropylene fibers: Structural changes and mechanical properties
Authors: Nadella Hari P. , Spruiell Joseph E. , White James L. 
Published: April 2003

AbstractA study has been carried out on the influence of cold drawing (25°C), hot drawing (140°C), and annealing (140°C) on the structure and mechanical properties of a series of four different well‐characterized melt spun polypropylene filaments. The influence of the interaction between melt spinning and drawing variables was given special attention. Cold drawing increased the orientation in the samples, disrupts the initial monoclinic crystal structure and the morphology of the filaments, and it results in extensive fibrillation. Annealing restored the monoclinic structure but eliminated only a small part of the fibrillation. Hot drawing produced changes which were qualitatively similar to the combined effects of cold drawing and annealing. The orientation and morphology of the asspun filaments were found to have major effects on drawing behavior and the mechanical properties of the drawn fibers for a given draw ratio. It was found, however, that the mechanical properties (tensile strength, tangent elastic modulus, and elongation to break) of the melt spun, hot drawn and cold drawn, and annealed fibers could all be correlated with birefringence measurements.
Correlating and predicting polymer thermal conductivities
Authors: Luba Michael , Pelt Thomas , Griskey Richard G. 
Published: April 2003

AbstractGeneral correlations were developed to estimte polymer thermal conductivities for four cases—amorphous polymers above the glass temperature; amorphous polymers below the glass temperature; semicrystalline polymers above the melting temperature, and semicrystalline polymers below the melting temperature. The correlations based on readily available parameters (mer weights, densities at 25°C, specific heats) yielded calculated thermal conductivities that deviated by only 1%–2% from experimental values.
Effects of composition and processing conditions on the properties of a series of shock mitigating phenolic foams
Authors: Mendelsohn M. A. , Meier J. F. , Rudd G. E. , Rosenblatt G. B. 
Published: April 2003

AbstractThe effects of variations in the chemical composition and processing conditions of the series of phenolic foams described in the two previous papers were studied. Compressive stiffness and density increased with increasing concentrations of the acid catalysts, the slower reacting phenolic resin component, water, the lipophilic component of the surfactant system, and age of the phenolic resins. These properties decreased with increasing concentration of the fluorocarbon blowing agent and process temperature. The compressive stiffness and density increased to a maximum and then decreased with increasing concentrations of the hydrophilic surfactant. Permeability or “breathability” of the foam decreased with the hydrophilic surfactant at low concentrations and then became essentially independent of further increases of this component. Increasing concentrations of the lipophilic surfactant gave foam having greater breathability. In all other cases the permeability of the foam decreased as its density increased. Effects of the variations in processing and composition on the dependency of load bearing upon density, on relationships between permeability and density and permeability and compressive stiffness, and upon cell structures are also described.
Biodegradable polymers: Chymotrypsin degradation of a low molecular weight poly(ester‐urea) containing phenylalanine
Authors: Huang Samuel J. , Bansleben Donald A. , Knox James R. 
Published: April 2003

AbstractA low molecular weight poly(ester urea), poly(L‐phenylalanine/ethylene glycol/1,6‐diisocyanatohexane), and a model diester diurea, dimethyldiphenylalaninehexamethylenediruea, were synthesized and found to be hydrolyzed by α‐chymotrypsin solutions at pH 7.8. After ten‐day exposure to 0.1 mg/ml enzyme solution at room temperature, 79.9% weight loss was observed for the model diester diurea (containing two ester linkages per molecule). A weight loss of 19.4% was observed for the poly(ester urea) of M̄n 1930 (containing an average of eight ester linkages per molecule) after the same period of exposure. A poly(ester urea) of similar molecular weight, but derived from glycine instead of phenylalanine, was found to resist chymotrypsin hydrolysis.
Flame retardant polyesters based on bromine derivatives
Authors: Ram Arie , Calahorra Arie 
Published: April 2003

AbstractUnsaturated polyesters containing halogens in the backbone of the polymer chain were synthesized. Derivatives used had brominated functional groups such as tetrabromobisphenol A, tetrabromophthalic anhydride, and dibromoneopentyl glycol. These were compared to chlorine‐containing polyesters based on HET acid and tetrachlorophthalic anhydride and an additive exhibiting a synergistic effect of phosphorus and halogen, trichloroethyl phosphate. Optical properties before and after artificial weathering (up to 1650 hr), were determined on cast specimens, and mechanical properties (flexural strength, modulus, and hardness) and flame retardancy were determined on glass fiber laminates. The flammability tests consisted of the “oxygen index” and the “self‐extinguishing time” tests, which were correlated for various halogen concentrations and different compositions. The efficiency of bromine in flame retardancy has been found to be much higher than that of chlorine. The minimal concentration of bromine required for self‐extinguishing is 10–12%, as compared with 20–25% for chlorine. A general performance index for polyesters has been derived which incorporates both flame and weather resistivity factors of the modified polyesters.
Emulsion of polyurethane having thermosetting properties. II. Relation between the mechanical properties of film and the polyurethane structure
Authors: Matsuda Kazuo , Ohmura Hidemasa , Sakai Takeyo 
Published: April 2003

AbstractA self‐emulsifiable polyurethane emulsion having thermosetting property was prepared by the following procedure: the polyurethane–urea–amine was first prepared by the reaction of diethylene–triamine with a prepolymer containing terminal isocyanate groups in a ketone solvent, and then the primary amino group in the polyurethane–urea–amine was reacted with epichlorohydrin. The mixture was neutralized with an aqueous acid, and finally the ketone solvent was removed by distillation in vacuo. In the polyurethane, polytetramethylene glycol (PTMG) was the base polymer functioning as the soft segment. The present paper reports the effects of the following variables on the mechanical properties of the film prepared from the polyurethane emulsion, i.e., the Mn of PTMG, the molar ratio of diethylene–triamine (DTA) to prepolymer containing terminal isocyanate groups, the structure of the isocyanate end group and the molar ratio of tolylene diisocyanate (TDI) with PTMG. The best elastomer property was realized when Mn of PTMG was 2000, TDI/PTMG molar ratio was 2.0, and prepolymer/DTA molar ratio was 0.85.
Basic principles of thermal degradation and thermal stabilization of poly(vinyl chloride). Synergism of stabilizer action
Authors: Prochaska Krzysztof , Wypych Jerzy 
Published: April 2003

AbstractChanges in the quantities of active stabilizing components during thermal aging of plasticized poly(vinyl chloride) containing a mixture of calcium and zinc stearates were analyzed. A mathematical model of the stabilization process by using the stabilizer mixture and a computer program for analyzing the process of PVC thermal degradation after the beginning of HCl evolution are given.
Flame resistant cotton fabrics prepared by radiation‐initiated polymerization with vinyl phosphonate oligomer and N‐methylolacrylamide
Authors: Harris James A. , Arthur Jett C. , Goynes Wilton R. 
Published: April 2003

AbstractRadiation‐initiated polymerization of vinyl phosphonate oligomer (molecular weight 500–1000) and N‐methylolacrylamide from aqueous solutions was investigated with cotton printcloth, flanelette, and sateen fabrics and with cotton (50%)–polyester (50%) flannelette fabrics. Determinations were made of the effects of radiation dosage, mole ratio of vinyl phosphonate in the oligomer to N‐methylolacrylamide in aqueous solution, concentration of reactants, wet pickup of solutions on fabrics, and irradiation of both dry and wet fabrics on efficiency of conversion of oligomer and monomer in solution to polymer add‐on. The effects of vinyl phosphonate oligomer and N‐methylolacrylamide radiation‐initiated polymerization on some of the textile properties of cotton printcloth and on flame resistances of cotton and cotton–polyester fabrics were evaluated. The breaking strength of modified cotton printcloth was about the same as that of unmodified fabric; however, the tearing strength and flex abrasion resistance of modified fabric were reduced. The textile hand of the modified printcloth fabrics that had flame resistance indicated: interaction between cellulose and vinyl phosphonate oligomer–poly(N‐methylolacrylamide) and uniform deposition in the fibrous cross section (transmission electron microscopy); surface areas of heavy deposits of oligomer–polymer (scanning electron microscopy); and phosphorus located throughout the fibrous cross section (energy dispersive x‐ray analysis). Polymerization of vinyl phosphonate oligomer and N‐methylolacrylamide was radiation initiated with cotton–polyester fabric; however, this modified fabric did not have flame‐resistant properties.
Plasma polymerization of ethylene in an atmospheric pressure‐pulsed discharge
Authors: Donohoe Kevin G. , Wydeven Theodore 
Published: April 2003

AbstractThe polymerization of ethylene in an atmospheric pressure‐pulsed discharge has been studied. Partial pressures of ethylene up to 4 kN/m2 were used with helium as a diluent. Deposition rates (on glass slides) were the same throughout the discharge volume over a wide range of operating conditions. These rates were in the 1–2 Å/sec range. The films were clear, soft, and showed good adhesion to the glass substrates. Oligomers large enough to visibly scatter 637.8‐nm light were observed in the gas phase under all conditions in which film deposition occurred. The experimental results suggest that Brownian diffusion of these oligomers was the rate‐limiting step in the film deposition process.
Electrical resistivity and ESCA studies on neutral poly(alkylbenzimidazoles), their salts, and complexes
Authors: Aharoni Shaul M. , Signorelli Anthony J. 
Published: April 2003

AbstractA series of metal and acid salts having poly(alkylbenzimidazoles) as the parent ligand were synthesized. The room‐temperature electrical resistivity of the parent and the salts was measured. Values for the dc electrical resistivity varied from ∼1 × 1013 ohm.cm for the neutral polymers to ∼1 × 106 ohm·cm for the acid conjugate formed by reaction with HCl. Unexpectedly, changes in resistivity did not correlate with acid strength as measured by us but could be roughly correlated with the molar volume of the corresponding acid or metal salt. The nature of the complexes was elucidated using the ESCA technique. The electron core levels of nitrogen, chlorine, and the various metals were examined. The observed photoelectron spectra indicated the formation of polybenzimidazole/acid and polybenzimidazole/metal salts. In addition, one was able to conclude that the complexes of Co and Ni were high spin, thus ruling out a planar geometry for the Ni(II) complex.
NH3‐modified swelling of silica‐filled silicone rubber
Authors: Vondráček Petr , Schätz Miroslav 
Published: April 2003

AbstractThe NH3‐modified swelling method was used for fume silica‐filled silicone rubber compounds and vulcanizates. The method provides an estimation of the polymer–filler interaction in the system. Bound rubber reduction due to the modified swelling is shown to be dependent on the silica surface silanol content in the compound. The swelling behavior of silica‐filled vulcanizates was also studied in an NH3 atmosphere. The fraction of polymer–filler attachments in the vulcanizates was found not to depend on the particle size of silica and its surface modification, depending only on the total polymer–filler contact area in the system. No relation was found between bound rubber content in a compound and swelling of a filled vulcanizate of the same composition. The strong rubber‐to‐filler adherence found in toluene changed to nonadherence under NH3‐modified swelling conditions. The NH3‐induced cleavage of silica–silicone rubber attachments was found to be nearly completely reversible. In the silica‐filled silicone rubber vulcanizates, the fraction of polymer–filler attachments due to polymer–filler interaction represents a substantial contribution to the total number of network chains.
Mie scattering from sphere structures in polymer blends
Authors: Uemura Yukikazu , Chikaishi Kazuhiro , Yamazaki Takashi 
Published: April 2003

AbstractPolymer blends of transparent poly(methyl methacrylate) and polystyrene become opaque due to light scattering at the boundaries of the two polymers. The polymer blend is light brown when it is illuminated by white light. The coloring depends on the spherical domain structures existing in the polymer blend. The coloring was analyzed by using the rigorous Mie theory. The Mie results were compared with the semiempirical results previously reported by the authors. The wavelength dependence of theoretical scattering efficiencies on radii of scattering spheres from 0.05 to 1.2 μm was obtained for polystyrene spheres in poly(methyl methacrylate) matrix, and vice versa. The scattering at the short wavelength region is stronger than at the long wavelength region. The scattering efficiencies become almost constant in the visible wavelength region for sufficiently large spheres.
The chemistry and development of tannin/urea–formaldehyde condensates for exterior wood adhesives
Authors: Pizzi A. 
Published: April 2003

AbstractNovolak‐like materials were prepared by condensation of urea–formaldehyde resins with resorcinol and/or resorcinolic A‐rings of polyflavonoids such as condensed tannins. The copolymers formed were used as thermosetting and cold‐setting exterior‐grade wood adhesives. Condensation of tannins with small amounts of urea–formaldehyde resins can prevent the water deterioration normally experienced by the latter resins. Conversely, urea–formaldehyde resins improve crosslinking and strength of wood tannin–formaldehyde networks.
Plasma polymerization of tetrafluoroethylene. II. Capacitive radio frequency discharge
Authors: Morosoff N. , Yasuda H. , Brandt E. S. , Reilley C. N. 
Published: April 2003

AbstractThe plasma polymerization of tetrafluoroethylene (TFE) is studied in a capacitively coupled system with internal electrodes using radio frequency (13.56 MHz) power. The emphasis is on identifying conditions that are compatible with continuous coating of plasma polymer on a substrate moving through the center of the interelectrode gap. At high pressure (500 mTorr), deposition of plasma polymer is primarily on the electrodes rather than on a substrate placed midway between electrodes. Glow is observed in only part of the interelectrode gap at low powers and fills the gap only at high power levels. The use of a magnetic field effects barely discernible changes. Low‐pressure (below 100 mTorr) operation is more favorable for deposition of a substantial portion of the plasma polymer on a substrate placed midway between electrodes. The plasma polymer deposited at low pressure is characterized by ESCA and deposition rate data and compared to that deposited in an inductively coupled system. The polymers formed in both systems are broadly similar and completely different from conventional poly(TFE). Subtle system‐dependent differences are identified. The known susceptibility of fluorine‐containing polymers (including plasma polymer) to a high‐power plasma has been used as a probe of plasma power density within the interelectrode gap in the capacitively coupled system. Without magnets the most active zone of the plasma is in the center of the interelectrode gap. The use of a magnetic field moves this active zone closer to the electrodes and leads to a more efficient coupling of energy to a polymerizing glow discharge.
Composition analysis of crosslinked styrene–ethylene dimethacrylate and styrene–divinylbenzene copolymers by Raman spectroscopy
Authors: Štokr J. , Schneider B. , Frydrychová A. , Čoupek J. 
Published: April 2003

AbstractA method for the determination of composition and content of pendent double bonds in untreated samples of styrene–ethylene dimethacrylate and styrene–divinylbenzene copolymers from Raman spectra has been developed. By computer treatment of spectra it was shown that Raman spectra are sensitive to the distribution of components in the studied copolymers.
Pilot‐plant process for starch xanthide encapsulated pesticides
Authors: Stout E. I. , Shasha B. S. , Doane W. M. 
Published: April 2003

AbstractA small pilot‐plant batch process for the encapsulation of pesticides with crosslinked starch xanthate (starch xanthide) has been developed. Multipound quantities of several encapsulated pesticides have been prepared that have slow‐release properties. Products were made from starch xanthates of varying degrees of substitution (0.1 to 0.3) and with various crosslinking agents (H2O2, NaNO2, NaOCl, NaClO2, and FeCl3). Recovery of the pesticides as the encapsulated product ranged from 62% to nearly 100%. In a single experiment, processing water was recycled without apparent problems.
Reverse osmosis characteristics of cellulose acetate butyrate membranes
Authors: Ohya Haruhiko , Akimoto Naoyuki , Negishi Yoichi 
Published: April 2003

AbstractCellulose acetate butyrate membranes were cast from five different formulations. The pure water flux through the membrane increased with evaporation period. The separation of 4000 ppm NaCl aqueous solution remained unchanged until it reached a critical flux; at that point, separation decreased inversely proportional to the flux. Scanning electron microscope photography of the membranes corresponding to each evaporation period is reported.
Morphology and mechanical behavior of poly(vinyl chloride)/poly(butadiene–co–acrylonitrile) latex interpenetrating polymer networks
Authors: Sionakidis J. , Sperling L. H. , Thomas D. A. 
Published: April 2003

AbstractA series of poly(vinyl chloride)/poly(butadiene–co–acrylonitrile) interpenetrating polymer networks (IPNs), all having 50/(25–25) weight compositions, was synthesized in latex form. The latex particles were studied after each step of the two‐staged polymerization and after molding or casting. Transmission electron microscopy together with dynamic mechanical spectroscopy suggest a graded composition within the latexes, in which the poly(vinyl chloride) seed latex network I forms a core that is partially penetrated by the poly(butadiene–co–acrylonitrile) network II, yielding increased amounts of poly(butadiene–co–acrylonitrile) in the shell of the latex particles.
Phenolic and tannin‐based adhesive resins by reactions of coordinated metal ligands. II. Tannin adhesive preparation, characteristics, and application
Authors: Pizzi A. 
Published: April 2003

AbstractThe accelerating effect due to bivalent metal ions observed in simple phenol–formaldehyde reactions are also observed in tannin–formaldehyde resins. Tannin steric hindrance prevents the retarding effect of trivalent metallic ions on tannin–formaldehyde reactions. Small amounts of metal ions do not significantly increase flavonoid B‐ring participation to the crosslinking of tannin–formaldehyde networks. Improved plywood strength and shorter pressing times are obtained by the addition of metal ions to tannin/formaldehyde resins. These results are due to faster curing promoted by the presence of the metal ions.
Characterization of transport across cellulose acetate membranes in the presence of strong solute–membrane interactions
Authors: Burghoff H.‐G. , Lee K. L. , Pusch W. 
Published: April 2003

AbstractCertain organic solutes, including phenol, undergo anomalous enrichment when hyperfiltered through cellulose acetate membranes: the solute concentration is higher in the permeate than in the feed solution. A number of existing theoretical approaches describing hyperfiltration phenomena are presented and their merits and limitations upon application to the transport of phenol discussed. A new two‐parameter transport relationship is derived based on an extension of the solution–diffusion model. The enrichment, or negative solute rejection by the membrane, is predicted to occur whenever the pressure‐induced solute permeation velocity exceeds that of water. By acknowledging and incorporating the effect of pressure on the chemical potential of the solute, the present extended solution–diffusion model relationship successfully describes hyperfiltration data of phenol in homogeneous and asymmetric cellulose acetate membranes provided the contribution of convective flow to the overall solute transport is insignificant. In addition to the transport parameters of the extended solution–diffusion model, the transport parameters of the phenomenological, Kedem–Spiegler, and combined viscous flow–frictional relationship are evaluated from hyperfiltration data obtained with 0.05 and 0.1 wt % phenol feed solutions and homogeneous cellulose acetate membranes of different acetyl content.