bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photodegradable polymers. II. Preparation of styrene copolymers with alkyl and phenyl β‐styryl ketones and their photodegradability
Authors: Shiraishi Shinsaku , Senō Manabu , Ishii Masao , Asahara Teruzo 
Published: April 2003

AbstractPhotodegradable polymers having pendent carbonyl groups attached directly to the polymer chain were prepared by copolymerization of styrene (St) with alkyl and phenyl β‐styryl ketones (RCOCHCHC6H5), where R = CH3, C2H5, n‐C5H11, n‐C11H23, t‐C4H9, cyclo‐C6H11, and C6H5. The photodegradability of these copolymers was traced by viscometric and IR spectroscopic measurements. The degradability of St–benzalacetophenone (BAPh) copolymer is greater than that of St–alkyl styryl ketone copolymers under the irradiation of a high‐pressure Hg lamp. The photodecomposition behavior St–BAPh copolymer was investigated in detail by a spectoirradiation technique. The changes in molecular weight and its distribution by photodegradation were measured by gel permeation chromatography, and the quantum yield for bond scission along the main chains of the copolymer was estimated to be about 5 × 10−3 by 328 nm irradiation in a benzene solution. Examination of the effect of wavelength of the radiation on the bond scission showed that 328‐nm light is most effective. The photochemical degradation process was shown to occur chiefly via triplet state of carbonyl groups by the quenching technique using 1,3‐cyclohexadiene as a triplet quencher. The quantum yield of decarbonylation process was also estimated to be about 4.2 × 10 −2 in benzene.
Structure and properties of abs polymers. X. Influence of particle size and graft structure on loss modulus temperature dependence and deformation behavior
Authors: Morbitzer L. , Kranz D. , Humme G. , Ott K. H. 
Published: April 2003

AbstractABS systems which differ distinctly in particle size and degree of grafting were prepared and investigated by dynamic mechanical measurements as function of temperature in the glass transition region of the rubber phase. Variation of rubber content within different sample series results in effects which were mainly referred to thermal stresses as consequence of phase interactions. Basic aspects of the deformation behavior of some of these ABS systems are studied by mechanical and morphological methods, and the operation modes of the component of a bimodal/bigraft‐system concerning toughness are discussed.
Effect of perchloric acid on the molecular weight and yield of poly‐THF
Authors: Matsuda Kazuo , Tanaka Yoshiaki , Sakai Takeyo 
Published: April 2003

AbstractPolytetramethylene glycol (molecular weight range 1000–8000) was prepared by the polymerization of tetrahydrofuran (THF) using a binary catalyst system of fuming sulfuric acid and perchloric acid. When 28% fuming sulfuric acid alone was used as the catalyst, the average molecular weight of polymer was low, the maximum value being 1000–1100. By the combination of fuming sulfuric acid with a small amount of perchloric acid, the average molecular weight of the polymer was increased to about 8000. Furthermore, the molecular weight was readily controlled in the range of 1000 to 8000 by varying the amount of the binary catalyst.
Studies of polymeric systems for absorbing airborne sound
Authors: Chen Alex C. F. , Williams H. Leverne 
Published: April 2003

AbstractSound absorption properties of polymer systems were investigated as functions of temperature, frequency, and chemical composition. Viscoelastic polymers were mixed with rigid polymers to obtain improved acoustical performance. In the case of foamed polymers, it was found that the chemical nature of the polymer is the most important factor controlling sound attenuation if the thin membranes of the closed‐cell foams are “acoustically transparent.” Polyurethane‐based polymer foams have been developed which possess excellent sound absorption characteristics. The foams are closed‐cell, leathery, and “dead,” and can absorb as much as 96% of the normal incident sound energy at 1250 Hz (foam thickness 25 mm). The temperature‐dependent acoustical properties of various polymer systems are discussed in terms of viscoelastic theory of polymers.
A semiempirical equation of state for polymer melts
Authors: Olabisi Olagoke , Simha Robert 
Published: April 2003

AbstractAn explicit reduced equation of state is developed by combining results of the hole'theory with a semitheoretical expression for the temperature dependence of the reduced Tait parameter B̃ which is found to be in good agreement with experiment. This approach circumvents the implicit character of the theoretical equations.Two procedures are explored to derive for a given system the PVT surface and the compressional energy and entropy changes from the corresponding reduced functions. One rests on the usual superposition of experimental and analytical isotherms and isobars. The other, and more approximate method, utilizes a correlation between the scaling temperatures, pressures, and volumes obtained previously, and requires only experimental data at atmospheric pressure and a single temperature above the glass transition (Tg) or the melting temperature (Tm). The good agreement between experiment and theory noted previously is shown to extend to the semiempirical relationships. Finally, internal pressure data for oligomers and polymers at atmospheric pressure and encompasing a wide range of reduced temperatures are examined. The ensemble of data can be described by simple power relationships between the internal energy and the density. The exponents, however, depart significantly from the van der Waal's value of unity.
Photochemical degradation of glassy polyesters of low softening point
Authors: Husband S. , Russell K. E. , Stone J. A. , Wan J. K. S. 
Published: April 2003

AbstractThe photodegradation of polyesters prepared by the reaction of o‐phthalic, adipic, and “dimer” acids with ethylene glycol has been studied. The polyesters softened at temperatures in the range of 25–50°C. Polymer films were irradiated in air by means of a medium pressure mercury lamp and the extent of formation of COOH groups determined by infrared spectroscopy. The films were also irradiated in vacuo and in air by means of a high‐pressure mercury lamp, and the volatile products, consisting mainly of carbon monoxide and carbon dioxide, were determined by gas chromatography.The results are interpreted in terms of simultaneous Norrish type I and type II decompositions of the polyesters. The type I process accounts for the formation of carbon monoxide and carbon dioxide in the absence of air. The enhanced yield of carbon dioxide in irradiations performed in air is ascribed to the formation of hydroperoxide which undergoes further photolysis. The type II process accounts for the formation of COOH groups. The photodegradation of these glassy polyesters parallels that of crystalline poly(ethylene terephthalate) and is relatively unaffected by changes in composition of the aromatic polyester.
A semiempirical derivation of phase domain size in interpenetrating polymer networks
Authors: Donatelli A. A. , Sperling L. H. , Thomas D. A. 
Published: April 2003

AbstractIn previous papers, interpenetrating polymer networks were shown to display a cellular structure. The phase domain size of polymer II was shown to depend inversely on the crosslink density of polymer I. The present paper presents a semiempirical derivation of equations which show quantitatively the dependence of the phase domain size of polymer II on the crosslinking density of polymer I, and also on the interfacial energy and the overall composition. If polymer II is linear, the dependence on the molecular weight of polymer II is also included. The values of the phase domain sizes so estimated are compared with experimental results. While theory and experiment yield good agreement, the semiempirical nature of the equations must be borne in mind.
Wet spinning of aliphatic and aromatic polyamides
Authors: Hancock Tony A. , Spruiell Joseph E. , White James L. 
Published: April 2003

AbstractBench‐scale equipment for wet spinning was designed and built. An experimental study of the wet spinning of several polyamides has been carried out. The polymers studied include nylon 6, nylon 66, redissolved Nomex, and redissolved Kevlar. The superstructure of the wet‐spun fibers were studied by optical and scanning electron microscopy as well as small‐ and wide‐angle x‐ray diffraction. Mechanical properties were measured and related to the spinning variables. For nylon 6 and nylon 66, the coagulation bath composition was found to be of major importance in determining fiber superstructure. For the case of the redissolved Kevlar, anisotropic spinning dopes were obtained from redissolved fiber, and the wet‐spun filaments produced from such solutions were investigated. These fibers proved to have relatively high modulus and strength as spun. They had even greater strengths after hot drawing.
Viscoelastic properties of epoxy resins. III. Effect of molecular weight of antiplasticizers in highly crosslinked antiplasticization system
Authors: Hata Naoaki , Kumanotani Ju 
Published: April 2003

AbstractAntiplasticization, defined as an increase in glassy modulus of polymers upon dilution with low molecular weight compounds, was studied for highly crosslinked epoxy resins. A series of oligomers with average molecular weight 500–4000 was incorporated with epoxy resins for elucidating the effect of their molecular weight on antiplasticization. The antiplasticization was found to be dependent on the molecular weight of the oligomers used. It was most evident when the lowest molecular weight oligomer was incorporated, and seems to be suppressed by increasing molecular weight of the oligomers. These results were discussed in correlation with the behavior of dynamic mechanical properties and the changes in specific volume as a function of the epoxy resin and diluents.
Melt viscosity characteristics of methacrylate–styrene copolymers
Authors: Terrell D. R. , Katiofsky H. 
Published: April 2003

AbstractThe activation energies of flow EA of methacrylate–styrene copolymers containing n‐butyl, n‐hexyl, n‐heptyl, n‐octyl, n‐decyl, n‐dodecyl, n‐tridecyl, n‐octadecyl, and cyclohexyl methacrylate have been investigated as a function of molecular weight, composition, and methacrylate monomer. Below a critical pendent group molar volume per chain unit (120 ± 10 ml Le Bas units), EA was found to increase with molar volume; and above this value, a decrease in EA was observed, reflecting a decrease in copolymer density. Copolymers with pendent group molar volumes per average chain unit of between 96 and 140 ml (Le Bas units) were found to exhibit sufficiently high EA values to render them suitable for use in thermoplastic and photothermoplastic devices with superior development and erasure rates, at temperatures which enabled the attainment of the development and erasure viscosities with a low expenditure of heat energy. Methacrylate–styrene copolymers with long‐chain ester methacrylates (viz., n‐decyl and n‐dodecyl methacrylate) were found to exhibit critical molecular weights Mc below 3000; and Mc was found to decrease with increasing methacrylate tail length and methacrylate concentration. These Mc values correspond to critical chain lengths Zc below 45. Similar Zc values have been previously reported for acrylonitrile–methyl methacrylate copolymers30 and ethylene–propylene copolymers.28
Modified bead‐spring theory of polymer solutions. IV. Extension to polymer melts
Authors: Everage A. E. , Gordon R. J. 
Published: April 2003

AbstractA constitutive equation which has proven quite successful in describing the nonlinear viscoelastic behavior of dilute polymer solutions is extended to the case of molten polymers. The techniques utilized and similar to those discussed by Ferry in a similar adaptation of the Rouse–Zimm Theory. The resulting model is found to quantitatively portray the shear rate dependence of the non‐Newtonian viscosity and primary normal stress functions and the frequency dependence of the storage and loss moduli. Extensional flow data reported by Spearot and Metzner for two polyethylenes are well described, using parameters calculated from steady shearing measurements. Of major significance is the ability of the model to account for influences of molecular weight, molecular weight distribution, and temperature.
N‐(morpholinothio)imides as curing agents in semiefficient vulcanization systems
Authors: Son P. N. , Krueger R. A. 
Published: April 2003

AbstractSemiefficient vulcanization systems (semi‐EV) are often used when a stock requires good aging properties as well as good fatigue resistance. A partial replacement of sulfur in a conventional cure system with 4,4′‐dithiobismorpholine or 2‐mercaptabenzothiazyl 4‐morpholino disulfide (BMD) is an example of semi‐EV system. However, with BMD the scorch time is not always long enough for multisteps involved in the manufacturing of tires. Such new cure retarders as N‐(cyclohexylthio)phalimide or N, N′‐bis(cyclohexylthio)oxanilide showed very little efficiency in BMD cure systems. This paper describes the usage of new curing agents, (N‐morpholinothio)imides, which can overcome the disadvantage of scorchness in BMD cure system and provide excellent aging properties. This is rationalized by the formation of BMD during vulcanization. The facile formation of BMD from N‐(4‐morpholinothio)phthalimide (MTP) and 2‐mercaptobenzothiazole (MBT) serves to illustrate the feasibility of in situ formation of BMD during cure and to explain long scorch time observed with N‐(4‐morpholinothio)imides.
Free‐radical polymerization with long‐chain branching: Batch polymerizations of vinyl acetate in t‐butanol
Authors: Chatterjee A. , Kabra K. , Graessley W. W. 
Published: April 2003

AbstractVinyl acetate was batch polymerized at 60°C in t‐butanol solution. Conversion and molecular weights were measured as functions of time for several initiator and solvent concentrations. Although the overall rate constant depends somewhat on solvent concentration, the reaction is first order in monomer concentration up to at least 60% conversion and one‐half order in the concentration of initiator. Molecular weights were independent of initiator concentration, confirming that the polymerization is transfer dominated. Measurements of M̄w and M̄w versus conversion were used to establish the individual transfer constants. All are independent of solvent concentration, except Cp, the polymer transfer constant, which decreases systematically with increasing solvent concentration.
Products of polyaddition of toluene 2,4‐dicarbonimide with triethylene glycol glycolate, thioglycolate, lactate, and p‐hydroxybenzoate
Authors: Zochniak A. 
Published: April 2003

AbstractInvestigations on the suitability of triethylene glycol glycolate, thioglycolate, lactate, and p‐hydroxybenzoate for the synthesis of new polyurethanes from toluene 2,4‐dicarbonimide were carried out. The products obtained were subjected to physicomechanical, thermal, dielectric, and analytical tests. IR, DTA, and TG analyses were also done.
Parameters for prediction of reverse osmosis performance of cellulose acetate propionate membranes
Authors: Kutowy O. , Matsuura Takeshi , Sourirajan S. 
Published: April 2003

AbstractData on reverse osmosis separations have been obtained for 12 alkali metal halide solutes and 24 organic solutes (including eight alcohols, four aldehydes, seven ketones, and five ethers) with cellulose acetate propionate (CAP) membranes using single‐solute dilute aqueous feed solutions at 250 psig. From the analysis of these data, the parameters and correlations needed to calculate the values of solute transport parameter DAM/Kδ for the above classes of inorganic and organic solutes for a CAP membrane of any surface porosity from data on DAM/Kδ for NaCl only have been generated. These parameters and correlations enable one to predict reverse osmosis separations of different solutes included in the classes of compounds studied in this work, from a single set of experimental data on membrane specifications given in terms of pure water permeability constant and DAM/Kδ for NaCl. The reverse osmosis characteristics of CAP material lie intermediate between those of cellulose acetate and aromatic polyamide materials reported in the literature.
Flammability and degradation characteristics of styrene–butadiene rubbers
Authors: Kratzer R. H. , Paciorek K. L. , Kaufman J. , Nakahara J. H. , Hartstein A. M. 
Published: April 2003

AbstractUncured styrene–butadiene gum, a known cured composition, and four SBR beltings used in underground coal mining were subjected to thermal oxidative degradation in static and dynamic systems. The room temperature volatiles produced under the static conditions at 370°C were identified and quantitated. Monomers and their interaction products were liberated by the raw gum; the cured composition formed together with the above products materials traceable to the curing ingredients. The four beltings gave a large spectrum of products; an attempt was made to correlate these with possible components used in belts manufacture. In the dynamic system, the occurrence of glow, the rate of smoke generation, and char yields were determined at 400°C and 500°C. None of the materials glowed at 400°C. At 500°C, the raw gum volatilized completely, and the cured rubber and two beltings glowed. One of the beltings, which failed to glow, liberated the smallest quantity of toxic products.
Kinetics of epoxy resin polymerization using differential scanning calorimetry
Authors: Peyser P. , Bascom W. D. 
Published: April 2003

AbstractThe kinetic parameters of the polymerization of diglycidyl ether of bisphenol A with hexahydrophthalic anhydride and benzyldimethylamine as catalyst were determined using differential scanning calorimetry. The reaction was found to be first order with some variation with temperature, and the activation energy and natural log of the frequency factor were 25 kcal/mole and ∼25 sec−1, respectively. These results are discussed with respect to a steady‐state mechanism of the polymerization and compared with results reported for other epoxide–anhydride reactions.
Depolymerization of poly‐ϵ‐caprolactam catalyzed by sodium hydroxide
Authors: Mukherjee A. K. , Goel D. K. 
Published: April 2003

AbstractDepolymerization of poly‐ϵ‐caprolactam chips was carried out at low pressures (3–15 mm Hg) and elevated temperature (225°–270°C) in the presence of sodium hydroxide as catalyst. The effects of variation of amount of sodium hydroxide, time, temperature, and pressure on ϵ‐caprolactam yield were studied. With increase in alkali content the yield increases linearly, reaching a maximum at 1% (w/w) NaOH and then falls. The yield increases with time of depolymerization up to 4 1/2 hr and then becomes practically constant. Between 240° and 250°C there is a sudden increase in depolymerization rate. Further increase in temperature has very little effect. Decrease in pressure from 15 to 3 mm Hg shows a nine‐fold increase in yield. The optimum conditions for the depolymerization were a temperature of 250°C, a pressure of 3 mm Hg, and a time 4 1/2 hr in the presence of 1% NaOH (w/w), which gave a 90.5% yield of ϵ‐caprolactam. Physical properties, IR spectra, and behavior toward polymerization of the recovered monomer indicated the presence of some impurities.
Binding of heavy metal ions by formaldehyde‐polymerized peanut skins
Authors: Randall John M. , Hautala Earl , McDonald Gary 
Published: April 2003

AbstractPeanut skin, when treated with formaldehyde to polymerize tannins, is a highly efficient substrate for removal of many heavy metal ions from aqueous waste solutions. The ions Ag1+, Cd2+, Cr6+, Cu2+, Hg2+, Ni2+, Pb2+, Zn2+, as well as Ca2+ and Mg2+, were contacted with formaldehyde‐treated peanut skin. Quantitative removal could be achieved with Ag1+, Cd2+, Cu2+, Hg2+, Pb2+, and Zn2+. Capacity of the substrate for ions was promising for Pb2+ (2.1 meq/g substrate), Cu2+ (3.0 meq/g), and Cd2+ (1.3 meq/g). Sorption from a solution containing Cd2+, Cu2+, Hg2+, Ni2+, Pb2+, Zn2+, on a packed column of formaldehyde‐treated peanut skin indicated that Hg2+, Pb2+, and Cu2+ were rapidly and completely bound to the packing, while Cd2+, Ni2+, and Zn2+ were poorly bound until the preferred ions had been removed from solution.
Mechanical properties of urea–formaldehyde foam
Authors: Sarig Y. , Little R. W. , Segerlind L. J. 
Published: April 2003

AbstractThe mechanical behavior of urea‐formaldehyde foam was studied to evaluate its potential for energy absorption applications. The apparent elastic modulus (Ef) as a function of foam density was obtained from force‐deformation tests. The values of energy absorption capacity were derived from a numerical integration technique. Poisson's ratio (v) was determined by a method of uniaxial compression of cylindrical samples. An increase in foam density results in an increase in the apparent elastic modulus of the material and therefore in its energy absorption capacity. Poisson's ratio is independent of the foam density. The mechanical properties' values obtained can be incorporated in various analyses for predicting desired characteristics for energy absorption applications.
Solvation and phase separation in ABA block copolymers
Authors: Picc Efrain R. , Williams Michael C. 
Published: April 2003

AbstractA conceptual scheme is presented for classifying the phase behavior of ABA block copolymers and solvents. The effect of solvent fraction ϕS on microphase separation is described for macroscopically homogeneous systems, but more attention is focused on the limits of solubility. A “miscibility map” is developed in terms of solubility parameters δA, δB, and δS and used to define regions of macrophase separation, complete miscibility, and partial miscibility. Combined with known triblock molecular structure, the miscibility map can be used to predict the character of solvated systems and guide the selection of solvents for special purposes. A survey of reports in the literature shows qualitative consistency with this treatment. New observations are reported on solvation of a polystyrene–polybutadiene–polystyrene polymer in numerous solvents; these are used to infer microstructural information and define the miscibility map more realistically.
A new biodegradable plastic made from starch graft poly(methyl acrylate) copolymer
Authors: Dennenberg Ronald J. , Bothast Rodney J. , Abbott Thomas P. 
Published: April 2003

AbstractA starch graft poly(methyl acrylate) copolymer was developed having grafted side chains with molecular weight of less than 500,000. This material can be easily extruded into a film which shows excellent initial tensile strength and elongation. Tensile strength, however, falls off rapidly after 70 hr of water immersion at 25°C. Starch graft poly(methyl acrylate) films show excellent susceptibility to fungal growth, some samples losing more than 40% of their weight after 22 days of incubation with Aspergillus niger. Tensile tests and scanning electron micrographs of the incubated samples, after being freed of mycelium, indicate substantial biodegradation of the starch portion of the copolymer. This material may have application as a biodegradable plastic mulch.
Kinetics of sorption of aliphatic acids by oleophilic anion exchange resins in toluene
Authors: Walden John , Miller Irving F. , Gregor Harry P. 
Published: April 2003

AbstractThe rate of sorption of toluene by dry oleophilic anion exchange resins in the hydroxide state was measured both by direct weight measurements and also by the visual observation of the rate of movement of a refractive index gradient between unreacted and reacted zones. The rate of sorption of carboxylic acids from solution in toluene was also measured by beads swollen in toluene, both by direct chemical analysis of the solution and by the visual method. Diffusion coefficients of acids in the resins were calculated using three different theories for diffusion in gels coupled with chemical reactions, and reasonable agreement between theory and experiment was found.