bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modification of cellulose acetate reverse osmosis membranes by radiation grafting
Authors: Bentvelzen J. M. , Kimura‐Yeh F. , Hopfenberg H. B. , Stannett V. 
Published: April 2003

AbstractLarge excesses of a chain transfer agent, carbon tetrachloride, were introduced to a recipe for the mutual radiation grafting of styrene to cellulose acetate film. The effect of the carbon tetrachloride on the molecular characteristics as well as the reverse osmosis and time dependent mechanical properties of resulting graft copolymers was determined. Extremely short side chains were generated as a consequence of the high concentrations of chain transfer agent and the composite results further suggest that the morphology of the grafted films is best described as “destructured” or internally plasticized consequent to grafting in the presence of CCl4. Reverse osmosis fluxes increased with percent graft; salt rejection was high and unaffected by per cent graft up to 40% graft; and the tensile creep under wet conditions was significantly retarded by the grafting. These effects were shown to accrue from grafting per se by control experiments involving α‐methylstyrene which will not propagate to form a polymer under these conditions. These results are compared and contrasted with earlier work on grafting in the absence of CCl4 where long side chains of polystyrene were generated resulting in a structuring of the polymer involving domains of polystyrene‐rich material and domains of cellulose acetate rich polymer.
Effect of the continuous medium on the color of discontinuous substrates. IV. The effect of the refractive index of the continuous medium
Authors: Allen E. Hope , Faulkner D. L. , Goldfinger G. , McGregor R. 
Published: April 2003

AbstractIt is known from experience that light scattering–absorbing substrates are darker when the continuous medium is water instead of air. This is due to the decrease in scattering efficiency of the scattering particles caused by the smaller value of the ratio n1/n2 of the refractive indices of the scattering particles (n1 = 1.5 to 1.7) to that of water (n2 = 1.33) as compared to that ratio when the continuous medium is air (n2 = 1). Experimental evidence for this phenomenon is presented for polyester fabric viewed in air, water, and a concentrated sucrose solution. The wavelength range from 0.4 to 0.7 microns, and absolute “dry” reflectances from 0.02 to 0.7 were covered. The phenomenon cannot be adequately described with the Kubelka‐Munk theory of the color of scattering–absorbing substrates.1 Evidence is presented that at high reflectance values (0.4–0.7), the theory describes the color adequately and the results are consistent with a prediction based on a modified Mie equation for the scattering efficiency of “large” particles.2,3 At low reflectance values (<0.05), the Kubelka‐Munk theory breaks down completely. This is consistent with the observation that this theory is not capable of predicting precisely high dye concentrations on textiles but is quite adequate for low concentrations.
The effect of methods of drying on the fine structure, density, and some mechanical properties of jute and allied fibers
Authors: Ray P. K. 
Published: April 2003

AbstractThe degree of crystallinity and crystallite orientation in jute, mesta, and roselle fibers have been studied by x‐ray diffraction. Removal of water, indirectly, has been carried out by alternate immersion in methanol and benzene. It has been found that an increase in crystallinity and a decrease in crystallite orientation take place in these fibers as a result of direct drying, presumably because of the formation of an increased number of hydrogen bonds associated with direct drying. Density, tenacity, and rigidity of the fiber in the two drying conditions are in agreement with the x‐ray results.
The role of diffusion in the Ziegler polymerization of ethylene
Authors: Crabtree J. R. , Grimsby F. N. , Nummelin A. J. , Sketchley J. M. 
Published: April 2003

AbstractA theoretical and experimental study has been made of the polymerization of ethylene in a slurry reactor using a highly active Ziegler catalyst in the presence of hydrogen. A model of the polymerization system has been set up in which polymerization is assumed to proceed with encapsulation of catalyst subparticles. Allowance is made for an experimentally observed first‐order decay in intrinsic catalyst activity. The theoretical prediction of the model for the monomer absorption rate behavior and the molecular weight characteristics of the polymers formed are in agreement with experimental findings. Experimental evidence is presented that in the earliest moments of a polymerization significant amounts of polymer are formed with molecular weights 100 times those in the balance of the polymerization. It is concluded that in this system the polymerization is diffusion controlled throughout the major part of the catalyst lifetime. This diffusion phenomenon, together with the gradual loss of active sites, is of vital importance in determining the molecular weight and molecular weight distribution of the polyethylene product.
Some aspects of monuron‐accelerated dicyandiamide cure of epoxy resins
Authors: Son Pyong‐Nae , Weber Carl D. 
Published: April 2003

AbstractThe synergistic effect of dicyandiamide and certain trisubstituted ureas in the curing of epoxy resin is shown by differential scanning calorimetry and exotherm profiles. When 3‐(p‐chlorophenyl)‐1,1‐dimethylurea (Monuron) was reacted with dicyandiamide, we could isolate dimethylamine and a derivative of dicyandiamide. The role of these products in epoxy resin curing is speculated.
Adhesion of polymers to shale rock surfaces
Authors: Raff R. A. V. , Haugen J. A. , Mostafa M. F. 
Published: April 2003

AbstractIn the course of a project on the application of polymers for rock bonding and reinforcement of coal mine structures, the adhesion of epoxy resins to shale mine rock was studied by infrared and Mössbauer spectroscopy. Two types of bonding were identified: primary bonds between silicates and polymer, and hydrogen bonds from organic compounds on the surface of the shale to oxygen in the polymer. These bonds contribute to the adhesive strength when epoxy resins are used to bind shale. The bonding model, when applied to furfuryl alcohol and polyester resins, predicts inferior binding in the shale system.
In situ formation and incorporation of additives into polymers during interfacial polycondensation reactions
Authors: Raff R. A. V. , Sorathia U. A. K. 
Published: April 2003

AbstractOne of the objectives of the work was to attempt the in situ formation of inorganic fillers during interfacial polycondensation reactions. The complementary components of the filler were added separately to the organic and aqueous phases of the system so that they formed the insoluble filler at the interface simultaneously with the polymer. Since the polyamide plastics have good molding properties, nylon 610 was selected as the principal model, but some work was also carried out with a urethane polymer. Further, coloring of nylon 610 and of a polyurethane resin was investigated by lake formation at the interface with the help of 1,2‐dihydroxyanthraquinone in the organic phase and a metal salt in the aqueous phase. In this way, red‐ and blue‐colored polymers were prepared. Finally, by adding zinc ions to the aqueous and pentachlorophenol to the organic phase, zinc pentachlorophenate was incorporated into nylon 610 during its formation. The ignition point of the resultant product was significantly higher than that of a sample to which zinc pentachlorophenate had been added by mechanical mixing.
Analysis of tanks‐in‐series model with backflow for free‐radical polymerization
Authors: Shastry J. S. , Fan L. T. , Erickson L. E. 
Published: April 2003

AbstractFree‐radical polymerization in a flow reactor represented by the tanks‐in‐series model with backflow was considered. Conversions and molecular weight distributions were computed as functions of the backflow parameter, and the results were compared with the conversion and molecular weight distribution from a CSTR and those from a plug‐flow reactor. Backflow was found to be undesirable for the polymerization mechanism under investigation. Values of the degree of segregation for the tanks‐in‐series model were calculated by using Zwietering's approach as a function of backflow.
Flow properties of polystyrene solutions under high shear rates
Authors: Abdel‐Alim A. H. , Balke S. T. , Hamielec A. E. 
Published: April 2003

AbstractThis manuscript reports on the development of a high‐shear Couette viscometer. The main design considerations for a high‐shear concentric cylinder viscometer are reviewed and discussed. In principle, the instrument is identical to those used by other investigators. However, some modifications were found necessary. Attention is drawn to the importance of the concentricity problem. The instrument was first tested and calibrated using Newtonian standard oils. Then non‐Newtonian runs were performed using narrow polystyrene standards of molecular weights 97,200, 411,000, and 860,000. Solutions of the polymer in n‐butylbenzene ranged in concentration from 0.08 g/cc up to 0.5 g/cc. The shear rates applied ranged from 103 sec−1 up to 105 sec−1. The results obtained were compared to the molecular entanglement theory, and excellent agreement was observed.
A new apparatus for continuously monitoring the deformation of a thermoplastic material
Authors: Martinelli F. J. , Hodgkin J. H. 
Published: April 2003

AbstractA new apparatus is described whereby the thermal behavior, including the deformation temperature, of a thermoplastic material may be obtained. The apparatus is intended to replace ASTM procedure No. D648‐56 and has several advantages over that procedure. Thermal behavior of several common thermoplastics under two different stresses and for three different heating rates is described. An application to the determination of optimum cure times for certain thermosetting epoxides is also described.
Intrinsic viscosity calculated by computer
Authors: Hofreiter B. T. , Ernst J. O. , Williams W. L. 
Published: April 2003

AbstractA computer program has been devised for routine use which processes raw data such as polymer sample weight, moisture content, solution volume, and viscometer flow times to calculate a least‐squares‐derived intrinsic viscosity. In addition to eliminating errors inherent in graphic solutions and freeing technicians from tedious calculation, the computer output provides the 95% confidence interval of the intrinsic viscosity.
Strain rate dependence of failure processes in polycarbonate and nylon
Authors: Arad S. , Radon J. C. , Culver L. E. 
Published: April 2003

AbstractA study has been made of two types of failure, namely, monotonic fractures using Charpy‐type specimens and fatigue crack propagation using rectangular plates containing an initial central notch. The work was conducted on an amorphous polymer (polycarbonate) and a semicrystalline polymer (nylon N 6.6). Monotonic tests were performed in an Instron testing machine between 0.002 and 20 in./min, and in a Charpy testing machine between 2000 and 11800 in./min. The cyclic tests (under constantKconditions) were carried out at frequencies that ranged from 0.1 to 20 Hz. A model for the relationship between the cyclic rate of crack growth and appropriate LEFM parameters, previously described, has now been converted into cyclic strain energy transformations. In computing the strain energy, the value of the time‐dependent modulus of the material was used; and under cyclic loading conditions the glassy (short time) value was employed. The authors have proposed that the modulus measurements obtained at very low temperatures, where the viscous response of the material is highly restricted, will approximate the glassy value,Eg, found by conducting relaxation measurement tests at different temperatures down to −197°C. Within the range of tests conducted, the fracture toughness values of both PC and N 6.6 apparently decrease with increase in loading rate. Fatigue crack growth in both materials is influenced by loading frequency and cyclic waveform. These variations may be related to the magnitude of the viscous energy loss and hence to the available energy for crack extension per cycle.
Polymerization in an electrodeless glow discharge. III. Organic compounds without olefinic doublebond
Authors: Yasuda H. , Lamaze C. E. 
Published: April 2003

AbstractThe rates of polymer deposition from various organic compounds which do not contain an olefinic doublebond in an electrodeless glow discharge were studied. The polymerization rates of these unconventional monomers are by and large similar to those of olefinic monomers reported in the previous study (part II). The rate of polymer deposition R0 from pure monomer flow can be characterized, according to the analysis used in part II, by Ro = apM2 and R0 = kFw, where pM is the vapor pressure of the monomer, Fw is the weight basis flow rate of the monomer. Type A monomers which predominantly polymerize and type B monomers which decompose in a glow discharge were also found with these unconventional monomers. The effects of structural factors on the values of a amd k and on the classification of types A and B were examined. These structures and groups—aromatic, heteroaromatic, nitrogen‐containing (e.g., >NH,NH2,CN), Si‐containing, and olefinic doublebond—favor the polymerization. These structures and groups—oxygen‐containing chlorine, aliphatic hydrocarbon chains, and cyclic hydrocarbon chains—favor the decomposition of the monomer in a glow discharge. It is postulated that the polymerization of organic compounds proceed by the recombination of excited species (probably free radicals) created by glow discharge and reexcitation followed by further recombinations in the vapor phase and at the interface.
Terpolymers. II. Mechanical properties and transition temperatures of terpolymers of vinyl stearate, vinyl acetate, and vinyl chloride
Authors: Jordan Edmund F. , Artymyshyn Bohdan , Riser George R. , Nidock Jonathan , Wrigley A. N. 
Published: April 2003

AbstractVinyl stearate was studied as a major internal plasticizer in terpolymers containing vinyl acetate and vinyl chloride. The terpolymers were prepared by systematically replacing vinyl acetate by close increments of vinyl stearate starting with combinations of vinyl acetate and vinyl chloride, in increments, over all compositions. For comparison of properties, a complete range of copolymers of vinyl stearate and vinyl chloride, as well as mixtures of poly(vinyl chloride) and di‐2‐ethylhexyl phthalate (DOP) were also made. The external plasticizer was more efficient in reducing the glass temperature than was vinyl stearate. The decline in Tg with weight fraction of plasticizer was linear for the copolymers and terpolymers but concave downward with the liquid diluent. The linear decline was shown to involve mere additivity of the free volume contributed by each side‐chain methylene (or methyl) group in both vinyl esters to reducing Tg. The mechanism of the diluent system was more complex. However, the magnitude of the reduction of tensile modulus at a given weight fraction of DOP could be equaled or exceeded by the same amount of vinyl stearate, by increasing the vinyl acetate content of the base copolymer to 40 mole‐% or more. Unfortunately, the ultimate strengths and elongations of internally plasticized systems were reduced more than those of the mixtures at comparable compositions. Vinyl stearate was found to markedly retard photolytic degradation compared to both vinyl acetate and the external plasticizer in unstabilized samples having nearly the same thermal treatment. The effect was greater than could be ascribed to dilution by the long alkyl group. The production of a stearoyl radical more stable than the radicals initiating dehydrochlorination is suggested as a possible mechanism.
Evaluation of steady‐state flow curves from model molecular weight distributions
Authors: Cote J. A. , Shida M. 
Published: April 2003

AbstractGraessley's theory of entanglement was applied to several model distributions. The distribution functions chosen were such that the differential weight distributions were triangular with respect to a log molecular weight axis. The molecular weight level, breadth of the molecular weight distribution, skewness, and blending of simple distributions were studied in their effect on the steady‐state flow curve. The governing factor for the shape of the reduced flow curve was shown to be M̄z+1·M̄z/M̄w2. Other general features of the flow curve predicted by Graessley's theory were discussed.
Studies on biaxial stretching of polypropylene film. IX. Melting behavior of biaxially stretched film in one step
Authors: Tanaka Hiroshi , Masuko Toru , Okajima Saburo 
Published: April 2003

AbstractMelting temperature of a film biaxially stretched in one step in air at 152 or 140°C increases with increase of vA, whereas heat of fusion and density decrease with increase of vA, where vA is the degree of stretching in area. The rapid decrease in density occurs for vA > 10. Extrapolation of the plot of the density versus vA−1/2 gives a value of 0.870 g/cm3 at infinite vA, which has been reported as the amorphous density of isotactic polypropylene by Farrow. This is so because the fine structure of the film becomes more and more amorphous with further stretching and reaches completely amorphous state at infinite vA. The temperature of stretching has a strong effect on the thermal behavior of a film; a low stretching temperature (140°C) brings about lower melting temperature, heat of fusion, and density. Crystallinity after melt press has not so large an effect on the melting behavior as the stretching temperature. Melting temperature and the shape of the thermogram also depend on the heating rate. There is an appropriate heating rate depending on vA which gives the minimum melting temperature. With stretched samples, a small side peak or a shoulder appears at a relatively low temperature in the thermogram when a high heating rate is used.
Studies in chemically modified celluloses. V. Affinities of vat dyes for chemically modified celluloses
Authors: Shenai V. A. , Veeramani M. 
Published: April 2003

AbstractCotton cellulose was separately oxidized by potassium metaperiodate, potassium dichromate–sulfuric acid, and potassium dichromate–oxalic acid at two oxidation levels, and the resulting oxycelluloses were further modified by treatment with chlorous acid and sodium borohydride in order to prepare a series of chemically modified celluloses with different functional groups. These fiber substances were dyed with leuco‐flavanthrone at 40°C for different periods till equilibrium was reached. Adsorption isotherms were obtained with three purified vat dyes, and thermodynamic affinity of the dyes for the modified celluloses was determined, taking into consideration the adsorption of hydroxyl ions by cellulosic material and of sodium ions by carboxylate groups of oxycellulose. The presence of aldehyde and carboxyl groups is shown to decrease the rate of dyeing as well as the affinity of the dyes.
A method of calculating densities of polymers
Authors: Sewell J. H. 
Published: April 2003

AbstractMolar volumes of substantially amorphous polymers may be calculated by using additive constants derived from constitutive atomic and structural parachor contributions. For 34 polymers, ranging in density from 0.83 to 2.03 g/cm3, the greatest error in the calculated molar volume compared with the measured value was 13.9%, while for 30 of the polymers the error was less than ±7%, with a mean error of ±3.9%.
Sorption of vapors in cellulose film
Authors: Dollimore D. , Holt B. 
Published: April 2003

AbstractThe rates of sorption of water vapor and of methanol vapor in cellulose film were examined by stepwise increments of vapor pressure. In addition, the rates of sorption of the series of vapors water, methanol, ethanol, n‐propanol, and n‐butanol were studied at pressures just below the respective saturated vapor pressures. The results obtained from both parts of the study are explained in terms of a bimodal diffusion mechanism. This consists of the simultaneous diffusion of vapor into the microporous structure of the cellulose film and diffusion from the micropores into the polymer matrix.
The chemistry of fast‐curing phenolic adhesives. I
Authors: Tiedeman G. T. , Sanclemente M. R. 
Published: April 2003

AbstractCertain low molecular weight, resinous polymers, such as those derived from phenol and formaldehyde, may be chemically modified with aromatic amines to produce other resins of physical properties similar to those of the original resins, but with chemical reactivity which is orders of magnitude faster than that of the unmodified resins. This means that while an ordinary phenolic adhesive cures in minutes at high temperature, a properly modified phenolic can be advanced in seconds at ambient conditions to a cured resin of strength and durability comparable to those of ordinary phenolic adhesives.
Coatings for plastics. Dispersions of clean metal particles in polymer matrices
Authors: Lupinski J. H. 
Published: April 2003

AbstractOxides are frequently used to improve the mechanical properties of plastics. Here we report how oxides of zinc, lead, cadmium, and indium, when embedded in a polymer matrix, can be electrochemically reduced, resulting in a polymer‐metal “composite” of high electrical conductivity. This method of preparation provides a uniform dispersion of small, clean metal particles, not obtainable by blending metal powder and polymer. The “composites” are somewhat porous, and other metals can be deposited on the “composites” from either electroplating or electroless plating solutions.
Fracture studies in rubber‐modified acrylics. I. Experimental method: Design of sandwich‐tapered double‐cantilever beam cleavage specimens
Authors: Kobayashi T. , Broutman L. J. 
Published: April 2003

AbstractDouble‐cantilever beam cleavage specimens are very useful in characterizing the fracture behavior of isotropic, homogeneous, brittle, and semibrittle polymers. However, until this time they have not been used for ductile materials such as rubber‐modified polymers or polycarbonates because of excessive yielding or breakage of the specimen arms before crack propagation can occur. In order to make it possible to measure the fracture surface work of these materials, a new sandwich cleavage specimen was developed by bonding rigid reinforcement plates to both sides of the specimen sheet. With this sandwich‐tapered double‐cantilever beam cleavage specimen, one can create conditions under which controlled crack propagation through tough ductile materials and measurement of the fracture surface work–two previously unobtainable results–are readily determined. In this paper, the design and construction of the sandwich specimens, test procedure, and the data analysis will be discussed in detail.
Effect of various triazine derivatives on the thermal oxidative degradation of isotactic polypropylene
Authors: Osawa Zenjiro , Seng Ng Mok , Ogiwara Yoshitaka , Oto Yukio , Matsui Koji 
Published: April 2003

AbstractA number of triazine derivatives, mostly aryloxy‐s‐triazines, were prepared, and the effects of these compounds on the thermal oxidative degradation of isotactic polypropylene were examined by conventional oxygen uptake. Almost all triazine derivatives prepared showed a more or less inhibitive effect on the degradation of the polymer. Among them, α‐ and β‐napthyloxy‐s‐triazines were found to be excellent inhibitors. On the basis of the results obtained, the relationship between inhibitive effect and the structure of the triazine derivatives is discussed.