bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the development of improved reverse osmosis membranes from cellulose acetate–acetone–formamide casting solutions
Authors: Pilon Rachel , Kunst B. , Sourirajan S. 
Published: April 2003

AbstractImproved membranes from cellulose acetate–acetone–formamide casting solutions have been prepared for low‐pressure reverse osmosis applications. The film‐casting details for one such type of membranes (Batch 400) are as follows. Casting solution composition: cellulose acetate (E‐398‐3), 17 wt‐%, acetone, 56 wt‐%, formamide, 27 wt‐%; temperature of casting solution, 24°C; temperature of casting atmosphere, 24°C; casting atmosphere, ambient air in contact with 30 wt‐% acetone in aqueous solution; solvent evaporation period, 30 sec; gelation medium, ice‐cold water. Using aqueous feed solutions containing 3500 ppm of NaCl, the product rates obtained with the above membranes at 95, 90, and 60% levels of solute separation were 15.9, 22.1, and 58.7 gallons/(day ft2), respectively, at 250 psig under feed flow conditions corresponding to a mass transfer coefficient of 45 × 10−4 cm/sec on the high‐pressure side of the membrane. The effects of casting solution composition, presence of acetone in the casting atmosphere, evaporation period, evaporation rate constant, and the remoteness of casting solution composition from the corresponding phase boundary composition on membrane performance and shrinkage temperature profile were found to be similar to those reported earlier for membranes obtained from cellulose acetate–acetone–aqueous magnesium perchlorate casting solutions. The results illustrate the practical utility of the approach based on the solution structure–evaporation rate concept for creating more productive reverse osmosis membranes.
Time and temperature dependence of the mechanical properties of polystyrene bead foam
Authors: Rinde J. A. , Hoge K. G. 
Published: April 2003

AbstractTensile and compressive properties of polystyrene bead (PSB) foams at room temperature for strain rates from 10−3 to 105 min−1 can be represented as nearly linearly increasing functions of modulus or stress versus the logarithm of the strain rate. The shear modulus and tensile data, including failure properties, on 0.054 g/cc PSB foam at various temperatures and strain rates can be represented by master curves of log (stress or modulus) versus log (reduced strain rate). These master curves are formed by a time and temperature superposition method, wherein data at one temperature are superposed on data at another temperature by a shift along the log (strain rate) axis. These time–temperature shift factors are calculated using a form of the Arrhenius equation.
An x‐ray study of crystalline orientation and mechanical properties of swollen cotton fibers using cadoxen solution as swelling agent
Authors: Varma D. S. , Bhatia H. C. 
Published: April 2003

AbstractBundles of cotton fibers were given swelling and stretching treatment using Cadoxen solution containing 3.58% cadmium. The fibers were stretched from −2% to +8% in steps of 2%. The crystallite orientation and mechanical properties of treated fibers are markedly improved. Results clearly indicate that the swelling of cotton in Cadoxen solution is intercrystalline and the swollen fiber has retained the cellulose I structure.
A study of the low molecular weight components of furfuryl alcohol polymers
Authors: Wewerka E. M. , Loughran E. D. , Walters K. L. 
Published: April 2003

AbstractLow molecular weight components of both an acid‐polymerized and a γ‐alumina polymerized furfuryl alcohol polymer were separated by gas chromatography utilizing a Porapak type P‐S column packing. The identities of the separated polymer components were established by infrared spectroscopy, mass spectrometry, and nuclear magnetic resonance analysis. Volatile constituents found to be common to both furfuryl alcohol resin types were: furfuryl alcohol, water, difurylmethane, difurfuryl ether, and 2,5‐difurfurylfuran. Also, 5‐furfurylfurfuryl alcohol was found to be present only in the acid‐polymerized resin, and 4‐furfuryl‐2‐pentenoic acid γ‐lactone was a constituent only of the γ‐alumina‐polymerized resin. Contrary to expectation, no esters of levulinic acid were found among the low molecular weight components of the γ‐alumina‐polymerized furfuryl alcohol polymer.
Visible dichroism of polypropylene–disperse dye system at high temperatures
Authors: Nakayama Kazuo , Okajima Saburo , Kobayashi Yasuji 
Published: April 2003

AbstractThe dichroism of polypropylene film dyed with C. I. Disperse Yellow 7 was investigated at various temperatures up to 160°C. The dichroic value D drops as the temperature is raised. So long as the amorphous structure does not change irreversibly, D changes reversibly with temperature. The experimental results agree qualitatively with those obtained on poly(ethylene terephthalate) in our previous paper, although the effect of temperature on the extent of the reversible change in D is larger in PP than in PET. The plot of D versus temperature exhibits breaks at 40°–50°C (T0), 70°–80°C (T1), and 115°–120°C (T3). These temperatures agree with the transition points of polypropylene in the literature. From the change in the intrinsic dichroism D0 with temperature, it is concluded that the decrease in D at high temperatures is due to the drop of D0 caused by the disorientation of dye molecules in the amorphous region, while the amorphous polymer chain is not disoriented. Such a conclusion is supported by the fact that Δn of a heat‐set specimen is kept constant during heating, in contrast to D.
Influence of compacting pressure on the permeability of vectorized membranes for liquids
Authors: Peterlin A. , Williams Joel L. 
Published: April 2003

AbstractThe theory of liquid diffusive flow through graded membrane under applied pressure difference is developed and demonstrated on four simple models. The grading of the membrane, caused by a gradient of chemical composition or physical structure, results in a gradient of liquid uptake (hydration) which in turn is reduced by the compacting pressure existing in the membrane during the permeation experiment. The hydration established in equilibrium between the swelling tendency and compacting pressure determines the local permeability. It has different values K+ = K− for opposite flow direction. The total membrane permeability 〈K〉, however, depends on the current direction only in the case that the relative depression of local hydration, and hence of permeability by pressure, is not uniform but has a gradient. In mathematical formulation, the directionality of membrane requires the local permeability to be an irreducible function of location and pressure p, continuously increasing or decreasing with x. Th permeability of the membrane is higher if the driving pressure is applied at the side of the membrane with higher relative reduction of hydration and permeability by compacting pressure.
Effect of fluid motion on radiation‐induced polymerization of ethylene in a tubular reactor
Authors: Kawakami Waichiro , Wada Takeshi , Watanabe Terutaka , Machi Sueo , Kagiya Tsutomu 
Published: April 2003

AbstractThe influence of the turbulence of reactant on the radiation‐induced polymerization of ethylene in 40 mole‐% Freon‐114 (C2Cl2F4) was studied using a tubular reactor at 400 kg/cm2 and 25°C with a dose rate of 1.3 × 105 rad/hr. At constant linear velocity and tube diameter, the polymer concentration was shown to increase linearly with the reactor tube length. This indicates that the polymerization is in a stationary state. By changing the linear velocity from 3.5 to 42.7 cm/sec and the tube diameter from 5 to 14 mm, the space time yield and the molecular weight of polymer were found to vary between 0.21 and 0.46 mole ethylene/1.‐hr and from 5.0×103 to 10.5×103, respectively. The space time yield and molecular weight decreased sharply to about one half those in the static polymerization with increasing fluid turbulence and then slowly increased in the highly turbulent state. Similar effects were observed in a tank reactor when the stirring speed was changed.
Deuterium isotope effect on the refractive index of liquids and its application to permeation chromatography
Authors: Carignan Yvon P. , Turngren Edward V. 
Published: April 2003

AbstractDifferences in refractive index between deuterated and normal solvents have been determined using a conventional gel permeation chromatograph equipped with a differential refractometer detector. Three molecular systems have been studied, namely, water–deuterium oxide, acetone–acetone (d6), and tetrahydrofuran–tetrahydrofuran (d8). A plot of the signal intensity versus the concentration of the deuterated solvent in the normal solvent gave a linear relationship for all three systems studied. The effect of deuteration is found to result in a lowering of the refractive index which is at least three orders of magnitude larger than the sensitivity of the differential refractometer. Consequently, for permeation chromatographic studies, the addition of 1% or less of the deuterated solvent in the injection sample would be more than sufficient to produce a peak characteristic of the mobile phase.
Heat‐resistant polymers containing the low molecular weight closo‐carboranes. II. Thermal behavior of polycarboranesiloxane SiB‐1 elastomers from C2B5H7
Authors: Kesting R. E. , Jackson K. F. , Newman J. M. 
Published: April 2003

AbstractUnmodified 5‐SiB‐1 polymers have been found to be virtually equivalent to their 10‐SiB‐1 counterparts with respect to thermal stability. The 5‐SiB‐1 polymers, however, are substantially more amenable to conversion into elastomers. The introduction of 15 to 20 mole‐% of m‐C2B10 into the 5‐SiB‐1 backbone results in elastomers whose thermal stability, although less than that of the parent homopolymer, is nevertheless substantially in excess of the published values for the higher SiB polymers. The crystallization of the 5‐SiB‐1 copolymer containing 15 mole‐% C2B10 was inhibited by irradiation with 50 megarads of 3 MeV betas. The 5‐SiB‐1 copolymer containing 20 mole‐% C2B10, on the other hand, remained a rubber at room temperature.
Diffusion in concentrated polystyrene solutions
Authors: Paul D. R. , Mavichak V. , Kemp D. R. 
Published: April 2003

AbstractThe wedge interferometer technique was used to measure the diffusion coefficients for concentrated solutions of polystyrene. A wide range of molecular weights, all monodisperse except for one, and 14 solvents were studied. Reproducibility of the data was demonstrated in the concentrated region, and good agreement with the sparse literature was observed. The experimental results are discussed and analyzed in terms of current knowledge and theories. In the concentrated region, the solvent type plays a significant role in determining the diffusion coefficient. Its effect cannot be explained simply in terms of hydrodynamics nor the molecular structure of the solvent. In cyclohexanone the diffusion coefficient was found to increase with polymer molecular weight up to 100,000 and to become independent thereafter.
The size analysis of polymer latices by electron microscopy using freeze‐etched preparations
Authors: Reed R. , Barlow J. R. 
Published: April 2003

AbstractA range of styrene–butyl acrylate copolymer latices has been studied in the electron microscope, using the freeze‐etching method of specimen preparation. This involves the rapid freezing of a small specimen, fracture of the frozen block, followed by replication of the fracture surface. The process of freezing rapidly to liquid air temperatures minimizes deformation of “soft” latex particles and allows their size to be determined. Certain latices were also investigated using a conventional method of specimen preparation, involving size measurements on dried, deformed particles. The particles observed in freeze‐etched preparations appeared to have slightly smaller diameters.
Poly(ethylene sulfide). IV. A rheological method for determination of “apparent molecular weight”
Authors: Catsiff E. H. 
Published: April 2003

AbstractBy combining a number of theoretical relationships concerning the effect of molecular weight on melt rheology, an equation may be derived for conversion of melt indexer flow rate to “apparent molecular weight.” In spite of certain evident theoretical shortcomings of this derivation, the method was applied to the determination of the molecular weight of highly crystalline insoluble poly(ethylene sulfide), for which no other method appeared to be satisfactory. When applied to polymer specimens of presumably known molecular weight (e.g., certain ionically initiated specimens), reasonable agreement was found.
The production of rubber‐modified polystyrene. I. Rheological behavior of the polymerizing system
Authors: Freeguard G. F. , Karmarkar M. 
Published: April 2003

AbstractThe rheological behavior of the two‐phase systems consisting of a polystyrene‐in‐styrene phase distributed in a rubber‐in‐styrene phase is shown to exhibit increasing non‐Newtonian behavior up to the phase inversion point, as a consequence of its two phase nature. The equation

is recommended for the prediction of the viscosity of the polymerizing mass up to phase inversion during the production of HIPS by the in situ bulk polymerization of styrene in the presence of dissolved rubber.
The production of rubber‐modified polystyrene. II. The significance of shear in the phase inversion
Authors: Freeguard G. F. , Karmarkar M. 
Published: April 2003

AbstractPhase inversion of the two‐phase system consisting of a polystyrene‐in‐styrene phase distributed in a rubber‐in‐styrene phase is shown only to occur above a minimum shear rate, which is experimentally determined for a range of rubber concentrations. The conditions for agitation of the system to give a smooth and nondelayed inversion point are separated into meeting two requirements, one of which is related to mass transfer to the discontinuous phase and the other, to meeting the shear requirement; these are discussed in terms of the known rheological behavior of the system.
Ionic reverse osmosis membranes of grafted polyethylene
Authors: Lamaze C. E. , Yasuda H. 
Published: April 2003

AbstractMembranes of graft copolymers of polyethylene with poly(sodium styrene sulfonate), poly(4‐vinylpyridinium methyl bromide), and poly(sodium acrylate) were prepared by using the technique of peroxide grafting. The reverse osmosis characteristics of the membranes were examined as a function of grafting yield. In these membranes, the grafting can be considered as a process of introducing ionic sites, and it depends on the conditions of the grafting reaction, such as monomer concentration and temperature. However, the overall reverse osmosis characteristic is not only dependent on the number of ionic sites introduced but also on the swelling capability of the membrane. Consequently, the salt rejection of grafted membrane of a fixed graft yield depends on the conditions of the grafting reaction. All grafted membranes which have grafting yields above a certain value behave as normal ionic polymer membranes, and their interrelationship of salt rejection and water permeability follow the general dependence found for ionic polymer membranes.
Structure–concentration equivalence in carbon black reinforcement of elastomers. III. Application to tensile strength
Authors: Kraus Gerard 
Published: April 2003

AbstractUsing carbon blacks of constant specific surface area and surface chemical characteristics, but differing in degree of structure, it is shown that tensile strength, elongation at break and rupture energy are functions of the product av2, where v2 is the volume concentration of carbon black and a is a structure dependent factor. Moreover, reductions of failure data to a common effective filler concentration are accomplished with the identical structure factors used earlier in modulus reductions. The values of the structure factors are linearly related to the dibutyl phthalate (DBP) absorption of carbon black, when care is taken to equalize the packing density prior to conducting the DBP test.
Relative thermophysical properties of some polyimides
Authors: Jewell Robert A. 
Published: April 2003

AbstractA comparative thermogravimetric study of ten polyimide films of varying composition revealed that thermal and thermo‐oxidative stability of the polymers increases directly with increasing imide content. Films degraded more rapidly in air than in vacuo; the insertion of connecting groups within the polymer repeat unit decreased stability in both environments. The effect of inserting “ladder‐like” segments in the polymer structure did not enhance resistance to oxidation; but under vacuum, those segments probably operated beneficially in promoting the retention of the carbon‐like residue. Infrared spectral measurements showed little loss of imide bands with progressive weight loss in air, indicating unit‐by‐unit degradation. Conversely, infrared spectra of films heated under vacuum conditions showed that progressive loss of imide bands occurred simultaneously with an increasing development of bands related to carbon–nitrogen double bonds. Dynamic heating under vacuum developed singularly uniform weight loss curves; however, concurrent mass‐spectrographic analyses indicated two distinct reactions. Gaseous carbon monoxide and carbon dioxide species accounted for the major weight change, and their periods of maximum evolution occurred at different temperatures for each film. A subsequent minor weight loss period was associated with the liberation of hydrogen cyanide which maximized at the same temperature for all ten films.
Thermal conductivity of polymer melts
Authors: Fuller T. R. , Fricke A. L. 
Published: April 2003

AbstractA concentric cylinder conductivity cell with guard heaters was constructed and used to determine the thermal conductivity of polymer melts. Thermal conductivity was found to be a linear function of temperature for the melts studied, and the thermal conductivity decreased as the complexity of the polymer chain increased. The polymers studied were a linear polyethylene, branched polyethylene, polypropylene, polystyrene, nylon 6, and nylon 6,10. The measurements are precise to within ±6%.
Photochemical reactions of the substituent groups of cotton cinnamate fabric
Authors: Bertoniere Noelie R. , Franklin William E. , Rowland Stanley P. 
Published: April 2003

AbstractThe extents to which the substituents of cotton cinnamate fabrics dimerize and undergo cis–trans isomerization upon irradiation with 2537 Å light were determined. It was shown that these photochemical reactions occur primarily on the surface of the fabric. Simple crosslinking via the truxillic and/or truxinic acid residues, although directly related to the increases in conditioned wrinkle recovery angles, was sufficient to produce fabrics with only moderate levels of wrinkle recovery properties.
Modification of emulsion polymerization by multiple addition of modifier
Authors: Uraneck C. A. , Burleigh J. E. 
Published: April 2003

AbstractModel equations were used to determine approximately the optimum conditionneeded to obtain the lowest molecular weight, P̄v, with a fixed molar amount of modifier by the addition in three portions of modifiers with different regulating indexes. Simulated calculations were also conducted to determine the effect two‐ and three‐portion additions of a modifier had on the P̄v/P̄n ratio. The simulated calculations served as guides for two‐, three‐, and manyfold incremental modifier addition experiments. The calculations and experiments establish the need for matching the portioning of the modifier to the regulating index in order to obtain efficient use of the modifier.
Graft polymerization of some vinyl monomers onto acrylic rubber. II. Mechanical properties of graft polymers
Authors: Ide Fumio , Sasaki Isao , Deguchi Seiji 
Published: April 2003

AbstractSome mechanical properties of styrene and acrylonitrile copolymers grafted onto acrylic rubber are investigated. The impact strength of graft polymers depended upon the nature and the concentration of the catalyst, the composition and the intrinsic viscosity of the rubber, and the acrylonitrile content in the rigid matrix. The most desirable result was obtained when benzoyl peroxide as the catalyst, n‐butyl acrylate–acrylonitrile copolymer of 7–10% acrylonitrile content, and about 0–5% acrylonitrile in the rigid matrix were used. Dynamic mechanical tests show the increase in efficiency of rubber modification by the grafted chains. The better weathering resistance of these graft polymers, as compared with commercial ABS plastics, was confirmed.
Change of mixing state of polybutadiene rubber–polyolefin resin blend by remilling and heat treatment
Authors: Satake Kunio 
Published: April 2003

AbstractThe change of the mixing state of polybutadiene rubber–polyolefin resin blend resulting from remilling and heat treatment was studied. Polyolfin resins studied here were high‐pressure polyethylene, low‐pressure polyethylene, and polypropylene. As in case of polybutadiene rubber–general purpose polystyrene resin blend, we made use of the results obtained through hardness and compression modulus measurement and microscopic observation. Even in case of polybutadiene rubber–polyolefin resin blend, the change of mixing state and the softening phenomenon by remilling were observed. The hardening phenomenon by heat treatment of the sample softened by remilling was also observed at high polyolefin resin content. But at low polyolefin resin content, the hardness which had increased once often decreased as the heat treating time increased, and in some cases the nonremilled sample was observed to soften with heat treatment. These phenomena attendant on heat treatment show that the intrinsic nature of a heterogeneous blend system also appears in a microheterogeneous polymer blend system.
The influence of chemical structure on the dynamic properties of sulfur‐vulcanized, carbon black‐reinforced natural rubber
Authors: Doyle G. M. , Humphreys R. E. , Russell R. M. 
Published: April 2003

AbstractA comparison is made of the composition and properties of the different rubber vulcanizate networks obtained by varying the ratio of sulfur to sulfenamide accelerator and by the thermal aging of vulcanizates containing predominantly polysulfide crosslinks. It is concluded that the changes in network structure which can take place, for example, during the service life of natural rubber tires are not the direct cause of failures of the type associated with rubber fatigue at high temperatures. However, a reduction in the total number of crosslinks can accelerate failure by increasing the amount of heat generated during flexing. More stable networks giving improved resistance to fatigue at high operating temperatures are obtained by the use of higher ratios of accelerator to sulfur than are conventionally employed.
Bead‐spring model of dilute polymer solutions: Continuum modifications and an explicit constitutive equation
Authors: Gordon R. J. , Everage A. E. 
Published: April 2003

AbstractA continuum modification of the bead‐spring (elastic dumbbell) theory of dilute solutions of linear macromolecules, recently introduced by Gordon and Schowalter, is used to obtain explicit constitutive equations for the stress and polarizability tensors. The stress constitutive equation, closely related to a semiempirical result obtained earlier by Spriggs, is superior in predictive capability to the constitutive equation obtained from the elastic dumbbell theory. Results are presented for steady shearing flow, large‐amplitude oscillatory shearing, and stress relaxation following cessation of steady shearing and are compared with the results of the elastic and rigid dumbbell theories. In general, predictions are similar to those of the rigid dumbbell and thus are in qualitative agreement with experiment.