bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diffusion with simultaneous reaction of reactive dyes in cellulose. II. Effect of hydrolysis
Authors: Motomura Hiromi , Morita Zenzo 
Published: April 2003

AbstractTheoretical equations that describe the concentration profiles of immobilized and active species for reactive dyes were derived from the diffusion equation accompanied by the reaction with cellulose and water in the substrate. The diffusion coefficient D and the rate constant of the reaction with cellulose, kcell, and that with water in cellulose, kw, were estimated by using the theoretical equations and the cylindrical film roll method. The theory predicted that the apparent diffusion coefficients decreased with the hydrolysis of active species in cellulose. Results from diffusion experiments with C.I. Reactive Yellow 4 and Orange 1 show that the ratio P of kw to kcell for Orange 1 increased with increase in pH to about pH 13 and that the P for Yellow 4 was smaller than unity. Using an alternative experiment to diffusion, P of Orange 1 was measured to be 1.0–1.5, and that of Yellow 4 was smaller than unity at pH 11.6 at 30°C. It was therefore concluded that the D of active species was constant to a highly alkaline region and that the decrease in the apparent diffusion coefficient of Orange 1 was mainly due to the hydrolysis of active species in cellulose.
A study of PVC stabilization with epoxides using dynamic pH determinations
Authors: Gonzalez‐Gonzalez V. 
Published: April 2003

AbstractThe activation energy (Ea) for the dehydrochlorination of PVC and PVC stabilized with an epoxide was determined by a method involving dynamic pH measurements. The Ea increase was 5 kcal/mole between unformulated PVC (Ea = 22.6 kcal/mole) and any of the other formulations (Ea = 27.7–28.6 kcal/mole). On the basis of this and data contained in the literature, research alternatives for the stabilization mechanism are proposed using model compounds.
Synthesis, photodegradation, and energy transfer in a series of poly(ethylene terephthalate–co–2,6‐naphthalenedicarboxylate) copolymers
Authors: Cheung Ping‐Sun R. , Roberts Carleton W. , Wagener Kenneth B. 
Published: April 2003

AbstractTriplet–triplet energy transfer has been shown to occur from poly(ethylene terephthalate) (PET) units to the 2,6‐naphthalenedicarboxylate (2,6‐ND) monomer units in a series of poly(ethylene terephthalate–co–2,6‐naphthalenedicarboxylate) (PET–2,6‐ND) copolymers, as filament yarns, by an exchange mechanism at 77°K. The radius of the “quenching sphere” has been calculated to be 19.7 Å, indicating the presence of triplet energy migration. Photostabilization was observed in the copolymer yarns with the concentration of the monomer dimethyl 2,6‐naphthalenedicarboxylate (2,6‐DMN) at or above 2 mol %; the rate of phototendering in an air atmosphere was shown to decrease from 2.0 × 10−19% breaking strength loss/quantum absorbed/cm2 in the homopolymer PET to 0.7 × 10−19% breaking strength loss/quantum absorbed/cm2 in the copolymer yarns. The photophysical processes in the monomers, dimethyl terephthalate and 2,6‐DMN, were examined by absorption and luminescence studies. The lowest excited singlet and triplet in both monomers were identified to be the 1(π, π*) and 3(π, π*) states, respectively. The phosphorescence of PET was shown to originate from a 3(π, π*) state, while the complex fluorescence spectrum may arise from some oriented aggregates in the polymer matrix. In copolymer yarns, only the fluorescence emission from the 2,6‐ND monomer units at 380 nm was observed. The phosphorescence spectra of the copolymer yarns showed phosphorescence emissions from the PET and 2,6‐ND monomer units; in addition, delayed fluorescence from the 2,6‐ND monomer was also observed.
Solubility and diffusivity of bis‐(2‐chloroethyl)‐sulfide in polypropylene
Authors: Hjermstad Hans P. 
Published: April 2003

AbstractSolubility and diffusivity have been determined for bis‐(2‐chloroethyl)sulfide in isotactic polypropylene at temperatures from 15 to 40°C and relative pressures from 0.34 to 1.00. While the solubility in films annealed above 90°C followed the normal variation with the amorphous content, the quenched film had a significantly lower amorphous volume fraction than determined from its density, 46 instead of 60%. The diffusion behavior in the film was found to be invariably Fickian and not dependent on the amorphous volume fraction of the polymer between 0.34 and 0.46. The solubility was found to be independent of the temperature over the range 15–40°C, but dependent on the diffusant concentration. The isotherms were well represented by the Flory‐Huggins relation for crosslinked polymers, and values for the interaction constant and the average molecular weight between crystallites have been obtained. The value of the interaction constant, μ = 1.13, is an expression of the low affinity bis‐(2‐chloroethyl)sulfide has for polypropylene. The intrinsic diffusivity was only weakly dependent on the diffusant concentration. The results were found to be in agreement with Fujita's free‐volume theory. The apparent activation energy for the diffusion of bis(2‐chloroethyl)sulfide in isotactic polypropylene was found to be 22.5 kcal/mol.
Stability of continuous emulsion polymer reactors
Authors: Chiang Anthony S. T. , Thompson Robert W. 
Published: April 2003

AbstractThe stability of continuous emulsion polymer reactors having steady feed streams was studied. Analysis of a population balance model supported the notion of micelle deprivation as the chief cause of reactor instabilities. Analysis of the moments of the distribution indicated that the system may be uniquely stable in one case. Only one steady‐state operating point was predicted for the case where the decrease in the termination rate constant due to the gel effect was neglected.
Statistical study of the application of the huggins equation to measure intrinsic viscosity
Authors: Reilly Park M. , Van Der Hoff B. M. E. , Ziogas M. 
Published: April 2003

AbstractIntrinsic viscosities of polymers are most often estimated using the Huggins equation, which relates the quotient ηsp/c to intrinsic viscosity and concentration c. It is shown that when this method is used, the error structure is distorted by the presence of concentration in the quotient. The result is that when dilution series experiments are analyzed, the estimates are ordinarily poorer the more dilutions are made. A rearrangement of the Huggins equation is introduced which allows precise estimation from any experiment. It is also shown that dilution series experiments with more than three different concentrations including that of the pure solvent are inefficient by any method of analysis, and convenient experiments which may be considered practical optima are described. When they are used the conventional analysis is restored to full efficiency. Design and analysis of experiments where there is important uncertainty in polymer concentration are also studied.
Influence of carbon black on processability of rubber stocks. V. Extrusion
Authors: Cotten G. R. 
Published: April 2003

AbstractA study of postextrusion relaxation (shrinkage) rates identified two separate processes, only one of which is influenced by carbon black structure and surface area. One of these processes is thought to be a solidlike fast elastic recovery and was found to be influenced by carbon black and polymer characteristics. The other process reflected slow randomization of oriented molecular chains: it was mainly influenced by polymer nature and carbon black had almost no effect. In the previous paper of this series, work with various carbon blacks in SBR–1500 indicated that both types of polymer deformation originate within the converging flow region at the die entrance, where extensional flow takes place. In the present work the extensional flow behavior of five polymers (filled with various carbon blacks) was examined at elevated temperatures. The magnitude of shrinkage caused by molecular alignment was related to extensional viscosity of the rubbers. This confirms the hypothesis stated above. Extensional viscosity was measured using the previously described instrument, which is inexpensive to construct, easy to operate, and can be attached to any standard stress–strain tester. The characteristics of extensional flow are defined and it is shown that for polymeric materials it differs substantially from shear flow, since a rapid orientation of the molecular chains takes place during the extensional flow. The effect of carbon black on the extensional viscosity at elevated temperatures is illustrated.
Functionalization of polymer supports for polymerization catalysts by graft polymerization method
Authors: Kritskaya D. A. , Pomogailo A. D. , Ponomarev A. N. , Dyaschkovskii F. S. 
Published: April 2003

AbstractThe specific features of the gas‐phase radiation‐induced and plasma‐initiated graft polymerization of certain monomers possessing the functionality needed for immobilization of transition metal compounds were studied. The radiation yields of allyl monomers grafted to polyethylene, polypropylene, and poly(vinyl chloride) (5–25 molecules/100 eV) were found to be close to the radiation yields of the polymerization of these monomers in a liquid state. The kinetics of methyl methacrylate and acrylic acid postgrafting to polyethylene pretreated with helium discharge plasma were also studied. The graft‐initiating effect of PE powder treated with plasma for 5–10 min was found to be comparable with that of γ‐irradiation in a dose 0.5–4 Mrad. The results of immobilization of transition metal compounds [TiCl4, VCI4, VO(OC2H5)3, Ti(OC4H9)4, etc.] on carriers prepared by the method of polymer support functionalization by grafting are described. The extent of completion of the immobilization reaction is found to vary from 0.1 to 0.96 and to depend both on the nature of the transition metal and on the specificity of the grafted fragments.
The influence of poly(styrene sulfonate) addition to cellulosic fibers by wet processing on the physicomechanical properties of paper
Authors: Eroglu H. , Andreolety J. P. , Silvy J. , Cheradame H. 
Published: April 2003

AbstractThe study of the effect of sodium poly(styrene sulfonate) addition to suspensions of fibers, in the presence of aluminum salts as adsorption aids, revealed the retention effect of fine solids during sheet formation. Polyelectrolyte adsorption also causes an increase of bounding energy in the web. It is shown that the improvement observed for the dry strength properties of paper is a consequence of these two effects. (In this paper the words “fine solids” or “fines” indicate the parts of the cellulosic material which filtrates through a 150‐mesh screen, regardless of its nature.)
Influence of moisture on the flame retardance of textile fabrics
Authors: Zeronian S. H. , Ellison M. S. , Alger K. 
Published: April 2003

AbstractFor cotton fabric not treated with a flame retardant (FR), the oxygen index (OI) increases slowly but at a constant rate with moisture content (MC). Above a MC of roughly 33% which roughly equals the water fiber saturation point of the cotton fiber, the increase becomes more rapid but the relation appears to remain linear. The relation between OI and MC is also linear for all the FR cotton fabrics examined up to an OI of at least 40. It is suggested that the moisture in the FR samples is not reducing flammability by entering into solid and/or gaseous phase reactions but by absorbing thermal energy owing to the endothermic process of heating and vaporization. Empirical relations appear to be present between the inherent hydrophilicity of the FR cotton fabrics and the OI of the dry fabric (OI)o and the temperature of the zenith of the first exothermic peak for the FR cotton fabrics as determined by differential thermal analysis. OI–MC relations for wool fabric and wool treated with an FR are similar to those found for the cotton fabrics except that the slopes of the lines found for the wool samples are lower than those of the equivalent cotton samples. The relation reported by Van Krevelen between OI and char residue for polymeric materials is tested for both the cotton and wool samples. Agreement with Van Krevelen's relation is not good when (OI)o values are used. Better agreement can be obtained if OIs are determined on samples with MCs between 2 and 10%.
Synthesis of phenol‐terminated polyisobutylene: Competitive chain transfer reactions
Authors: Rooney J. M. 
Published: April 2003

AbstractPolymerization of isobutylene initiated by either aluminum trichloride or tin tetrachloride were conducted in the presence of alkyl phenols in both n‐heptane and methylene dichloride solutions at temperatures between −10 and −70°C. The resultant polymers contained both unsaturated and phenolic endgroups in varying proportions dependent upon reaction conditions. Increased phenol concentrations in the polymerization medium resulted in decreased polymer molecular weights and increased phenol endgroup content. Increased reaction temperature reduced polymer molecular weights and phenol endgroup content. Chain lengths governed by ring alkylation were found to be less sensitive to polymerization temperature than those determined by other modes of chain transfer.
A study of the drawing behavior of poly(ethylene terephthalate)
Authors: Perena J. M. , Duckett R. A. , Ward I. M. 
Published: April 2003

AbstractCold‐drawn and hot‐drawn samples of poly(ethylene terephthalate) were studied by means of measurements of shrinkage stress, birefringence and differential scanning calorimetry (DSC). The values of shrinkage stress were comparable for both types of sample, implying that the deformation of a molecular network is important for both cold drawing and hot drawing. The DSC results indicate that substantial crystallization occurs in hot drawing for other than the lowest draw ratios, and this crystallization gives rise to an additional peak in the shrinkage stress measurements. In addition to temperature, strain rate is also an important variable, and changes in strain rate caused significant changes in both hot‐drawn and cold‐drawn samples.
Shrinkage and mechanical properties of poly(ethylene terephthalate) filaments treated with various organic solvents
Authors: Venkatesh G. M. , Khan A. H. , Bose P. J. , Madan G. L. 
Published: April 2003

AbstractThe effects of a number of chemically nonreacting organic on shrinkage and stress–strain properties of preoriented semicrystalline poly(ethylene terephthalate) filaments have been studied. The changes in shrinkage and mechanical properties are found to be highly dependent on time and temperature, as well as on tension applied on the yarn during the treatment. The changes brought about by the solvents at lower temperatures (i.e., below 100°C) are either comparable with or more than those produced by thermal treatments in air or silicone oil above 200°C. The possibility of using slovent treatment for setting polyester for dimensional stability at low temperature as an alternative to the normal dry‐heat‐setting method has been discussed.
Morphology and properties of α‐methylstyrene and butadiene diblock copolymers
Authors: Hsiue Gin‐Ho , Yang Chien‐Hua 
Published: April 2003

AbstractDiblock copolymers of α‐methylstyrene and butadiene were synthesized, using n‐BuLi as initiator, toluene as solvent, and tetrahydrofuran (THF) as accelerator. The addition of a small amount of THF in polymerization solution would greatly increase the 1,2‐addition of polybutadiene. However, this effect leveled off gradually as the amount of THF increased. Electron microscopic texture and viscoelasticity of diblock copolymer samples cast from THF, toluene, benzene and CCl4 were examined. Two peaks were observed in the dynamic mechanical loss (tan δ) curve at −27 and 145°C, corresponding to segmental motions of polybutadiene and poly‐α‐methylstyrene, respectively. This showed the microphase separation of the block copolymers. Different electron microscopic textures were observed for same sample cast from different solvents.
Selective permeation of hydrocarbon gases in poly(tetrafluoroethylene) and poly(fluoroethylene–propylene) copolymer
Authors: Yi‐Yan N. , Felder R. M. , Koros W. J. 
Published: April 2003

AbstractThe permeabilities and diffusivities of methane, ethane, propane, n‐butane, and isobutane in commercially available poly(tetrafluoroethylene) (TFE) and poly(fluoroethylene–propylene) (FEP) Teflon have been measured in a Pasternak‐type permeation cell. Experiments were carried out at upstream hydrocarbon partial pressures up to 50 torr (1000–60,000 ppm gas phase concentration) and temperatures from 40 to 195°C with films of 0.0508 and 0.127 mm thickness using nitrogen as carrier gas on the upstream and downstream sides of the membrane. The transient and steady‐state permeation data are described well by a combination of Henry's law and Fick's law with a concentration‐independent diffusion coefficient. Linear Arrhenius plots of both permeabilities and diffusivities were obtained. Linear correlations were found both between the activation energy for diffusion and the square of the gas molecule diameter, and between the logarithm of solubility at 90°C and the penetrant boiling point. Separation factors for binary mixtures of hydrocarbons were measured for TFE at 140°C and found to be similar to those predicted by individual permeabilities in most cases. Measurements with mixed gases were not made for FEP Teflon, but selectivities of FEP are expected to be similarly well described by the ratios of the pure gas permeabilities at the low partial pressures studied. The effect of annealing FEP Teflon for 24 hr at 200°C was found to produce an average of 20–30% reduction in solubility as well as a 9% increase in the activation energy for diffusion compared to as‐received films. These effects are believed to be due to increased crystallinity in the sample upon annealing.
Biodegradable polymers: Photolysis and fungal degradation of poly(arylene keto esters)
Authors: Huang Samuel J. , Byrne Catherine A. 
Published: April 2003

AbstractPoly(keto esters) were prepared from 4,4′‐bis(chloroacetyl) diphenyl ether, 4,4′‐bis(bromoacetyl)diphenyl ether, and 4,4′‐bis(2‐bromopropionyl)‐diphenyl ether and aliphatic diacids of 6, 8, 9, 10, and 12 carbon atoms. Low‐molecular‐weight polymers were found to support the growth of Aspergillus niger and Aspergillus flavus. Introduction of methyl group to the polymer chain decreased the susceptibility of the polymers to fungal attack. Although monomeric model compounds were found to undergo photodegradation the poly(keto esters) underwent mostly crosslinking when irradiated with UV light.
Surface characteristics of solvent‐cast polymers
Authors: Schreiber H. P. , Croucher M. D. 
Published: April 2003

AbstractFilms of poly(methyl methacrylate) (PMMA), polystyrene, and a styrene/acrylic terpolymer have been cast from solutions of varying thermodynamic quality and the film properties studied by inverse gas chromatography and by critical surface tension measurements. Surface properties of the non‐polar polystyrene were independent of solvent medium, but significant variations in these properties were observed in the case of PMMA and the terpolymer. Solvent balance also appeared to affect the bulk properties of the latter films, as judged by the penetration rates of interacting liquids. The observations indicate the feasibility of controlling film properties of the solid by the appropriate selection of solution media; a time‐dependent variation in solid properties is to be expected, however, as the film structure attains an equilibrium state.
New crystalline complex chlorides containing transition metal chlorides or oxychlorides as components of coordination catalysts
Authors: Greco Alberto , Bertolini Guglielmo , Cesca Sebastiano 
Published: April 2003

AbstractNovel complex chlorides have been obtained by reacting TiCl4, VOCl3, MoOCl4, WOCl4, or AlCl3, with Be, Mg, Ca, or Sr chlorides in the presence of electron donors such as POCl3(L) or C6H5POCl2, (L′). The resulting products, obtained with good yield, show defined stoichimetry, ionic character, and crystalline structure, and may be considered reference systems for high‐yield catalysts in the low‐pressure polymerization of ethylene (HDPE). Complexes (TiCl6)MgL6, (TiCl5L′)2MgL′6, and (Ti2Cl10)MgL6associated with (i‐C4H9)3Al were found very active in HDPE synthesis, but completely unable to polymerize propylene. This result and other evidence suggest that part of the catalytic activity of these systems is displayed by soluble species. The role played by the Mg ion in high‐yield catalysts is displayed by soluble species. The role played by the Mg ion in high‐yield catalysts is discussed in the light of the peculiar behavior shown by the complex chlorides containing this earth‐alkali metal.
Effects of absorbed water on physical properties of polyesters
Authors: Ito Eiko , Kobayashi Yasuji 
Published: April 2003

AbstractIn previous articles, we reported the change in physical properties of hydrophobic polymers caused by absorption of a very small amount of water. This article describes the changes in physical properties of three polyesters owing to absorption of water. The tested polymers were poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT), and polyethylene 2,6‐naphthalate (PEN). PBT has more flexible main chains than that of PET, and PEN has more rigid main chains. The dielectric measurements revealed that water absorption results in shortening the relaxation time for PET, while the relaxation time for moist PBT becomes longer. The larger amount of absorbed water yields the higher density of PET and the lower density of PBT. The water absorption of the polyesters also yields increments in dielectric constants and relaxation strength. Distribution of relaxation time of the polyesters is narrowed by absorption of water.
Dyeing of cellulose by direct dye in aqueous sodium alginate solution
Authors: Nango M. , Maekawa M. , Katayama A. , Kuroki N. 
Published: April 2003

AbstractDyeing of cellulose by direct dye in aqueous sodium alginate solutions containing sodium chloride has been studied to interpret thermodynamically the role of sodium alginate on the adsorption equilibrium of dye on cotton. The result has been compared with that of sodium chloride (low‐molecular inorganic electrolyte) by an adsorption model on cellulose. We have inferred, by the membrane‐equilibrium theory, that the dye has been concetrated into the internal solution of cellulose because of the presence of sodium alginate in the bulk solution.
Penetration‐sorption of cotton fibers measured by immersed weight
Authors: Rowland S. P. , Stanonis D. J. , King W. D. 
Published: April 2003

AbstractWeight of cotton immersed in an aqueous solution (various concentrations of NaOH) was explored as a basis for assessing penetration and sorption of the solute. The overall effects of swelling are indicated. Penetration and sorption phenomena can be identified with supplementary information, but they cannot yet be quantified. This methodology supplements and complements gel filtration as a means of measuring interactions between solutes in aqueous solution and cellulose fibers.