bluuebunny/crossref_metadata_2025_split huggingface dataset:
Specific refractive index increments of polymer solutions. Part II. Scope and applications
Authors: Huglin M. B. 
Published: April 2003

AbstractThe data of Part I are examined in the light of accepted theories. The specific refractive index increment ñ of most polymer solutions lies between −0.2 and +0.2 ml./g., although larger values can obtain in circumstances wherein the scattering unit is unusually large, e.g., solutions of partially neutralized polyacids the units of which contain the gegenions. ñ depends on the indices of solvent n1 and polymer n2. Among common solvents, water and 1‐bromonaphthalene are capable of affording high positive and negative values, respectively, for n. The Gladstone‐Dale rule applies rigorously to pure and mixed solvents, but the Lorenz‐Lorentz expression is preferable for evaluating n2. Results of current theories applied to mixed solvents and copolymers are summarized. In the former, the true molecular weight M is determined by using ñ and the variation of solvent index with composition. For a copolymer of monomers A and B, M as well as Ma and Mb are obtainable by using ñ, ña, and ñb. Dispersion is expressed as (ñ)λ = (ñ)436[D′ + D″/λ2] at a wavelength λ, and dispersive constants D′ and D″ are evaluated for some solutions. ∂ñ/∂T is generally 3.2 (±2.3) × 10–4 ml./g./°C. and changes very little with λ. When ñ increases with M, the limiting characteristic value is derived (at 1/M = 0) from a plot of ñ versus 1/M. ñ can be determined to a maximum accuracy of 1% by using n2 calculated from the Lorenz‐Lorentz equation and the experimental partial specific volume.
The effect of plasticizing compounds on acrylic fibers
Authors: Gur‐Arieh Z. , Ingamells W. , Peters R. H. 
Published: April 2003

AbstractComparison of the various solubility parameters of different plasticizing agents has shown that their plasticizing action on Acrilan filaments is governed by polar interactions. The diameter swelling of the filaments appears to decrease with increasing efficiency of the plasticizing agent. The diffusion of a disperse day through the plasticized fiber is not related to the fiber swelling and is controlled by the plasticizing action of the dyebath.
Refractometric and calorimetric studies of the van der Waals interactions between the molecules of polycarbonate and of the additives acting as plasticizers or antiplasticizers
Authors: Makaruk Leszek , Polańska Hanna , Staros Elżbieta 
Published: April 2003

AbstractConsiderable deviations of molar refraction from the additivity in the solutions containing polycarbonate and its antiplasticizers symmetrical trinitrotoluene and 1,1‐bis(4‐hydroxy‐3, 5‐dichlorophenyl)2,2,2‐trichloroethane diacetate are reported. In contrast to this, the solutions of polycarbonate with plasticizer di‐n‐butyl phthalate and the solutions of antiplasticizers in pure solvent show only insignificant deviation from the additivity. The calorimetric studies showed the differences in the heats of solution of the used antiplasticizers in pure solvent and in the solvent containing a constant amount of polymer, whereas there was no noticeable difference in the polycarbonate–plasticizer (di‐n‐butyl phthalate) system. Both deviations of the molar refraction from the additivity and differences of the heats of solution prove the existence of strong interactions between the molecules of polycarbonate and the antiplasticizer.
Thermal degradation of polymers. XI. Synthesis, polymerization, and thermal characterization of polymers of p‐N,N‐diethylaminostyrene in nitrogen
Authors: Oprea S. , Still R. H. 
Published: April 2003

AbstractThe monomer p‐N,N‐dimethylaminostyrene has been synthesized from p‐N,N‐diethylaniline and homopolymerized and copolymerized with styrene using 2,2′‐azobisisobutyronitrile as free‐radical initiator. The polymers have been characterized by thermal analysis (DTA, DSC, and TG). Glass transition temperatures have been measured and activation energies for degradation in nitrogen have been established by a variety of methods for comparative purposes.
Thermal degradation of polymers. XIII. Thermal analysis studies on p‐N,N‐dimethylaminostyrene homopolymers and copolymers with styrene in air
Authors: Still R. H. , Whitehead A. 
Published: April 2003

AbstractHomopolymers of p‐N,N‐dimethylaminostyrene and copolymers with styrene have been subjected to thermal analysis studies in air. Molecular weight and copolymer composition have been shown to influence the stability of the polymers and the shape of the TG and DSC curves obtained under dynamic conditions. Mechanisms to account for this behavior based on the anti‐oxidant effect of the chain‐bound p‐N,N‐dimethylamino substituent are discussed.
Reactivity of poly(vinyl chloride) containing N‐methyl dithiocarbamate toward metal ions in heterogeneous system and effect of γ‐irradiation on the reactivity
Authors: Nakagawa Tsutomu , Oishi Noriko , Fujiwara Yukihiko 
Published: April 2003

AbstractThe reaction of poly(vinyl chloride) containing N‐methyl dithiocarbamate (PMD) with metal ions in a heterogeneous system and the effect of γ‐irradiation on the reactivity were studied. PMD powder suspended in aqueous solutions did not show any reactivity toward metal ions. However, the PMD powder suspended in a methyl alcohol solution formed a chelate with various metal ions. The effects of the reaction time, pH, and the initial concentration of the metal ion were examined. PMD irradiated in methyl alcohol with γ‐irradiation doses up to 28 Mrad was compared with the original PMD. The reactivity of the irradiated PMD toward the metal ions did not show any apparent decrease.
A comparison of equations for the effect of pressure on the viscosity of amorphous polymers
Authors: Goldblatt Philip H. , Porter Roger S. 
Published: April 2003

AbstractSeveral equations which are used to predict the pressure coefficient of viscosity for amorphous polymers have been examined on the basis of type of information required and equation reliability. These equations can be useful in accounting for pressure effects observed in tubular flow and in other shear geometries. The correlations of Penwell and Porter and of Miller are evaluated and in the perspective of expressions by Matheson and by Eyring. Data on linear amorphous polystyrene (PS), polyisobutylene, poly(vinyl acetate), poly(methyl methacrylate) (PMMA), natural rubber, and polycarbonate are examined and presented. Predictions from the Penwell‐Porter and Miller equations are compared with experimental coefficients at one atmosphere for all data available. For PS and PMMA, it was found that Miller's equation tends to predict values somewhat higher than experiments but is closer to the data on PS and on a high molecular weight PMMA. The Penwell‐Porter equation, on the other hand, tends to predict values somewhat lower than experiments and does a slightly better job for lower molecular weight PMMA. Both equations require WLF or Vogel coefficients and Tg‐pressure‐molecular weight data. Miller's equation also requires compressibilities at Tg and at the temperature of interest, although an alternate method can be used which only requires average “K” values without Tg‐pressure or compressibilities at Tg.
Effect of dispersity on the Tll (>Tg) transition in polystyrene
Authors: Glandt C. A. , Toh H. K. , Gillham J. K. , Boyer R. F. 
Published: April 2003

AbstractThe presence of a high temperature (>Tg) relaxation in amorphous polystyrene has been investigated further. In the previous work,1 the techniques of differential thermal analysis (DTA) and torsional braid analysis (TBA) were employed to study polystyrene as a function of “monodisperse” molecular weight. The occurrence of the Tll transition appeared to be associated with the attainment of a critical viscosity level with also corresponded with a free volume level. An entanglement network developed at a critical value of molecular weight, Mc, giving a break in the Tll‐versus‐M plots. The present work deals with the influence of dispersity on the Tll transition, below and above Mc. A series of binary blends of “monodisperse” anionically polymerized polystyrenes with systematic changes in M̄n and heterogeneity index (M̄w/M̄n) was tested by TBA. The results show that when both components have molecular weights below Mc, single and average values of Tg and Tll are observed which are linearly related to M̄n−1, as predicted by free volume arguments. Although a single Tg is observed when one component has a molecular weight above and the other has a molecular weight below Mc, the components appear to undergo the Tll relaxation independently. The results indicate that both the glass transition and the Tll transition are basically governed by the same type of molecular motion but at different length ranges.
The spinnability of polymer fluid filaments
Authors: Ide Yoshiaki , White James L. 
Published: April 2003

AbstractA theoretical study of the stability of extending liquid filaments has been carried out. The interaction of surface tension and different fluid rheological properties is investigated. It is also hypothesized that cohesive failure or fracture will occur if a critical stress level is reached. It is predicted that viscosity and viscoelasticity tend to stabilize the filaments. However, even extremely high viscosity filaments will neck and exhibit ductile failure. In highly viscoelastic fluids, defects tend to heal during stretch. Highly viscoelastic fluid filaments fail by fracture. The theory is used to predict the failure of molten polymer filaments as a function of molecular weight. The extensibility or spinnability of filaments is predicted to exhibit a maximum at intermediate molecular weights with capillarity‐ductile failure occurring at low molecular weights and cohesive fracture, at high molecular weights. The results are compared to experiments on polyethylenes. There is general qualitative agreement especially with the behavior of low and high molecular weights where capillarity and fracture occur. The tendency to necking and ductile failure differs considerably among melts and is more pronounced in high‐density than in low‐density polyethylenes. The application to continuous spinline behavior is discussed, and draw resonance is suggested to be the continuous process analogue of ductile failure.
The crystallinity of poly(phenylene sulfide) and its effect on polymer properties
Authors: Brady D. G. 
Published: April 2003

AbstractThe crystallinity and crystallizability of poly(phenylene sulfide) have been examined by a number of common techniques. Several provided qualitative information, but only one, x‐ray diffraction, was considered sufficiently reliable and reproducible to allow quantitative comparisons. Based on x‐ray measurements, an approximate degree of crystallinity, termed crystallinity index (Ci), could be readily assigned. According to this method, virgin polymer possesses significant crystallinity (Ci ≈ 65%). Curing (crosslinking) the resin below its melting point did not change the crystallinity but did affect the crystallizability. Lightly cured resin suitable for molding and film extrusion was easily quenched from the melt to give amorphous polymer. The amorphous samples crystallized rapidly when heated to temperatures > 121°C (250°F). At mold temperatures below 93°C (200°F), moldings with very low surface crystallinity were produced. Annealing (204°C, 400°F) caused rapid crystallization of such moldings, and changes in crystallinity were correlated with observed changes in physical properties. The resin crystallizes so rapidly that these quenched moldings possessed a crystallinity gradient, the internal crystallinity being substantially greater. At high mold temperatures (121–204°C, 250–400°F), moldings very similar to fully annealed specimens were obtained.
Structure–property relationships in copolymers to composites: Molecular interpretation of the glass transition phenomenon
Authors: Kaplan Donald S. 
Published: April 2003

AbstractStructure is taken as the main theme in outlining the mechanical properties of polymer composites. Examples of two‐component polymer systems are selected from the literature showing their morphology, as evidenced from electron micrographs, and their corresponding mechanical properties, as evidenced by dynamic mechanical spectra. A compatibility number, Nc, is defined in a continuous scheme from a compatible system (one glass transition, Nc → ∞) to an incompatible system (two glass transitions, Nc → 0). The point at which semicompatibility occurs, Nc ≅ 1, is taken as the approximate universal segmental length associated with a glass transition. This length of 150 Å allows for 100 to 5000 CC bonds for an associated glass transition. The ramifications of this molecular interpretation of a glass transition are discussed, resulting in a denouncement of the time–temperature correspondence principle and a new interpretation of short‐segmental block copolymers.
New catalyst system for easy‐care cotton finishing
Authors: Hebeish A. 
Published: April 2003

AbstractA new catalyst system, based on a mixture of boron trifluoride–acetic acid complex (BF3·2CH3COOH) and magnesium chloride hexahydrate (MgCl2·6H2O), has been examined in cotton finishing treatment for producing easy‐care properties. It provides strong catalysis in crosslinking cotton with a series of N‐methylol finishing agents when the pad‐dry‐cure process is applied. Curing can be carried out at a temperature of 130–150°C for a period of 1–3 min, dependent on the temperature used. The resilience and abrasion resistance properties as well as the degree of polymerization (D.P.) of the crosslinked cotton so obtained were equivalent or slightly better than those of crosslinked cottons catalyzed by conventional catalysts. The influence of the new catalyst as well as a number of conventional catalysts, viz., ammonium chloride, ammonium dihydrogen phosphate, magnesium chloride hexahydrate, and zinc nitrate hexahydrate, on some properties of cotton fabrics was also investigated. The behavior of these catalysts in the presence of the N‐methylol finishing agent was quite different from their behavior in its absence. With the exception of ammonium salts, the D.P. of crosslinked cotton was much higher than that of cotton treated with the catalyst only. The opposite holds true for the abrasion resistance.
Elementary steps in Ziegler‐Natta catalysis
Authors: Fink Gerhard , Rottler R. , Schnell D. , Zoller W. 
Published: April 2003

AbstractThis paper is a short review of our recent advances in Ziegler‐Natta catalyst system of the type (C5H5)2TiRCl/AlEtn Clm. These are, for instance, the electronic changes after complex formation, the parallel reactions of the alkyl and chain transfer between both the Ti centers of two complexes and the Ti center and an Al center of two complexes; furthermore, the alkyl, chain, and chlorine transfers between these complexes and dimer Al–alkyl, the time which the insertion step of one ethylene requires, and the mathematical calculation of the kinetics of the polyreaction.
Phosphorylation of cellulose with phosphorous acid and thermal degradation of the product
Authors: Inagaki Norihiro , Nakamura Satoshi , Asai Hitoshi , Katsuura Kakuji 
Published: April 2003

AbstractThe reaction of cellulose with phosphorous acid in molten urea afforded a white, water‐soluble product. The product was a monoester of phosphorous acid, and all the phosphorus residues were in phosphonic form, i.e., cellulose phosphonate. Quantitative addition of acrylonitrile to the PH bonds in cellulose phosphonate occurred in the presence of sodium ethoxide. By alkali hydrolysis of the adduct, a polyelectrolyte having two different ionization groups, POH and COOH, could be prepared. Thermal degradation of three cellulose phosphonates, ammonium cellulose phosphonate (I), ammonium cellulose 2‐cyanoethlyphosphonate (II), and ammonium cellulose 2‐carboxyethylphosphonate (III), was examined. All three samples decomposed at a temperature around 270°C, but their thermal behaviors were different. Replacement of hydrogen in the phosphonic residue by 2‐cyanoethyl and 2‐carboxyethyl groups retarded dehydration of cellulose. Sample I had a satisfactory flame retardance; samples II and III were not flame resistant. Reduction of flame retardance may be due to the electron‐withdrawing effect of the cyano and carboxyl groups.
Effect of hydrogen bond formation on dynamic mechanical properties of amorphous cellulose
Authors: Yano Shoichiro , Hatakeyama Hyoe , Hatakeyama Tatsuko 
Published: April 2003

AbstractThe temperature dependence of the dynamic modulus (E′) and the mechanical loss tangent (tanδ) of amorphous cellulose prepared from cellulose triacetate by saponification was measured and compared with that of cellophane, recrystallized cellulose obtained by immersing amorphous cellulose in water, and cellulose triacetate. The E′ of amorphous cellulose decreased initially with increasing temperature and then began to increase at about 70°C with a maximum at 80°C, decreasing again at about 100°C. Another decrease in E′ was observed at 220°C accompanied by a discontinuity at 155°C. In the tan δ‐versus‐temperature curve, a medium peak at 60°C a shoulder peak at 146°C, and a broad peak at 200°C were observed. It was found that the transition at about 60°C was related to hydrogen bond formation by free OH groups. The transition at about 150°C was attributed to a recrystallization process by heating, and the relaxation at 200°C, to the glass transition of the polymer. The decrement in E′ observed at about 100°C was attributed to the cooperative motion of an individual pyranose ring in amorphous cellulose, juding from the E′ and tan δ assignment of other cellulose materials. The change in E′ was also measured isothermally as a function of time in the temperature range between 40°C and 80°C, where a maximum in tan δ and an increment in E′ were observed as the temperature dependence of the dynamic viscoelasticity. The change in E′ with elapsed time was analyzed kinetically, and an activation energy of 2.6 kcal/mole was calculated. This value is the expected activation energy of hydrogen bond formation.
Reaction of hexamethylene diisocyanate with poly(vinyl alcohol) films for biomedical applications
Authors: Caro S. V. , Sung C. S. Paik , Merrill E. W. 
Published: April 2003

AbstractThe objective of this work was to obtain primary amine groups on the surface of poly(vinyl alcohol) films by means of a reaction with hexamethylene diisocyanate. The reaction was run in such a way as to minimize the internal crosslinking by employing a large excess of hexamethylene diisocyanate in toluene and then hydrolyzing the unreacted isocyanate endgroup to primary amine. After dialyzing out the adsorbed hexamethylenediamine from the aqueous solution of reacted poly(vinyl alcohol), the extent of covalent bonding of hexamethylene diisocyanate onto the polymer was determined by measuring aminohexyl content through a fluorescence assay. This assay is based on the reaction of fluorescamine, 4‐phenylspiro[furan‐2(3H)‐1′‐phthalan]‐3,3′‐dione, with a primary amine to yield a fluorophor which will emit a strong fluorescence at 475–490 nm when excited at 390 nm. Analyses show a range of 1.1 × 10−10−3.6 × 10−10 mole of amines per cm2 of reacted poly(vinyl alcohol) film. When assuming 47% as degree of crystallinity approximated by IR spectroscopy for these polymer films, the availability of hydroxyl groups in amorphous region was estimated to be 3.7 × 10−10 mole/cm2. The extent of reaction based on available hydroxyl groups was then in the range of 31–97%. The primary amine groups attached by this method can now be exploited for binding biomolecules such as heparin (anticoagulant) or fibrinolytic enzymes in an attempt to achieve biocompatible materials.
The effect of solution variables on the solution of cellulose in dimethyl sulfoxide
Authors: Seymour Raymond B. , Johnson Earl L. 
Published: April 2003

AbstractThrough the study of the effects of concentration, temperature, and molar ration (of paraformaldehyde to cellulose) on solution viscosity and per cent transmittance (at 530 nm), it has been demonstrated that cellulose solutions in dimethyl sulfoxide (DMSO) are readily produced. By heating 1, 2, and 50 to 100 parts by weight of cellulose, paraformaldehyde, and DMSO, respectively, extremely viscose cellulose solutions and gels were prepared. Solutions with concentrations as high as 10% were prepared. However, the optimum conditions to effect complete cellulose solution in DMSO at 75°C were found to be 0.5% cellulose and 0.8 and 1.0% paraformaldehyde. This corresponds to a paraformaldehyde‐to‐cellulose molar ratio of about 10:1.
The effect of glass transition on gas permeabilities
Authors: Yasuda H. , Hirotsu Toshihiro 
Published: April 2003

AbstractGas permeabilities of a copolymer of acrylonitrile and methyl acrylate were examined at the temperature range of 25° to 80°C. The change of activation energy of gas permeability constant at the glass transition temperature (65°C) was observed with N2, Ar, O2, and CO2, but no change was observed with He. The observation of the change of slope of the Arrhenius plot of gas permeability is discussed as a function of the diffusion constant (D) of a permeant gas at the glass transition temperature (Tg). The change occurs only if the value of D at Tg is smaller than a certain value (i.e., 5 × 10−8), according to the analysis of data appearing in the literature.
Flame retardancy effects of halogenated phosphates on poly(ethylene terephthalate) fabric
Authors: Inagaki Norihiro , Onishi Hiroyoshi , Kunisada Hideshi , Katsuura Kakuji 
Published: April 2003

AbstractA Chemical research on the flame retardancy effect of halogenated phosphates on poly(ethylene terephathalate) fabric was carried out by thermogravimetry, infrared spectral analysis, and mass spectrometry. The following conclusions were drawn: (1) The flame retardancy effect of halogenated phosphates such as tris(2,3‐dibromopropyl) phosphate is due to altering the pyrolysis reaction of polyester by aldol condensation. (2) The probability that liberated halogen compounds from the phosphates act as radical acceptors in a flame zone may be low. (3) Incorporation of halogen elements into phosphates appear to depress evaporation of phosphates, which act as acidic catalysts in aldol condensation from the condensed phase.
Bimodal character of polyester–solvent interactions. II. Evaluation of the chemical structures of the aromatic and aliphatic ester residues of poly(ethylene terephthalate)
Authors: Knox B. H. 
Published: April 2003

AbstractThe chemical structures of the aromatic (A) and the aliphatic ester (B) residues of poly(ethylene terephthalate), PET, are evaluated from a comparison of their Hansen solubility parameters, as determined experimentally, and with those calculated for the various residues of PET. From such a comparison it is proposed that the structures of residues A and B are best represented by “hybrid” structures which may be taken as linear combinations of two or more structures rather than by single chemical structures. That is, the 1,4‐carbonyl group which separates the benzene ring of the aromatic residue and the ethylene group of the aliphatic ester residue effectively acts as a common plane between the two residues and is “shared” by the benzene ring and the ethylene glycol group. It is proposed that the extent to which the 1,4‐carbonyl group is “shared” by residues A and B is 0.33 and 0.67, respectively, which is consistent with the most probable molecular conformation of the 1,4‐benzenoid residue of PET as calculated from the data of Tonelli23 and Daunbeny et al.21 and which gives support to the view that the bond connecting the benzene ring and the carbonyl group is not rigid, but free to rotate as proposed earlier by Flory27 and by Tonelli23