bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anionic graft copolymers. II. Extension of techniques of preparation and characterization
Authors: Lechermeier G. , Revillon A. , Pillot C. 
Published: April 2003

AbstractGraft copolymers with poly(vinyl chloride) backbones and controlled amounts of polystyrene, poly(1,2‐butadiene), or poly(1,2‐butadiene–styrene) are prepared by carbanionic deactivation. Synthesis is by two methods: a classical step‐by‐step anionic polymerization technique and a new one‐apparatus technique. The reaction products are characterized by osmometry, selective extraction, and gel permeation chromatography to test the consistency of the three methods. A few words are said about the yields of grafting compared with temperature, size, and nature of carbanions.
Viscoelastic properties of tire cords
Authors: Willett P. R. 
Published: April 2003

AbstractThe viscoelastic properties of commercial rayon, nylon 66, and poly(ethylene terephthalate) tire cords have been investigated by dynamic mechanical techniques using the Vibron viscoelastomer DDV‐II. The effect of temperature, humidity, and geometric structure on the viscoelastic response has been determined for the tire cord assemblies. Subsequently, the underlying mechanisms and the polymer and fiber structural factors which influence them are discussed. Also, the consequences of the cord properties on tire hysteretic characteristics are discussed. This enables tires to be designed to meet specific service requirements. Characterization of materials in this way is becoming more important, particularly as the performance demands on tires become more stringent.
Audio‐frequency mechanical spectra of a butadiene terpolymer
Authors: Fitzgerald Edwin R. 
Published: April 2003

AbstractMeasurements of complex shear compliance (J* = J′ − iJ″) as functions of frequency and temperature for an unvulcanized sample of a butadiene terpolymer are presented. The measurements reveal the existence of a broad retardation dispersion at audio frequencies and temperatures between −30° and +35°C; but at temperatures below 0° and above 24°C, there are superimposed several series of sharp resonance dispersions. The appearance of these fine spectra below 0° and above 24°C correlates well with observed transitions in specific volume–temperature curves for the material at 1° and 24.5°C. Analyses of the spectra at 35.7°C reveal four separate series each with mode frequencies increasing as 1, 4, 9, 16, …, etc. in agreement with predictions of the momentum‐wave description of nonelastic deformation. Further, the ratios of frequencies for a common mode are in good agreement with the inverse atomic mass ratios of the atoms or atomic group to which each series is assigned. Thus, for the first mode of each series at 35.7°C, the frequency ratios are 1.000:1.142:1.220:1.335 for modes assigned to oxygen, nitrogen, the CH group, and carbon. These ratios, in turn, are in good agreement with the inverse atomic mass ratios, 1.000:1.142:1.230:1.333, as expected from momentum‐wave deformation theory. Examination of the microstructural and stress requirements for observation of nonelastic resonances in vibration experiments suggests that some type of one‐dimensional order extending over about 6 micrometers is present in the terpolymer below 0° and above 24°C, but is absent between these temperatures. The successful explanation of the dynamic mechanical behavior of this terpolymer, together with previous results cited for other materials, indicates the usefulness of the momentum‐wave theory of mechanical deformation in correlating microstructure and macroscopic mechanical response.
Changes in the CN group infrared absorption of dicyandiamide in the presence of moisture
Authors: Fountain Roger , Haas Thomas W. 
Published: April 2003

AbstractA correlation between lap shear bond strength and an infrared absorbance ratio of reactive groups in a commercial dicyandiamide (dicy.)‐cured epoxy adhesive was explained by the presence of a hidden factor in the nitrile absorbance measurement of the dicyandiamide. The absorbance at 2210 cm−1 due to the CN of the dicy. was the denominator of the absorbance ratio in the correlation. Water present in the adhesive changed the two infrared absorptions in the 2200 cm−1 region of the spectrum resulting in a lower 2210 cm−1 absorbance than expected stoichiometrically for high (0.4%) water concentrations in the adhesive.
Styrene–divinylbenzene copolymers. II. The conservation of porosity in styrene–divinylbenzene copolymer matrices and derived ion‐exchange resins
Authors: Hilgen H. , De Jong G. J. , Sederel W. L. 
Published: April 2003

AbstractThe collapse of pores in styrene–divinylbenzene copolymers and corresponding ion‐exchange resins was studied during the removal of solvating liquids. The process can be followed in a most simple way by measuring the volume of the bead‐shaped copolymers upon drying. Other parameters observed during drying were the apparent density and incidently the internal surface. The collapse of pores is considered to be a result of cohesional forces when solvated polymer chains are approaching each other by loss of solvent. The effect will thus be more pronounced in gel‐type networks than in porous ones. In porous networks, the effect will be stronger in smaller pores than in larger ones. It is shown that crosslinks, increasing the rigidity of the structures, will favor the conservation of porosity. In ion‐exchange resins the pore stability is best when the material is in its lowest state of hydration. Generally, the collapse of pores is a reversible process. The collapsed material can in most cases be reswollen by the proper choice of solvent.
Method for correcting molecular weight from gel‐permeation chromatography. I. Skewing and concentration corrections
Authors: Nakano Seikou , Goto Yukitaka 
Published: April 2003

AbstractThe purpose of this paper is to present a metod to calculate real molecular weight averages of polymer samples from GPC chromatograms where the instrumental spreading functions are skewed and the concentration effect exists. In this method, it is assumed that (1) the skewed chromatograms of monodisperse polymer samples can be represented as resultant of halves of two different Gaussians, (2) the resolution factors are regarded as constant in the case of low sample loading, and (3) the peak elution volume is independent of the presence of other components in the case of low sample loading. Adequate monodisperse polystyrenes and the mixtures (binary, seven and ten components) were examined for this purpose; and the molecular weight averages calculated by this method were compared with the ones obtained by Rosen and Provder's method. From the results in our study, it is found that this method can be available for correcting molecular weight from GPC chromatograms except for very narrow high molecular weight samples.
Manganese(IV)‐initiated graft polymerization of vinyl monomers on polyamide fibers
Authors: Khalil M. I. , Abdel‐Fattah S. H. , Kantouch A. 
Published: April 2003

AbstractThe feasibility of potassium permanganate to induce graft polymerization of vinyl monomers onto nylon 6 was investigated. The graft yield is greatly enhanced by increasing the monomer concentration, reaction time, and temperature. The addition of metallic ions as promoters to the grafting medium accelerates the graft polymerization. A mechanism for grafting was proposed. The activation energy of initiation Ei for methyl methacrylate was calculated and found to be 5 kcal/mole. The overall rate of graft polymerization Rp depends on the monomer concentration.
Autographic impact testing with increased efficiency and accuracy
Authors: Gonzalez H. 
Published: April 2003

AbstractThe objective of this work was to test modifications of an autographic impact device which would make autographic impact testing more suitable for routine work. Autographic impact devices allow the force transmitted to a specimen during impact to be recorded and displayed; thus, a detailed analysis of the impact process is possible. In addition to the measurement of the breaking energy, information on the load at which yielding begins and how the impact energy is absorbed by the specimen during impact can be obtained. Through the use of autographic impact devices, the impact resistance of plastics during an impact test has been shown to be composed of three basic areas of contribution: (1) an elastic deformation stage, (2) a plastic deformation stage, and (3) a tearing stage. The autographic method is not practical for routine evaluations because of the excessive time and effort necessary to set up, calibrate, and interpret each test. The following modifications of the autographic device were made to improve the efficiency of the method: (1) improved triggering technique, (2) improved calibration procedure, (3) elimination of the preloading force, and (4) a computer program to analyze the data much more efficiently. It is expected that these modifications will allow autographic tests to be performed efficiently.
Effect of short‐chain polymer on scission of long‐chain polymer in solution by high‐speed stirring
Authors: Nakano Akihiko , Minoura Yuji 
Published: April 2003

AbstractThe effect of short‐chain poly(methyl methacrylate) (PMMA) (P̄v = 950) on scission of longchain PMMA (P̄v = 6150) in solution by high‐speed stirring was investigated by measuring changes in [η] and GPC, stirring at 30,000 ± 500 rpm at 30° ± 5°C benzene solutions containing the above two polymers at several concentrations and at various mixing ratios. It was found that the scission of long‐chain PMMA was small or a little suppressed by addition of short‐chain PMMA. The scission‐suppressing effect of the coexisting polymers depended on the chain length. The longer the chain, the larger the effect. It was also found that the rate constant of scission, k, in Ovenall's equation had a certain significance in polymer systems with the same MWD but no significance in those with different MWDs.
Hydraulic permeation of liquids through swollen polymeric networks. III. A generalized correlation
Authors: Paul D. R. , Ebra‐Lima O. M. 
Published: April 2003

AbstractAn approximate equation was developed that permits calculation of the solvent tracer diffusion coefficient in a homogeneous swollen membrane from the measured hydraulic permeability coefficient. This relation was applied to data for 28 polymer–solvent systems that included 15 different organic solvents and 5 hydrocarbon polymer networks whose equilibrium swellings ranged from 16.1 to 91.5% polymer on a volume basis. The calculated tracer diffusion coefficient divided by the pure solvent self‐diffusion coefficient for these systems formed a unique correlation when plotted versus the polymer volume fraction in the membrane. This relation agreed well with tracer diffusion coefficient data in the literature for the benzene–natural rubber system measured by radioactive tagging. Discussion centers on the evidence for the validity of the equation developed and the role of hydrodynamics on diffusion in swollen membranes.
Molecular weight changes in polyacrylates on ultraviolet irradiation
Authors: McGill W. J. , Ackerman L. 
Published: April 2003

AbstractFilms of poly(methyl acrylate), poly(ethyl acrylate), and poly(n‐butyl acrylate) were irradiated by means of a high‐pressure mercury lamp in oxygen and nitrogen atmospheres, and the molecular weight changes accompanying degradation were studied as a function of radiation dose. Crosslinked material was formed in all cases though less crosslinking occurred in oxygen than in nitrogen atmospheres. Scission was the major reaction in the photo‐oxidation of poly(ethyl acrylate), and this was explained in terms of acetal formation. In a nitrogen atmosphere, the proportion of units fractured to the proportion of units crosslinked per unit radiation dose was constant for the three polymers. Gel permeation chromatographic studies showed the accumulation of low molecular weight fragments on prolonged photolysis, and this was explained in terms of a chain reaction mechanism.
Formation of free radicals in photo‐irradiated cellulose. IV. Effect of ferric ions
Authors: Hon Nyok‐Sai 
Published: April 2003

AbstractThe effects of wavelength and concentration of ferric‐ion photosensitizer on radical formation in cellulose irradiated with ultraviolet light were studied by means of electron spin resonance spectroscopy. Irradiations were carried out at 77°K. The absorption spectra of ferric complexes with cellulose model compounds, namely, glucose, lactose, and cellobiose, indicate that light absorption of iron–cellulose complex takes place at 365 nm, to initiate free‐radical formation. A three‐line electron spin resonance spectrum with a relative signal intensity 1:1:1 was observed when the sample was treated with 0.1‐mmole/l. ferric ion and irradiated with light λ > 3400 Å. Five‐line spectra with different signal intensities were observed when the sample was irradiated with light λ > 2800 Å and λ > 2537 Å, respectively. Further, the 1:1:1 three‐line spectrum was immediately changed to a five‐line spectrum when the sample was re‐irradiated with light λ > 2537 Å. The concentration of ferric ion strikingly affected the radical formation in cellulose and caused changes of the line‐shape and of the relative signal intensities of the spectra. The sample with 0.1‐mmole/l. ferric ion exhibited the 1:1:1 three‐line spectrum; however, when the concentration was increased to 20 mmoles/l., a prominent five‐line spectrum with relative signal intensity 1:2:0.8:2:1 was observed, when the sample was irradiated with light λ > 3400 Å. On the basis of these findings, it is apparent that several kinds of radical species can be formed by employing suitable wavelengths and varying concentrations of ferric ion.
Thermoplastic behavior of lignin with various synthetic plasticizers
Authors: Sakata Isao , Senju Ryoichi 
Published: April 2003

AbstractThe thermoplasticization of thiolignin (TL) and dioxane lignin (DL) with various synthetic plasticizers has been investigated. The thermal softening temperatures Ts of the lignin–plasticizer systems were measured applying the flow tester technique which is useful for investigating the thermal properties of polymers. It was found that the Ts of the lignins were lowered considerably as the solubility parameters (after Hildebrand) of the plasticizers approach close to that of lignin, namely, around 11. The lowering in the Ts of the lignins with the plasticizers was described by a linear equation with respect to the plasticizer concentration which ranged up to 20 wt‐%. The sorption of the limited amounts (< 5%) of water to the lignins also considerably decreased the Ts, however, the extent of lowering in the Ts by water sorption is less than that by the plasticizer addition at their contents over about 15%. The relationship of Ts to water content (up to about 30%) was curved, not linear. It was clearly shown that a combined use of the plasticizer and water brought about the most effective plasticizing for the lignins compared with the use of either of those alone.
Flow of polymer melts through a well‐lubricated, conical die
Authors: Shaw M. T. 
Published: April 2003

AbstractThe concept of gross melt fracture of polymer melts as a tensile failure in the die entry region was supported in this work by the observation of a dramatic increase in the melt fracture of poly‐ethylene extrudates upon lubricating thoroughly a conical, converging extrusion die. This flow, according to an analysis using a Fromm viscoelastic model, was found capable of producing axial tensile stresses in the extrudate in excess of 106 dynes/cm2 at the very moderate exit shear rate (no lubricant) of 100 sec−1. A calculated stress level of about 5 × 106 dynes/cm2 caused sharp, deep transverse cuts to appear in the extrudate. The ability of tensile stresses of this magnitude to fracture melts was demonstrated by separate experiments run in simple tension on molten rods, using similar rates and total deformations. A large qualitative difference between high and low‐density polyethylene in both these experiments was noted.
The effect of mixing on the modes of dispersion and rheological properties of two‐phase polymer blends in extrusion
Authors: Han Chang Dae , Kim Young Woo , Chen S. J. 
Published: April 2003

AbstractAn experimental study was carried out to investigate the effect of mixing on the state of dispersion and rheological properties in the two‐phase flow of polymer blends. For the study, blends of polystyrene and polypropylene were used, and two mixing devices were employed: a single‐screw extruder combined with a “static mixer,” and a twin‐screw compounding machine. Materials of various blending ratios were extruded at a constant temperature (200°C) through a capillary die having an L/D ratio of 20 (D = 0.125 in.). The state of dispersion in the two‐phase system was investigated from pictures taken of the microstructure of the extrudate samples. It was found that different mixing devices have a profound influence on the state of dispersion of one polymer in another. Also determined were the rheological properties of the two‐phase system investigated, from wall normal stress measurements. Our results show that, when shear stress is used as a parameter, the melt viscosity goes through a minimum, whereas the melt elasticity goes through a maximum. This is regardless of the type of mixing device employed, although the shapes of the curves are affected by the type employed. It is suggested that shear stress, instead of shear rate, be used in correlating the viscoelastic properties of two‐phase polymer systems.
Polymerization of organic compounds in an electrodeless glow discharge. VI. Acetylene with unusual comonomers
Authors: Yasuda H. , Marsh H. C. , Bumgarner M. O. , Morosoff N. 
Published: April 2003

AbstractPolymerizations of acetylene with nonpolymerizing gases and vapors such as H2O, N2, and CO in a plasma generated by inductive coupling of 13.5 MHz radio frequency are investigated. It is found that acetylene copolymerizes with those comonomers and that properties of copolymers are distinctly different from that of plasma polymer of acetylene. The copolymerization with H2O has a significant effect in reducing the trapped free radicals in the plasma polymer (to a nonexistent level). Infrared and electron spin resonance (ESR) spectroscopies and elemental analysis of polymers are used to investigate the incorporation of H2O, N2, and CO into the plasma polymers.
Evaporation of solvent in mixed polymer systems of limited miscibility
Authors: Lloyd Douglas R. , Burns Charles M. 
Published: April 2003

AbstractThe evaporation of the solvent 1,2,3,4‐tetrahydronaphthalene from the ternary system polystyrene/polybutadiene/tetrahydronaphthalene was studied. Ternary solutions of precisely known weight concentrations were prepared and then dried under vacuum and elevated temperatures. When the solution was assumed completely dried to a solid, the solvent content was calculated by difference. The deviation between the two solvent contents, namely, that known by exact weighing of components and that calculated after drying, was found to be significant, the reason for this discrepancy resting in the fact that solvent is assumed entrapped in the polystyrene fraction of the polymer residue. The possibility of the formation of interpenetrating networks causing this solvent entrapment is discussed as is a possible means of achieving more efficient solvent evaporation.
Study of the degradation of polyurethanes. I. The effect of various metal acetylacetonates on the photodegradation of polyurethanes
Authors: Cheu Eng‐Liang , Osawa Zenjiro 
Published: April 2003

AbstractPhotodegradation of polyurethanes based on polyester diol‐diphenylmethane‐p,′p‐diisocyanate in the absence and presence of various metal acetylacetonates (Ti, V, Cr, Mn, Co(II), Co(III), Fe, Ni, Cu, Zn, Mg, Al, and Sn) was carried out; and the effect of these metal compounds on the degradation was examined by investigating the changes in the stress–strain properties and infrared‐ and ultraviolet‐visible spectra of the polymer. The results obtained were as follows: Co(III), Co(II), Cu, Ti, and Sn acetylacetonates substantially enhanced the photo‐oxidation of the polyurethane; and Al, Ni, and Zn acetylacetonates scarcely affected, or slightly retarded, it. The other metal acetylacetonates accelerated more or less the photo‐oxidation of the polymer. Co(III), Co(II), and Cu acetylacetonates extremely degradation. Wavelength of the irradiated light was responsive to photochemical reactions of functional groups in the polymer. CN and CO bonds of urethane groups were very accessible to the photo‐irradiation both without and with a glass filter, while methylene groups were rather stable to the irradiated light longer than 300 nm, through a glass filter. The effect of the metal compounds on the coloration of the polymer was also consistent with that of mechanical strength and infrared spectral changes.
Viscoelastic properties of plasticized amylose triacetate films
Authors: Chang Yung Ho , Murakami Kenkichi 
Published: April 2003

AbstractThe viscoelastic properties of amylose triacetate films plasticized with diisobutyl phthalate were studied. The modulus–temperature curves of diisobutyl‐phthalate‐plasticized amylose triacetate are typical for amorphous polymers with the decrease of amylose triacetate content. The glassy modulus is not affected by the incorporation of diisobutyl phthalate, but the rubbery modulus and glass transition temperature are depressed with increased diisobutyl phthalate. The rubbery modulus appears at first to maintain for a wide temperature range, then disappears with increased diisobutyl phthalate. From the results of modulus–time measurements and x‐ray diffraction patterns: in a system of amylose triacetate–diisobutyl phthalate, amylose triacetate exists as an amorphous polymer at all concentrations of amylose triacetate and it acts intermediately between semicrystalline and amorphous polymers at lower concentrations below about 90%.
Specific resistances of hydrophilic membranes containing ionogenic groups
Authors: Vacík J. , Kopeček J. 
Published: April 2003

AbstractThis paper deals with an investigation of the dependence of specific resistances on pH for hydrophilic membranes containing ionogenic groups. Membranes based on poly(2‐hydroxyethyl methacrylate) crosslinked with ethylene dimethacrylate were investigated. This basic structure was modified by copolymerization with ionogenic comonomers, i.e., methacrylic acid and/or diethylaminoethyl methacrylate. It is shown that the dependence of the specific resistance on pH passes through a maximum for cation‐active membranes at pH ∼ 3.5, for anion‐active membranes at pH ∼ 10, and for ampholytic membranes at pH ∼ 6. The effect of the content of ionogenic groups, network density, and the degree of neutralization of membranes on the above dependence is discussed. In the final part of the paper the results are compared with more hydrophilic systems based on poly(2‐hydroxyethyl acrylate) and it is shown that maxima in the dependence of specific resistances on pH can be suppressed by increasing the hydrophilicity of polymers.