bluuebunny/crossref_metadata_2025_split huggingface dataset:
Viscoelastic properties of sulfonated ethylene–propylene terpolymer neutralized with zinc cation
Authors: Granick Steve 
Published: April 2003

AbstractStress–relaxation measurements in uniaxial extension, in the terminal zone, were made of sulfonated ethylene–propylene terpolymer (EPDM), neutralized with zinc cation. The sulfonation levels were 15 to 20 meq/100 g polymer (0.47 and 0.62 mol %), and for each level the effect of the ionic plasticizer, zinc stearate, was investigated. For all the polymers, the decay of the modulus with elapsed time was gradual and featureless, reflecting a broad distribution of relaxation times. Sensitivity of the ionomers' structures to thermal history before an experiment was suggested by irreproducibility in the magnitudes, but not the distribution, of relaxation times at a given temperature. For polymers containing zinc stearate measured at 80°C, the amount of permanent set was low for relaxation up to about 20h, but increased rapidly with additional hours of stretch. Time–temperature superposition did not apply. Composite curves were constructed by matching the stress–relaxation response at short times; moduli measured at long times fell above the composite curve. The shapes of the composite curves were similar, regardless of the level of EPDM sulfonation or the presence of zinc stearate. The apparent Arrhenius activation energy for short‐time relaxation at similar levels of the modulus was about 35 kcal/mol at 140°C for the unplasticized polymers and about 70 kcal/mol at 90°C for the polymers containing zinc stearate, in contrast to the usual effect of plasticizer on the rate of relaxation of amorphous polymers except near the glass transition temperature.
Synthesis and viscoelastic properties of new thermosetting resins having isocyanurate and oxazolidone rings in their molecular structures
Authors: Kinjo Noriyuki , Numata Shun‐Ichi , Koyama Toru , Narahara Toshikazu 
Published: April 2003

AbstractA new type of thermosetting resin can be obtained from solventless varnishes composed of polyfunctional isocyanates and epoxides. The IR spectra show that the cured resins have isocyanurate and oxazolidone rings in their chemical structure, hence their name, isocyanurate–oxazolidone resins. The viscoelastic behavior of the cured resins can be varied considerably by selecting an appropriate reactant species and changing the equivalent ratio of the isocyanate and epoxy groups in the varnishes. Three relaxations, labeled α, β, and γ, characterize their dynamic mechanical spectra. The α‐dispersion is due to the glass transition, the β‐dispersion, to local mode motions of the backbone chains of resins, and the γ‐dispersion, to the molecular motions of long alkyl chains. If certain additives are mixed into the varnishes before curing, microphase separation takes place during the reactions. The resins finally obtained have a peculiar physical structure in which rubber particles are dispersed throughout a matrix phase as confirmed by scanning electron‐microscopic analysis and viscoelastic behavior.
Electron beam irradiation induced grafting of acrylonitrile to polyethylene powder
Authors: Morgan Paul W. , Corelli John C. 
Published: April 2003

AbstractThis study focuses on the influence of various parameters on the post‐irradiation grafting of acrylonitrile monomer to a low density polyethylene powder having an average particle size of 20 μm diameter. The type of radiation used was 0.8 MeV electrons with a dose rate of either 0.1 Mrad/min or 4.0 Mrad/min. Irradiations were carried out in vacuum, air, and dry oxygen environments at room temperature to total doses ranging from 1 Mard to 15 Mrad. Several experimental techniques were used to investigate various interrelated aspects of both the graft copolymer product and the graft process, including infrared spectroscopy to measure percent graft, electron spin resonance to measure radical concentrations, scanning electron microscopy to investigate surface morphology, and differential scanning calorimetry to measure crystalline content. Comparisons of the percent graft determined from different probes were found to be consistent. The dose dependence of grafting exhibited a linear relationship below 8 Mrad. Initiation by both alkyl and peroxy radicals at 77°C was supported by results of decreased grafting with decreased temperature, increased dose rate or vacuum irradiation. Decreased grafting after oxygen irradiation suggested a unique change in grafting mechanism. Higher grafting yields were found for quenched relative to annealed samples. The amount of extractable homopolymer formed was found to be ∼ 10% at a dose of 10 Mrad and a dose rate of 4 Mrad/min.
Stress optical behavior in polystyrene; residual stresses and birefringences in large, quenched samples
Authors: Wust C. J. , Bogue D. C. 
Published: April 2003

AbstractIn a basic study of the nonequilibrium glassy state of polystyrene, two related areas have been investigated. The first dealt with homogeneous samples and included work on volume aging and the effect of temperature on the stress (and strain) optical coefficients and on the modulus. The second dealt with nonhomogeneous samples and included measurement of the frozen‐in birefringence in large, quenched samples and analysis of this residual birefringence, and also the stress, with residual stress theory. The theory used was that of Aggarwala and Saibel, which is a special case of the more general theory of Lee, Rogers, and Woo.
Viscoelastic properties of a gum vulcanizate at large static deformations
Authors: Sullivan J. L. 
Published: April 2003

AbstractThe loss tangent corresponding to small sinusoidal oscillations superposed on a large static deformation is found to decrease with increasing static deformation ratio for a natural rubber gum vulcanizate. Further, the response functions of the stress–relaxation and the incremental stress–relaxation vs. time and the storage modulus vs. frequency are found not to be separable functions of time and strain effects. These findings are shown to indicate that the elastic contribution to the viscoelastic response of this elastomer increases more rapidly with the static deformation than does the relaxation contribution. The loss modulus, however, is found to be a separable function of time and strain effects. Hence, only one relaxation function is needed in the viscoelastic constitutive theory applied to this elastomer. The finite linear viscoelasticity theory as modified by Morman has a form which can account for these results. Predictions of the incremental stress–relaxation function from dynamic data are within 1% of experimental values.
Synthesis, characterization, and study of thermal properties of methyl‐substituted arylene sulfone ether polyimides, polyamides, and poly(amide–imides)
Authors: Adduci J. , Chapoy L. L. , Jonsson G. , Kops J. , Shinde B. M. 
Published: April 2003

AbstractA number of methyl‐substituted bis[(phenyleneoxy) sulfone] dianilines were synthesized and reacted with pyromellitic dianhydride (PMDA), benzophenone tetracarboxylic acid dianhydride (BTDA), terephthaloyl chloride (TPC), isophthaloyl chloride (IPC), and trimellitic anhydride acid chloride (TMAC) to prepare a series of polyimides, polyamides, and poly(amide–imides), respectively. Low temperature solution and interfacial polymerization techniques were utilized to prepare the above polymers. Most of the polymers prepared formed tough, transparent flexible films. The prepared polymers were characterized by solution viscosity, thermal gravimetric analysis (dynamic and isothermal), and differential scanning calorimetry. The effect of the number and the ring substitution of methyl groups on polymer properties is discussed.
Dynamic mechanical analysis of polymers in the liquid state: Use of a perforated shim stock support
Authors: Keinath Steven E. , Boyer Raymond F. 
Published: April 2003

AbstractThis report summarizes some initial results on the use of a perforated brass shim stock support to extend the useful range of dynamic mechanical testing well over 100 degrees above the traditional limiting polymer softening points of Tg or Tm. Weak secondary relaxations were observed above Tg in both polyisobutylene (PIB) and polystyrene (PS) homopolymer, copolymer, and blend systems and above Tm in gutta percha (trans‐polyisoprene). The DuPont 981 Dynamic Mechanical Analyzer (DMA)–990 Thermal Analyzer system was used to characterize these weak liquid state processes. The DMA instrument deforms the specimen in flexure, thus minimizing the shear component present in some other techniques. Specimen‐coating weights are typically in the range 20–40 mg. The perforations are particularly useful for polymers having low inherent adhesion to metals or systems which are very brittle in the glassy state, e.g., low MW PS's and many methacrylates.
Analysis of the calendering of compressible fluids
Authors: Chung Tai‐Shung 
Published: April 2003

AbstractAssuming that the compressible behavior of polymeric melt obeys the Spencer–Gilmore equation of state, the effect of melt compressibility on calendering process has been investigated. The compressible model is distinctly different from the incompressible model in three ways. (1) It has substantially lower maximum pressure, (2) the location having maximum pressure moves closer to the nip region; (3) the contact point shifts closer to the nip region.
Gradient innterpenetrating polymer networks. II. Polyacrylamide gradients in poly(ether urethane)
Authors: Elsabee M. Z. , Dror M. , Berry G. C. 
Published: April 2003

AbstractThe surface of poly(ether urethhane) is modified by preparing gradient interpenetrating polymer networks (IPNs) with polyyacrylamide hydrogels. Soveral experimental methods are used for preparing the gradient IPNs. Attenuated total reflection Fourier transform infrared (ATR‐FTIR) is used as the main characterization technique.
Crystallinity of pure and nucleated PET
Authors: Aharoni S. M. , Sharma R. K. , Szobota J. S. , Vernick D. A. 
Published: April 2003

AbstractPure and Al(OH)3‐containing PET films were prepared, quenched, and subsequently annealed under identical conditions. The level of crystallinity of the films was determined by three methods: density measurements, X‐ray crystallinity determination, and measurements by IR of the relative concentration of trans OCCO conformation in the polymer. For pure PET it was found that the percentage crystallinity measured in annealed samples by X‐ray and IR is about the same. The density measurements agree with these techniques only when the amorphous density is taken as 1.348 g/cm3. In the case of quenched pure PET, a 7% correction to the concentration of trans conformation must be introduced (in agreement with recent literature) to fit the IR results to the X‐ray and density data. Annealed PET containing Al(OH)3 crystallizes to about the same level as annealed pure PET. The agreement between X‐ray and IR data is reasonably good. In the quenched PET/Al(OH)3 there exists a higher level of trans conformation (enhanced order), probably resulting from adsorption of relatively extended PET chain segments on the surface of the hydroxide particles. These extended units may possibly serve as nucleation sites for PET crystallization upon cooling from the melt.
Photoinduced graft copolymerization of nylon 6 fibers with acrylamide. II. Characterization and evaluation of properties
Authors: Mukherjee A. K. , Sachdev H. S. , Gupta Achla 
Published: April 2003

AbstractNylon 6‐g‐polyacrylamide graft copolymer prepared by photoinduced initiation was characterized and some of its properties were evaluated. Intrinsic viscosity of the graft copolymer increased continously with percent grafting. Thermal stability decreased corresponding to the increase in add‐on %. The moisture regain, diameter, and density showed an increase with percent grafting. The acid dyeability of the graft copolymer decreased with increase in graft level, whereas the disperse dye uptake increased initially up to a graft add‐on of 28.9% and then showed a decrease.
Kinetics of swelling of cotton fibers in aqueous ethylenediamine solutions using moisture regain data
Authors: Lokhande H. T. , Pawar A. D. , Shukla S. R. , Chidambareswaran P. K. , Patil N. B. 
Published: April 2003

AbstractKinetic studies of swelling of cotton cellulose with 75% (w/w) EDA solution have been carried out. Three rates of the reaction were observed in the temperature range 10–35°C: first, the very fast rate (k1) lasting for about 10 s; second, the extremely slow rate (k2) lasting for 30–50 s; and third, once again a fast rate (k3), k1 being faster than k3. k1 was attributed to the swelling action of EDA–monohydrate in amorphous regions of cellulose; k2 was assigned to the penetration of swelling species into crystallities accompanied by breakage of H bonds in these regions; and k3 was assigned to the opening up of the crystallites. Activation energy values confirmed this trend. At higher temperatures (35–55°C), the middle rate k2 merged with k3, giving only two rates, k1 and k2+3, as the higher temperatures brought about simultaneous diffusion of swelling agent into, and decrystallization of, the crystalline portions of cellulose. EDA solution of 65% (w/w) concentration gave only two rates: the initial fast rate assigned to the swelling of the amorphous portion, followed by a slow one, operating in mesomorphous regions of cellulose, without any appreciable decrystallization. This was atributed to the important fact, viz., the absence of EDA–monohydrates in the solution.
Wide‐angle X‐ray diffraction studies of nylon–ionomer blends
Authors: Venkatesh G. M. , Fornes R. E. , Gilbert R. D. 
Published: April 2003

AbstractBlends of nylon 6 with poly(acrylic acid) polyacrylamide, poly(ethylene‐co‐acrylic acid), poly(ethylene‐co‐vinyl alcohol), poly(acrylamide‐co‐acrylic acid), and polypropylene were prepared by melt blending. Annealing treatments included treatments in Vacuum, in water, and in 20% formic acid at various temperatures. WAXS (wide‐angle X‐ray scattering) patterns of melt chips and of undrawn, drawn and textured yarns were obtained. The melt chips of 100% nylon 6 crystallize in the α form while the chips of all the blends exhibit a single diffracton ring. All the blends behave similarly during different annealing treatments. When annealed in 20% formic acid at 102°C, the α structure results. The as‐spun fibers of nylon 6 and of the blends with poly(acrylamide‐co‐acrylic acid) and poly(ethylene‐co‐vinyl alcohol) exhibit a broad diffraction maximum in the region 2θ = 19–25°. The α content and its purity increase with increasing severity of the annealing treatment. The as‐spun fibers of the blend with poly(acrylic acid), on the other hand, exhibit a highly oriented γ structure which is highly resistant to conversion to the α from during the annealing treatments. Only when treated in 20% formic acid at 102° does the pure α form result. The drawn textured yarns of nylon 6 exhibit both the α and the γ forms. However, the γ content of the textured yarns from the blends varies with the type and concentration of the additives. The textured yarns from the blends with low levels (0.125%) of poly(acrylic acid) have a very high α content. It is very unusual that the as‐spun fibers with almost pure γ structure, when drawn, produce a structure with a high α content.
Influence of long chain branching on extrudate swell of low‐density polyethylenes
Authors: Hamielec L. A. , Vlachopoulos J. 
Published: April 2003

AbstractAn experimental study of extrudate swell has been carried out, involving five low‐density polyethylene (LDPE) samples of approximately the same molecular size but of different frequencies of long‐chain branching (LCB). The results show that the samples with higher frequencies of LCB exhibit a tendency to swell more than samples of lower frequency. This tendency is more pronounced for short L/D dies and high shear rates. It seems possible that LDPE samples of varying LCB frequencies can be differentiated by determining the swelling ratio (d/D) with orifice dies (L/D ⋍ 0) at high throughput rates.
Effect of high pressure on some electrophysical properties of polymers: Polyconjugated systems doped by iodine
Authors: Zhorin V. A. , Beshenko S. I. , Berlin Yu. A. , Enikolopian N. S. 
Published: April 2003

AbstractThe effect of pressure P up to 2.5 × 103 MPa on the dielectric constant ε and conductivity G of a number of conjugated polymers doped by iodine has been studied. Polyphenylacetylene prepared with FeAcAc, polyphenylacetylene obtained with Ziegler catalyst, anionic polydiphenylacetylene, and polydiphenylbutadiene were chosen for investigation. It has been found that after doping the values ε and G increase and strongly depend on P. The possible mechanism of this phenomenon has been discussed.
Isothermal transient current studies in cellulose acetate films
Authors: Kumar Ashok , Nath Rabinder 
Published: April 2003

AbstractStep voltage transient current studies have been made in cellulose acetate films as a function of filed and thickness. A logarithmic plot (Scherr‐Montroll plot) of the transient current vs. time gives a knee at a time tT, which is interpreted as the transit time of the charge carrier. The value of the carrier mobility has been estimated to be 3.9 × 10−9 cm2.V−1.S−1 in cellulose acetate film. The carrier mobility in iodine‐doped (2% w/w) cellulose acetate film has also been determined from Scher‐Montroll plot and is found to be 3.3 × 10−7 cm2.V−1.S−1.
Synthesis of rigid polyurethane foams from oligoester alcohols based on the residues from the distillation of crude dimethyl terephthalate and recrystallization of the dimethyl terephthalate/dimethyl isophthalate fraction
Authors: Troev K. , Todorov K. , Borisov G. 
Published: April 2003

AbstractOligoester alcohols are synthesized from the resudes from the distillation of crude dimethyl terephthalate and recrystallization of the fraction dimethyl terephthalate/dimethyl isophthalate, diols, triols, tetrols, and tall oil. The polyol component containing various oligoester alcohols is suitable for preparing rigid polyurethane foams with good thermal stability and improved resistance to combustion.
Syntheses and properties of urethane prepolymers and their corresponding crosslinked films
Authors: Yang Chin‐Ping , Wu Wen‐Lin 
Published: April 2003

AbstractTrimethylol propane (TMP), polyglycol (PG), and toluene diisocyanate (TDI) were reacted in various molar ratios to produce TMP–TDI–PG–urethane prepolymers and then mixed with equivalent isocyanate generator (Desmodur AP‐Stable) in a mixture of m‐cresol and naphtha to give polyurethane varnishes which finally became crosslinked films by the casting method. The mechanical properties and viscoelasticities of the PG‐modified and PG‐free polyurethane crosslinked films and the practicability of magnet wires coated with them were studied in this article. Three different PGs used in this experiment were polyethylene glycol, PEG(#400), polypropylene glycols, PPG(#1000) and PPG(#2000). In the case of adding PEG(#400) for modification, strength at break increased but elongation did not change. Meanwhile, glass transition temperature (Tg) shifted to lower temperature with increasing molar ratio. In the case of adding PPG(#1000) and PPG(#2000) for modification, the samples changed their mechanical properties from hard and brittle to soft and tough. With increasing molar ratios, strength at break initially increased and then decreased gradually, and elongation varied a lot and was consistently contrary to strength at break. Tg occurred at two regions: one at high temperature above 100°C for small molar ratios and the other at low temperature below 100°C for high molar ratios. Besides, for all PG‐modified polyurethane crosslinked films, strength at break showed a local maximum at TMP/TDI/PG = 1/1/0.5, which indicated their homogeneous structures. The molar ratios of PG‐modified urethane prepolymers, which are suitable for manufacturing practical magnet wires according to testing method JIS‐C‐3211, are as follows: TMP/TDI/PPG(#100) = 1/1/0.15–0.35 and TMP/TDI/PPG(#2000) = 1/1/0.10. PEG(#400)‐modified magnet wires were not accepted on the aging test. The properties of crosslinked films of practical magnet wires are generally as follows: strength at break at 200–700 kg/cm2, elongation less than 41%, and Tg at 100–200°C.
The radiation crosslinking of poly(vinyl chloride) with trimethylolpropanetrimethacrylate. III. Effect of diundecyl phthalate: Chemical kinetics of a three‐component system
Authors: Bowmer T. N. , Vroom W. I. , Hellman M. Y. 
Published: April 2003

AbstractThe radiation chemistry of poly(vinyl chloride) (PVC) blended with trimethylolpropanetrimethacrylate (TMPTMA) and diundecyl phthalate (DUP) has been examined. This three‐component mixture contains a base resin (PVC), a crosslinking sensitizer (TMPTMA), and a physical modifier (DUP). These are the basic components in any radiation‐curable coating. The kinetics and mechanism of the crosslinking reactions were studied with reference to the dependence on radiation dose and blend composition. The polyfunctional TMPTMA underwent polymerization incorporating the PVC into a 3‐dimensional network. DUP remained chemically inert during the irradiation, not being bound to the network. However, DUP by plasticizing the macromolecules and diluting the monomer, changed the kinetics extensively. DUP enhanced TMPTMA homopolymerization, TMPTMA grafting, and PVC crosslinking reaction rates. The effect on the competition between polymerization, grafting, and degradation reactions was examined in terms of enhanced mobility of the reacting species. The influence of these kinetic considerations in selecting a blend composition for a coating application was discussed.
Accelerated heat age testing of phenolics: Applicable temperature range
Authors: Stransky Paul D. , Yates W. Ross , Johnson Julian F. 
Published: April 2003

AbstractAn upper bound in temperature for accelerated heat aging of a phenolic molding compound has been determined. Oxidative degradation based on time and temperature follows the Arrhenius relationship up to this upper temperature bound, after which thermal shock becomes the primary mode of failure.
On Zhurkov's approach to the strength of solids
Authors: Papazian Harold A. 
Published: April 2003

AbstractTwo modifications to the Zhurkov kinetic concept of static (creep) rupture is discussed: (a) solids where the common pole τ0 is much larger than that associated with a vibrational frequency of bonded atoms in the solid and (b) materials where a common pole does not occur. Both cases are discussed within the Zhurkov framework. The activation thermodynamics and the association with transition state theory are revealed.
Reinforcement mechanism of polyester‐fiber‐reinforced rubber—A model study
Authors: Xue Gi , Koenig Jack L. , Wheeler Donald D. , Ishida Hatsuo 
Published: April 2003

AbstractThe reinforcement mechanism of polyester tire cord was studied by Fourier‐transform infrared spectroscopy using various model compounds. Three model compounds representing the main chain of polyester and the terminal groups, namely carboxylic acid and hydroxyl groups, were used. Chemical reactions between these polyester models and an epoxy functional silane coupling agent were studied qualitatively as well as quantitatively. Among the many possible reactions, the reaction between the carboxylic acid and epoxy group was found to proceed readily. Kinetic studies of the major reactions also show quantitative differences in their activation energies as well as the rate constants. Based on the quantitative studies, we have estimated the expected rate of interfacial reaction at the heat treating temperature of polyester tire cord.