bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electroplating on crystalline polypropylene. II. Injection molding and adhesion
Authors: Fitchmun D. R. , Newman S. , Wiggle R. 
Published: April 2003

AbstractThis paper describes the effect of injection molding conditions (melt temperature, mold temperature, and fill time) and etch conditions on metal adhesion in electroplated isotactic polypropylene (PP). It is found that injection molding PP homopolymer produces a lamellar surface morphology which can consistently develop after‐plated peel strengths of 30 lb/in or better as measured by the Jacquet peel test. Surface etching of PP homopolymer prior to plating develops crack patterns characteristic of injection molding; a directional crack pattern is always evident in specimen surfaces crystallized under shear. The surface pattern is developed in the oxidative process by swelling of amorphous material, followed by oxidative dissolution and oxidative stress cracking. Additionally, the depth and number of the surface cracks is a function of the solvent swell and acid etch times. Crack depth increases in lamellar surfaces as the sample immersion times are increased; however, as crack depth increases, crack density decreases.Metal‐to‐polymer adhesion, as measured by the peel test, represents a balance between crack depth and diminished surface strength incurred in the oxidative cracking process. Although peel adhesion usually increases with crack depth, overetching may actually reduce adhesion even though the crack depth has been increased. Any advantage from deeper cracks may, therefore, be offset by a loss in the surface strength of the polymer. Comparison of the surface and cross‐sectional crack patterns in TiO2‐filled PP indicates that the surface morphology is similar to that of unfilled polymer. Molding conditions that produce the desired morphology is similar to that of unfilled polymer. Molding conditions that produce the desired morphology are important for high peel adhesion values but appear to be less critical than in unfilled PP. A propylene–ethylene copolymer (90/10) developed 12–15 lb/in. peel adhesion—50% lower than for the filled and unfilled homopolymer when molded under similar conditions; peel adhesion in this composite system is, however, relatively insensitive to changes in molding conditions. Aging of 2–3 weeks after plating is required for maximum peel adhesion in all samples studied.
The design and application of an automatic endless‐belt polymer fractionator
Authors: Blair David E. 
Published: April 2003

AbstractThe automatic endless belt polymer fractionator utilizes a continuous application and multistage extraction technique. A thin coating of polymer deposited on a slowly moving endless belt which passes through a series of solvent–nonsolvent mixtures of increasing solvent strength is fractionally dissolved. Discussion includes the description of the construction of the apparatus, details and results of fractionations of Neoprene W and polytetramethylene ether glycol, fractionation techniques and subsequent work‐up of the fractions, “large scale” preparative fractionations, and general performance characteristics.
Remarks on copolymer sequence distributions
Authors: Strate Gary Ver 
Published: April 2003

AbstractDistribution functions for the unit X in copolymers of the type
equation image
are given. These functions have been used to calculate the expected degree of crystallinity using the Flory theory of copolymer crystallinity. The calculations indicate that differences can be expected between polymers prepared from XA and XX on the one hand and A and X on the other when the kinetics constants of the polymer‐forming reactions are identical. In addition, it has been shown that the Flory results carry over to the terpolymer case with the propagation probability given in its terpolymerization form. The addition of more than one comonomer can lead to increased or decreased crystallinity with a given constant melting point, depending on whether the noncrystallizable monomers tend to alternate or “block” with one another.
Kinetics of autoxidation of atactic polypropylene by infrared spectroscopy
Authors: Jadrnicek B. R. , Stivala S. S. , Reich Leo 
Published: April 2003

AbstractThe autoxidation of a film of atactic polypropylene was studied by means of infrared spectroscopy. Reaction temperatures varied from 110°C to 135°C and oxygen concentrations, from 5% to 100% by volume. A general reaction scheme previously reported for the autoxidation of polyolefins was utilized for atactic polypropylene. Various results obtained for this polymer were compared with those previously reported for isotactic polypropylene.
Oligomer of o‐xylene as a heat stabilizer for isotactic polypropylene
Authors: Boor John 
Published: April 2003

AbstractOligomers of o‐xylene (molecular weight ∼400) have been shown to be novel heat stabilizers for isotatic polypropylene film. In contrast to unstabilized films which failed after exposure of 5 hr in a 150°C air oven, a film containing 0.5 and 1.0 wt‐% of the o‐xylene oligomer survived 100 and 226 hr, respectively. Furthermore if 0.25% dilauryl thiodipropionate (DLTP) was also present, only 0.1 wt‐% of the o‐xylene oligomer was necessary to maintain a film intact up to 124 hr. In absence of DLTP, this low level of o‐xylene oligomer was not effective. Oligomers of toluene, m‐xylene, p‐xylene, and 1,2,4‐trimethyl benzene were found less effective.
Effects of aluminum ionomer surface layers on polymer properties
Authors: Otocka E. P. , Sharpe L. H. 
Published: April 2003

AbstractBulk samples of carboxylic acid containing copolymers may be treated with solutions of aluminum isopropoxide, Al(OC3H7)3, to produce ionically gelled surface layers. The behavior of treated specimens is different from that of untreated specimens in tests which measure friction coefficient, stress crack resistance, and tensile strength. In several instances the results are compared to those produced by CASING, another technique for producing crosslinked surface regions.
Graft copolymers of starch and poly(2‐hydroxy‐3‐methacryloyloxypropyltrimethyl‐ammonium chloride). Preparation and testing as flocculating agents
Authors: Fanta George F. , Burr Robert C. , Russell C. R. , Rist C. E. 
Published: April 2003

AbstractThe title monomer (I) has been graft polymerized onto whole wheat starch with both ceric ammonium nitrate and ferrous ammonium sulfate–hydrogen peroxide initiation. Three graft copolymers, which contained 4.5, 12.1, and 15.2% grafted poly(I), were characterized as to molecular weight of grafted branches and grafting frequency. Graft polymerization was proved by fractional precipitation. Graft copolymers were tested as flocculating agents for diatomaceous silica and nonmagnetic iron ore. The graft copolymers with 12.1 and 15.2% grafted poly(I) compared favorably in flocculating ability with a commercial high molecular weight cationic polyacrylamide.
Decay of free radicals in irradiated PMMA at high pressures studied by ESR
Authors: Szőcs F. 
Published: April 2003

AbstractThe decay of free radicals in irradiated PMMA subjected to high pressures has been studied by the method of ESR. The rate constants and activation energies has been determined for the decay of free radicals at the pressures of 5000 and 10,000 atm over the temperature range of 100–170°C. It has been found that the rate of decay was reduced essentially by the effect of high pressure. The mechanism of the decay of free radicals in solid polymers is being discussed. The important influence of the motion of macromolecule segments on the course of radical reactions in solid phase is printed out.
Cryogenic relaxations of polystyrene and poly(fluorinated styrenes)
Authors: Armeniades C. D. , Baer Eric , Rieke J. K. 
Published: April 2003

AbstractThe effect of structural and morphologic modifications of styrene and fluorinated styrene polymers on their internal friction was studied by means of a free‐oscillating torsional pendulum at temperatures from 300° to 4.2°K and frequencies of 1 to 2 Hz. Atactic and isotactic polystyrene gave the previously observed δ and β′ loss peaks at 38° and 100°K, respectively. These losses decrease in intensity with crystallinity in isotactic polystyrene but remain relatively unchanged in uniaxially drawn atactic polymer. Atactic polypentafluorostyrene showed an intense δ loss peak at 52°K and a broad shoulder around 100°K, which extends toward the β′ relaxation. In poly‐α,β,β‐trifluorostyrene, the δ loss peak is largely suppressed, the logarithmic decrement showing only broad maxima at 22° and 100°K. Plasticization of atactic polystyrene with 2% mineral oil gives rise to a sharp loss maximum at 100°K, which does not occur in the pure atactic polymer.
Examination of a master curve method of characterizing steady‐state flow of polymers
Authors: Nakajima Nobuyuki 
Published: April 2003

AbstractMaster curve methods or superposition techniques are rather widely used for characterizing the steady‐state flow behavior of polymers. One method, developed by Sabia,1 is examined with respect to its applicability and limitations. In the original development of the method, it was assumed that a universal curve (master curve) exists. Based on this, a theoretical explanation was presented for the sample parameters. Such explanation became dubious because experimental evidence was found later to nullify the master curve assumption.2,3 In this paper, Sabia's method is treated as a curve‐fitting procedure to represent observed data. In order to do so, the shear rates of observation must be limited to two or two and a half decades. Also, the range of shear rates are defined from 1 to 1000 sec.−1 The results of curve fitting and molecular interpretation of the parameters are presented.
Development of chlorendic anhydride‐cured epoxy systems with wide variations in the resin: Anhydride ratio
Authors: Levy M. F. , Canestaro M. J. 
Published: April 2003

AbstractUsing the epoxy resins Epon 828 (diglycidyl ether of bisphenol A) and DEN 438 (an epoxylated novalak) with chlorendie anhydride as the curing agent, a series of formulations were developed having a very wide range in the anhydride: resin ratio (40–160 phr). This range was made possible by the use of metal chelate catalysis. While these systems were not evaluated for fire retardancy, it is anticipated that they would exhibit this property dependent on their chlorine contents.
Non‐Newtonian flow and the steady‐state shear compliance
Authors: Prest W. M. , Porter Roger S. , O'Reilly J. M. 
Published: April 2003

AbstractA survey of viscoelastic data on amorphous polymer melts indicates that the steady‐state shear compliance, Je, of many systems can be approximated from a knowledge of their flow response. For systems with monomodel molecular weight distributions, the absolute value of the reduced complex viscosity, η*/η0, is found to equal 0.67 ± 0.03 at the frequency ω, where ωη0Je = 1. This result applies to a variety of polymer systems and to a wide range of molecular weights and distributions as long as the highest molecular weight dispersion of the distribution constitutes more than 20 weight per cent of the sample. This relationship determines Je from non‐Newtonian flow data and thus provides a consistent way to relate differently shaped reduced variable curves and to calculate compliances from characteristic times reported in the literature. The connection between some commonly used times and Je is given. The method of calculating Je is successfully applied to capillary measurements of melt viscosities and to characteristic times determined from steady‐state shear measurements of concentrated polymer solutions.
Amine‐catalyzed polymer encapsulation of cotton fibers by vapor phase application of formaldehyde
Authors: Goswami J. C. , Brenner W. , Rugg B. , Liu W. 
Published: April 2003

AbstractA process for encapsulating cotton fibers in the form of woven clothes at ambient temperatures with polyoxymethylene is described. It involves pretreatment of the cotton with a carbon tetrachloride solution of tributylamine and diphenylamine to deposit the basic catalyst on the surface of the fibers. Subsequent exposure to dry, purified vapors of monomeric formaldehyde at 25°C results in the encapsulation of individual fibers with high molecular weight polyoxymethylene. The process is relatively fast (30% fiber weight gain in approx. 20 min) with the polymer located only at the fiber surfaces. Fiber cementation does not become pronounced for weight increases below approximately 60%–65% based upon the weight of the fibers. Thickness of the polymer sheath increases with the time of the polymerization reaction. Because of the uniformity of the polymer layer deposition, the encapsulated cotton cellulose fibers can be expected to exhibit substantially different physical and chemical surface properties even at low polymer add‐on. The tensile and tear strengths of the polyoxymethylene‐encapsulated cotton fibers are generally improved, with some gains in abrasion resistance also noted. Differential staining techniques and polarized light microscopy have shown the location and uniformity of the polymer sheaths.
Graft polymerization of 1,1‐dihydroperfluorobutyl acrylate onto cellulose fabric
Authors: Watanabe Haruhiko , Chiba Akira , Tuchida Toshio , Kobayashi Yoshio 
Published: April 2003

Abstract1,1‐Dihydroperfluorobutyl acrylate was prepared and grafted onto cellulose fabric by means of γ‐ray preirradiation to produce oil and water repellency. A 2% grafting was sufficient to impart oil and water repellency to cellulose fabric. In the case of 19.1% or 29.4% grafted fabrics, the grafting decreased rapidly with laundering, and the laundered fabric which possessed no oil and water repellency still had about 10% grafting of the perfluoro compound. Thus, the apparent graft polymerization takes place both on the surface and in the inner structure of the cellulose fiber; the polymer grafted onto the surface imparts oil and water repellency and is easily removed by laundering, whereas the polymer grafted onto the inner structure is hardly eliminated but does not impart oil and water repellency to the fabric.
A theoretical study of liquid‐film spread heights in the calendering of newtonian and power law fluids
Authors: Brazinsky I. , Cosway H. F. , Valle C. F. , Jones R. Clark , Story V. 
Published: April 2003

AbstractThe relationship between spread height and upstream reservoir thickness, with power low coefficient as parameter, was obtained analytically. At all values of n studied, the value of r (ratio of spread height to nip width) increases with increasing values of H/ho where H is upstream reservoir thickness and ho is nip width. At higher values of H/ho, the curves of r, versus H/ho tend to “flatten” out, and r approaches an asymptotic value. For example, the asymptotic value of r for Newtonian fluids (power law constant of 1) is 1.226. Asymptotic values of r increase with decreasing values of the power law constant.
Morphology and structure of silica agglomerates in silica‐reinforced silicone rubber
Authors: Galanti A. V. , Sperling L. H. 
Published: April 2003

AbstractLight‐scattering and optical microscope observations of silica‐reinforced silicone rubber have shown that the filler is dispersed in a complex manner. Much of the original material appears agglomerated into particles several microns in size. These particles apparently further cluster to form agglomerates of about 20 μ in diameter. In an earlier paper in this series it was shown that the thermodynamic function fe/f (the fraction of the retractive force due to internal energy changes) was a measure of the reinforcement level. It is now proposed that the corresponding physical mechanism of reinforcement may have its origin in the large amounts of energy required to deform the filler particle agglomerates.
The effect of internal temperature rise on the tensile behavior of polymeric materials at subambient temperatures
Authors: Skelton J. , Freeston W. D. , Schoppee M. M. 
Published: April 2003

AbstractThe tensile properties of nylon, Dacron, and Nomex yarn are given at liquid helium temperatures, −450°F, and at two strain rates, 1.67 and 3000%/sec. The data are compared to similar results obtained at −320°, −109°, and 70°F. A theoretical analysis of the thermodynamics of straining under both isothermal and adiabatic conditions is presented, and theoretical maximum temperature rises occurring within both adiabatically and isothermally strained yarns are given for a range of subambient test temperatures. The initial modulus of the yarns increases, the tenacity increases, and the breaking elongation decreases with decreasing temperature at the lower rate of straining. However, at the higher rate of straining, although the initial modulus of the yarns at −450°F is considerably greater than the modulus at −320°F, the nylon yarn shows a lower breaking load and greater breaking elongation at −450°F than at −320°F. The Dacron follows the expected trend with the breaking load higher and the breaking elongation smaller at −450°F than at −320°F. The Nomex has a lower breaking load, but its breaking elongation is also lower at −450°F than at −320°F. The calculated yarn internal temperature rises are sufficient to explain these differences in the stress–strain behavior of the yarns.
Viscoelastic behavior of interpenetrating polymer networks: Poly(ethyl acrylate)–poly(methyl methacrylate)
Authors: Sperling L. H. , George H. F. , Huelck Volker , Thomas D. A. 
Published: April 2003

AbstractThe creep behavior of a series of poly(ethyl acrylate)–poly(methyl methacrylate) interpenetrating polymer networks was investigated. For comparison purposes, some stress relaxation data were included. Master curves containing a single broad transition covering approximately 20 decades of time were found for midrange compositions. Although the time–temperature superposition principle and the WLF equation should not strictly apply, reasonable agreement was found over a large portion of shift factor versus temperature plots. Application of a modified Tobolsky‐Aklonis‐Dupre glass–rubber theory suggested that the breadth of the transition could be attributed to a near continuum of phase compositions in the material, each phase composition making its specific contribution to the relaxation spectrum. Whether or not these phase regions are so small as to arise from random concentration fluctuations in an otherwise compatible polymer pair remains unknown.
Thermal runaway of nylon 6–10 during drawing under constant load
Authors: Kramer Edward J. 
Published: April 2003

AbstractAnhydrous nylon 6–10 filaments were cold drawn (by propagation of a preexisting neck) under constant load. The extension rate i, which is proportional to the neck velocity, was observed to be a continuous function of the load up to a certain critical extension rate ic above which i increased discontinuously (“runaway”) by approximately two orders of magnitude. If the filaments is in N2 gas, ic ≃ 0.4 cm/min, whereas if it is in He gas, ic ≃ 1 cm/min. The structure of the drawn filament produced by runaway is an opaque, microvoid structure which, after a suitable change in load, forms first in the center of a filament and spreads toward the surface. This instability is attributed to the heating of the shoulder of the neck during neck motion. An analysis based on the measured activation enthalpy for neck motion and the thermal properties of nylon and the gas is used to predict ic values that are in rough agreement with experiment.
Graft copolymerization to cellulose in the presence of hydrogen peroxide with ultraviolet irradiation
Authors: Kubota Hitoshi , Ogiwara Yoshitaka 
Published: April 2003

AbstractThe decomposition of hydrogen peroxide in the presence of cellulose with ultraviolet irradiation and graft copolymerization occurring upon addition of methyl methacrylate to this system was investigated. Graft copolymerization barely began in the hydrogen peroxide system without ultraviolet irradiation, but was markedly accelerated by ultraviolet irradiation. Ultraviolet light is capable of initiating the graft copolymerization even without addition of hydrogen peroxide, and this capability is enhanced further with the use of hydrogen peroxide. However, an increase in the hydrogen peroxide concentration was observed to exercise a zero or negative effect on the number of grafts. Such a phenomenon is absent in the ceric ion initiator system and, in the present study, is believed to be brought about by a characteristic enhancement of the stabilization of grafting sites effected by hydroxyl radicals. The number of grafts of copolymers obtained in the present initiator system is only approximately 0.085 mmole/100 g of cellulose at its maximum and is within the range of results obtained for the hydrogen peroxide initiator system in general.
The manganic hydroxide–hydrazine system as an initiator of vinyl polymerization. II. The emulsion polymerization of methyl methacrylate
Authors: Brown C. W. , Longbottom H. M. 
Published: April 2003

AbstractThe reaction between hydrazine hydrate and manganic hydroxide has been studied as an initiator for the emulsion polymerization of methyl methacrylate. The system has proved to be effective, and polymerization occurs at favorable rates over a wide temperature range extending from below 10°C to over 50°C. The pH range, however, is rather limited, the most effective value being 9. The main features of the initiator's behavior are similar to those found previously in the corresponding solution polymerization and are explained on the basis of a surface reaction between the hydrazine and the insoluble hydroxide. A complicating feature is the reaction between hydrazine and monomer, which exerts an inhibiting influence.