bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of density and orientation on the permeability of polypropylene film
Authors: Conner W. P. , Schertz G. L. 
Published: December 2004

AbstractThe permeability of films to O2, CO2, and H2O vapor is reduced by drawing processes. The permeability data are compatible with the hypothesis that crystallinity reduces permeability because of (1) a decrease in the volume fraction of penetrable amorphous polymer; (2) a lengthening of the diffusion path by impenetrable barriers, presumably crystallites; and (3) a reduction in segmental motion within the amorphous volume. Analysis of the effect of molecular diameter on diffusion rate shows that the segmental motion within amorphous polypropylene regions is less than that in natural rubber.
Continuous mixing of very viscous fluids in an annular channel
Authors: Schrenk W. J. , Cleereman K. J. , Alfrey T. 
Published: December 2004

AbstractMixing of viscous fluids in an annular channel is analyzed theoretically. Four basic mixing patterns are described which can be generated by altering the relative rotational velocities of the annular boundaries. Only one aspect of the mixing problem is isolated, i.e., reduction in striation thickness. Problems of front to back mixing to iron out variations of feed stream composition and mixing of solid particles are not considered. The theory was verified experimentally using molten polystyrene.
The physical significance of acid‐anhydride cures on epoxy adhesive properties
Authors: May C. A. 
Published: December 2004

AbstractThe influence of bulk physical properties on the bond strength of an adhesive was studied. A conventional epoxy resin when cured with various mixtures of phthalic acid and anhydride exhibits maximum bond strength when the curing agent is 75% acid and 25% anhydride. This effect is explained on the basis of physical properties of the unfilled resin systems. Most significant of these were the heat distortion temperature and the compressive break and yield strengths.
A rheological study of the injection molding of styrene polymers
Authors: Pezzin Giovanni 
Published: December 2004

AbstractSeventeen different samples of styrene polymers and copolymers were examined in a capillary extrusion rheometer over broad ranges of temperatures and shears. They were injection molded in a spiral mold over the same temperature range. If viscosities at constant shear stress are obtained from the rheometric data, they cannot be correlated with spiral flow results. However, if viscosities are calculated at a proper “high” shear rate, capillary data correlate will with spiral flow results at all temperatures and for all materials.
Glass transitions in polypropylene
Authors: Beck D. L. , Hiltz A. A. , Knox J. R. 
Published: December 2004

AbstractDilatometric measurements show that both isotactic and atactic polypropylenes have two distinct glass transition temperatures. Because of the two transitions, three values for the cubical coefficient of thermal expansion are necessary to accurately define the volume expansion of polypropylene from −80° to +90°C. A method is outlined for calculating the content of amorphous atactic, amorphous isotactic, and crystalline isotactic polymer in a given polypropylene sample.
An infrared spectroscopic study of the chemical changes in polyethylene during flame spraying
Authors: Goldenberg A. L. 
Published: December 2004

AbstractThe chemical changes taking place in polyethylene in the process of flame spraying have been investigated qualitatively and quantitatively by a spectroscopic method. It has been shown that oxidation occurs during the process with the formation of acidic, ketonic, ester carbonyls, associated hydroxyls and ‐C‐O− bonds. The degree of unsaturation also increases due to growth in the number of vinyl and trans‐vinylene groups. A small increase in the number of CH3 groups is also observed.
Radiation‐induced polymerization at high pressure of n‐tetradecafluoroheptene‐1; 1,1,2‐trifluorovinyl phenyl ether; and 1,2,3,4,5‐pentafluorophenyl 1,1,2‐trifluorovinyl ether
Authors: Brown Daniel W. , Wall Leo A. 
Published: December 2004

AbstractThe radiation‐induced polymerization of n‐tetradecafluoroheptene‐1 was investigated at pressures of 8100, 11,900 and 17,100 atmospheres and temperatures between 90 and 267°C. The data are interpreted in terms of a free radical mechanism and the polymer has a low ceiling temperature. As temperature is increased, the depropagation step becomes important and reduces the rate of polymerization. Under some conditions transfer seems to be a significant part of the mechanism. Several radiation‐induced polymerizations at high pressure were carried out with 1,1,2‐trifluorovinylphenyl ether as well as one with 1,2,3,4,5‐pentafluorophenyl 1,1,2‐trifluorovinyl ether. The results suggest that transfer limits the molecular weight of the polymers.
Screw extrusion‐flow patterns and recent theoretical developments
Authors: Squires P. H. 
Published: December 2004

AbstractThe melt‐filled portion of an extruder screw has been examined in a quantitative analytical fashion by numerous workers during recent years. The progress which has been made in defining flow patterns in this portion of the screw is reviewed, with special attention devoted to edge effects of the screw flights and the contribution of the circulatory cross‐channel component of flow. More recent work on the complex problem introduced by the existence of curvature in the screw channel is presented, along with consideration of distortion of the streamlines caused by non‐isothermal conditions and non‐Newtonian fluid properties of the molten polymer.
Pyrolysis of polytrifluoroethylene: Influence of gamma radiation and alkali treatment
Authors: Straus S. , Wall L. A. 
Published: December 2004

AbstractPyrolysis in vacuum of gamma‐irradiated polytrifluoroethylene indicates increased rates of volatilization with increased dosage. At the higher radiation doses, the rate curves no longer show a maximum but resemble those previously obtained with branched polyethylenes. Studies of swelling with acetone indicate crosslinking increases with radiation dose. It is estimated that for each chain fracture caused by radiation there are approximately seven crosslinks formed. However, in addition to the crosslinks a branched structure is also being produced as evidenced by the character of the thermal degradation rate curves. Alkali treatment of the polymer sensitizes it towards dehydrofluorination and double bond formation. Subsequent rate and pyrolysis studies showed the formation of very stable residues, indicating a relatively greater thermal stability of the main chain.
Correlation of extrudate swelling measurements for polymer solutions by a reduced‐concentration technique
Authors: Middleman S. 
Published: December 2004

AbstractPrevious work has demonstrated the possibility of obtaining curves of normal stress as a function of shearing stress for polymer solutions through the measurement of the swelling of a jet of the solution extruded from a long capillary. A new formulation of reduced variables is offered which allows results obtained at different concentrations to be correlated by a single curve for a given polymer system. Results are presented for water solutions of carboxymethylcellulose, and for xylene solutions of polyisobutylene. For polyisobutylene, the correlation is similar to those obtained by other investigators who measured normal stresses by standard techniques.
The “ADL ball rebound tester”
Authors: Raphael T. , Armeniades C. D. 
Published: December 2004

AbstractThe paper presents the “Thermophysical Profiles” of selected plastics and discusses their significance in correlating the mechanical properties with the molecular and crystalline structure of these polymers. The profiles were obtained with a new instrument, by imposing a fixed, forced elastic vibration on the speciments' surface and by recording continuously the energy absorbed by the specimens through a temperature range from −200°F to +500°F The profiles locate the first and second order transition points of the test materials (defining, thus, the temperature limits of their use) and indicate the change in modulus with temperature in the viscoelastic region of the polymers. Profiles of the following materials are discussed, low and high density polyethylene, polypropylene and PVC films and unfilled samples of cast epoxy and polyester resins.
A new second‐order transition temperature relationship for copolymers
Authors: Dyvik G. K. , Bartoe W. F. , Steck N. S. 
Published: December 2004

AbstractRecent dielectric measurements at 60 cycles per second have shown a good correlation amond α‐peak, Vicat and dilatometric Tg temperatures. Other measurements of copolymer systems have suggested a re‐examination of existing second‐order transition temperature relationships. This study has revealed that the most common of these equations are mathematically equivalent and not fully satisfactory for explaining all observations. A relationship is proposed which is capable of fitting either linear or non‐linear second‐order transition data for compatible copolymer systems.
Structural characteristics and optimization of filament‐wound cylindrical rocket motor cases
Authors: Foerster A. F. , Boller T. J. 
Published: December 2004

AbstractThe basic requirements for optimization of filament‐wound pressure vessels are a high strength‐to‐density ratio of the fiberglass‐resin composite and an arrangement of the glass fibers in such fashion that each fiber carries, at a given pressure, the same constant load throughout the cylindrical portion as well as the end closures. The basic relations governing the isotensoidal design are derived, and the ideal shape of the end closure is defined. The relative merits of geodesic and “in‐plane” wrapping are discussed. Structrual efficiencies accomplished in several practical applications are reviewed.
The oscillating shear phenomenon in high density polyethylenes
Authors: Metzger A. P. , Hamilton C. W. 
Published: December 2004

AbstractStudies of capillary extrusion measurements using an Instron rheometer show that certain types of high density polyethylene exhibit a discontinuity in the shear stress/shear rate curve. This behavior which is separate and distinct from the phenomenon of melt fracture is caused by a change in the flow regime. It is manifested by oscillation of the recorded load while the rheometer piston is operated at a constant rate. Therefore, this behavior has been termed “oscillating shear phenomenon”. The location and magnitude of the fluctuations are functions of the molecular parameters of the polymer as well as the melt temperature, capillary geometry, and other rheometer variables. Evidence is presented which indicates that the change in flow regime could result from the orientation of the melt as it enters the capillary.
The effect of glass surface chemistry on glass‐epoxy systems
Authors: Laird J. A. , Nelson F. W. 
Published: December 2004

AbstractCarefully controlled experimental techniques were used to study the effect of variations in bulk E glass surfaces on bound life and wetting. Bond life (stability of the bound in the presence of moisture) was determined visually as the time required for hot water to remove an epoxy resin coating from the glass surface. Wetting was determined by the captive bubble technique. Both properties were significantly affected by variations of the glass surface. The bound life studies emphasized the importance of the coupling agent in promoting bound stability in a hot water environment. The only example of the glass surface not treated with a coupling agent that had a satisfactory bound life was the alkali‐deficient glass surface prepared by acid leaching. The surprisingly poor bound lives of the degassed and freshly cleaved (high energy) glass surfaces indicated that the wet strength retention of laminates would be poor when prepared by instantaneously applying epoxy resin without a coupling agent to the glass fibers directly as the fibers are formed. Cleanliness and surface and surface roughness were the only two variables found that promoted wetting. This discrepancy with respect to cleanliness indicated that wetting was not the controlling factor for bond life.
Rheological properties of polyvinyl chloride. Parts III–post extrusion swelling
Authors: Sieglaff C. L. 
Published: December 2004

AbstractThe post extrusion swelling behavior of PVC has been studied as a function of the rheological flow variables and as a function of the molecular weight of the polymer. An expression which correlates the swelling with the apparent non‐Newtonian viscosity has been found for each of the five molecular weight samples studied. No mechanism for this elastic effect was proposed.
The relationship between crystallization and deformation processes in crystalline high polymers
Authors: Lindenmeyer P. H. 
Published: December 2004

AbstractThe relationship between crystallization and deformation is two‐fold: (1) deformation or flow in polymers prior to crystallization has an important influence on the resultant crystalline morphology and (2) the morphology in turn largely determines the response of the structure to further deformation after crystallization. Thus, an understanding of deformation processes in crystalline polymers is intimately related to the crystallization processes and vice versa. The crystallization process may be approached by considering the observed morphological structures as being analogous to the usual crystal habits with the addition of various crystal‐defects which add bending and twisting to the more common crystallographic variations. The crystal habit or morphology may be characterized by its surface to volume ratio. Crystallization of polymers may be considered as three steps (1) the formation of primary nuclei (2) crystallographic growth (also a nucleation controlled process) and (3) the introduction of crystal‐defects which cause bending and twisting.
Biodeterioration of plastics
Authors: Wessel C. J. 
Published: December 2004

AbstractThe deterioration of plastics by biological agents of considerable concern not only to the U. S. Department of Defense but to the national economy as a whole. Although the importance of the subject was recognized by some since the early days of the plastics industry, widespread investigation first began during World War II when serious problems were encountered in the tropics with electrical and electronic equipment. In the recent past the great developments in oceanography have emphasized that marine biodeterioration of plastics requires much more investigation. Biodeterioration of plastics is characterized according to that caused by microbiological agents, macrobiological agents, and marine biological agents. the important past and recent knowledge in each category is summarized.
Flame‐resistant rigid polyurethance foams from monobrominated toluene diisocyanate
Authors: Nametz R. C. , Deanin R. D. , Lambert P. M. 
Published: December 2004

AbstractToluene diisocyanate was partially replaced by monobrominated toluene diisocyanate in conventional rigid polyurethane foam formulations, producing self‐extinguishing foams for thermal insulation, with only moderate sacrifce of compressive strength, and with no significant effects upon reactivity, odor, density, cell structure, or resistance to aging.
The correlation of the non‐newtonian flow of polymeric melts with the theories of Bueche
Authors: Brodnyan J. G. , Shoulberg R. H. , Kelley E. L. 
Published: December 2004

AbstractBueche and Harding [J. Polymer Sci. 32 177 (1958)] obtained an empirical “standard flow curve” to relate viscosity and shear rate by using a particular poly(styrene) solution and positioning the flow curve on a dimensionless rate of shear axis via the viscosity average molecular weight, MV and Bueche's expression for the relation time, τ, where

Here R is the gas constant, ηo is the low rate of shear Newtonian viscosity, T is the absolute temperature, C is the Concentration in grams per cubic centimeter, and MR is te molecular weight which determines the relaxation time. Bueche implies by his standard curve that MV correlates with MR. In Gereral, it was found that: 1) MR does not equal MV but it is usually significantly lower than MV or MW; (2) the value of MR increases with increasing polymer concentration and temperature; and (3) the shapes of the flow curves are slightly different from the shape of the standard curve. A survey of the data available in the lon the flow of polymer melts supports these conclusions. Thus, the Bueche‐Harding method can only give semi‐quantitative help I predicting the flow behavior of polymeric melts.
The criterion of fracture
Authors: Bikerman J. J. 
Published: December 2004

AbstractDupre's theory that work of rupture equals increase in surface energy, and Griffith's hypothesis (based upon Dupre's that a crack propagates when strain energy decrease equals or exceeds work required to creat two new surfaces are shown to be incorrect. Work is required for deformation to repture, not for the actual rupture.An alternative criterion, i. e., that crack propagation occurs when strain energy decrease exceeds the increase required for elastic deformation of the “critical domain” to the breaking point, offers the following advantages: (1) continuity between macro‐ and micro‐effects, (2) avoidance of surface energy (unmeasurable for solids), (3) accounting for heat effect, (4) reasonable explanation of unexpectedly high “surface energy” values.
Study of flow properties of polymer melt with the screw extruder
Authors: Ui J. , Ishimaru Y. , Murakami H. , Fukushima N. , Mori Y. 
Published: December 2004

AbstractIt has been shown that a standard screw‐extruder with a little modification is very useful for the measurement of flow properities of various plastics melt over a wide range. Results obtained are very interesting and it is expected that they have applicability to polymer processing. A range of flow rates covering both extrusion and injection molding applications were considered.
Theoretical aspects of polymer crystallization with chain folds: Bulk polymers
Authors: Hoffman J. D. 
Published: December 2004

AbstractThe Theory of Crystallization of bulk linear polymers with chain folding is discussed in terms of recent developments. Specific topics covered are: (a) Rate of crystal growth and size of folded nuclei, (b) theoretical and experimental estimates of the fold surface free energy, and estimates of the surface free energy of “friged micelle” and “switchbord” type crystals, (c) basic causes of essentially regular folding in bulk, (d) rejection of short chain species during crystallization, (e) melting behavior of thin chain‐folded lamellae, (f) gradual thickening of lamellae on isothermal storage, (g) homogeneous, pseudohomogeneous, and heterogeneous nucleation, (h) voids and included point defects as a paret of the concept of the degree of crystallinity, and (i) phenomena occurring in stage 1 and stage 2 of bulk crystallization isotherms (annealing). A comparison of theory and experiment is carried out using data, some previously unpublished, on polyethylene and polychlorotrifluoroethylene. The theory with essentially regular golding is found to be satisfactory.
The surface tension of polyethylene
Authors: Starkweather H. W. 
Published: December 2004

AbstractExtrapolation from data on low molecular weight n‐alkanes indicates that the surface tension of polyethylene at 150°C is 26 dynes/cm. The total surface energy, γ — Tdγ/dT, is 51 dynes/cm and is much less dependent on chain length. The surface tension of polyethylene extrapolated to 20°C is 34 dynes/cm, consistent with the critical surface tension below which liquids will wet the polymer. The total surface energy is in reasonable accord with the incremental energy of vaporization, 1.029 kcal/mole of CH2 groups. The surface entropy is less than that of low molecular substances. This is attributed to a reduction in the opportunities for rotational isomerism at the surface.
Transitional phenomena in α‐polyolefin melts
Authors: Beck D. L. , Hiltz A. A. 
Published: December 2004

AbstractA first order transition was observed in the temperature range of about 210°C by dilatometric studies on both isotactic and atactic polypropylene and for isotactic poly (butene‐1) and poly (pentene‐1). No such transition was observed for polyethylene. It was found that the transition is not due to the measurements per se, to polymer treatment, to catalyst residues, or to polymer degradation. It is suggested that the transition could be due to the disappearance of liquid crystals.
Polyaromatic heterocycles
Authors: Marvel C. S. 
Published: December 2004

AbstractThis article is a brief review of recent work in the author's laboratory on heat stable polyaromatic heterocycles. New polymers based on 2,7‐disubstituted‐1,3,6,8‐tetraazopyrene structure are described.Some background material on ladder or two‐strand polymer structures will be discussed. This will be followed by a description of recent work aimed at producing polyquinoline types and some properties of such polymers.
Infra‐red spectroscopy of brominated epoxy resins
Authors: Mackinney Herbert W. , Spalik Joseph T. 
Published: December 2004

AbstractThe method of determining the epoxy equivalent weight of resins derived from Bis Phenol A and epichlorohydrin described by Kagarise and Weinberger has been extended to resins derived from epichlorohydrin and Tetra Brom Bis Phenol A and/or Bis Phenol A. In the infrared spectra of the latter, the characteristic aromatic band at 1610 cm−1 is replaced by a strong band at 738 cm−1, the intensity of which increases linearly with the content of Tetra Brom Bis Phenol A. The logarithm of the epoxy equivalent weight is linearly related to the ratio of the absorbance at 915 cm−1 to a linear combination of those at 1610 and 738 cm−1, respectively.
Effect of nuclear radiation on the thermal conductivity of polyethylene
Authors: Tomlinson J. N. , Kline D. E. , Sauer J. A. 
Published: December 2004

AbstractThermal conductivity curves for the 0°C to 170°C temperature region are presented for six irradiated low density polyethylene samples (radiation doses from 0 to 3100 megarads) and one irradiated high density sample (120 megarad dose). In agreement with data in the literature for unirradiated polyethylene, the thermal conductivity values for lightly irradiated polyethylene are found to decrease with increasing temperature in the elevated temperature region where the crystallites begin to melt. Beyond the crystalline melting point, test results for lightly irradiated and crosslinked samples indicate that the thermal conductivity is almost independent of temperature. Although radiation doses of less than 250 megarads produce only small changes in the thermal conductivity, higher radiation doses result in a significant lowering of the conductivity in the room temperature region and an increase of the conductivity at temperatures above the melting point. The decrease in conductivity at low temperatures is considered to be a result of disordering of the crystallites by the radiation, and the increase above the melting point is attributed primarily to radiation induced crosslinking.
The influence of resin strength and defects on the interlaminar shear strength of filament‐wound composites
Authors: Petker I. 
Published: December 2004

AbstractThe interlaminar shear strength of reinforced plastic composites has long been recognized as a critical property in the structural performance of composites. However, its role in structural performance and the many factors that influence it have not been clearly elucidated. Although much attention has been given to the importance of resin‐glass adhesion, little is known regarding the contribution of resin strength and composite quality. In this article it is shown that interlaminar shear strength is a direct function of both resin strength and composite void content. The curves of resin tensile strength vs interlaminar shear strength indicate a limiting value for interlaminar shear above which increases in resin tensile strength do not increase defects.