bluuebunny/crossref_metadata_2025_split huggingface dataset:
An empirical method for … The prediction of liquid permeation in polyethylene and related polymers
Authors: Salame Morris 
Published: December 2004

AbstractPermeability properties depend on the size, shape and polarity of the permeating molecule. Permeability of organic liquids, polar or non‐polar, can be quite accurately predicted if the chemical composition of the permeant is known. By the choice of an arbitrary value (unity) as an indicator for the carbon atom, numbers specific to each structural element of the permeating molecule can be computed from previous experimental data. These numbers, herein called “Permachor” values (π), then combine by simple addition to relate the logarithm of a liquid's permeation in polyethylene.
A study of the finish mechanism: Glass to finish, finish thickness and finish to resin
Authors: Eakins William J. 
Published: December 2004

AbstractA solution of substituted alkyl alkoxy silanes was applied to E‐glass filament strands before forming glass‐resin composite hoops, which were tested to relate changes in hoop physical properties to the nature of the coupling agent‐size application. Continuously heat cleaning E‐glass in oxygen‐enriched air gives a strand that, when properly coated with size and laminated, makes a hoop with superior strength and modulus properties.
Transitions in polymers by nuclear magnetic resonance¨ a study ¨
Authors: Woodward A. E. 
Published: December 2004

AbstractThe principles of nuclear magnetic resonance, NMR, are briefly reviewed and the use of proton resonance for the study of segmental motion in solid high polymers is outlined. Studies of the temperature dependence of NMR spectra have shown that both completely amorphous and partially crystalline polymers exhibit NMR line narrowing processes at temperatures near the respective glass transition temperature due to increased segmental motion. The presence of small molecules, such as H2O or D2O in the polyamides, or a change of tacticity to a greater isotatic content, such as for poly(methyl methacrylate), is found to lower this line narrowing process on the temperature scale. Heating of polyethylene single crystal aggregates at temperatures somewhat below the melting point also leads to a decrease in temperature for this line narrowing process, presumeably due to the introduction of defects in the polymer crystals. In the ⩽ 77°K to 200°K region numerous polymers having methyl and methyl group containing side chains are found to exhibit line width and second moment dispersions, attributed to methyl group rotation. If the methyl group is attached to a phenyl or ester side chain, methyl rotation takes place at 77° K and below.
Olefin–substituted silicas as active fillers for polymers
Authors: Neimark I. E. , Chuiko A. A. , Slinyakova I. B. 
Published: December 2004

AbstractSilicas have been synthesized of which the OH groups have been substituted for organic radicals with double bonds. The methanol, benzene and heptane sorption isotherms of the olefin‐substituted silica specimens have been determined. It has been shown that the sorption of the vapors decreases with increasing substitution of the OH group by the organic radicals. The organosubstituted silicas were used as fillers of polymethylmethacrylate.
The use of microscopy to aid surface coating evaluation
Authors: Lindquist J. A. , Widmer V. E. , McKinley G. G. 
Published: December 2004

AbstractBy observing the surface and internal portions of a film with an electron microscope, information is obtained about the binder structure, pigment distribution and compatibility of the plasticizer. On a larger scale the light microscope can detect imperfections in vortex cells, which can be eliminated by proper solvent formulation, and crystalline bloom which is influenced by plasticizer and light polymer migration. When plasticizer exudes to the surface the durability of the coating is lowered in the two types of exposure, the difference of which can be determined by plasticizer migration.
Chromatographic fractionation of polyolefins
Authors: Guillet J. E. , Combs R. L. , Slonaker D. F. , Summers J. T. , Coover H. W. 
Published: December 2004

AbstractThe results compare favorably with those obtained by careful refractionation of fractions isolated by the precipitation method. A convenient parameter, U, related to the breadth of the molecular weight distribution can be calculated from the slope of the log‐probability plot. When the plot is linear, U, is numerically equal to the ratio Mw/Mn. Values of U obtained for a number of commercial and experimental polypropylenes indicate that, with a given type of polypropylene, the breadth of the distribution increases as the average molecular weight of the sample increases, and that wide differences in distribution can be expected from polymers made by different processes.
Evaluation of brittle failures of polyethylene by subjection to biaxial stress
Authors: McFedries R. , Brown W. E. , McGarry F. J. 
Published: December 2004

AbstractFirst and second order effects of density and melt index were found to be significant with stress level a significant factor in determining failure time using Maltese Cross shaped specimens. Stress and temperature had the greater influence on failure. Influence of temperature‐viscosity interaction is of concern along with transition in the mode of failure from ductile to brittle type. Reduction in the effect of melt index with increasing density is in accord with new theories on polyethylene crystal structure. It was also shown that higher modulus materials fail more rapidly.
An evaluation of polypropylene by dynamic mechanical tests
Authors: Maxwell Bryce , Heider James E. 
Published: December 2004

AbstractThe loss factor ratio is dependent upon temperature and the rate of change of mechanical load or frequency of the oscillatory loading. The limit of linear viscoelastic response is another variable which occurs at the break in the stress‐strain curve. If storage modulus varies slightly, with magnitude of stress or strain, the data is considered linear viscoelastic. The only true test is in the limit of zero strain and independent modulus. Polypropylene's dynamic properties are most dependent on test temperature. The loss factor peak which can be controlled by temperature and pressure history during crystallization is an indication of the ductile‐brittle transition point.
Physical properties of ethylene‐1‐olefin copolymers
Authors: Folt V. L. 
Published: December 2004

AbstractWith the advent of the newer catalyst systems it is now possible to prepare copolymers of ethylene and 1‐olefins possessing useful physical properties. A wide range of physical properties is readily achieved through variations in the concentration and type of 1‐olefin used as the comonomer. The era of tailor‐making ethylene type polymers to fit any specification regarding stiffness, strength and melt flow properties is now at hand. A comparison of physical properties of ethylene/1‐olefin copolymers with those of the corresponding polyethylene/poly (1‐olefin) blends indicates true copolymers are formed.Decrease in crystallinity of copolymers is due to the number of branch sites introduced into the main chain rather than to the bulk of the comonomer or the length of side chain.
The relative stability of cation impurities and silica fiber surfaces
Authors: Eakins William J. 
Published: December 2004

AbstractThe effects of heat soaking and leaching with HCl at pH 6.0, 5.0 and 4.0 of five fiber glass formulations are investigated. Silane coupling agents are applied and acid titration is used to determine the specific ions reacting and the approximate quantity reacted. Fiber glass surfaces are largely uncovered, and bare glass reactivity can be determined if a non‐ionic alkoxy silane is applied. While aqueous applications of a silane covers only a proportion of the silica sites, a vapor phase application covers a proportion of all reactive cation sites. With nonporous silica a large propotion of the amphoteric and alkali impurities are on the surface.
Anomalous flow behavior of high density polyethylene melts
Authors: Metzger A. P. , Hamilton C. W. , Merz E. H. 
Published: December 2004

AbstractAttempts to operate plastic processing equipment at higher production rates is often accompanied by erratic flow behavior of the polymer melts. In order to study this problem, a constant‐rate, capillary rheometer was used to study the melt flow over a wide range of shear rates. These data demonstrate that many high‐density polyethylenes exhibit a discontinuous shear‐stress shear‐rate curve; that is, under certain conditions the observed load oscillates “between two values differing by about 15%”. This region of unstable melt flow is not necessarily allied with melt fracture although it is dependent on molecular weight and melt temperature. Unstable melt flow occurs at lower shear rates with a decrease in the melt index (increase in molecular weight) or melt temperature.
Some bonding characteristics of nitrile‐phenolic liquid adhesives
Authors: Rice Rip G. , Hay Wallace S. , Bell Landon , Toothaker Wallis L. , Perkins Dee M. 
Published: December 2004

AbstractIt is demonstrated that the bonding characteristics of commercial liquid adhesive primers made from nitrile rubbers and phenol‐formaldehyde polymers, cured by means of hexamethylenetetramine can be quite sensitive to the presence of small amounts of excess water and ammonia. The added water partially decomposes the hexamethylenetetramine to formaldehyde and ammonia, the concentration of the latter thus increasing to such a point as to promote a lower temperature curing of the phenolic resin. Restoration of the original adhesive properties can be attained by the addition of reagents which remove either the water or the ammonia, or both, from the adhesive. Examples of such reagents are certain organic acids, anhydrides and peroxides. The addition of these reagents has been found to reactivate and increase greatly the useful lives of nitrile‐phenolic liquid adhesive primers containing hexamethylenetetramine.
Structure property relationships of chlorinated polyethylene
Authors: Oswald H. J. , Kubu E. T. 
Published: December 2004

AbstractResin structures available from chlorinated polyethylene have been determined by studies of the infrared absorption spectra, and have been related to the glass transition temperatures and degree of crystallinity of the products. The relationships between chlorine content, molecular weight, glass transition temperature and a number of mechanical and rheological properties are described. Data are presented on the effect of blends of various resins in this series on glass transition phenomena. The stability of the resins to dehydrochlorination is discussed.
Polymers and telomers of 4‐chloroperfluoroheptadiene‐1,6
Authors: Fearn James E. , Wall Leo A. 
Published: December 2004

AbstractThe polymer was prepared by pyrolyzing the sodium salt of 3,5,7,8,‐tetrachloroperfluoro‐octanoic acid and subsequent dechlorination of the resulting heptene with activated zinc. The heptadiene was separated from other dechlorination products and brought to a high degree of purity through use of vapor phase chromatography and polymerized in bulk utilizing gamma rays at room temperature, 100°C and 150°C, and utilizing ultraviolet light at 150°C. The properties of these brittle and glossy polymers were determined. Also the purified 4‐chloroperfluoroheptadiene‐1,6 was telomerized with dibromodifluoromethane yielding a cycle, clear, colorless, liquid telomer.
Evaluation methods for ablative plastics. A review of the techniques used
Authors: Schmidt Donald L. , Schwartz Herbert S. 
Published: December 2004

AbstractA determination of the performance indices of ablative plastics is indeed a formidable task because of the severity of the high‐temperature test environment, nonstandard test methods, limitations of available evaluation facilities and the complex interrelationship between materials performance and environmental parameters. In spite of these difficulties, considerable progress has been made in establishing new test methods for evaluating very high‐temperature (ablative) plastics. This article describes the test facilities and measurement techniques available for obtaining research and design data on ablative plastics.
Properties of high density polyethylenes with bimodal molecular weight distribution
Authors: Zabusky H. H. , Heitmiller R. F. 
Published: December 2004

AbstractThe effect of a bimodal molecular weight distribution on the flow properties and stress crack resistance of polyethylene is investigated. It is found that the melt viscosity of a bimodal polyethylene is less shear dependent at high shear rates than a log normal distribution of equivalent weight average molecular weight and ratio of weight average to number average molecular weight. Spiral mold studies indicate that the bimodal polymer flows more readily under injection molding conditions. The stress crack resistance of the bimodal polymer is shown to be superior to other polyethylenes of the same weight average molecular weight.
The transparency of crystalline polymers
Authors: Pritchard Ruth 
Published: December 2004

AbstractMuch past confusion has originated from attempts to describe the complete optical properties of a plastic in terms of a few ill‐defined parameters. Simple light‐scattering theory and studies of morphology have been combined in this article to suggest the causes of polymer opacity; methods cited for the improvement of transparency and properties of reflectance have been re‐examined in this light. It is concluded that the optical properties displayed by a polymer which is allowed to crystallize without external stress depend on fundamental molecular and morphological parameters. The extent to which these inherent characteristics can be modified depends on such widely different factors as the Tg of the polymer and the physical form of the desired article.
The interface microscopy of crystalline linear high polymers
Authors: Sullivan P. , Wunderlich B. 
Published: December 2004

AbstractSolution‐grown crystals of polyethylene may reach lateral dimensions large enough for optical microscopy. Interference microscopy represents, in this case, a suitable method of observation of morphology and defects as well as quantitative determinations. The double‐beam interference method used in the Baker type microscope has been applied to determine refractive indices and lamellar thicknesses. The Nomarski double‐beam interferometer has been used for hot‐stage experiments. Multiple‐beam techniques involving silvering of crystal surfaces and using an ordinary light microscope for observation have been developed. The applicability of the different types of interference microscopy to polymer research is illustrated in a series of representative photomicrographs of polyethylene.
Theoretical aspects of polymer morphology— crystallization from solution
Authors: Price Fraser P. 
Published: December 2004

AbstractInvestigation of the crystallography of the thin platelike polymer crystals precipitated from dilute solution has led to the concept of chain folding in polymer crystallization. This unexpected and unusual phenomenon has produced much speculation about both its origin and its implications concerning the morphology of the polymer crystals. The theories which have been proposed to account for the observed effects fall into two categories: (a) equilibrium theories; and (b) kinetic theories. At the moment the kinetic theories appear to be the more successful in explaining the observed morphology and behavior of the polymer crystals. Essentially it is proposed that the plate‐like habit of the crystals results from the formation of crystal uncleii from single polymer molecules followed by a growth process whose rate is controlled by nucleation of new crystal layers on existing completed crystal faces. Quantitative observations of crystal growth rates and of the influence of supercooling on the thickness of the crystals are consistent with the predictions of these theories.
Structural interpretations of mechanical properties of polycrystalline polymers
Authors: Stein R. S. 
Published: December 2004

AbstractStructural changes are considered in light of the two differing views of the structure of crystalline polymers involving either a two phase structure or a single phase structure involving detects. A compromise picture is proposed which appears consistent with existing experimental evidence. Optical methods are described for analyzing structural changes accompanying deformation of these polymers. These include x‐ray diffraction, static and dynamic birefringence measurements and dynamic light scattering studies. The results are consistent with a two stage deformation process involving first the elastic deformation of a spherulitic or crystalline structure followed by an internal rearrangement of crystals within this structure, taking place by a number of mechanisms such as recrystallization, defect migration, plastic flow and crystal rotation. The time dependence of some of these processes is studied and related to structural features.
How to improve glass cloth laminates
Authors: Oswald R. C. 
Published: December 2004

AbstractThe combination fo dicyandiamide and diaminodiphenyl sulfone in the presence of a tertiary amine, like 2,4,6‐tris (dimethyl amino methyl) phenol, will crosslink liquid epoxy resins (E.E.W. 180‐200) of diglycidyl ether of Bisphenol A type, or brominated resins, and if used to impregnate glass cloth will produce printed circuit laminated boards combining interlaminar bond and flexural strength retention of NEMA‐G‐10 and G‐11 grades.
Auxiliary stabilizers for plasticized polyvinyl chloride
Authors: Barnes W. A. , Franke N. W. 
Published: December 2004

AbstractMore than seventy materials were examined for their ability to improve the performance of DTDP plasticized PVC wire formulation in a modified 105°C wire oven aging test. Twenty of these were as effective as the widely used Bisphenol A, four of which were effective at a lower concentration.
Plastics processing and fabricating problems involving membranes and rotational symmetry
Authors: Alfrey Turner 
Published: December 2004

AbstractEquations of equilibrium can be used as tools to convert observations of plastic processing operations into a complete process analysis, including the interpretation of simulated fabrication experiments. If material properties of the plastic are known under the fabrication conditions, a predictive process analysis can be made, yielding such data (in the case of extrusion) as membrane thickness and radial velocity. Such predictive analyses also may be used to develop valuable insights into thermoforming operations by means of simulation experiments.
Heat‐resistant epoxy‐boroxine foams for high temperature applications
Authors: Chen H. H. , Nixon A. C. 
Published: December 2004

AbstractFoams are produced by mixing an epoxy resin, a primary polyamine and a trialkoxyboroxine without applied heat. The reaction heat evolved, predominantly from the reaction between the boroxine and the amine, speeds up the gelation of the epoxy resin and simultaneously evaporates methanol, a by‐product, to form the foam, leading to the formation of a highly crosslinked polymer. A theory for the mechanism involves the chemical properties of intermediates, the basicity of the nitrogens, the acidity of the borons, and the mode of curing of the epoxy resin. The physical properties can be varied using different epoxies, amines and boroxines and different proportions. With a typical mixture, the foams produced have densities and thermal conductivities similar to polystyrene foam but have heat resistance up to 300°C. Adhesion to various substrates is excellent. Compression strengths are low but can be increased by the addition of fillers. The foams are self‐extinguishing. Potential applications and method of dispensing the foams are suggested.
“Dynamic mechanical properties of polymers‥ a review”
Authors: Silberberg Melvin 
Published: December 2004

AbstractThere has been a marked increase in the interest shown in the field of characterization of polymeric materials via dynamic techniques, so much so that symposia devoted exclusively to “dynamic” properties of materials are now commonplace (1, 2). This article provides both a frame of reference with regard to the wide variety of “dynamic” test techniques now in use, and…as well…dynamic test data for a wide range of polymers. Particular emphasis will be placed upon the difference in function of varying test techniques and the applicability of data obtained for specific R & D vs engineering applications. For the purposes of the presentation an arbitrary distinction will be made between “dynamic” tests of the cyclic type and “dynamic” tests of the unidirectional type.
Thermal degradation of polytetrafluoroethylene in a closed system. Effect of the nature of the surface of the reaction vessel wall
Authors: Jellinek H. H. G. , Kachi H. 
Published: December 2004

AbstractThe thermal degradation of polytetrafluoroethylene has been investigated in a closed system as a function of the nature of the surface of the reaction vessel wall. Reproducible results cannot be obtained in a stainless steel vessel as metal fluoride is continuously formed and a stable fluoride is not formed on the wall. Quartz spoon reaction vessels coated with calcium fluoride give a few reproducible runs, before the coating has to be renewed. If the dimerization of the monomer, which takes place very rapidly around 600°C, is considered, first order rates are obtained up to about 75% monomer formation. The kinetics is briefly discussed on the basis of random initiation followed by depropagation with a relatively short kinetic chain length and disproportionation as termination reaction.
Principles of polymer stability
Authors: Mark Herman F. , Atlas Sheldon H. 
Published: December 2004

AbstractThere are essentially two ways to arrive at high softening polymers: crystallization and cross linking. The first approach leads to thermoplastic materials which have a more or less sharp and reversible melting point; the second produces three dimensional unmeltable networks which are thermosetting and can support very high temperatures without degradation. Factors which affect the mechanical behavior of a polymer exposed to high temperatures are degradation and cross linking. The first process is caused by scission of the chain molecules. The second process, cross linking, ties individual polymer chains into a rigid network, increases the molecular weight and leads to a very hard, brittle product which can neither be melted nor dissolved. The stability of a polymer against oxidation is always improved by the addition of an oxygen scavenger which reacts with oxygen in preference to the polymer and also by the addition of a UV absorber.
Melt flow of polyethylene at high rates
Authors: Lupton J. M. , Regester H. W. 
Published: December 2004

AbstractThe flow of high‐density polyethylene at high shear rates in round dies in laboratory instruments and in extruders depends in an unusual way on capillary diameter. With small diameters this dependence can be explained in terms of slippage of the melt at the wall of the capillary; with large diameters, in terms of temperature increases developed through viscous flow. A rapid increase in slip velocity appears to be responsible for a discontinuity in the flow curve determined in laboratory instruments. Recurring transitions between the two branches of the flow curve are responsible for the oscillating flow observed in equipment operating at constant or nearly constant throughput rate. The energy stroage capability of the over‐all system, apparatus plus melt, controls the dynamic aspects of flow in the vicinity of the discontinuity.