bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic measurement of mechanical moduli I
Authors: Lewis Armand F. , Tobin Marvin C.
Published: December 2004

Equipment is described for measurement of Young's and shear modulus on the same identical polymer sample, by a free‐vibration method. Strain gauges are used as sensors in an automatic recorder. Young's modulus and damping, shear modulus and damping and Poisson's ratio are reported over a range of temperature for polypropylene, Nylon 66 and poly (methylmethacrylate). It is found that Poisson's ratio shows a dip in the glass transition region and that values greater than the infinitesimal strain limit of 0.5 are obtained in the rubbery region.
Study of the interaction of organic monomers and water with fiberglass by Sorption methods
Authors: Gutfreund K. , Weber H. S.
Published: December 2004

Interfacial reactions between organosilane‐treated fiberglass and styrene, and bond conditions in these and in polymerized ethylene oxide and epichlorhydrin‐E‐glass systems were investigated. The vinyl functionality of some alkenylsilanes showed little effect on the polymerization of styrene on E‐glass. The polymerization of this aromatic monomer on vinyltrichlorosilane‐reacted fiberglass did not result in interfacial bond formation. Sorption of water on organosilane‐coated glass at different temperatures suggested that permeation of the adsorbate into the bulk of the substrate was determined by diffusive transfer of water molecules.
The chemistry of chromium complexes used as coupling agents in fiberglass resin laminates
Authors: Yates Paul C. , Trebilcock John W.
Published: December 2004

The chromium complex is chemically bonded by ion exchange with alkali cations to strongly acidic sites in the glass surface. These sites are formed by the isomorphous replacement of silicon by boron and aluminum in the network structure. Polymerized complexes are better bonding agents than monomeric ones. Specific interactions between organic groups on the chrome complex and the bonding resins also determine laminate strength and water resistance.
A new interpretation of the glass‐coupling agent surface through use of electron microscopy
Authors: Sterman S. , Bradley H. B.
Published: December 2004

Theoretically a monolayer or insignificant weight per cent of coupling agent should give optimum properties for fiber glass‐resin composites, contrary to commercial practice. Studies of variation of chemical bonding between the coupling agent and the resin and the study of the degree of bonding of the coupling agents to the glass by extraction techniques have not explained this effect. However, new techniques of electron microscopy have revealed details of loading distribution and agglomeration on the glass fiber which tend to explain this effect.
The degree of bonding between coupling agents and glass filaments ¨ a study ¨
Authors: Eakins William J.
Published: December 2004

Evidence indicates that there is a chemical bond between the coupling agent of either silane or chrome complex type and the glass substrate, but that this chemical bond may be strong or weak, depending on the elements making up the bond and the other elements in the immediate area surrounding the bond. These elements can exert either a beneficial or detrimental effect on the strength of that bond. Other evidence is given to show that a vapor phase treatment that applies silane coupling agents like A‐1100 to “E” glass gives the highest known strength retention values. A mechanism is advanced to explain the bridging of unreactive sites on glass surfaces by silane coupling agents applied from solution.
Crystallization kinetic studies of vinylidene chloride‐alkyl acrylate copolymers by torsional measurements
Authors: Riser George R. , Witnauer L. P.
Published: December 2004

By following the changes in torsional modulus as a function of time, the kinetics of crystallization of three copolymers of vinylidene chloride containing 10% mole % alkyl acrylate were investigated and the geometrical growth and nucleation constant of the Avrami equation was determined. Isotherms were superimposable within certain temperature ranges while the nucleation constant decreased with a decrease in temperature. Rate of crystallization increased with increase of the alkyl side chain length.
Radiation and moisture effects in polymerized epoxy resin
Authors: Kline D. E. , Sauer J. A.
Published: December 2004

The effects of moisture and rather large doses of reactor radiation (∼4 × 1011 ergs/gm) on the dynamic properties of polymerized epoxy resins have been investigated over the temperature range of 80°‐450°K and at frequencies from 200 to 1400 cps. Data are presented for both unfilled and aluminum‐filled systems of a bisphenol A based epoxy, (Epon 828) cured with metaphenylenediamine. Moisture absorption (0.88%) causes a shift of the main glass transition near 440°K to lower temperatures (∼25 degrees for unfilled epoxy). This is similar to the plasticizing action of small molecules absorbed in other polymers such as nylon 6‐6. Irradiation to a dose of 4 × 1011 ergs/gm (4 × 109 rads) causes a shift to lower temperatures (∼50 degrees) of the onset of the main transition, and, in addition, results in both a shift to lower temperatures and a decrease in maximum height of the damping peak near 250°K. Chain scission, in a loosening of the structure and the breaking up of the partially flexible connecting groups, may be responsible for these radiation effects.
The relationships between the structures of organic phosphites and their effectiveness in poly(vinyl chloride) stabilization
Authors: Scullin James P. , Rosen Marvin , Girard Theodore A.
Published: December 2004

A series of thirty‐three phosphites of varied structural variations were tested at 177°C in a vinyl compound utilizing co‐precipitated barium cadmium laurate or a combination of barium nonylphenate and cadmium 2‐ethylhexoate as the primary stabilizer. Best activity was found with mixed alky‐aryl phosphites.
Dielectric properties of solid polymers
Authors: Curtis Alexander J.
Published: December 2004

Dielectric measurements were used to study dielectric constant and loss index of poly(p‐chlorostyrene) and poly(m‐chlorostyrene) over a temperature and frequency range. Relaxation processes are observed and mechanisms are proposed for crystalline structures. Axial rotation discussed here has been used to explain NMR data.
Prediction of long‐term strength of reinforced plastics. Treatment of prot linear stress‐rupture data
Authors: Loveless Harold S. , Deeley Charles W. , Swanson Donald L.
Published: December 2004

Failing stresses of glass‐reinforced plastics and of polystyrene were determined at room temperature. It was found that if an initial load of 40% of the short‐term tensile strength of the material is imposed, good agreement exists between the results of accelerated tests and long‐term, fixed load measurements for periods of 10,000 hours for the reinforced plastics.
High‐speed testing… A new dimension in polymer evaluation
Authors: Silberberg Melvin , Supnik Ross H.
Published: December 2004

A new universal tester is described, basically capable of testing samples in the 0.2 to 8000 inches/minute range. With servo controls a load‐elongation curve is obtained which is a measure of material response independent of the machine. Load cell output is fed into the Y axis of an oscilloscope and displacement to the X axis. Useful where deviation from viscoelastic theory is suspected in time‐temperature behaviour, for following impact behaviour and molecular decomposition.
Gas chromatography. A new tool for the analysis of plastics
Authors: Cobler John G. , Samsel E. P.
Published: December 2004

Identification was described by analysis of pyrolysis products, a method which is complicated by the variety of degradation products, but the decomposition products are fairly specific. The pyrolysis technique was used for a quantitative analysis of acrylate and maleate esters in polymers via a hydriodic acid hydrolysis technique. Because of the low volatility of the higher alkyl halides higher esters were saponified at elevated temperatures and the resultant alcohols were chromatographed. Then vinyl acetate was analyzed on the basis of the quantitative yield of acetic acid from polyvinyl acid pyrolysis.
Free radical kinetics in irradiated ethyl cellulose as determined by electron spin resonance measurements
Authors: Loy B. R.
Published: December 2004

Electron spin resonance techniques are used to investigate the structure and decay of radicals produced in irradiated ethyl cellulose. Approximately 99% of the radicals trapped at liquid nitrogen temperature appear to be—C2H4. radicals. These decay immeasurably fast at room temperature. The relatively stable doublet that remains is believed to be due to the CHO radical. The kinetics of the doublet decay are studied as a function of temperature and dose. The data may be interpreted as resulting from simultaneous first and second order processes at lower doses and from a second order process at higher doses.
Oxyluminescence‐a new tool for testing the stability of polymers
Authors: Ashby G. E.
Published: December 2004

It was observed that light is emitted upon polymer oxidation; intensity of light is proportional to oxygen concentration on the surface and presence of an antioxidant effects the emission of light. A linear relationship was found to exist between integrated light intensity and the number of carbonyl atoms formed. In addition concentration of antioxidants present and their synergistic effects can be measured by this method.
Methods of studying heterophase conditions in resinous materials
Authors: Kronstein Max
Published: December 2004

The paper discusses polymer materials and synthetic resins as multiphase or heterophase materials. They contain three‐dimensional, insoluble, non‐volatile phase material, as well as soluble and volatile material, which can act as “sweller” for the insoluble phase. As long as the insoluble phase is in a relatively low concentration, the resins are glassy, fusible without decomposition, and thermoplastic. They are like “frozen” solutions of the various phases. As the concentration of the insoluble phase increases, the resins turn insoluble. These gelling, thermosetting materials can be dispersed in strong “sweller fluids”; and from these dispersions, the three‐dimensional material can be precipitated and further investigated. Methods are being discussed.
Dynamic mechanical properties of epoxy resins
Authors: May C. A. , Weir F. E.
Published: December 2004

Although dynamic mechanical properties of thermoplastic polymers have been studied in great detail and much has been learned about their structure, little has been done in the field of thermosetting resins. The present study involves the use of dynamic methods for determining certain salient features about epoxy resins. A torsion pendulum operating in the range of one cycle per second was used to measure the properties of various epoxy systems. The instrument enabled rapid determination of both internal friction and shear moduli.

Two transition peaks in the dynamic loss tangent were observed; one occurring at −60°C, the other at 165°C when a conventional epoxy resin was cured with m‐phenylenediamine. The low temperature peak was effectively demonstrated as due to the glycidyl ether portion of the cured resin system. The major peak or glass transition temperature could be varied in accord with the substituents on the central carbon bridge of the bisphenol portion of the molecule and to a lesser extent by the degree of cross‐linking.
Surface conductance, syneresis and adhesion
Authors: Bikerman J. J.
Published: December 2004

Electric surface conductivity χ of purified polyethylene wax in nearly saturated water vapor was about 8 × 10−13mho and in vapor of 0.5% aqueous NH3about 17 × 10−12mho. When 0.1% oleic acid (OA) was added to the wax, χ in the 0.5% NH3vapor was not markedly changed but it was greater at 0.2% and higher concentrations; at 1% OA it was 2 × 10−10mho. These results show that surface conductance (a) may be “developed” by vapors, (b) can be used to detect the onset of syneresis, and (c) is the bulk conductance of the surface film, and, further, that in the polyethylene‐OA system syneresis occurs between 0.1% and 0.2% OA as was deduced from the strength of adhesive joints made with mixtures of OA and polyethylene. Thus, the results confirm the “weak boundary layer” theory of adhesion.
New organic resins and reinforced laminates for service to 300°C
Authors: Freeman James H. , Traynor Edward J. , Miglarese John , Lunn Richard H.
Published: December 2004

Demand for structural insulating materials for service in high temperature environments is widespread and the performance characteristics of special grades of silicone or phenolic‐glass laminates at temperatures up to 250°C have been well documented. A new family of polymers, completely aromatic in structure, except for the amido coupling linkage, now shows promise of giving excellent performance at temperatures to at least 300°C in air. Comparative data concerning the retention of mechanical and electrical properties of such laminates after aging at the higher temperature is provided.
Studies of polycarbonate plasticization
Authors: Kozlov P. V. , Asimova R. M. , Perepelkin A. N.
Published: December 2004

The plasticization by dibutyl phthalate, camphor and butyl sterate of polycarbonates prepared by phosgenation of 2,2‐bis‐(4′‐hydroxyphenyl) propane was investigated. Thermomechanical and dynamometric studies of the plasticized polycarbonates show that both intrapacket and interpacket plasticization is possible as for cellulose. In the first case, the lowering of the glassy transition point of polycarbonate films is strictly proportional to the logarithm of the concentration of added plasticizer (dibutylphthalate, camphor). In the second case, after a small drop in the transition point, the latter remains unchanged over a broad range of plasticizer concentrations (butylsterate). A similar relation was observed with respect to the elasticity modulus of the films.
Antioxidant efficiency versus structure
Authors: Baum Bernard , Perun A. L.
Published: December 2004

Antioxidant efficiency versus structure was investigated using rate of carbonyl formation at 110 and 170°C of a 20 mil plaque of polyethylene containing 0.01 weight % additive. This study indicates that the following are important in phenolic and amine antioxidants:

The number of H. atoms available: Antioxidant efficiency is increased by adding a second hydroxyl group as well as by introducing a methylene bridge.

The number and location of substituents: Alkyl substitution of the phenolic ring is an important factor in stabilization. Groups which decrease the strength of the NH bond increase the effectiveness of amine antioxidants.

Solubility: The less compatible the antioxidant, the poorer its stabilizing action.

Volatility: Many stabilizers are ineffective at high temperature because of volatilization.

Bridge between rings: A sulfide bridge can be equivalently substituted for a methylene bridge.

The need for stabilization of the radical formed after removal of H: This stabilization could occur via; Hydrogen bonded chelates, resonance and steric hindrance.
Influence of normal stress on creep in tension and compression of polyethylene and rigid polyvinyl chloride copolymer
Authors: O'Connor D. G. , Findley W. N.
Published: December 2004

New apparatus suitable for compression creep tests of slender specimens is described. The apparatus is designed to prevent buckling and to introduce a minimum of friction. Results are reported for tension and compression creep of polyethylene and annealed, unplasticized polyvinyl chloride copolymer at 75 deg F and 50 per cent relative humidity. The stress, σ, strain ε, time t data from these tests were found to be describable with reasonable accuracy by the equation

where εm′, m′, σε and σm are material constants.

The results for polyethylene show that the creep in tension and compression were virtually the same. Creep in tension was similar but larger than in compression for polyvinyl chloride.
The stereospecific homogeneous polymerization of vinyl chloride
Authors: Minsker K. S. , Kronman A. G. , Teplov B. F. , Rylov E. E. , Bort D. N.
Published: December 2004

Polymerization of the monomer was investigated in organic solvents such as nitro‐compounds, amines, amides, nitriles, ethers, esters, ketones, aldehydes, acids, anhydrides, and some heterocyclic compounds. Crystalline polyvinylchloride was produced in aliphatic aldehyde media at temperatures ranging from 0° to 60°C and highly crystalline polyvinylchloride was synthesized in the presence of preliminarily oxidized butyric aldehyde. The electron diffraction picture of the non‐oriented specimen of the polymer exhibited 19 distinct reflexes.
Use of a new torsion pendulum for polypropylene property evaluation
Authors: Weir F. E.
Published: December 2004

A new recording system for a torsion pendulum is described. By its use data on the internal loss and shear modulus of a polymeric material can be obtained quickly and easily in digital form, rather, than the more usual graphical form. The system is simple and easy to operate, is rugged and is inexpensive relative to other systems. The precision available is excellent. An application of the instrument in the determination of the crystallinity of polypropylene is described.
Surface effects of various environments and of thermosetting resins on the strength of glass
Authors: Outwater J. O. , Ozaltin Oguzcan
Published: December 2004

Glass rods were etched to reduce their surface flaws and hence to increase their flexural strength. They were then subjected to various environments to see how these would affect their strength and hence their surface. It appeared that no liquid environments affected their strength. This included boiling water. The effect of curing resin against the surface was also shown as was subsequent boiling: Shell Epon 828 appeared to increase the strength of the rods, but only when there was a surface treatment of Union Carbide A‐1100 or Owens‐Corning 801.
Interfacial properties of an amine‐modified silane and its performed polymer at E‐glass surfaces
Authors: Roskos T. G. , Radloff H. R. , Young F. M.
Published: December 2004

The adsorption of triethoxysilylpropylamine and its polymer onto 325 mesh E‐glass from both aqueous and non‐aqueous systems has been investigated. The amount adsorbed from an aqueous solution onto an E‐glass surface corresponds to that obtained by others workers using different techniques. Solid preformed A‐1100 polymer (II) was found to be unstable. Upon prolonged standing a basic gas, identified as ammonia, was liberated. Experimental results indicate that the amount adsorbed is related to the number of ethoxy groups on the molecule. However, the mechanism of silane attachment is still not completely understood.
Some further studies on the effect of glass‐resin type and cure on the strength of laminates
Authors: Brookfield K. J. , Pickthall D.
Published: December 2004

The technique of testing resin/glass laminates has been extended to include three alkali‐containing glasses. NOL rings have been made by a direct filament drawing technique using an epoxide resin system. In each case the strength developed is less than with “E” glass.
Investigations on the strength of alkali‐containing glass fibers
Authors: Weisbart Hans
Published: December 2004

The assertion was checked that alkali containing glass fibers, which evolve caustic bases when attacked by water, are, by this fact, responsible for the mechanical deterioration of reinforced plastics. Glass fibers of different chemical composition, when extracted with water, showed no correlation between amount of alkali in the glass and alkali leached out. Tensile strength of glass fibers is not a function of alkali content. Subjected to water, all types of glass fibers keep their strength except when boiled. This applies to fibers coated with coupling agent or in the native state. Deterioration of laminates under the influence of water seems to be primarily a function of the interface.
New aspects of melt fracture
Authors: Benbow J. J. , Lamb P.
Published: December 2004

The movement of coloured markers (polydimethyl siloxane and low density polythene) placed near the die entry before extrusion or injected through the side of the die during extrusion has been measured both above and below the onset of instability. During stable flow the observed velocity distributions are similar to those predicted by assuming that polymer at the die wall is stationary, but when melt fracture occurs there is movement at the wall. The possibility of a stick‐slip mechanism being responsible for unstable flow is examined and evidence in support of this hypothesis is presented. Available evidence suggests that for a given molecular weight, the critical shear stress increases with the polarity of the polymer, and the material of which the die is made has been found to affect the instability.
The status of non‐Newtonian polymer flow
Authors: Porter Roger S. , Johnson Julian F.
Published: December 2004

This study summarizes the flow behavior of concentrated and melt systems of linear amorphous polymer. For low molecular weight polymer, viscosity increases regularly with a lower power dependence on molecular weight. This dependence decreases towards first power with increasing temperature but is independent of shear, with viscosities being constant up to the highest attainable steady state stresses, about 106 dynes/cm2. At a higher molecular weight, 2,000–40,000, depending on polymer type, the viscosity dependence on molecular weight changes abruptly to a high power which is generally about 3.4. Above the transition, this high power function is independent of temperature but depends markedly on shear. Non‐Newtonian flow sets in abruptly and predictably above the transitional molecular weight.
Polymers with conjugated bonds in the macromolecular chains
Authors: Berlin A. A. , Popova Z. V. , Yanovskii D. M.
Published: December 2004

The effect of polymers with conjugated bonds, namely polyphenylvinylene, phenylacetylenep‐diethinylbenzene copolymer and thermally dehydrochlorinated polyvinylchloride, upon the stability of polyvinylchloride suspensions has been investigated. It has been shown that polymers with conjugated double bonds are efficient inhibitors of the thermal dehydrochlorination of polyvinylchloride. The most active inhibitor, polyphenylvinylene, is not light stabilized.
Crystalline organization in useful plastics
Authors: Starkweather Howard W.
Published: December 2004

The size of the crystallites in nylon 66, polytetrafluoroethylene, and polyethylene correlates with the degree of crystallinity. This supports the suggestion that the amorphous content of partially crystallized polymers can be attributed to chain folds and other regions directly related to the crystalline structure, at least down to a level of 40–60% crystallinity. In all cases, the term “percent crystallinity” is a useful unifying concept expressing the over‐all degree of order including mesomorphic structures, the relative amounts of ordered and disordered material, and the quality of the ordered regions.
Tensile creep and recovery of compression molded polypropylene samples
Authors: Hiltz A. A.
Published: December 2004

A simplified creep apparatus was used to evaluate the creep and recovery of polyethylene and polypropylene. The creep resistance of polypropylene containing as much as 9% n‐heptane (boiling) soluble material is superior to that of linear polyethylene. The lower the boiling n‐heptane soluble content, the better the resistance to creep. The creep resistance of polypropylene is also improved by annealing.
Determination of functional groups in epoxy resins by near‐infrared spectroscopy
Authors: Dannenberg H.
Published: December 2004

Analysis in liquid or solid state and in various conditions of cure, have been developed. The analysis is carried out by spectroscopy in the near‐infrared region. Epoxy values are determined preferably at 2.205 microns, or else at 1.159 microns. The required path length in the specimen is between 1 and 10 mm, solid resins were examined either in disposable glass cells or in the form of cast sheet. A direct method of evaluation is used when the path length is precisely known, a relative method based on internal calibration when this is not the case. Similarly, a near‐infrared method for the determination of hydroxyl groups in epoxy resins was developed. The use of the isosbestic principle led to an accurate method for the determination of hydroxy values in uncured epoxy resins.
Influence of channel curvature on flow, pressure distribution, and power requirements of screw pumps and melt extruders
Authors: Booy M. L.
Published: December 2004

The influence of channel curvature on flow through screw pumps and melt extruders is derived for infinite channel aspect ratios. Flow rate and horsepower relations for flow of Newtonian liquids are given as functions of design parameters. The results of this cylindrical theory are compared with those of conventional theories. Curvature factors converting the equations of the flat plate theory to those of the cylindrical theory are shown. Pressure distributions in screw pump channel are analyzed.
Effect of density and orientation on the permeability of polypropylene film
Authors: Conner W. P. , Schertz G. L.
Published: December 2004

The 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

Mixing 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

The 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

Seventeen 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

Dilatometric 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

The 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

The 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

The 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

Pyrolysis 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

Previous 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

The 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

Recent 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

The 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

Studies 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

Carefully 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 I–general flow properties
Authors: Sieglaff C. L.
Published: December 2004

The melt flow properties of PVC Resins have been investigated. The Effects of molecular weight, temperature, and plasticizer (DOP) concentration on the Melt rheology have been examined and correlated with molecular properties of polymers.
Rheological properties of polyvinyl chloride. Parts II–unstable flow
Authors: Sieglaff C. L.
Published: December 2004

Unstable flow involving extrudate distortion have been observed in the extrusion of PVC. Two types of distortion have been isolated and the factors which are operative have been examined. These Factors are discussed in the light of existing knowledge of “melt fracture”.
Rheological properties of polyvinyl chloride. Parts III–post extrusion swelling
Authors: Sieglaff C. L.
Published: December 2004

The 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

The 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

The 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

Toluene 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

Bueche 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

Dupre'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

It 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

The 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

Extrapolation 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

A 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

This 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

The 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.