bluuebunny/crossref_metadata_2025 huggingface dataset:
1,2,2‐Trifluorovinyl phenyl ether and 2,3,4,5,6‐pentafluorophenyl 1,2,2‐trifluorovinyl ether and their polymers
Authors: Pummer Walter J. , Wall Leo A.
Published: December 2004

1,2,2,‐Trifluorovinyl phenyl ether and 2,3,4,5,6,‐pentafluorophenyl 1,2,2‐trifluorovinyl ethers have been prepared, and the nucleophilic reactions of the phenoxide and 2,3,4,5‐pentafluorophenoxide salts with tetrafluoroethylene have been investigated. In general, it is some‐what difficult to control the reaction so as to produce the desired olefinic monomer. Under truly anhydrous conditions and when other sources of active protons are avoided, the olefin is the chief product if excess tetrafluoroethylene is used. The monomer produced is very reactive with phenoxide ions, and the diphenoxyolefins are the chief secondary products. Both monomers failed to polymerize under normal, free radical conditions. With boron trifluoride an oily material was obtained from the trifluorovinyl phenyl ether. High pressure and gamma rays converted both monomers into polymers.
Synthesis of perfluorostyrene and (2,2‐difluorovinyl) perfluorobenzene (a‐hydroheptafluorostyrene)
Authors: Antonucci Joseph M. , Wall Leo A.
Published: December 2004

These compounds were synthesized by starting with the addition of the Grignard reagent of bromopentafluorobenzene to trifluoroacetaldehyde and chlorodifluoroacetaldehyde, respectively. The new alcohols, 2,3,4,5,6‐pentafluoro‐α‐(trifluoromethyl) benzyl alcohol and 2,3,4,5,6‐pentafluoro‐α‐(chlorodifluoromethyl) benzyl alcohol, are formed in good yield and undergo smooth conversion to (1,2,2,2‐tetrafluoroethyl) perfluorobenzene and (2‐chloro‐1,2,2‐trifluoroethyl) perfluorobenzene, respectively, in excellent yield when treated with sulfur tetrafluoride using n‐pentane as diluent. The major pyrolysis product was identified as (2,2‐difluorovinyl) perfluorobenzene (α‐hydroheptafluorostyrene) and the minor one as perfluorostyrene. Perfluorostyrene was also synthesized in excellent yield by bromination of (1,2,2,2‐tetrafluoroethyl) perfluorobenzene and subsequent pyrolysis of the brominated derivative. The dehydrochlorination of (2‐chloro‐1,2,2‐trifluoroethyl) perfluorobenzene provided another good synthesis of perfluorostyrene.
Heat‐transfer calculations in crystalline plastics
Authors: Gloor W. E.
Published: December 2004

The problems of unsteady‐state heat transfer associated with the melting and cooling of crystalline plastics such as polyacetals, high density polyethylene and polypropylene, are complex because of the latent heat of fusion that must be dealt with in problems where the temperature range being considered extends across the melting range. In the case of polyacetals, the use of a computer is shown in the literature to provide solutions to those problems. For many molding shops, such aids are not available. Numerical methods for the solution of such problems have been investigated, and their results are compared with those obtained using a computer and published for polyacetals. Cooling curves derived from numerical calculations, for slabs and rods made from high density polyethylene and polypropylene, are presented. Applications of the method are indicated.
Gamma irradiation of polytetrafluoroethylene in chlorine
Authors: Florin R. E. , Wall L. A.
Published: December 2004

Films of polytetrafluoroethylene, irradiated in halogen atmospheres, decrease in ultimate tensile strength and elongation at break almost as rapidly as in oxygen. The rate of degradation is approximately independent of chlorine pressure down to about 1 mm Hg. The phenomena can be explained semi‐quantitatively in terms of first order, cage reactions of scission, recombination, and reaction with chlorine, complicated by diffusion at low pressures. However, all reaction and diffusion parameters must shift with gradual increase of crystallinity.

For a given decrease of elongation at break, polytetrafluoroethylene irradiated in a vacuum retains a relatively higher ultimate tensile strength. In the copolymer of tetrafluoroethylene and hexafluoropropylene, the changes in ultimate tensile strength and elongation at break are much slower under all conditions. Both polytetrafluoroethylene and the copolymer retain appreciable tensile strength but little elongation up to a dose of 2 x 108r.
Vinyl chloride/bicyclo (2.2.1) hepta‐2,5‐diene copolymers: High softening, easily processed vinyl resins
Authors: Zutty N. L. , Whitworth C. J.
Published: December 2004

Bicyclo [2.2.1] hepta‐2,5‐diene, the reaction product of acetylene and cyclopentadiene, and vinyl chloride readily copolymerized by a novel mechanism, to form copolymers containing the nortricyclene group whose softening points rapidly increase with increasing nortricycl one concentration. For each weight per cent copolymerized bicycloheptadiene, the softening point of the vinyl resin is increased about 1°C, making it the most effective comonomer known for this purpose. At the same time increasing nortricyclene concentration disrupts polymer crystallinity, lowers the resin's melting point, and hence its processing temperature, by about 3°C for each weight per cent copolymerized.
Tensile impact properties of thermoplastics
Authors: Simpson E. H. , Polleck R. E.
Published: December 2004

The impact strength of a thermoplastic is shown to be a strong function of several variables. Among these are type of molding, molding conditions, molecular orientation, test temperature, and notches. Particularly significant is a maximum in the response of impact strength to molding temperature. The tensile impact test was used as a tool for these determinations.
The quenched state of polypropylene
Authors: Gailey J. A. , Ralston R. H.
Published: December 2004

There are several pieces of evidence in the published literature for the existence of a hexagonal crystalline form of polypropylene. Evidence obtained by infrared absorption, x‐ray diffraction, differential thermal analysis, and annealing experiments is consistent with the view that the quenched state of polypropylene is a truly crystalline one (presumably of hexagonal type) with a very small crystallite size.
Dielectric measurements elucidate structure of acrylic polymers
Authors: Steck Naomi S.
Published: December 2004

Dielectric measurements made at 60 cycles per second over a temperature range of −40 to 200°C on small (0.2 g) samples arc most useful in studying acrylic polymers. Not only has this method elucidated structure, but the study of some structures has led to new interpretations emphasizing the value of this type of measurement. Data on a number of acrylic polymers are shown. Several copolymer systems are discussed. It is suggested that 60 c/s measurement of stereospecific PMMA samples can show more about molecular arrangements than has previously been revealed.
Fireproofing of polymers with derivatives of phosphines and with halogen‐phosphorus compounds
Authors: Boyer N. E. , Vajda A. E.
Published: December 2004

Chemical structures limited to phosphines and their derivatives, including phosphine oxides, phosphonium salts and halogen‐phosphorus compounds useful for fireproofing are discussed. In addition to these P‐C bond containing compounds, structures containing P‐O‐C bonds are mentioned only if they are directly formed from halophosphorus substances. The general approaches to fireproofing are described. They include physical changes, unreactive additives, reactive comonomers, substitution of other functional groups and addition to a preformed polymer. Much of the literature is reviewed and the commercial importance of certain methods for both cloth and plastics are indicated.
Pyrolysis of new fluoropolymers
Authors: Straus S. , Wall L. A.
Published: December 2004

Four new fluoropolymers were pyrolyzed in a vacuum to study rates of volatilization and to identify decomposition products. The polymers thus studied were polyperfluoropropylene, polyperfluoroheptene, poly‐4‐chloroperfluoroheptadiene‐1,6 and poly (1,2,2‐triflluorovinyl phenyl ether). Polyperfluoropropylene yielded 100% monomer at temperatures of 300 to 400°C gave an activation energy of 56.6 Kcal/mole. Polyperfluoroheptenes of different molecular weights also yielded 100% monomer on heating. However, they had lower thermal stability than polyperfluoropropylene, but a higher activation energy and a higher pre‐exponential factor. Poly‐4‐chloroperfluoroheptadiene volatilized at a rate of approximately 1% per minute at 380°C. There was very little monomer produced on thermal decomposition and an activation energy of 60 Kcal/mole was obtained from rates of volatilization at 362, 374, and 381°C. Poly (trifluorovinyl phenyl ether) showed a 25% carbonized residue at 500°C pyrolysis. The polymer decomposes into fragments containing very little monomer. Undesirable low molecular weight components in the polymer are still to be eliminated.
The relationship between chemical structure and properties of polyester resins
Authors: Hayes B. T.
Published: December 2004

Attempts are made, in the light of published information, to decide the factors affecting network structure in commercial polyester resins and the effect of network variations on physical properties of polyfumarate‐styrene copolymers. An approach towards the optimum in chemical and heat resistant polyester laminates is suggested by examination of the influence of polyester chain structural variations on these properties.
Phosphorus‐containing phenolic resins
Authors: Kindley L. M. , Filipescu N. , Pappas E. , Huether C.
Published: December 2004

The character of the residues from pyrolytic decomposition of organo‐phosphorus polymers has suggested the use of such materials in ablative materials required for heat shields in reentry vehicles, rocket nozzles, etc.

Phosphorus‐containing phenolic resol and novolak resins were prepared by condensing di(p‐hydroxyphenyl)‐phenyl‐(phosphine oxide) with aldehydes. The mechanical properties of the basic phosphorus‐phenolics were improved by internal plasticization through chemical reaction of the resin in the early stages of polycondensation with acrylonitrile‐butadiene copolymers (NBR) and with silences and slicone resins. To improve the compatibility of the phosphorus phenolics with NBR copolymers, the phosphorus‐containing phenolics were initially etherified by “butanolization” in order to decrease their polarity.

The preparation of coatings and molded discs from some modified and unmodified phosphorus‐containing phenolic‐resin formulations is described. Preliminary observations relating to the properties of the trial products are reported.
Thermal and oxidative degradation of polymers
Authors: Hawkins W. L.
Published: December 2004

Oxidation of many polymers occurs by a free‐radical, chain mechanism similar to that developed for the oxidation of volatile hydrocarbons. The rate at which various polymers oxidize and the extent of the reaction is influenced both by the physical and by the chemical structure of the particular polymer. Important morphological changes may also occur as a result of oxidation. Polymer degradation by oxidative reactions can be inhibited effectively at several stages in the over‐all reaction. Synergistic combinations in which each component of a stabilizer system inhibits primarily at one of these stages are particularly effective.
Time effects on textile fibers
Authors: Hamburger W. J.
Published: December 2004

Stress‐strain relationships and evaluations thereof at testing and evaluation speeds from 1 to 50 inches per minute are presented. Behavior characteristics at “static” and dynamic strain rates are discussed and a brief reference to lateral critical velocity is made.
Why do plastics stress‐crack?
Authors: Howard J. B.
Published: December 2004

In this brief review, environmental stress‐cracking in polyethylene is taken as a typical example of the broad phenomenon of stress‐cracking and the major variables affecting its operation are enumerated. In addition to stress, these include molecular weight, molecular weight distribution, the amount and nature of the crystalline phase present, the nature of the “environment,” the importance of its ability to alter the surface energy characteristics of the affected polymer, and the effects of temperatrue. The need for selecting an appropriate test procedure is stressed, and the probable significance of certain recent advances in comprehension of the crystallization mechanics of these materials is suggested.
On aging of plastics in structural applications
Authors: Ingle George W.
Published: December 2004

Expanding interst in using plastics for structural pruposes immediately focuses attention on their poermanence. This desired quality is broadly defined as the persistence of a specific set of properties of a given asembly or manufactured product, in its appropriate environment, for an economically justified duration. Analysis of existing test methods, primarily those standardized by ASTM, shows no really applicable techniques for measuring permanence. By contrast, more advanced thinking presented by recent ASTM stmposia indicates two general routes to the porediction of performances. Whether a rigorous “micromechanistic” technique is used, or the empirical “macroanalytical” approach, or some combination of the two, is considered irrelevant. What is important is that experimental programs be started to provide better measures of permanence.
Weathering of plastics
Authors: Kinmonth Raymond A.
Published: December 2004

The current status of weathering of plastics is reviewed. As a better understanding of the effective degradative parameters of weather are obtained, it is aparent that complex interactions occur. Present laboratory exposure tests do not simulate natural conditions sufficiently to provide the much neede reliable short term exposure test for predicting long term durability. While a major step forward occurred with the introduction of filtered xwnon lamps, which simulate terrestrial sunlight both in intensity and distribution, industry‐wide support of fundamental studies of degradation is necessary if weathering studies are to be conducted scientifically.
Fifteen years of weathering results
Authors: Rugger George R.
Published: December 2004

The work carried out at Picatinny Arsenal on the weathering of plastics over the lat 15 years is briefly described. Although the perid of work was 15 years, individual systems were exposed for only three years. The need for running parallel tests on materials stored indoors for the three years is pointed out as a means of separating the effects of daging from weathering. Also brielfy discussed is the influence which the test method chosen can have on the judgment reached. The requirements of the application are as important as the inherent durability of the material. Improved compounds are becoming available and complete reporting of both favorable and unfavorable resuts is urged as a means of lending guidance in the search for still better compounds.
Poly‐β‐hydroxybutyric acid—a naturally occurring thermoplastic material
Authors: Werber F. X. , Baptist J. N.
Published: December 2004

Poly‐β‐hydroxybutyric acid has been isolated in quantities sufficient for characterization and evaluation of mechanical properties from both Bacillus megaterium and a special strain of Rhizobium. Its presence in a larger variety of bacteria than previously suspected has been demonstrated by a screening method based on density‐gradient centrifugation. The intrinsic viscosity of the isolated polymer has been shown to depend on the technique of isolation; basic solvents facilitate hydrolytic cleavage of the polyester. Mechanical properties of the polymer are based on the high crystallinity and polarity of the material; in a highly crystallized state, it is quite brittle, but its rigidity exceeds that of polypropylene. Thermal degradation of molecular weight, due to beta‐eliminatin of the carboxyl group from the polyester structure, severely limits processing of the polymer in the melt.
Studies of the thicknesses of adsorbed glass finishes by ellipsometry
Authors: Tutas D. J. , Stromberg R. , Passagila E.
Published: December 2004

The thickness of the adsorbed layer of two glass finishes, vinyl tris (2‐methoxyethoxy) silane and gamma‐aminopropyltriethoxysilane, was measured by ellipsometry. The vinyl silane was adsorbed on glass from solutions in water and in methyl ethyl ketone. The adsorption from water resulted in a film initially at least 50 Å thick, which increased in thickness with time. Adsorption from methyl ethyl ketone solution resulted in a film of about 10 Å. The amino silane was adsorbed on glass and on chrome from soutions in water. Adsorption on glass resulted in a film at least 60 Å in thickness, which remained constant over a period of about 5 hours. Adsorption on chrome resulted in a film about 10 Å in thickness. From the results it appears that a polymer, rather that small molecules of glass finish, is adsorbed from the water solution on glass and that small unpolymerized “finish” molecules are adsorbed from the methyl ethyl ketone solution.
Material properties of reinforced plastics
Authors: Shaffer Bernard W.
Published: December 2004

The moduli of elasticity of reinforced plastics with uni‐directional filaments either parallel or normal to an applied force are evaluated in terms of the material composition. Expressions are then derived which relate its moduli of elasticity and Poisson's ratios for an arbitrary filament orientation with its material properties in the direction of and normal to the unifilament orientation with its material properties in the direction of and normal to the unidirectional filaments. Filaments. The stress‐strain relations of filament reinforced plastics are also derived.
Nonlinear viscoelastic behavior of cellulose acetate butyrate
Authors: Sharma M. G. , Wen P. R.
Published: December 2004

Creep experiments under variable loading conditions are reported for tubular specimens of cellulose acetate butyrate. Experiments include the application of torque loading that corresponded to various loading programs. Results indicate that the material response in creep is nonlinear. The character of the results is described reasonably by assuming the behavior as linear and using the Botzmann superposition principle. However, the interpretation of the data based upon a non‐liner creep law and modified superposition principle yields better agreement with experiments in certain cases.
Degradation of polymeric compositions in vacuum to 10−9 mm Hg in evaporation and sliding friction experiments
Authors: Buckley D. H. , Hohnson R. L.
Published: December 2004

Solid compositons studied included PTFE, PCFE, polyimides, both filled and unfilled, and fluorocarbon telomers. Evaporation experiments were conducted at ambient temperatures to fluorocarbon telomers. Evaporaton experiments were conducted at ambient temperatures to 1100°F and pressures to 10−8 mm Hg. Various molecular weights of different polymers were examined. Results indicate that evaporation rates in vacuum for polymers vary with molecular weight. Friction and wear experiments were conducted with a 3‐16‐inch‐radius rider hemisphere (usually polymer) sliding on a flat disk (various materials) at speeds to 1480 feet per minute with a 1000‐gram load on the rider specimen and at an ambient pressure of 10−9 mm Hg. Fillers were found to influence markedly the wear of PTFE and PCFE in vacuum as a result of changes in heat dissipation properties, but they showed little or no influence on friction.
Kinetics of spherulitic crystallization
Authors: Baer Eric , Collier J. R. , Carter D. R.
Published: December 2004

Polymer crystallization is discussed with attention given to primary nucleation, spherulite growth, and bulk crystallization. Primary nucleation is the area of least knowledge, and the authors discuss the kinetics of nuclei appearance and recent observations concerning the effects of foreign materials and surfaces. Spherulitic growth rates are discussed in general and specifically with respect to data at low degrees of supercooling in conjunction with secondary nucleation theory. The Avrami Theory and its limitations are discussed in the interpretation of bulk crystallization data. The authors propose that n = 4 in all cases and that the Avrami Theory be used for calculating the primary nucleation rate, kn, not for determining n itself.
Thermal decomposition of unsaturated materials
Authors: Bailey W. J.
Published: December 2004

Unsaturated polymers thermally degrade by a number of different mechanisms depending on the structure of the polymer and the experimental conditions. By use of deuterium tagging it was shown that polyisobutylene degrades stepwise from the end by a cyclic unimolecular mechanism. Volatile products from isotactic polypropylene contained 75% propane at 340°, 64% n‐pentane at 375° and 49% propylene plus 12% isobutylene at 495°. Polyethylene was shown to give mostly propylene at lower temperatures but gave a 60% yield of ethylene at 600°.
Polyimides—new high temperature polymers: H‐film, a polypyromellitimide film
Authors: Heacock J. F. , Berr C. E.
Published: December 2004

H‐Film is a polypyromellitimide which results from polycondensation of pyromellitic dianhydride and an aromatic diamine. Its unique blend of thermal, physical, and electrical properties make it an outstanding candidate for a variety of electrical and non‐electrical end‐use applications. These properties recommend H‐Film for use as Class H (220°C) electrical insulation. Thermal aging of this polymeric film to embrittlement in air will require on the order of ten years at 250°C (482°F), one year at 275°C (527°F), and three months at 300°C (572°F). Even greater thermal durability in inert atmospheres has been observed. Our continuing thermal characterization studies on this polypyromellitimide have resulted in data relating to weight loss and decomposition products.
Structure‐property studies in polymer melt rheology
Authors: Huseby T. W. , Gogos C. G.
Published: December 2004

Various continuum theories of viscoelastic materials have predicted that extrudates issuing from a die will swell and this phenomenon is well known experimentally. One such continuum theory has been formulated by Pao in terms of relaxation times which can be evaluated independently in other tests. Since relaxation times are qualitatively understood in terms of molecular mechanisms, the swelling of extrudates can be given a molecular interpretation. We have found that the phenomenon originates from entanglement and those molecular motions characterized by relaxation times in the terminal zone of the viscoelastic spectrum. Extrudate swelling has been associated also with the capacity of materials to store energy. Since stored energy is also related to relaxation times, there must exist a functional relation between stored energy and swelling. For this same reason there must also exist a relation between swelling and recoverable strain. We have also presented in this paper some data concerning this latter relation.
Degradation of polymers by thermal gravimetric techniques
Authors: Levi D. W. , Reich L. , Lee H. T.
Published: December 2004

The techniques involved in dynamic thermal gravimetric analysis are reviewed. Methods of studying overall kinetics of degradation, especially with respect to evaluation of order of reaction and overall activation energy, are outlined. Some applications to polymers such as Teflon and epoxide resins are described. Since the use of thermal gravimetric results for evaluating thermal stability raises the problem of a suitable standard for describing decomposition, some indices of thermal stability of polymers are discussed.
Relationship between structure and mechanical properties of polyolefins
Authors: Matsuoka S.
Published: December 2004

Recent studies of the morphology of semicrystalline polymers have demonstrated the inadequacy of the familiar fringed micelle concept. It is now generally recognized that polyolefins crystallize in a spherulitic form having a skeletal structure of coherent crystals with a fibrous habit. Crystallization occurs in two stages: (1) spherulitic growth of crystalline lamellae, and (2) partial crystallization of residual melt in regions between lamellae. The dependence of modulus on degree of crystallinity in polyethylene indicates that the crystalline network carries much of the elastic energy acquired when the plastic is subjected to stress. Two of the mechanical transitions are also related to morphological structure. The high temperature or α transition is attributed to motion within lamellae while the intermediate or β transition is attributed to motion in disordered regions between lamellae.
The deterioration of polypropylene by oxidative degradation
Authors: Oswald H. J. , Turi E.
Published: December 2004

An explanation is presented to account for the deterioration of the mechanical properties at very low concentrations of absorbed oxygen. The induction time as measured by the oxygen absorption technique overestimates the time to failure with respect to the mechanical properties. Furthermore, it is shown that the extrapolation of accelerated aging data as obtained at elevated temperatures should not be carried out below 50°C. Data are presented to show that an anti‐oxidant is one of the major constituents of a stabilizer system against UV radiation, because the oxidative degradation mechanism is involved. A modified oxygen uptake equipment is described which allows the simultaneous determination of the oxygen absorption and the deterioration of the mechanical properties on the same sample.
Fracture topography of brittle polymers
Authors: Newman Sanford B.
Published: December 2004

Fracture surfaces record the kinetics of failure at two levels in the structure of polymeric solids. The first is evidenced by the formation of geometric markings resulting from the interaction of the primary fracture front with secondary fractures developing radially just ahead of the primary fracture. These markings are often visible to the unaided eye and have minimal dimensions in the micron range. The second fracture phenomenon appears to involve the orientation of molecular chains or bundles. Such orientation manifests itself in the interference‐color producing film found on the fracture surfaces of poly (methylmethacrylate) and polystyrene. It is also apparent in the free or adherent film found on the surfaces of large fractured crazes. Some evidence is presented for the existence in these films of chain bundles 30A or less in diameter. It would seem that similar mechanisms are operating in the production of “craze matter” and of fracture surface films.
Weathering of epoxy resins systems
Authors: Pschorr F. E. , Cianciarulo A. N.
Published: December 2004

This article presents data on outdoor weathering of unfilled epoxy resins. The data have been accumulated after five years of weathering. The anhydride cured epoxy resin system was least affected by outdoor exposure. In addition, systems with higher deflection temperatures were more resistant to attack by outdoor exposure than those of lower deflection temperatures. It was also evident that heat curing is better than curing at room temperature. Hardness, for all systems, decreased with exposure time. Microscopic examination of the exposed systems showed that surface change closely correlated with changes obtained in the mechanical and electrical properties tested in this program. Systems showing the greatest change also had the worst surface appearance.
The nature of time effects in solid polymeric systems
Authors: Andrews R. D.
Published: December 2004

The time‐dependent mechanical behavior of solid polymers can be classified into linear viscoelastic, nonlinear viscoelastic and rheological types. The linear viscoelastic theory has now been worked out in detail, and applies with particular success to amorphous polymers above their glass transition temperature. Examples of systems falling outside this category are principally discussed, including glassy, composite, and crystalline materials. These systems are characterized by the fact that structure and structural changes are playing a major role in the mechanical behavior. Specific theories must be developed in the future which adequately treat this type of behavior.
Stabilization of polypropylene
Authors: Hansen R. H. , De Benedictis T. , Martin W. M.
Published: December 2004

The effectiveness of polyproylene antioxidant systems in other than a simple oxidative environment has been studied. For example, it has been found that contact of stabilized propylene polymers with a number of materials, particularly with plasticized poly (vinyl chloride) and with copper and copper salts, markedly decreases the resistance of the composition toward oxidative degradation. The use of antioxidants having higher molecular weights results in improved retention of stabilization when polypropylene is used in contact with materials such as plasticized poly (vinyl chloride), presumably because partition of the antioxidant from the polypropylene composition is decreased. Antioxidant effectiveness in polypropylene compositions in contact with copper can be greatly increased by the addition of new and more effective copper inbibitors. The usefulness of copper compleming agents such as hydrazides, triazoles, tetrazoles, and derivatives of malonamide and oxamide are compared in polypropylene compositions containing copper dust and antioxidants.
Deformation and failure of plastics and elastomers
Authors: Smith Thor L.
Published: December 2004

The effect of various environmental conditions, other than chemical, on the mechanical properties of amorphous polymers is considered. The response of such polymers to an applied stress or strain depends on the mobility of polymeric chains which in turn is largely a function of free volume. The free volume varies with temperature, pressure, and plasticizer concentration; in the glassy state, it also depends on thermal history and tensile strain. These concepts are reviewed and some illustrative data, primarily from the published literature, are presented. A discussion is also given of the nonlinear viscoelastic properties (in uniaxial tension) of amorphous network polymers in the rubbery state. Methods for characterizing the ultimate tensile properties of such polymers are also described. Finally, some comments are made about the mechnical characteristics of polymers in the glassy state.
The use of visible and ultraviolet spectroscopy to identify carbonyl compunds in photodegraded plastics
Authors: Gray V. E. , Wright J. R.
Published: December 2004

A method was developed for identifying certain carbonyl compounds formed in plastics during exposure to carbon‐ac or solar radiant energy. The reaction of aldehydes and certain ketones with phenylenediamines (o‐, m‐, p‐, and N, N‐dimethyl‐p‐) in glacial acetic acid was found to yield stable colored products whose transmittance spectra are charactersitic of the carbonyl compound. Similar colored products were also formed when exposed plastics were dissolved in acetic acid solutions of the diamine. A comparison of the spectra of solutions of the plastics with those from known carbonyl compounds facilitates identification. The method was applied to the identification of carbonyl compounds from photodegraded poly (methyl methacrylate) and cellulose acetatebutyrate.
Radiation‐induced solid state polymerization
Authors: Marans N. S.
Published: December 2004

The literature on radiation‐induced solid state polymerization has been increasing exponentially in the last five years. Major advances have been made in retention of crystalline morphology during polymerization, in stereospecific polymerization, in modification of reactivity ratios in copolymerization and in molecular weight control of the product. However, at the present time, no commercial products have resulted from the study of radiation‐induced solid state polymerization. Chemically induced polymerization techniques have been keeping abreast of this explosive development in the solid state polymerization field and have up to this time precluded the use in industry of solid state polymerization. The major potential at the present time appears to be in the area of producing fibers without additional processing.
Failure of polymeric materials under biaxial stress fields
Authors: Sharma M. G.
Published: December 2004

The paper reviews the various classical failure theories essentially developed for metals and then seeks to show that the same theories with slight modifications could be used to describe failure of polymeric materials. These modifications consist in the consideration of the effect of rate loading on failure behavior. In addition, the paper reports experimental results on failure of two polymeric materials under uniaxial tension loading and several biaxial stress fields corresponding to pure internal pressure, internal pressure combined with tension and torque loadings and several biaxial stress fields corresponding to pure internal pressure, internal pressure cobined with tension and torque loadings. The failure behavior under various stress fields has been studied for maximum principal rates ranging from 0.05 to 60 psi. sec. The predictions based on various criteria of faliure, which considers the effect of rate of loading, are compared with the experimental results. Finally, it is shown that failure behavior under triaxial stress fields can be reasonably predicted from biaxial stress failure data.
The phenomenon of draw resonance in polmeric melts. Part II—correlation to molecular parameters
Authors: Bergonzoni A. , DiCresce A. J.
Published: December 2004

The Phenomenon of draw resonance and the cyclic size fluctuation of an extruded shpae are related to basic changes in the “melt strength” (force per average cross‐sectional area required to draw the molten fiber down under fixed conditions). Melt strength values are obtained by a modified rheometer which consists of a vertical chamber to melt and hold the polymers at 190–250°C, a piston for extrusion, a take‐up system, a strain gauge to measure the drawdown force and a recorder for continuous force‐time plots. Melt strength increases with take‐off speed but not proportionally. At higher velocities, draw resonance is apparent through a sinusoidal‐like variation in fiber diameter. The amplitudes of melt strength and diameter waves are correlated with molecular weight, melt viscosity, swell, melt temperature and take‐off speeds.
Polymerization of 2‐allyl‐1‐methylenecyclohexane by the cyclic polymerization mechanism
Authors: Butler George B. , Miles Marion L.
Published: December 2004

2‐Ally‐1‐methylenecyclohexane is a compound which is functionally capable of undergoing polymerization by the alternating intra‐intermolecular propagation mechanism to produce poly[1,8‐methylene[4.3.0] bicyclononane]. This monomer was synthesized and its polymerization through use of cationic and Ziegler‐type initiators was studied. Synthesis of the monomer was accomplished by the following reaction sequence: (1) conversion of cyclohexanone to 2‐allycyelohexanone by reaction wtih allyl bromide and sodium amide and (2) conversion of 2‐allycyclohexanone to the desired monomer by reaction with the phosphorane derived from methyltriphenylphosphonium bromide. Polymerizaton was accomplished by use of boron trifluoride resulting in 44% conversion to polymer, of which 94% was soluble. Through use of infrared and nuclear magnetic resonance techniques, the soluble portion of the polymer was shown to contain 54% of bicyclic units and the remainder to be non‐cyelized monomer units in which the residual unsaturation was composed predominantly of allyl groups.
Thermal and oxidative effects in polyethylenes above 200°C
Authors: Quackenbos H. M.
Published: December 2004

There is considerable literature on the behavior of polyethylene below 200°C and above 400°C. This paper presents results on both high and low density polyethylene between 2000 and 400°C, a range of practical import for various fabrication and processing steps. Practical exposure times may be short and the experimental procedures were designed to give meaningful results for times as low as 1 min. The principal effects are chain‐session and oxidation. Session was isolated by applying an atmosphere of pure nitrogen and proved uite shlow at 300°C but rapid at 400°C. The course of scission and produces discoloration, odor, and rising carbonyl content. A brief discussion is given of the role of diffusion in oxidation.
Development of an impact test for evaluation of weatherability of rigid plastics
Authors: Neuman R. C.
Published: December 2004

Color development in outdoor applications has been widely used as an indication of breakdown in plastic materials although this does not always indicate a change in physical properties. Appearance factors are easily and precisely evaluated by measuring color and surface changes. Measurement of physical property changes is more comples and more meaningful. An optimum test method should measure a property with time, environment and sample form. Ideally, the data should determine service life. The test specimen should be adaptable to a variety of samples. Of the many physical tests of weatherability, impact strength appears most interesting. An inexpensive Variable Impact Tester was Modified and Developed for Measuring the effect of aging on rigid PVC. Data are presented showing the relation between impact values and temperature, sample thickness, process conditions and various environmental exposures.
Pressure‐volume‐temperature behavior of polypropylene
Authors: Foster George N. , Waldman Nathan , Griskey Richard G.
Published: December 2004

The pressure‐volume‐temperature behavior for both solid and molten polypropylene was determined for pressures up to 618 atmospheres. These data were measured with a newly developed compressibility device capable of obtaining precise and accurate data. Compressibilities calculated from the experimental data compared favorably to the limited existing literature data. Constants were determined for the Spencer‐Gilmore polymer equation of state for both the solid and molten material.
Internal pressure measurements of diisooctylphthalate and dioctylsebacate
Authors: Bagley E. B. , Wood H. H.
Published: December 2004

Internal pressure measurments have been made on two common plasticizers, di‐isoöctylphalate and dioctylsebacate, as a function of temperature. The ratios of internal pressure to cohesive energy density (as calculated by the method of Small) were 1.22 for dioctylsebacate and 1.17 for di‐isoöctylphthalate. As in the case of simpler molecules the product of internal pressure and the square of the specific volume was constant for each plasticizer over the temperature renge studied. This implies that even in the absence of any other effects both an upper and lower critical solution temperature would be expected in mixed systems if the coefficients of thermal expansion of the components of the mixed system are sufficiently different.
The impact behavior of rigid PVC compounds
Authors: Hyndman John R.
Published: December 2004

Many rigid PVC compounds show a sharp transition from tough to brittle fracture with decreasing temperature in impact testing, and this temperature becomes a criterion of compound quality in addition to the impact strength observed at specific temperatures. This BT (brittle fracture) has been investigated individuall in commercial and experimental elastomer modified rigid PVC compounds. Factors affecting the BT include speciman thickness, composition and processing conditions. Apparently the discontinuity in impact behavior is a sudden manifestation of a gradual change, resulting in a near ten‐fold decrease in notched impact strength without any obvious change in properties. The BT provides a continuous scale for comparing impact properties of compounds, and is thus more versatile and sensitive than impact tests run at a single temperature.
Compressibility of bulk polymers
Authors: Warfield R. W.
Published: December 2004

Bulk compressibilities of a series of linear and crosslinked polymers have been measured, in a Matsuoka‐Maxwell apparatus, at pressures up to 10,000 atmospheres and at temperatures to 202°C. These polymers exhibited nonlinear compressibility characteristics and a maximium compressibility of about 15% at 10,000 atmospheres. At slow loading rates, data were obtained for the amorphous polymers which could be expressed as glass‐rubber phase gisgrams. The nature of the observed compressibilities are discussed and the usefulness of the data is indicated.
Fundamentals of plasticating extrusion. I. A theoretical model for melting
Authors: Tadmor Zehev
Published: December 2004

A steady state model for melting in a screw extruder has been developed based on the assumption that a stable solid bed of polymer granules is melted by heat that is conducted from a hot barrel and heat that is generated by viscous dissipation in the film that separates the solid bed and the surface of the barrel. The solid bed gradually decreases in width, as it proceeds in the channel, until it disappears at which point the melting is terminated. The model predicts the solid bed width profile and the required length of melting in terms of physical properties, operating conditions, and geometry of the screw. The model has been tested based on experimental data.
Use of the spectrophotometer to control carbon dispersion quality in polyethylene
Authors: Howard John B.
Published: December 2004

Renewed interest in the development of a quantitative optical technique for assessing the quality of carbon dispersion in weather‐resistant polyethylene compositions has given fresh significance to the findings of a study conducted earlier by a task group of ATSM Committee D‐20 but not previously reported in the literature. This group evolved and refined a spectrophotometric procedure which was shown to be capable of good interlaboratory reproducibility when the same film was measured by each of the participants in turn. When each laboratory prepared its own film specimen from a standard lot of pellets, however, this reproducibility dropped to a very unsatisfactory level. It was concluded that fine‐grained inhomogeneities even in compounds considered to have excellent dispersion quality preclude reproducible test results when sample weights of only a few milligrams are involved. The problem is aggravated by the difficulty of preparing thin, uniform films and complicated by a nonlinear dependence of transmission on film thickness.
Stereoregulation and stereoregular polymers
Authors: Schildknecht C. E.
Published: December 2004

The discovery of methods for regulating stereoisomerism in polymer synthesis, and thereby controlling polymer properties, is one of the most significant recent developments in polymer science. Polypropylenes and propylene copolymers are the outstanding products resulting already. This review includes both European and American contributions from the beginning of the idea. It emphasizes researches on polymerization of vinyl ethers and of 1‐olefms which have been most important in development of the basic concepts of stereoregulation. The review is based in part upon a paper presented at the Canadian Polymer Forum in Ottawa in September 1965.
In‐line annealing—a new approach to the extrusion of high quality rigid vinyl products
Authors: Socha Robert P.
Published: December 2004

Most polymers exhibit a very fluid melt rheology during extrusion and can be distorted, drawn down, and cooled without building excessive residual stresses into the product. In contrast, rigid vinyl is usually extruded as a stiff, almost selfsupporting mass. Care must be taken to prevent the formation ot oriented stresses in the product which will be relieved during long periods of exposure resulting in dimensional instability and related loss of physical properties. A newly developed method of in‐line annealing has shown to be an effective means of relieving oriented stresses developed during extrusion. By use of this instrumented technique, rigid vinyl products can be controlled to much tighter shrinkage specifications in a single step process, thereby eliminating post‐annealing treatments.
Glass‐resin joint strength and their effect on failure mechanisms in reinforced plastics
Authors: Broutman Lawrence J.
Published: December 2004

The various methods which have been used to measure the joint strength of a glass‐polymer interface have been reviewed and the results compared. Conclusions have been made regarding the strength of polyester and epoxy joints and the role of the coupling agent in enhancing this strength. Bond strength methods discussed include the flat plate test as well as the single filament techniques. The stresses which exist at the interface in an actual comosite are calculated. The relation of the glass‐polymer joint strength to the final strength to the final strength of a glass reinforced plastic composite is dissussed. The interaction of the interface with an advancing crack is also considered.
The strain response of plastics to complex stress histories
Authors: Turner S.
Published: December 2004

Whereas the creep behaviour of plastics is conventionally studied by the application of a simple step‐function of stress, the stress conditions encountered in service are often much more complicated. The response of a liner viscoelastic material to a complex stess history can be calculated from the step‐function response, but this is not so for plastics which are non‐liner viscoelastic. The paper considers this from a mainly experimental viewpoint and underlines the general inadequacy of the current continuum echanical approach. The sections on recovery and intermittent stressing are of particular practical importance since it is under these conditions that plastic display particulary useful characteristics.
Cause and effect in time dependent flow of thermoplastic melts—a review
Authors: Schreiber H. P.
Published: December 2004

The factors leading to time dependnt variations of melt viscosity during capillary extrusion of thermoplastics are reviewed. An initial increase in melt viscosity has been attributed to melt elasticity while three mechanisms are cited to account for a subsequent drop in melt viscosity, which may or may not attain a steady‐state value. These are frictional heational heating of the melt, increasing shear stress as the viscometer reservoir empties, and cain orientation. The relative importance of the mechanisms is examined for various melts and the importance of time effects is discussed in terms of their influence on standard flow evaluations, such as the melt index determination.
Laboratory evaluation of plastic pipe from a gas service field‐test installation
Authors: Kuhlmann H. W. , Leininger R. I. , Wolter Fritz
Published: December 2004

This article presents the background and results of the first two‐year interval test of a projected 10 or more years field gas service test of various types of plastic pipes. The study is part of a program to establish the suitability of plastic pipes for gas distribution uses. A number of short‐term laboratory tests were used to characterize the condition of the pipe after the first two‐year exposure period some, like the cursh test, are recognized and accepted methods; others, like the ring‐tensile, tensile‐impact, and the tear‐propagation tests were developed or modified for this stdy. The results show that comparatively little change had taken place in this test period; the possible exception being in the ductility of two kinds of pipe subsequent evaluation should confirm or deny this behavior.