bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relation of structure to properties in polyurethanes
Authors: Cluff E. F. , Gladding E. K. 
Published: April 2003

AbstractA polyurethane bearing pendant hydroxyl groups and carbon‐carbon double bonds was prepared. Curing was carried out by diisocyanates of different lengths and by an accelerated sulfur recipe. The vulcanizate properties of modulus, hardness, and resilience were found to be independent of both the length and chemical nature of the crosslink. Compression set, however, was always higher for the sulfur cures, an effect which can be attributed to the disulfide structure of this particular crosslink. Both physical and chemical evidence support this structure. Diisocyanate curing of the dolyurethane via the hydroxyl groups is a clean‐cut, essentially quantitative reaction which provided an absolute method for determining the degree of crosslinking. Excellent agreement was obtained between the physical degree of crosslinking as determined by equilibrium modulus and the chemical degree of crosslinking. This agreement provides further verification of the network‐statistical theory of rubber elasticity in highly swollen systems. No chain entanglement was observed.
The superstructure of melt‐crystallized polyethylene. I. Screwlike orientation of unit cell in polyethylene spherulites with periodic extinction rings
Authors: Fujiwara Yasuna 
Published: April 2003

AbstractThe ringed structure in polyethylene spherulites was investigated by an x‐ray microdiffraction method. A spherulite with extinction rings whose interval is about 50 μ was observed when viewed under the polarization microscope. An asymmetric x‐ray diffraction fibrous pattern about the b axis was obtained for this specimen. This indicates that in the area of spherulite (several microns in diameter) the unit cells are never randomly oriented around a common b axis but have nearly similar orientations. A series of micro‐diffraction patterns was obtained at intervals of 13 μ (about 1/4 the extinction fringe interval), and it was shown that the unit cells have screwlike orientations with their common b axis along the spherulite radius. The distance corresponding to one‐half the pitch of the screw is just in accordance with the extinction ring interval.
Polymers from vinyl fluoride
Authors: Kalb G. H. , Coffman D. D. , Ford T. A. , Johnston F. L. 
Published: April 2003

AbstractThe free‐radical polymerization of vinyl fluoride has been studied with the use of organic peroxide and azo initiators over the temperature range of 60–150°C. and at pressures of 75–1000 atm. Molecular weights of the polymers by osmotic pressure or radiotracer techniques were found to vary over the range of 45,000 to 180,000 depending on polymerization conditions employed. Stabilized high molecular weight polyvinyl fluoride may be compression‐molded into tough, high‐impact strength bars, or the unstabilized material may be cast into films from solvents such as dimethylformamide. The films, which may be cold drawn, are tough, brilliantly clear, and have tensile strengths near 8000 lb./in.2 They are also extremely resistant to weathering, maintaining clarity and cold drawability even after ten years' exposure in Florida.
The structure of chlorosulfonated polyethylene
Authors: Nersasian Arthur , Andersen Donald E. 
Published: April 2003

AbstractThe chlorines in chlorosulfonated polyethylene have been characterized by kinetic analysis according to the method of Salomon. It is found that 2.7% of the total chlorine is primary, 89.8% secondary, 3.5% tertiary, and 4% is sulfonyl chloride. These results are in accord with statistical calculations based on a polyethylene model containing the same methylene‐to‐methyl group ratio as the polyethylene precursor. The types and approximate quantities of dichlorides in the chlorosulfonated polyethylene have been determined by reactions with potassium iodide and zinc dust
The tensile properties of highly filled polymers. Effect of filler concentrations
Authors: Bills Kenneth W. , Sweeny Keith H. , Salcedo Frank S. 
Published: April 2003

AbstractThe systematic study of the variation in tensile properties with the extent of loading in highly filled systems has received little attention even though it is important to a variety of industries. An investigation was therefore made of the mechanical properties of a polyurethan rubber loaded with uniform glass spheres. Systems containing up to 62.5 vol.% fillers were investigated in tension on a strain rate range of 0.074 to 1850 min.−1 and temperatures of −50 to +80°C. The mechanical behavior at low extensions was found to be represented by the generalized Maxwell model. The Williams‐Landel‐Ferry relationship was satisfactorily applied to the reduction of the data. Good agreement was obtained between the glassy‐state transition temperature calculated from the reduced tensile data and from experimental differential thermal analysis results. The increase in the modulus with increasing filler content was satisfactorily described by an empirical modification of the Eilers relationship. The application of the reduced tensile data to the calculation of the stress relaxation modulus is also shown. Reasonable agreement was obtained between the calculated and experimental data.
Response of elastomers to any forcing function
Authors: Berger M. 
Published: April 2003

AbstractThe dynamic behavior of elastomers is usually studied in terms of a sinusoidal system. The theoretical and practical limitations of such analysis are discussed. A method which permits calculation of dynamic properties over a wide range of frequencies and forcing functions is described. The theoretical justification and limitations as well as the experimental setup are presented. Using SBR, natural rubber, and butyl, examples of the dynamic responses for various forcing functions are shown. The analogue computer is used to show properties of the above described rubbers which are useful from both the theoretical and application‐oriented viewpoints.
The development of crystallinity and transparency in irradiated polyethylene
Authors: Levy Boris 
Published: April 2003

AbstractA procedure has been developed for producing highly transparent polyethylene by use of high‐energy electron irradiation above the melting point. The polyethylene retains about 60% of its original tensile strength after receiving the optimum irradiation dose of 50 Mrad at room temperature followed by 50 Mrad at 150°C. The transparency of a 0.02 in. sample increases from about 20% to 75% under this treatment. Changes in transparency with time and temperature, during cooling of the polyethylene from 150°C. to various quench temperatures were investigated as a function of irradiation dose. The increase in transparency is a result of reduction in crystallinity, in size of crystallites and spherulites, and in rate of crystallization caused by the restraints imposed by the radiation‐induced crosslinking.
Peel testing of adhesive bonded metal
Authors: Yurenka S. 
Published: April 2003

AbstractIn this paper the subject of peel is divided into two parts: (1) A mathematical determination of peeling stresses in an adhesive bond due to the applied peeling loads which leads to a mathematical definition of “peel strength.” (2) A review of suitable peel test methods examined in the light of this definition. Employing the assumption that the adhesive bond behaves as an ideal homogeneous elastic material under load, the classical derivation of the deflection of a loaded beam on an elastic foundation is applied to the calculation of peel strength of a metal adhesive. This theory results in a mathematical definition of peel strength and offers a reasonable explanation of the effects of the important variables such as metal and adhesive thickness and strength properties and provides a basis for the comparison and evaluation of the few testing methods presently in use.
Relaxation processes in vulcanized rubber. II. Secondary relaxation due to network breakdown
Authors: Gent A. N. 
Published: April 2003

AbstractAn experimental study is described of a “secondary” relaxation process in stretched vulcanizates, which becomes dominant after long periods at normal temperatures. It is shown to be affected markedly by the temperature, the atmosphere in which the test is conducted, and the presence of oxidation inhibitors. It is therefore attributed to oxidative deterioration of the molecular structure. In some vulcanizates, however, a similar or even greater relaxation is found to occur in vacuo, and this is attributed to the failure of specific crosslink structures. The extent of recovery on releasing the extended test pieces has also been investigated for a number of natural rubber vulcanizates.
Stress crazing of some amorphous thermoplastics
Authors: Spurr O. K. , Niegisch W. D. 
Published: April 2003

AbstractTensile stress‐induced crazing in polystyrene, poly(methyl methacrylate), and polycarbonate has been carefully examined by optical and electron microscopy. Examination of the surface of crazed specimens and the cross sections of individual crazes leads to the conclusion that the crazes are not void cracks, but are filled with a craze matter. The craze matter is readily distinguishable from the surrounding resin and is seen to exist in continuity with it. Further experiments confirm the existence of the craze matter and tend to indicate its structural and mechanical properties. These experiments include: microscopic examination of the walls of fractured crazes, micro x‐ray diffraction of craze matter, studies of the strength of crazed specimens under static loads and under increasing tensions, studies of the effect of heat and solvent on crazed specimens, and observations on the ability of crazes to form special networks. The results indicate that the craze matter may be formed by localized resin deformation leading to a load bearing oriented structure. A hypothesis of the mechanism of craze formation is proposed in light of the new and varied information reported in the paper. Study of the kinetics of craze growth suggests the division of the mechanism into three parts: initiation, propagation, and termination. The initiation step describes the concentration of strain energy and the precursory molecular arrangements in the immediate vicinity of inhomogeneities. These are the changes which occur during the time lapse between stress application and first appearance of crazes. The propagation step comprises the sudden and relatively rapid localized resin deformation which creates the craze matter. The shapes of the growing crazes and their diminishing growth rates are attributable to known resin properties. The termination step represents the apparent cessation of craze growth with continued long times of stress application. At this stage in the existence of crazes the proposed hypothesis must blend into the theories of time delayed rupture. It is concluded that stress crazing is basically a molecular slippage rather than a molecular cleavage phenomenon. Considerations, therefore, are to be directed more towards intermolecular forces than intramolecular forces.
The early stages of isotactic polypropylene oxidation
Authors: Russell C. A. , Pascale J. V. 
Published: April 2003

AbstractThe initial stages of isotactic polypropylene oxidation were investigated by oxidizing at 130°C. to various extents up to 10 ml. of oxygen consumed per gram of polymer. The development of infrared absorption bands in the carbonyl regions was followed, as increasing amounts of oxidation occurred. The oxidation uptake curves showed that both autocatalytic rate and induction time depended primarily on the thickness of the sample, contrary to the case of polyethylene. This indicated the initiation process was primarily diffusion controlled for samples of the thickness range studied. The presence of copper shortened the induction times and increased the autocatalytic rate. In this case, the dependency of the induction time on thickness was less. Dielectric data showed that polypropylene became unsuitable electrically at about the point where the autocatalytic oxidation set in. It was also found that the effects of prior exposure to oxidative conditions were cumulative to a considerable extent, and thus resulted in shorter induction times.
Study of epoxy compounds. Part I. Curing reactions of epoxy resin and acid anhydride with amine and alcohol as catalyst
Authors: Tanaka Yoshio , Kakiuchi Hiroshi 
Published: April 2003

AbstractThe curing reaction of an epoxy resin and acid anhydride with an amine and/or alcohol was studied kinetically. No etherification reaction occurred at 70–140°C. and the initial reaction rate was proportional to the concentration of epoxide, acid anhydride, and catalyst (tertiary amine or alcohol). The apparent activation energies of the reaction in two systems of epoxy resin–hexahydrophthalic anhydride/triethanolamine (0.5 wt. %) were obtained as 14.1 and 14.4 kcal./mole. The effects of the substitution R of the tertiary amine NR3 or alcohol R3COH as catalyst on the curing reaction of the epoxy resin and acid anhydride were studied. The polar reaction constant ρp for amines, obtained negatively, indicates that electron‐repelling substituents of NR3 increase the curing rate; ρp for alcohols, obtained positively, indicates that electron‐withdrawing substituents of R3COH increase the rate of curing reaction. These results supported the proposed curing mechanism better.
Mathematical description of the stress‐strain behavior of filled binders
Authors: Brock Fred H. 
Published: April 2003

AbstractThe result of a phenomenological study in the analysis of uniaxial and biaxial tensile behavior of a variety of filled systems is described. A correlation is given that appears to serve as a tensile failure criterion for most of the systems investigated. The storedenergy function W, assumed to be equal to the area under the stress‐strain curve, has been found to obey the relation W = A(1 – exp {–B(Q – 3)}), where A and B are constants and Q is related to the first or second strain invariant. In general, the total stored energy up to break, divided by A, has a value between 0.7 and 0.8, which appears to be independent of strain rate and temperature. This constancy has also been verified by an independent set of data.
Gas permeation through lexan polycarbonate resin
Authors: Norton Francis J. 
Published: April 2003

AbstractValues have been determined over a considerable temperature range for the permeation rate, diffusion constant, and solubility of the following gases in Lexan: H2, H2O, He, Ne, O2, argon, CO2, and SF5. There is some discussion of the interrelationships and the variation of activation energies with molecular weight.
Melt elasticity and viscosity of neoprene WB at high shear rates
Authors: Eckert Roger E. 
Published: April 2003

AbstractAn elastomer developed for superior processing characteristics, Neoprene WB, has been studied in a capillary rheometer from 80–125°C. and shear rates of 0.4–11,000 sec.−1 Both the viscous and elastic properties of the bulk polymer are evaluated from pressure drop measurements. Per cent increase in diameter of the elastomer when extruded (“die swell”) and its surface characteristics provide direct evidence of extrusion processibility. A principle of corresponding shear rates at different temperatures simplifies the understanding and application of rheometer data. Data on all responses obtained at a low temperature can be laterally superposed to higher shear rate to agree with data obtained at higher temperature. Equilibrium shear stress vs. shear rate curves show Neoprene WB undergoes shear thinning with, for example, viscosity at 100°C. dropping from over 106 poise at low shear rate to 5 × 102 poise at high. The entrance or elastic effect drops very slowly to a minimum with increasing shear and then rises rapidly. This shear rate‐temperature condition at which the entrance effect is a minimum is a critical condition for the polymer; it is the transition from smooth to rough extrudate. Die swell of smooth extrudates increases as the shear rate is increased but decreases with greater orifice length to diameter ratio. Above the transition the die swell of rough extrudates drops to a minimum and then rises again at still higher shear rates.
Protective effect of nitrous oxide on radiation‐induced degradation of polyisobutylene
Authors: Okada Yoichi 
Published: April 2003

AbstractPolyisobutylene was irradiated by γ‐rays from a Co60 source in vacuum and in nitrous oxide atmosphere. The irradiated specimens in N2O were damaged to a lesser extent than those in vacuum. Irradiated specimens were dissolved in CCl4 and their viscosity was measured at 30°C. A plot of reciprocal of viscosity‐average molecular weight against dose gives a straight line in each case for specimens irradiated in vacuum and in N2O. Moreover, the presence of nitrous oxide reduces the extent of main‐chain fracture to 63%. The degree of branching is nearly the same for all of the specimens, since Huggins' constant k' is constant (k' = 0.40) throughout our experiments. It can be concluded that the N2O has a protective effect for main‐chain fracture of polyisobutylene.
Characteristics of experimental cis‐1,4‐polyisoprene latices
Authors: Preiss D. M. , Sawyer W. M. , Simpson W. C. 
Published: April 2003

AbstractExperimental latices of synthetic cis‐1,4‐polyisoprene and films and cellular objects produced from them are described. The latices of the synthetic polymers with molecular weights of about 2,000,000 are stabilized by anionic surfactants and have weight median particle diameters of about 0.9 μ and log normal particle size distribution. Tensile properties and flow characteristics of unvulcanized latex films could be regulated by introduction of controlled, small, amounts of crosslinking into the latex. Procedures used for crosslink density determination on cis‐polyisoprene latex at various stages of use are described. Vulcanized latex films having maximum tensile strengths (5500–6000 p.s.i. and 800–950% elongation) were obtained when the final crosslink density was in the range 1.0–1.6 × 10−4 moles of effective chains/cc. Use of the synthetic cis‐polyisoprene latex in production of foam is described. Gelation with sodium silicofluoride at room temperature occurs within 2–10 minutes. Production of a controlled level of crosslinking in the latex prior to frothing and gelling was found to improve the uniformity of cell structure of foams and to increase their resistance to compression. Excessive crosslinking in the latex during maturation was shown to cause a loss of tensile strength in cured products presumably because the coalescence of latex particles during gelation is adversely affected. The properties of synthetic cis‐1,4‐polyisoprene latices and the physical properties of films and foams derived from them are shown in general to be very similar to those of natural rubber latex and its products.
Thermosetting vinyl and acrylic copolymers
Authors: Kelly D. P. , Melrose G. J. H. , Solomon D. H. 
Published: April 2003

AbstractInfrared spectra indicate that carboxyl‐substituted acrylic copolymers react appreci8bly with a butylated melamine–formaldehyde resin when heated at 120°C. for 30 min., but under these conditions acid catalysis is needed before epoxy‐ or amido‐substituted copolymers will crosslink with the melamine–formaldehyde resin. Two methods have been used to synthesize hydroxyl‐substituted acrylic copolymers. First, a glycidyl methacrylate copolymer was reacted with diethplamine. Second, an acrylic acid copolymer was heated under reflux with butylene oxide in the presence of a basic catalyst. This second method was used to esterify a vinyl toluene–acrylic acid–acrylamide copolymer which was subsequently treated with paraformaldehyde. The resulting hydroxy‐methylolamido copolymer intercondensed when heated at 120°C. for 30 min., somewhat as did the hydroxy copolymer with melamine–formaldehyde resin blends.
Polyhydroxyethers. II. Effect of structure on properties of high molecular weight copolymers from dihydric phenol mixtures and epichlorohydrin
Authors: Reinking N. H. , Barnabeo A. E. , Hale W. F. 
Published: April 2003

AbstractThe glass transition temperature and gas barrier properties of a number of high molecular weight thermoplastic hydroxyether copolymers have been determined. These copolymers were derived from mixtures of two dihydric phenols and epichlorohydrin. The property data are analyzed in terms of copolymer composition and the random or alternating distribution of monomer units in the polymer chains. In general, the glass transition temperatures of the copolymers were found to be intermediate between the values for the two homopolymers. In one system, good agreement between the experimental data and a simplified equation for the prediction of glass transition temperatures of amorphous, random copolymers was obtained. No differences in the glass transition behavior of random and alternating hydroxyether copolymers could be detected. Gas barrier properties, in general, were found to be intermediate in value between those of corresponding homopolymers. The exceptions are discussed in terms of polymer structure variations.
Dilatation of granular filled elastomers under high rates of strain
Authors: Farris R. J. 
Published: April 2003

AbstractAn apparatus has been developed for measuring the dilatation of specimens tested in uniaxial tension in a constant volume chamber by determining the change in the volume of air around the specimen through precise measurement of air pressure. The dilatometer can be used on standard testing machines and has shown reproducible values at testing speeds from 0.66 to 666%/min., and temperatures from −75 to 210°F. Typical stress strain curves are shown with the simultaneously recorded dilatation versus strain.
High speed testing as a measure of the resistance to penetration of needle‐punched felts
Authors: Laible Roy C. , Supnik Ross H. 
Published: April 2003

AbstractNeedle‐punched felt samples differing widely in ballistic performance have been subjected to four different types of high speed mechanical tests. These tests included penetration, tensile, compression, and instrumented dart‐drop methods. The results from one of these high speed tests, the penetration test, can be consistently related to the ballistic resistance of the felts. This penetration test utilizes a compression cage equipped with a penetrant and is operated at test speeds about two decades lower than those realized ballistically. The other three tests are of only limited use in evaluating felts.
Exploratory studies in photomechanics
Authors: Becker Herbert , Zachar Andrew W. 
Published: April 2003

AbstractExploratory tests were conducted on a specially designed and fabricated photoviscoelastic plastic in order to develop a form for the relationship between fringe order and the mechanical behavior of the plastic. Because of the possible dependence of fringe order upon both stress and strain, the relationship has been termed the photomechanical law. The results which have been obtained so far were inconclusive. In addition, numerous problem areas were discovered which indicate the type of program which may lead to the photomechanical law.
Modification of the brice light‐scattering photometer for photoelectric polarimetry by the rouy method
Authors: Kahn Leo D. , Calhoun Robert R. , Witnauer Lee P. 
Published: April 2003

AbstractConstruction details for modifying the Brice light‐scattering photometer for use in photoelectric polarimetry have been given. The measuring technique is based on the Rouy method, which is perhaps the most sensitive of all photoelectric methods of measuring the optical rotation of liquids, especially at small angles. A standard deviation of 0.01° has been observed with the use of an instrument modified in this way.