Materials Literature
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The chemistry of the reactions which occur between polyisocyanates and ancillary raw materials for the manufacture of polyurethanes is described and discussed. The four principal fields of activity in which urethanes find application are (1) flexible foams; (2) rigid foams; (3) surface coatings, and (4) rubbers. It is…
The die le ctric co nstant and loss of glassy B20 3 have been measured from 500 to 800 O( ove r th e fr e qu e ncy ra nge 1 to 50 kHz. The mate rial be haves esse ntially lik e a nonpolar po l yrr;e~; no re laxatI on phenomena could be identified. Ove r th e e ntire fre qu e ncy and te mperature ran ge LI es betwee n…
Abstract Tensile fatigue failure of a gum vulcanizate of noncrystallizing SBR can be accounted for by the growth of small flaws initially present in the rubber. Fatigue of crystallizing natural rubber was shown in Part I to be attributable to the same cause. Cut growth results are interpreted in terms of the tearing e…
Abstract Poly(vinylidene fluoride), polytrifluoroethylene, and two rubbery copolymers with vinylidene fluoride were crosslinked by γ‐irradiation in vacuum. Radiation‐induced chain scissions in the copolymers were studied by observing the relaxation of stress at constant extension during further irradiation at 27°C., a…
The crimp in all-cotton, nylon, and polyester/spandex core stretch fabrics was ex amined by physical tests and by photographic enlargements of yarns and fibers removed from the fabrics. Measurements of total crimp and crimp due to yarn crossover indicate that yarn crossover crimp, external yarn crimp, has a major infl…
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The motion of edge and screw dislocations in a graphite polycrystal subjected to external forces and fast neutron irradiation is considered. A transient creep strain, proportional to the external stress and proportional to the ratio of the dimensions of the component crystallites in the a and c directions, is deduced.…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThermodynamics of Metal Cyanide Coordination. IV. Log βi°, ΔHi°, and ΔSi°, Values for the Zinc(II)-Cyanide System at 25°Reed M. Izatt, James J. Christensen, James W. Hansen, and Gerald D. WattCite this: Inorg. Chem. 1965, 4, 5, 718–721Publication Date (Print):May 1, 1965Publ…
Superpurity aluminium specimens subject to reversed cyclic torsion extend axially by accumulation of second-order plastic strain increments. These arise in quasi-isotropic strain-hardening metals because of the additional quadratic term in the stress-strain relation that is required by the condition of tensorial invar…
The nature of the light emitted from the cavitating flow of tap water through a Venturi tube has been studied. The light is emitted as flashes of duration less than 5 μsec and its spectrum lies between 400 and 700 nm with a maximum intensity at 470 nm. Shock waves were detected by miniature pressure transducers implan…
Expressions are derived for x-ray absorption factors for a liquid or amorphous sample confined within a cylindrical sample cell. Sufficient geometrical parameters are included in the formulation to cover many experimental cases of practical interest. Various integrals involved are formulated in numerical calculus form…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXT2-Methacryloxytropones. Intermediates for the Synthesis of Biologically Active PolymersRobert J. Cornell and L. Guy DonarumaCite this: J. Med. Chem. 1965, 8, 3, 388–390Publication Date (Print):May 1, 1965Publication History Published online1 May 2002Published inissue 1 May 1…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetic Studies on Reactions of Praseodymium Oxides in an Oxygen Atmosphere: PrO1.83 + O2 ⇄ PrO2B. G. Hyde, E. E. Garver, U. E. Kuntz, and L. EyringCite this: J. Phys. Chem. 1965, 69, 5, 1667–1675Publication Date (Print):May 1, 1965Publication History Published online1 May 2…
Ultraviolet and visible spectra are reported for 28 N-benzylidineanilines with their molar absorptivities given in absolute ethanol, and in isooctane when feasible. Infrared studies in the 2–15 micron region are reported for these compounds and also for three newly synthesized N-d-benzylidineamhnes. With the aid of th…
The magnetic and spect roscopi c properties of the neptunyl ion a re reco nsid ered. The effec t on the energy levels of covale ncy is discussed. New valu es for the pa ram e te rs of our earlie r theo ry are obtained, the analysis being based on more recent spectroscopi c data and arguments co nce rning the relative…
Abstract Methods are presented for estimating the entropy and heat of fusion of polyolefins, polyamides, polyesters, etc. Although the formulas are approximate, good agreement is obtained with experimental values, where available. For example, the calculated entropies for polypropylene, polyoxymethylene, nylon 66, pol…
Crystalline solubility relations in the system MgO‐Mg 2 SiO 4 MgAl 2 O 4 (periclase‐forsterite‐spinel) were studied using coprecipitated gels as starting materials. The substitution 2Al = Mg + Si was investigated along the join Mg 2 SiO 4 ‐Mg‐Al 2 O 4 ,. At 1720°C the maximum crystalline solution in forsterite is abou…
The process of shell repair in specios of Anodonta is re‐examined in the light of current views on the mantle/shell relationship in the Lamellibranchia. Experiments indicate that the epithelia of the general outer mantle surface and mantle isthmus normally responsible for the production, respectively, of the inner lay…
The formation of vapor‐deposited TiB 2 , ZrB 2 , and HfB 2 at 1400°C was studied with respect to the influence of process variables on structure and stoichiometry. Stoichiometric, nonporous deposits of TiB 2 were obtained; ZrB 2 and HfB 2 deposits contained β‐rhombohedral boron. Precision lattice parameters were deter…
The crystal structure of dalyite, a potassium (sodium) zirconium silicate K 1.70 Na 0.30 ZrSi 6 O 15 , has been determined and refined by two-dimensional Fourier methods. It is a new type of sheet silicate containing four, six- and eight-memebered rings of SiO 4 tetrahedra. The sheets are joined by ZrO 6 octahedra and…