摘要:
Ceramic fibers formed by the pyrolysis of organosilicon preceramic polymers are provided with increased resistivity by treating the fibers in air at temperatures of less than 1,000.degree. C. to oxidize the free carbon content of the fibers.
摘要:
A shunt device and a method are described for protecting electrical equipment when a fuse blows. The shunt device establishes a by-pass across the fuse for permitting a limited amount of current to begin to flow at a lower voltage than the fuse blowing voltage and before the fuse blows, thereby serving as a transitory relief valve for a portion of the current while minimizing or even substantially eliminating the inductive spike when the fuse blows. The shunt device is made of at least one pyrolyzed polyacrylonitrile (PPP) fiber having a selected switching voltage so that the PPP fiber switches to a low resistance state while the fuse is blowing. When the fuse and PPP characteristics are properly matched, the rate of change of the current with time is lowered, thus selectively decreasing the size of the voltage transients which occur after the fuse blows.
摘要:
An electrical device is made by partially pyrolyzing polymer material by heating the material to between 500.degree. C. and 800.degree. C. Electrodes are applied to the material at two different locations to define an electrically active element therebetween. The device exhibits negative resistance in a portion of its voltage current domain and function as bi-directional electrical switches.This application is a continuation of application Ser. No. 859,709, filed May 5, 1986, now abandoned, which is a divisional application of application ser. No. 487,401, filed Apr. 21, 1983, now U.S. Pat. No. 4,642,644.
摘要:
An electrical device is made by partially pyrolyzing polymer material by heating the material to between 500.degree. C. and 800.degree. C. Electrodes are applied to the material at two different locations to define an electrically active element therebetween. Devices made according to the teachings of the disclosure exhibit negative resistance in a portion of their voltage current domain and function as bi-directional electrical switches.
摘要:
Temperature detectors are disclosed which employ, as their active elements, pieces of partially pyrolyzed polymer material which switch to a more highly conductive state under appropriate imposed electrical bias conditions when the ambient temperature increases above the switching temperature of the detector.
摘要:
Films or other articles having a barrier coating derived from a concentrated nanocomposite dispersion which includes a silicate filler and a matrix polymer dispersed in an aqueous medium. The dispersions are condensed by selectively removing liquid therefrom to provide high solids coating formulations.
摘要:
An evacuated container assembly suitable for use in connection with blood collection including: (a) a container member formed of a first polymeric material and having a sidewall and one or more openings; (b) a nanocomposite barrier coating disposed on the container member having a thickness of up to about 30 microns and being derived from an aqueous dispersion including (i) a dispersed barrier matrix polymer; and (ii) a substantially exfoliated silicate filler having an aspect ratio of more than 50; and (c) one or more sealing members disposed in the opening(s) operative to hermetically seal the cavity; wherein the cavity is evacuated and maintains a pressure below atmospheric pressure and exhibits a draw volume loss lower than that of a like assembly without a nanocomposite barrier film by a factor of at least 1.5.
摘要:
Barrier coating mixtures include (a) a non-butyl elastomeric polymer; (b) an acid or base treated dispersed, substantially exfoliated silicate filler material that has not been functionalized with organic cations having an aspect ratio greater than 25; and (c) at least one additive, wherein the total solids content is less than 30% and the amount of filler is between 5% to about 60% of the total solids content. The coating retains its permeability properties under strain and has a strain to first damage of at least 5% biaxial elongation at 0% RH.
摘要:
Vibration damping composites suitable for use in construction panels or constrained-layer elements are described. The composites include a viscoelastic gel prepared from 99.5-92.5 wt. % water and 0.5-7.5 wt. % of a superabsorbent polymer. Preferably, the polymer is of the carboxylic acid type and optionally includes starch or cellulose.
摘要:
Provided is a method for reading information recorded in an information layer comprised of a fluorescent dye. In order to read the recorded information, the tip of a scanning tunneling microscope is passed over the information layer, said scanning tunneling microscope being of sufficient voltage to excite the fluorescent dye material to an excited state. Upon return of the dye material to ground state, fluorescence results. By measuring the fluorescence, or absence thereof, the recorded information can be deciphered.