The invention is embodied in an electrical device which includes at least a layer of a ferroelectric polyvinylidine fluoride polymer that has been processed to exhibit an electrostrictive strain of 4% or more when an electric field gradient of 50 megavolts per meter or greater is applied thereacross. The processing of the polymer preferably involves subjecting it to either electron beam radiation or gamma radiation. The polyvinylidine flouride polymer is selected from the group of: polyvinylidine fluoride, polyvinylidine fluoride-trifluoroethylene P(VDF-TrFE), polyvinylidine fluoride tetrafluoroethylene P(VDF-TFE), polyvinylidine fluoride trifluoroethylene-hexafluoropropylene P(VDF-TFE-HFE) and polyvinylidine fluoride-hexafluoropropylene P(VDF-HFE).
This Application claims priority from U.S. Provisional Application Serial No. 60/065,641, filed Nov. 18, 1997, and Provisional Application Serial No. 60/093,718, filed Jul. 22, 1998.
A manufacturing process is provided to increase fracture toughness and reduce brittleness for a semi-crystalline polymer material. A material such as poly(vinylidene fluoride-trifluorethylene) or p(VDF-TrFE) is placed in an inert oxygen-free atmosphere and heated to a temperature that is greater than room temperature but below the melting temperature of the material. The material is then irradiated with beta particles until a desired level of fracture toughness is achieved where fracture toughness is a function of the radiation dose.
Disclosed herein is a process of forming a ferroelectric polymer film from a solution, wherein the solvent composition is selected so as to adjust the properties of the film. Films formed by this method have improved properties, particularly with respect to roughness and crystal domain size.
There are disclosed new polymer materials having improved electric field induced strain levels, dielectric constants, and elastic energy densities for use in electromechanical and dielectric applications. Methods of manufacture of new polymer materials are also disclosed.
A method to electronically modulate the energy gap and band-structure of semiconducting carbon nanotubes is proposed. Results show that the energy gap of a semiconducting nanotube can be narrowed when the nanotube is placed in an electric field perpendicular to the tube axis. Such effect in turn causes changes in electrical conductivity and radiation absorption characteristics that can be used in applications such as switches, transistors, photodetectors and polaron generation. By applying electric fields across the nanotube at a number of locations, a corresponding number of quantum wells are formed adjacent to one another. Such configuration is useful for Bragg reflectors, lasers and quantum computing.
A suspended-load backpack designed to permit the load to move relative to the backpack frame during walking and running so that the large movements between the load and the frame of the backpack reduce the fluctuations of absolute vertical motion of the load. Because the hip (and thus the pack frame) go up a down a good deal during walking, a large relative movement between the frame and the load reduces the absolute excursion of the load. This movement may be, in turn, transferred to a motor through, for example, a rack and pinion gear, to convert the mechanical movement to electrical energy. The movement may also be converted to electrical energy by using an electroactive polymer (EAP) to connect the suspended load to the frame. Such designs allow the load to move in a controlled fashion to prevent the patient from losing his or her balance as the load moves up and down along the backpack frame. Such movement of the suspended-load relative to the frame also reduces the forces on the wearer's shoulders while walking or running, thus reducing the likelihood of orthopedic injury.
