Fiber formation by electrical-mechanical spinning

Abstract

A method of fiber formation by electrical-mechanical spinning is disclosed. A liquid starting material is fed to a rotating annular member such as a spinning cup. The liquid material is directed by centrifugal force to the periphery of the annular member where it is expelled in fibrous form. An electric charge is imposed on the liquid while on the annular member or while immediately being expelled from the annular member.

1 . A method of fiber production from a liquid material comprising
 a. feeding the liquid material to a rotating annular member having an interior surface extending to an open end and a periphery around the open end,   b. directing the liquid material by centrifugal force along the interior surface towards the periphery of the rotating member, and   c. expelling the liquid material from the periphery towards a target in fibrous form;   wherein the liquid material is electrically charged and the target is grounded.   
   
   
       2 . The method of  claim 1  in which the rotating annular member has a base or closed end and walls having the interior surface extending from the base or closed end to an open end and a periphery around the open end. 
   
   
       3 . The method of  claim 2  in which the liquid material is directed by centrifugal force along the base and across the interior surface of the walls toward the periphery of the rotating member. 
   
   
       4 . The method of  claim 1  in which the liquid material is in the form of a polymer solution or a polymer melt. 
   
   
       5 . The method of  claim 4  in which the polymer solution or polymer melt comprises an organic polymer, an inorganic polymer or a hybrid organic/inorganic polymer. 
   
   
       6 . The method of  claim 1  in which the fibers have a diameter of 5 to 5,000 nanometers. 
   
   
       7 . The method of  claim 3  in which the fibers have a diameter of 50 to 1200 nanometers. 
   
   
       8 . The method of  claim 1  in which the nanofibers are twisted together in the form of a twisted yarn. 
   
   
       9 . The method of  claim 3  in which the annular member is in the form of a truncated cone. 
   
   
       10 . The method of  claim 3  in which the rotating member is positioned in the front end of a hollow drive shaft that rotates therewith. 
   
   
       11 . The method of  claim 10  in which a feed tube for the liquid material extends through the hollow drive shaft and into the central area of the rotating member for the supply of liquid material to the rotating member. 
   
   
       12 . The method of  claim 3  in which the rotating member has spinning points located on its periphery. 
   
   
       13 . The method of  claim 12  in which the spinning points are V-shaped serrations. 
   
   
       14 . The method of  claim 13  in which the serrations extend outwardly from the periphery of the rotating member and are substantially parallel to the axis of rotation. 
   
   
       15 . The method of  claim 3 , which further includes propelling an airstream normally against the expelled fibers so as to shape the fibers into a flow pattern concentric with the axis of rotation of the rotating member and towards the target. 
   
   
       16 . The method of  claim 15  in which the air stream is generated at a pressure of 1 to 60 PSIG (6.9×10 3 −4.1×10 5 -Pascals). 
   
   
       17 . The method of  claim 3  in which the fibers are collected on the target. 
   
   
       18 . The method of  claim 17  distance from the periphery of the rotating member to the target is from 2 to 30 inches (5-76 cm) 
   
   
       19 . The method of  claim 1  in which the fibers are collected on an intermediate surface located between the target and the rotating member. 
   
   
       20 . The method of  claim 1  in which the rotating member is rotating at a speed of 1000 to 100,000 revolutions per minute. 
   
   
       21 . The method of  claim 1  in which the electrical potential between the expelled liquid material and the grounded target is at least 5000 volts.