Fibers from polymer nanoclay nanocomposites by electrospinning

Abstract

Thermoplastic polymer nanoclay nanocomposite fiber has silicate layers axially aligned through the fiber and enhanced crystallinity and average diameter ranging from 50 nm to 5 μm is produced by solution electrospinning or melt electrospinning where polarity and electric field in the spinning zone are provided so as to potentiate the axial alignment and solidification of polymer is controlled to potentiate increase in crystallinity.

1 - 7 . (canceled)  
   
   
       8 . A method for solution electrospinning to produce thermoplastic polymer nanoclay nanocomposite fiber with silicate layers axially aligned through the fiber, comprising the steps of: 
 (a) forming a polymer nanoclay nanocomposite containing from 0.5 to 10% by weight nanoclay having organic cation and from 99.5 to 90% by weight polymer by a method comprising melt extruding a dried premix of the nanoclay in powder form and the polymer in powder form,    (b) dissolving 2.5 to 25% by weight of the polymer nanoclay nanocomposite in solvent at room temperature, to form a solution,    (c) moving the solution through a zone where the solution is heated via conduction, free convection or radiation, where the moving is effected by a force supplier upstream of or at said zone,    (d) then forming droplets from the solution,    (e) in a spinning zone, providing an electric charge on the droplets to overcome the surface tension of a droplet, to produce a jet of solution and provide unstable flow involving a plurality of electrically induced bending instabilities/whipping motions and evaporation of solvent and elongation of and production of nanocomposite fiber,    effecting the electric charge with an electric field and providing reversed voltage polarity between the electric charge on a droplet and a fiber collecting zone, to potentiate axial alignment of silicate layers of the nanoclay and matrix polymer molecules through the fiber,    regulating temperature in the spinning zone and the fiber collecting zone and providing a rate of evaporation of solvent, to potentiate increase in crystallinity.    
   
   
       9 . A method for solution electrospinning to produce thermoplastic polymer nanoclay nanocomposite fiber with silicate layers axially aligned through the fiber, comprising the steps of: 
 (a) forming a homogeneous dispersion of nanocomposite particles of nanoclay with organic cation and solvent for the polymer and then adding polymer powder or pellets to form a solution containing from 2.5 to 25% by weight of the solution of the total of nanoclay and polymer at 15 to 60° C. with nanoclay being present in amount of 0.5 to 10% by weight of the total,    (b) moving the solution through a zone where the solution is heated via conduction or irradiation, where the moving is effected by a force supplier upstream of or at said zone,    (c) then forming droplets from the solution,    (d) in a spinning zone, providing an electric charge on the droplets to overcome the surface tension of a droplet to produce a jet of solution and provide unstable flow involving a plurality of electrically induced bending instabilities/whipping motions and evaporation of solvent and production of nanocomposite fiber,    effecting the electric charge with an electric field and providing reversed voltage polarity between the electric charge on a droplet and a fiber collecting zone to potentiate axial alignment of silicate layers of the nanoclay and matrix polymer molecules through the fiber,    regulating temperatures in the spinning zone and in the collecting zone and providing a rate of evaporation of solution to potentiate increase in crystallinity.    
   
   
       10 . A method of melt electrospinning to produce thermoplastic polymer nanoclay nanocomposite fiber with silicate layers axially aligned through the fiber, comprising the steps of: 
 (a) forming a polymer/organic cation containing nanoclay nanocomposite containing from 0.5 to 10% by weight of the nanoclay and from 99.5 to 90% by weight of the Polymer,    (b) melting the nanocomposite in a melting zone,    (c) moving the nanocomposite through the melting zone by a force supplier upstream of or in the melting zone,    (d) forming droplets on the melted nanocomposite,    (e) in a spinning zone, providing an electric charge on the droplets to overcome the surface tension of a droplet to produce a jet of melted nanocomposite and provide unstable flow involving a plurality of electrically induced bending instabilities/whipping motions and elongation of and production of nanocomposite fiber,    effecting the electric charge with an electric field and reversing the voltage polarity of electric charge on formed droplets and a fiber collecting zone to influence the degree of whipping motion and thus the degree of elongational deformation to potentiate axial alignment of nanoclay layers and matrix polymer molecules through the fibers,    regulating the temperature in the spinning zone and in a collecting zone to potentiate increase in crystallinity.    
   
   
       11 . The method of  claim 10  additionally comprising at least one of the following steps (f) and (g): 
 (f) providing a temperature for the nanocomposite being subjected to electrically induced bending instabilities/whipping motions and fiber elongation so as to provide against premature solidification and to provide against induction of relaxation of molecular orientation without affecting the electrically induced bending instabilities,    (g) shielding to prevent induction of voltage in the melting zone.    
   
   
       12 . The method of  claim 11  comprising the additional step of annealing nanocomposite fiber produced in step (e) to impart stability and molecular orientation and increase crystal structure.