Thermally Insulating Fiber

Abstract

The present application relates to a fiber having an elongated body defining a longitudinal axis and at least one cavity. The cavity is positioned symmetrically with respect to a plane containing the longitudinal axis. In addition, an insulating gas, less thermally conductive than air, is trapped in the cavity.

1 . A fiber having an elongated body defining a longitudinal axis and at least one cavity defined therein, the at least one cavity being defined symmetrically with respect to a plane containing the longitudinal axis, and an insulating gas trapped in the at least one cavity, the insulating gas being less thermally conductive than air, the at least one cavity being sealed by a coating having a lower permeability to the insulating gas than a material of the body. 
     
     
         2 . The fiber of  claim 1 , wherein the at least one cavity includes a plurality of cavities circumferentially spaced apart and distributed about the longitudinal axis in a symmetrical manner with respect to the plane. 
     
     
         3 . The fiber of  claim 1 , wherein the at least one cavity includes a plurality of spaced apart cavities extending along the longitudinal axis. 
     
     
         4 . The fiber of  claim 1 , wherein the at least one cavity includes a single cavity extending along the longitudinal axis. 
     
     
         5 . The fiber of  claim 4 , wherein the single cavity has a series of chambers interconnected by longitudinally spaced apart reduced diameter portions. 
     
     
         6 . The fiber of  claim 1 , wherein the coating covers an interior surface of the body enclosing the at least one cavity. 
     
     
         7 . The fiber of  claim 1 , wherein the coating covers an exterior surface of the body. 
     
     
         8 . The fiber of  claim 1 , wherein the coating is made of a material having a lower emissivity than that of the material of the body. 
     
     
         9 . The fiber of  claim 1 , wherein the coating is at least partly made of a metal or metal oxide selected from the group consisting of silver, aluminum, copper, gold, tin, tin oxide, indium oxide, zinc oxide and mixtures thereof. 
     
     
         10 . The fiber of  claim 1 , wherein the insulating gas is a noble gas. 
     
     
         11 . The fiber of  claim 10 , wherein the insulating gas includes one or more of krypton, argon, xenon and radon. 
     
     
         12 . The fiber of  claim 1 , wherein the elongated body is made from an extrudable material. 
     
     
         13 . The fiber of  claim 12 , wherein the extrudable material is an organic polymer, an inorganic material or mixture thereof. 
     
     
         14 . The fiber of  claim 1 , wherein the elongated body is made from an organic polymer selected from the group consisting of poly(ether sulfones) (PES), polyamide (PA), polyethylene terephthalate (PET), poly(p-phenylene sulfide) (PPS), polypropylene (PP), polyvinyl alcohol (PVA), polyether ether ketone (PEEK), polyacrilonitrile (PAN) and mixtures thereof. 
     
     
         15 . The fiber of  claim 1 , wherein the at least one cavity has a circular cross-section extending perpendicularly to the longitudinal axis. 
     
     
         16 . A material comprising the fiber as defined in  claim 1 . 
     
     
         17 . A method of manufacturing a fiber, said method comprising:
 a) extruding an extrudable material to form a fiber having an elongated body with at least one cavity defined in the body;   b) sealing the at least one cavity with a coating made of a material having a permeability to an insulating gas lower than that of the extrudable material;   c) introducing the insulating gas in the at least one cavity, the insulating gas being less thermally conductive than air; and   d) closing the at least one cavity to trap the insulating gas therein.   
     
     
         18 . The method of  claim 17 , wherein sealing the at least one cavity includes applying the coating to an exterior surface of the fiber. 
     
     
         19 . The method of  claim 17 , wherein forming the at least one cavity includes forming a plurality of circumferentially spaced apart cavities distributed about a longitudinal axis in a symmetrical manner with respect to a plane containing said longitudinal axis. 
     
     
         20 . The method of  claim 17 , wherein the steps a) and c) occur simultaneously. 
     
     
         21 . The method of  claim 17 , wherein the coating is made of a material having a lower emissivity than that of the extrudable material.