Preformed EMI/RFI shielding compositions in shaped form

Abstract

Electrically conductive preformed compositions comprising sulfur-containing polymers in shaped form and the use of preformed compositions in shaped form to seal apertures are disclosed. The preformed compositions can be used to seal an aperture having EMI/RFI shielding effectiveness.

What is claimed is:  
     
         1 . A preformed composition in shaped-form comprising: 
 a base composition comprising at least one sulfur-containing polymer, and at least one electrically conductive filler; and    a curing agent composition;    wherein the preformed composition is capable of shielding EMI/RFI radiation.    
     
     
         2 . The preformed composition of  claim 1 , wherein the preformed composition comprises 5 parts to 20 parts by weight of the curing agent composition, and 100 parts by weight of the base composition.  
     
     
         3 . The preformed composition of  claim 1 , wherein the at least one sulfur-containing polymer is present in an amount ranging from 10% by weight to 50% by weight of the total weight of the base composition.  
     
     
         4 . The preformed composition of  claim 1 , wherein the at least one sulfur-containing polymer is chosen from a polysulfide polymer, a mercapto-terminated polymer, and a combination of a polysulfide polymer and a mercapto-terminated polymer.  
     
     
         5 . The preformed composition of  claim 1 , wherein the at least one electrically conductive filler is present in an amount ranging from 40% to 80% by weight of the total weight of the base composition.  
     
     
         6 . The preformed composition of  claim 1 , wherein the at least one electrically conductive filler comprises Ni fiber, and Ni-coated graphite.  
     
     
         7 . The preformed composition of  claim 6 , wherein the Ni fiber is present in an amount ranging from 4% to 8% by weight of the total weight of the base composition, and the Ni-coated graphite is present in an amount ranging from 50% to 70% of the total weight of the base composition.  
     
     
         8 . The preformed composition of  claim 1 , further comprising at least one corrosion inhibitor.  
     
     
         9 . The preformed composition of  claim 8 , wherein the at least one corrosion inhibitor inhibits galvanic corrosion.  
     
     
         10 . The preformed composition of  claim 8 , wherein the at least one corrosion inhibitor comprises calcium chromate.  
     
     
         11 . The preformed composition of  claim 8 , wherein the at least one corrosion inhibitor is present in an amount ranging from 3% by weight to 7% by weight of the total weight of the base composition.  
     
     
         12 . The preformed composition of  claim 1 , further comprising at least one adhesion promoter.  
     
     
         13 . The preformed composition of  claim 12 , wherein the at least one adhesion promoter comprises a phenolic adhesion promoter, a mercapto-silane adhesion promoter, and an epoxy-silane adhesion promoter.  
     
     
         14 . The preformed composition of  claim 12 , wherein the at least one adhesion promoter is present in an amount ranging from 1% by weight to 6% by weight of the total weight of the base composition.  
     
     
         15 . The preformed composition of  claim 1 , wherein the preformed composition is curable at a temperature ranging from 10° C. to 30° C.  
     
     
         16 . The preformed composition of  claim 1 , wherein the preformed composition is refrigerated prior to application.  
     
     
         17 . The preformed composition of  claim 1 , wherein the cured preformed composition exhibits a surface resistivity of less than 0.50 Ω/.  
     
     
         18 . The preformed composition of  claim 1 , wherein the curing agent composition comprises a manganese dioxide curing agent.  
     
     
         19 . The preformed composition of  claim 18 , wherein the manganese dioxide is present in the curing agent composition in an amount ranging from 25% to 75% by weight of the total weight of the curing agent composition.  
     
     
         20 . A method of sealing an aperture to provide EMI/RFI shielding effectiveness comprising applying a preformed composition in shaped-form comprising at least one sulfur-containing polymer, and at least one electrically conductive filler to a surface associated with an aperture to seal the aperture and provide EMI/RFI shielding effectiveness.  
     
     
         21 . The method of  claim 20 , wherein the performed composition comprises a preformed composition according to  claim 1 .  
     
     
         22 . The method of  claim 20 , wherein the surface is a surface of a removable panel.  
     
     
         23 . The method of  claim 20 , wherein the surface is a surface adjacent to an opening.  
     
     
         24 . The method of  claim 20 , wherein the aperture is on an aviation or an aerospace vehicle.  
     
     
         25 . The method of  claim 20 , further comprising applying an adhesion promoter to at least one surface associated with the aperture prior to application of the preformed composition.  
     
     
         26 . The method of  claim 20 , further comprising applying a release agent to a least one surface associated with the aperture prior to application of the preformed composition.  
     
     
         27 . The method of  claim 20 , wherein the sealed aperture exhibits shielding effectiveness from 1 MHz to 18 GHz.