Foamable compositions and methods for fabricating foamed articles

Abstract

In one aspect, a foamable composition is disclosed, which comprises a base polymer, talc and a citrate compound blended with the base polymer. In some embodiments, the concentration of the talc in the composition is in a range of about 0.05% to about 25% by weight, e.g., in a range of about 2% to about 20%, or in a range of about 3% to about 15%, or in a range of about 5% to about 10%. Further, the concentration of the citrate compound in the composition can be, for example, in a range of about 0.05% to about 3% by weight, or in a range of about 0.02% to about 0.9% by weight, or in a range of about 0.03% to about 0.8% by weight, or in a range of about 0.04% to about 0.7% by weight, or in a range of about 0.05% to about 0.6% by weight

What is claimed is: 
     
         1 . A process for fabricating a foamed article, the process comprising:
 heating a composition comprising a base polymer, talc blended with the base polymer, and a citrate compound blended with the base polymer to a temperature sufficient to cause decomposition of talc so as to generate a gas for foaming the composition.   
     
     
         2 . The process of  claim 1 , further comprising extruding the heated composition to form the foamed article. 
     
     
         3 . The process of  claim 1 , wherein the foamed article comprises a separator suitable for use in a communications cable. 
     
     
         4 . The process of  claim 1 , wherein the temperature is at least about 600° F. 
     
     
         5 . The process of  claim 1 , wherein the citrate compound comprises at least one of calcium citrate, potassium citrate, and zinc citrate. 
     
     
         6 . The process of  claim 1 , wherein a concentration of the talc in the composition is in a range of about 0.3% to about 30% by weight. 
     
     
         7 . The process of  claim 6 , wherein the concentration of the talc in the composition is in a range of about 2% to about 20% by weight. 
     
     
         8 . The process of  claim 6 , wherein the concentration of the talc in the composition is in a range of about 3% to about 15%. 
     
     
         9 . The process of  claim 6 , wherein the concentration of the talc in the composition is in a range of about 5% to about 10%. 
     
     
         10 . The process of  claim 1 , wherein a concentration of the citrate compound in the composition is in a range of about 0.01% to about 1% by weight. 
     
     
         11 . The process of  claim 10 , wherein the concentration of the citrate compound in the composition is in a range of about 0.02% to about 0.9% by weight. 
     
     
         12 . The process of  claim 10 , wherein the concentration of the citrate compound in the composition is in a range of about 0.03% to about 0.8% by weight. 
     
     
         13 . The process of  claim 10 , wherein the concentration of the citrate compound in the composition is in a range of about 0.04% to about 0.7% by weight. 
     
     
         14 . The process of  claim 10 , wherein the concentration of the citrate compound in the composition is in a range of about 0.05% to about 0.6% by weight. 
     
     
         15 . The process of  claim 1 , wherein a concentration of the base polymer is in a range of about 50% to about 95% by weight. 
     
     
         16 . The process of  claim 1 , wherein the base polymer comprises a fluoropolymer. 
     
     
         17 . The process of  claim 1 , wherein the base polymer comprises a perfluoropolymer. 
     
     
         18 . The process of  claim 17 , wherein the fluoropolymer comprises at least one of tetrafluoroethylene/perfluoromethylvinyl ether copolymer (MFA), hexafluoropropylene/tetrafluoroethylene copolymer (FEP), perfluoroalkoxy (PFA), and perfluoroalkoxyalkane, and combinations thereof. 
     
     
         19 . The process of  claim 1 , wherein the base polymer comprises at least one of polyphenylenesulfide (PPS), polyetherimide (PSU), polyphenylsulfone (PPSU), polyethersulfone (PES/PESU), polyetheretherketone (PEEK), polyaryletherketone (PAEK), polyetherketoneketone (PEKK), polyetherketone (PEK), cyclicolefin copolymer (COC), polycarbonate (PC) polyphenylene ether (PPE), liquid crystal polymer (LCP) and combinations thereof. 
     
     
         20 . The process of  claim 2 , wherein the heated composition is in the form of a plurality of pellets. 
     
     
         21 . The process of  claim 2 , further comprising extruding the heated composition over at least one of a 16 AWg, 18 AWg, and 28 AWG copper wire to form the foamed insulation. 
     
     
         22 . The process of  claim 2 , wherein the extruding the heated composition comprises pressure extruding the heated composition. 
     
     
         23 . The process of  claim 22 , further comprising maintaining a pressure to which the heated composition is subjected to less than about 3500 psi. 
     
     
         24 . The process of  claim 22 , further comprising maintaining a pressure at which the heated composition is subjected less than about 2500 psi.