Fiber-filled molded articles

Abstract

Polymer molding processes, such as injection-molding processes, include use of a viscosity-reducing supercritical fluid additive resulting in less breakage of reinforcing fibers upon introduction into the mold.

1 . A molded article including a plurality of fibers dispersed in a polymer matrix, wherein at least 10% of the total number of fibers have a length greater than 0.55 mm. 
     
     
         2 . An article as in  claim 1 , having a void volume of at least about 5%. 
     
     
         3 - 6 . (canceled) 
     
     
         7 . An article as in  claim 1 , including at least one portion having a cross-sectional dimension of no more than about 0.100 inch. 
     
     
         8 . An article as in  claim 1 , having an average cell size of less than about 100 microns. 
     
     
         9 - 12 . (canceled) 
     
     
         13 . An article as in  claim 1 , wherein the article is injection-molded. 
     
     
         14 . (canceled) 
     
     
         15 . An article as in  claim 1 , having a cell density of at least about 10 6  cells per cubic centimeter. 
     
     
         16 . An article as in  claim 1 , having a length-to-thickness ratio is at least about 75:1. 
     
     
         17 - 18 . (canceled) 
     
     
         19 . A method of molding a polymeric article comprising:
 conveying polymeric material including a plurality of fibers dispersed therein in a downstream direction within a processing space in a polymer processing apparatus;   introducing a viscosity reducing additive into the polymeric material in the processing space to form a mixture of polymeric material and viscosity reducing additive;   injecting the mixture into a mold; and   forming a molded article, wherein at least 10% of the total number of fibers in the molded article have a length greater than 0.55 mm.   
     
     
         20 - 22 . (canceled) 
     
     
         23 . A method as in  claim 19 , wherein the article is microcellular. 
     
     
         24 . A method as in  claim 19 , further comprising forming a single-phase solution of the mixture and nucleating the single-phase solution while introducing the mixture into the mold, allowing the nucleated mixture to undergo cell growth, allowing the mixture to solidify in the shape of the mold to form a microcellular polymeric article in the shape of the mold, and removing the microcellular polymeric article from the mold while allowing the article to retain the shape of the mold. 
     
     
         25 . A method as in  claim 24 , comprising nucleating the single-phase solution by subjecting the solution to a pressure drop at a rate sufficient to cause nucleation while passing the stream into the mold. 
     
     
         26 - 43 . (canceled) 
     
     
         44 . A method of forming a polymeric article comprising:
 providing polymeric material including a plurality of fibers dispersed therein, the fibers having an average length of greater than 0.60 mm; and   injecting the polymeric material into a mold while maintaining the length of at least 10% of the total number of fibers at greater than 0.55 mm.   
     
     
         45 - 52 . (canceled) 
     
     
         53 . A method of molding a polymeric article comprising:
 conveying polymeric material including a plurality of fibers dispersed therein in a downstream direction within a processing space in a polymer processing apparatus;   introducing a viscosity reducing additive into the polymeric material in the processing space to form a mixture of polymeric material and viscosity reducing additive;   injecting the mixture into a mold; and   forming a molded article, wherein at least 70% of the total number of fibers in the molded article have a length greater than 0.21 mm.   
     
     
         54 - 57 . (canceled) 
     
     
         58 . A method of forming a polymeric article comprising:
 providing polymeric material including a plurality of fibers dispersed therein, the fibers having an average length of greater than 0.60 mm; and   injecting the polymeric material into a mold while maintaining the length of at least 70% of the fibers greater than 0.21 mm.   
     
     
         59 - 100 . (canceled)