Polypropylene filler rods for optical fiber communications cables

Abstract

A filler rod for occupying space in a stranded optical fiber communications cable having at least one buffer tube containing at least one optical fiber is disclosed. The filler rod comprises an elongated rod extruded from a polypropylene homopolymer, a polypropylene-polyethylene copolymer (i-PP) resin material, or preferably, from a polypropylene-polyethylene copolymer having a nucleating agent disbursed therein. The resin material is foamed during extrusion so as to have a plurality of void spaces therein and a relative density which is less than 1 relative to the unfoamed resin material. As compared to rods made from high density polyethylene, the i-PP filler rods show a greater foaming efficiency, more efficient use of material, an improved combination of mechanical properties and density, reduced post-extrusion shrinkage and a substantial reduction in the sticking of the filler rods to the outer jacket that is experienced with high density polyethylene filler rods.

Dependencies are inferred from the claim text.