a ratio of 1 88 1 and each filament exhibited a density of about 0 87 gm cc the foamed yarn had the following tensile properties denier equal to 138 20 tensile modulus equal to 12 5 g d tenacity equal to 1 4 g d and elongation at break equal to 31 4 the foamed yarn exhibited approximately 326 cells per 20 filament with asymmetric cell distribution the cell sizes varied from about 1 u03bc to about 5 u03bc if the foamed yarns were heated each foamed filament would exhibit the self crimping effect a blend of polyethylene terephthalate and ficel u00ae in an amount equal to about 0 5 by weight was spun through a 6 hole circular cross section spinnerette die to produce a foamed fiber product having a density of approximately 0 9 g cc the foamed fiber product was then drawn at a ratio of about 2 5 1 to produce 8 5 denier filament the foamed product produced by this process is a self crimping foamed fiber the void size over a given cross sectional area of the foamed fiber ranges from one micron to as much as ten microns the total percentage of close cells is at least about 10 of the cross sectional area of the.