such as taught within u s pat no 4 016 118 to hamada et al for example fibers clearly differ in structure since they must exhibit a length that far exceeds its cross sectional area such for example its diameter for round fibers fibers are extruded and drawn articles are blow molded or injection molded to name two alternative production methods also the crystalline morphology of polypropylene within fibers is different than that of standard articles plaques sheets and the like for instance the dpf of such polypropylene fibers is at most about 5000 whereas the dpf of these other articles is much greater polypropylene articles generally exhibit spherulitic crystals while fibers exhibit elongated extended crystal structures thus there is a great difference in structure between fibers and polypropylene articles such that any predictions made for spherulitic particles crystals of colored polypropylene articles do not provide any basis for determining the effectiveness of coloring agents as additives within polypropylene fibers for instance plaques made with pigments can exhibit bright deep shades and still appear transparent in fiber form dullness low brightness and opacity are prominent when deep shades of pigmented fibers are produced thus the significant differences in form and structure between sheet like articles and fibers and or yarns of the same thermoplastic make it difficult to predict how effective a specific coloring agent may perform within one through knowledge of the other the coloring agents particularly useful within this invention are those that are liquid in nature preferably though not necessarily polymeric in nature i e poly oxyalkylenated to the extent that.