One of the latest members of the rapidly growing therrnoplastic polymer family which appears capable of successfully competing with the currently saturated textile and chemical markets is polypropylene fiber. The objectives of this Thesis were to: (1) examine the effects of polymer characteristics and fiber processing conditions on the properties of polypropylene fibers, and (2) correlate all existing information on the physical, chemical, and mechanical properties of polypropylene fibers and comparatively evaluate this material with other fibers, natural and synthetic.

Polypropylene is the first member of a new group of polymers prepared by a mechanism defined as "stereospecific" polymerization. From a simple monomer, this technique produces a polypropylene with an exceptionally uniform molecular structure which imparts outstanding engineering properties into the polymer. Such structural regularity can be varied to tailor the properties of the polymer to best satisfy a given requirement.

The low costs of propylene monomer and the polymerization process give polypropylene a cost advantage over similar products. In addition, polypropylene fibers, because of their structural uniqueness, exhibit outstanding physical properties relative to other commercial fibers. The density of polypropylene is the lowest of any fiber available; super-tenacity polypropylene fibers have been prepared that exceed the strength of all commercial fibers - including the much more expensive nylons. Polypropylene fibers also excel in other important physical properties, such as toughness, resilience, permeability, chemical resistance, and abrasion resistance.

The major problem with regard to widespread use of polypropylene is limited dyeability, a characteristic which stems from the inherent inertness of the polypropylene structure to permeants. However, in view of the major research effort devoted to this problem, it is reasonable to expect that an answer is forthcoming.

In summary the relative low polymer cost and outstanding properties of polypropylene fibers rank this material as one of the important fibers of the future.