POLYPROPYLENE FIBERS

Polypropylene fibers represent a small percent of the total polypropylene production. (Most polypropylene is used as a thermoplastic.) The fibers are usually manufactured from isotactic polypropylene. Important characteristics of polypropylene are high abrasion resistance, strength, low static buildup, and resistance to chemicals.

Crystallinity of fiber-grade polypropylene is moderate and when heated, it starts to soften at approximately 145°C and then melts at 170°C. The physical properties of fiber-grade polypropylene are given in Table 1.1.

Melt spinning is normally used to produce the fibers.  The high MP of polypropylene is attributed to low entropy of fusion arising from stiffening of the chain. Polypropylene fibers are used for face pile of needle felt, tufted carpets, upholstery fabrics, etc.

The total 1997 U.S. production of polyolefin fibers, including polypropylene fibers, was approximately 2.5 billion pounds.

Table 1.1 Physical properties of fiber-grade polypropylene