Production and Properties of High-Modulus—High-Tenacity Polypropylene Filaments

Polypropylene (PP) filaments have become one of the most important industrial filaments. Fibers from advanced Ziegler-Natta and metallocene catalyst-based polypropylene have made inroads in technical textiles. High-modulus—high-tenacity PP filaments have found various uses in industrial applications on the basis of their superior properties and inert nature. The feed parameters as well as the processing variables - all have an important impact on the ultimate properties of PP filament, as has been observed by various researchers. This article critically reviews the production of high-modulus—high-tenacity PP filament along with proposed changes in microstructure leading to the superior mechanical properties. The contribution of crystallite and amorphous orientations, amorphous modulus, crystallinity, taut-tie molecules, and flaws in the shaping of mechanical properties of such filaments have been discussed. The chasm between practical and theoretical values in modulus and tenacity values are still large and a great deal of challenge involved in achieving high draw ratios. In most of the cases, high draw ratios have been achieved with single or multiple steps but with low strain rates and low processing speeds. Majority of the processes are batch processes and limits productivity.