High-modulus and high-strength polypropylene fibers and films

Abstract

Many studies on improvements of mechanical properties in isotactic polypropylene (iPP) fibers and films have been performed by researchers since 1964. The ultimate values of modulus and strength are the crystal modulus along molecular chains and theoretical strength calculated on the basis of the bond energies and the cross-section of a molecular chain. The high-modulus and high-strength fiber has to possess a high molecular orientation and a high crystallinity. Fortunately, iPP can be easily drawn and crystallized up to fairly high degrees of orientation and crystallinity. The maximum values of Young's modulus and tensile strength reported up to date are 36–40 GPa and 1.5 GPa, respectively. Further, the polymer has desirable characteristics, such as a low density, chemical resistance and hydrophobic properties. Therefore, the highmodulus and high-strength iPP fibers and films are highly ranked among those of flexible chain polymers.