The preparation of ultra-high modulus polypropylene films and fibres

Following the discovery that linear polyethylene can be drawn to very high draw ratios to produce oriented fibres and films with ultra-high initial moduli, a similar study has been undertaken for polypropylene. In particular, the modulus/draw ratio relationship has been obtained for a range of polymers of different molecular weight and molecular weight distribution. The effects of thermal history and draw temperature were studied, and it was shown that under optimum conditions material with an initial modulus at room temperature of 1.9 × 10¹⁰ Nm^?2 (205 gdtex, 3 × 10⁶ psi) can be obtained. This value is at least 50 percent greater than those previously recorded for drawn fibres and about one half of the theoretical modulus.