Relationship between molecular orientation and draw ratio of polypropylene monofilaments

Abstract

The following empirical equation was derived for the relationship between molecular orientation α and permanent extension ratio λ of polypropylene monofilaments: α = 0.91(1 − 1/λ). The permanent extension ratio λ is the measured draw ratio adjusted to 1 when the orientation is zero. The standard deviation of the data points for 44 experimental filaments having different molecular weights, molecular weight distributions, and isotacticities about the line described by the equation was only 0.03. This equation is similar to a general empirical relationship between birefringence and draw ratio for several synthetic fibers derived by De Vries.