The mechanical and optical properties of oriented fibres of semicrystalline polymers

The mechanical properties of semicrystalline polymers are very much dependent on the molecular orientation. The orientation function to deal with the elastic moduli data of Hadley et al. (1969) are treated under new aspects. To determine the nature of orientation function from empirical data a relation of the form Sinθ=f (n) Sinθ′ is assumed to describe the change in the orientation angle of a unit from θ′ to θ for the draw ration. Birefringence experimental data are used to find the orientation functionf (n) which is then used to calculate elastic properties. The agreement of the experimental values ofE ₀ andE ₉₀ over the entire draw ratio range is found to be satisfactory for Nylon, low density polyethylene and polyethylene terephthalate. This furnishes strong empirical evidence for the validity of the orientational model for the above substances.