Studies on the orientation phenomena by fiber formation from polymer melts. III. Effect of structure on orientation. Condensation polymers

Abstract

The principal regularities of molecular orientation occurring by fiber formation from polymer melts have been proved for several polyamides, copolyamides, polyurethane, and polyester. It has been found for these polymers, as for the formerly investigated polycapronamide, that fiber birefringence (used as a comparative measure of the mean degree of macromolecular orientation) practically does not depend on the deformation ratio S = V_E/V₀, and monotonically increases with velocity difference (V_E − V₀) and reciprocal fiber diameter ϕ_E⁻¹ (measure of cooling rate). Hence the general character of the postulated mechanism of orientation, simultaneous action of velocity field and thermal relaxation, seems to be proved for the typical fiberforming polymers. The differences between the shapes of characteristics birefringence–velocity difference, birefringence–spinning stress, and between the x‐ray patterns of polyamides and polyester have been interpreted in terms of molecular structure and occurrence of H bonds.