The state of high global chain orientation but nearly random segmental orientation of amorphous polymers

Abstract

AbstractIn the rubbery state of amorphous polymers under uni‐axial drawing the global chain orientation will relax in orders of magnitude slower than the relaxation of local segmental orientation. When this state of hot drawn sample is frozen at temperatures lower than its glass transition, Tg, an amorphous state with high global chain orientation but nearly random segmental orientation (GOLR) could result. Experimentally the GOLR state of amorphous polymers is easily realized by uni‐axial drawing the polymer at temperatures 20–30°C above its Tg. The characteristic features of a GOLR state are i) large recovery of the elastic deformation of global chain on being heated to temperatures above Tg, ii) very small birefringence and IR dichroism, iii) nearly isotropic sonic and ultrasonic velocity of propagation, iv) nearly isotropic WAXD pattern, while it shows v) pronounced anisotropy in stress‐strain behavior for large deformations and vi) appreciable anisotropy of thermal conductivity and of microwave dielectric properties. Concrete examples with detailed experimental results will be reviewed.