Ultradrawing of amorphous polymers by coextrusion illustrated with atactic polystyrene

Films of pure and high‐impact atactic polystyrene were prepared by the recently developed technique of solid‐state coextrusion. The films were produced at extrusion rates ≥4 cm/min at 126°C with a maximum extrusion draw ratio (EDR) of 11.6. These ultradrawn films are fibrous, have a high birefringence of −2.24 × 10−2, and exhibit a 72% elastic recovery. The material has a tensile modulus of ∼4–5 GPa and a tensile strength to break of 85 MPa. Thermal analysis suggests a constant Tg.