A method for manufacturing a film or sheet comprises deforming a polymeric alloy at a temperature effective to impart to the deformed alloy a birefringence retardation of greater than or equal to about 350 nanometers. A method of substantially eliminating comets and veins in an optical film or sheet...http://www.google.co.uk/patents/US7087682?utm_source=gb-gplus-sharePatent US7087682 - Polymeric blends for optical devices and method of manufacture thereof
