Patent ID: 8871130

Claim:
A process for solid state die drawing a polymer composition comprising: (a) providing a polymer composition comprising a filler and an orientable polymer, the polymer composition having a softening temperature, wherein the filler is organic, inorganic or a combination of organic and inorganic; (b) forming a billet from the polymer composition; (c) conditioning the temperature of the polymer composition to within an average drawing temperature, wherein the average drawing temperature is the average of the highest and lowest temperature along the cross sectional dimension and is at least 20° C. below the softening temperature and less than or equal to 40° C. below the softening temperature; (d) providing the billet to a drawing die, wherein the cross sectional dimensions of the billet before entering the drawing die and an exit of the drawing die correspond to a nominal draw ratio in the range of 1.2-8; (e) initiating drawing of the polymer composition while the polymer composition remains at the average drawing temperature; (f) drawing the conditioned polymer composition at the average drawing temperature through the drawing die at a minimum drawing rate of at least 127 centimeters (50 inches) per minute and a maximum drawing rate representative of a drawing force less than a tensile strength of the die drawn polymer composition; and (g) maintaining, during drawing, the temperature of the polymer composition at two different points along a cross sectional dimension of the polymer composition so that the temperature at the two different points differs by 10% or less from the average drawing temperature to reach a cavitation plateau in which a density of the die drawn polymer composition at the cavitation plateau differs by 10% or less from an average density calculated from the density of the polymer composition resulting from drawing at a rate above the minimum drawing rate for drawing rates differing by at least 10 centimeters per minute at a given average drawing temperature, wherein all cross sectional dimensions of the die drawn polymer are greater than 1.5 millimeters.