DENSE ARTICLES FORMED FROM TETRAFLUOROETHYLENE CORE SHELL COPOLYMERS AND METHODS OF MAKING THE SAME

摘要

A dense article that includes adense TFE copolymer film is provided. The denseTFE copolymer film includes a first endothermbetween about 50°C and about 300°C, a secondendotherm between about 320°C and about 350°C,and a third endotherm between about 350°C andabout 400°C. To form the dense article, a coreshell TFE copolymer is formed into a pellet, ramextruded into a tape, dried into a dried preform,and then stretched into a dense TFE copolymerfilm that exhibits improved physical andmechanical properties. The dense TFE copolymer film isproduced directly from the dried preform at adeformation temperature less than about 335°C andwithout increasing the porosity of the driedpreform, as would conventionally be done inexpansion processes. The dense TFE copolymer filmshave a methane permeability less than about20µg*micron/cm2/min. The dense articles have avoid volume less than about 20%.