this invention relates to a method of uniaxially expanding a fluoropolymer product including the steps of expanding a green fluoropolymer product in a first direction to create a first - expanded fluoropolymer product , and expanding the first - expanded fluoropolymer product in the same first direction . as a result with the subject invention , it has been found that ultra - high expansion and a variety of different porous / fibril structures can be achieved by using subsequent expansion steps in the same direction . various considerations exist with such methodology , including the selection of rates of expansion of both steps , the amount of expansion of both steps , pre - heating and cutting the product between expansion steps . although the present invention can be used with various fluoropolymer products , it is particularly well - suited for use with ptfe .