W. L. Gore & Associates, Inc.

Bryan Hutchinson

Justin John Skaife

Bret Alan Snyder

Self-supporting uniaxially expanded polytetrafluoroethylene (ePTFE) membranes that have high intrinsic strength, a high matrix modulus, and a high crystallinity index are provided. In some embodiments, the ePTFE membrane is stretched in the machine direction. Uniaxially oriented ePTFE membranes have a matrix tensile strength at least about 1000 MPa in the machine direction, a matrix modulus at least about 100 GPa ambient temperature (i. e., about 20° C.), and a crystallinity index of at least about 94%. In some embodiments, the ePTFE membrane has a tenacity greater than or equal to about 5 gf/d and a denier less than or equal to about 750 g/9000 m. In addition, the uniaxially oriented ePTFE membranes have a <P2> orientation of at least about 0.98. Also, the fibrils in the ePTFE membranes have a nearly perfect parallel alignment. The ePTFE membrane may be used to form composites, laminates, fibers, tapes, sheets, tubes, or other three-dimensional objects.

Highly oriented expanded polytetrafluoroethylene with superior stiffness

Thin, self-supporting biaxially expanded polytetrafluoroethylene (ePTFE) membranes that have a high crystallinity index, high intrinsic strength, low areal density (i.e., lightweight), and high optical transparency are provided. In particular, the ePTFE membrane may have a crystallinity index of at least about 94% and a matrix tensile strength at least about 600 MPa in both longitudinal nd transverse directions. In addition, the ePTFE membrane is transparent or invisible to the naked eye through a complete conversion of the PTFE primary particles into fibrils. The ePTFE membrane may have a thickness per layer of less than 100 nm and a porosity reater than 50%. Further, the ePTFE membrane is stackable, which, in turn, may be used to control permeability, pore size, and/or bulk mechanical properties. The ePTFE membrane may be used to form composites, laminates, fibers, tapes, sheets, tubes, or three-dimensional objects. Additionally, the ePTFE membrane may be used in filtration applications.

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Newark, DE, United States of America

Bryan Hutchinson