W. L. Gore & Associates, Inc.

Gregory J Shafer

Guy A Sbriglia

Lawrence A Ford

Michael E Kennedy

Shaofeng Ran

Todd S Sayler

VDF-co-(TFE or TrFE) polymers having a molecular weight of at least about 1,000,000 g/mol and a melt temperature less than about 240&#xb0; C. The VDF copolymer contains at least about 50 mol % VDF monomer and may include an amount of at least one other monomer. The VDF copolymer may be used to form a membrane that has a node and fibril structure. The membrane has a percent porosity of at least 25%. A VDF-co-(TFE or TrFE) polymer membrane may be formed by lubricating the VDF copolymer, subjecting the lubricated polymer to pressure at a temperature below the melting point of the VDF copolymer to form a preform material, and expanding the preform material at a temperature below the melting temperature of the VDF copolymer. Dense VDF copolymer articles, filled VDF copolymer membranes, and VDF copolymer fibers are also provided.

Articles Produced from VDF-co-(TFE or TrFE) Polymers

Articles produced from VDF-co-(TFE or TrFE) polymers

A tetrafluoroethylene (TFE) copolymer film having a first endotherm between about 50&#xb0; C. and about 300&#xb0; C., a second endotherm between about 320&#xb0; C. and about 350&#xb0; C., and a third endotherm between about 350&#xb0; C. and about 400&#xb0; C. is provided. In exemplary embodiments, the third endotherm is approximately 380&#xb0; C. In some embodiments, the second endotherm is between about 320&#xb0; C. and about 330&#xb0; C. or between about 330&#xb0; C. and about 350&#xb0; C. TFE copolymer films have a methane permeability less than about 20 &#x3bc;g*micron/cm/min. In addition, the dense articles have a void volume of less than about 20%. Methods for dense articles from core shell tetrafluoroethylene copolymers are also provided. The dense articles exhibit improved physical and mechanical properties such as adhesion and barrier properties.

Dense articles formed tetrafluoroethylene core shell copolymers and methods of making the same

Dense articles formed from tetrafluoroethylene core shell copolymers and methods of making the same

A dense article that includes a dense TFE copolymer film is provided. The dense TFE copolymer film includes a first endotherm between about 50&#xb0; C. and about 300&#xb0; C., a second endotherm between about 320&#xb0; C. and about 350&#xb0; C., and a third endotherm between about 350&#xb0; C. and about 400&#xb0; C. To form the dense article, a core shell TFE copolymer is formed into a pellet, ram extruded into a tape, dried into a dried preform, and then stretched into a dense TFE copolymer film that exhibits improved physical and mechanical properties. The dense TFE copolymer film is produced directly from the dried preform at a deformation temperature less than about 335&#xb0; C. and without increasing the porosity of the dried preform, as would conventionally be done in expansion processes. The dense TFE copolymer films have a methane permeability less than about 20 &#x3bc;g*micron/cm/min. The dense articles have a void volume less than about 20%.

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Oxford, PA, United States of America

Gregory J Shafer