| 摘要 |
Polyparaxylyiene (PPX) polymers that can be expanded into porous articles that have a node and fibril microstructure are provided. The fibrils contain PPX polymer chains oriented with the fibril axis. The PPX polymer may contain one or more comonomer. PPX polymer articles may be formed by applying PPX to a substrate by vapor deposition. The nominal thickness of the PPX polymer film is less than about 50 microns. The PPX polymer film may be removed from the substrate to form a free-standing PPX polymer film, which may then be stretched into a porous article. Alternatively, a PPX polymer article can be formed by lubricating PPX polymer powder, heating the lubricated powder, and calendering or ram extruding to produce a preform that can subsequently be stretched into a porous article. The heating and expansion temperatures are from about 80°C to about 220°C or from about 220°C to about 290°C or from about 290°C to about 450°C. |
