"Foil spintrusion" of high-performance polymer films

This article describes the development of high-performance polymer foils by direct orientation in the liquid-crystalline phase of a thermotropic copolyester, based on p-hydroxybenzoic acid (HBA) and 2-hydroxy-6-naphthoic acid (HNA), better known under the trade name Vectra®. Application of a simple air-gap-filament-fusion-extrusion process ("foil spintrusion") with the use of a newly developed die, results in highly oriented free-standing foils, as thin as 3 µm. These foils have a mechanical performance that is comparable with those of commercially produced fibers of the same material. These uniaxially oriented foils could be laminated upon hot-compacting without, or with as little as 5 wt % of an adhesive, yielding planar foils as thin as 18 µm, which feature excellent isotropic, in-plane mechanical properties, that is, a Young's modulus E = 20 GPa and a tensile strength s = 0.5 GPa.