High tenacity, high modulus thermoplastic fibres etc. - made by soln. spinning, two=stage gelling and drying to xerogel with stretching of gel

摘要

Solutions of ultrahigh molecular weigh polymers such as polyethylene in a relatively non-volatile solvent are extruded through an aperture (25) at constant concentration through the aperture and cooled to form a first gel of indefinite length (33). The first gels are extracted (D) with a volatile solvent to form a second gel (41) and the second gel is dried (E) to form a low porosity xerogel (47). The first gel, second gel or xerogel, or a combination, are stretched (F). Among the products obtainable are polyethylene fibers of greater than 38 or even 40 g/denier tenacity and of modulus greater than 1000 or even 1600 or 2000 g/denier.