Stability boundaries for spinning of fibres based on poly-p-phenylene terephthalamide through an air gap

Abstract

The restriction of the zone of stationary jet flow of LC sulfuric-acid solutions of PPTA and the conditions of stable spinning of fibres with small air gaps using spinnerets with small-diameter channels is explained with the well-known theory of resonance in drawing for viscoelastic, non-Newtonian media in continuation of the effect of shear flow in the channels on longitudinal flow in the jets. In spinning fibres from 19.5% LC sulfuric acid solutions of PPTA and copolyamide, drawing of the jet in the spinning bath supplements drawing of the jet in the air gap. The former is slight and is a function of the stress created in deformation of the LC solution in the air gap, area of the jet cross-section on the surface of the spinning bath, and type of polymer. The conditions of extreme spinning regimes with breaks in PPTA and polyamide monofilaments in the spinning bath medium in the absence of resonance in drawing of the jet in an air gap are presented.