PREPARATION AND CHARACTERIZATION OF SPINNING DOPES FOR DRY SPINNING OF CONTINUOUS ALUMINA GREEN FIBERS

Aqueous spinning dopes for dry spinning of alumina green fibers were prepared by using basic aluminium chloride Al2(OH)5Cl . 2.5 H2O and SiO2 sol as inorganic components and poly(vinyl alcohol) (PVA) as polymeric organic component. Certain rheological properties of the mixtures are essential to achieve good spinnability at high spinning speeds. The rheology of the dope is influenced by the molecular weight and the degree of hydrolysis of the PVA, as well as by the composition and the concentration of the mixture. For mixtures without SiO2 best resultS were obtained at a PVA: Al2O3 mass ratio of 18:82 and an oxide content of about 27 wt.-%. The PVA used has an average molecular weight of 70000 and a degree of hydrolysis of 89%. The dopes were spun to continuous green fibers at speeds up to 500 m/min. The structure and the ageing behaviour of concentrated solutions of basic aluminium chloride has been intensively studied.