ALIGNMENT OF SILICON-CARBIDE WHISKERS IN POLYMER MATRIX

Polyacrylonitrile (PAN) loaded with up to 70% by weight of silicon car bide whiskers has been used as a model system to demonstrate the poten tial of whisker alignment by a technique similar to the conventional f ibre spinning. Continuous fibres containing high percentages of whiske rs can be readily produced using a laboratory scale conventional wet-s pinning apparatus. Excellent whisker alignment along the fibre axes wa s found even for the as-extruded filaments without drawing. However, a n improved alignment was obtained through optimizing whisker loading a nd by drawing the as-spun fibres. Drawing tends to improve the fibre m echanical properties considerably, rendering them easily handable or e ven useful as a ''composite fibre'' reinforcement in their own right. Although whisker alignment generally gets better with drawing, over-st retching leads to irregular fibre diameters. Preliminary experiments s how that after some minor modifications, this technique may be applied to fabricate whisker reinforced ceramic composites.