Alignment of silicon carbide whiskers in polymer matrix

Polyacrylonitrile (PAN) loaded with up to 70% by weight of silicon carbide whiskers has been used as a model system to demonstrate the potential of whisker alignment by a technique similar to the conventional fibre spinning. Continuous fibres containing high percentages of whiskers can be readily produced using a laboratory scale conventional wet-spinning apparatus. Excellent whisker alignment along the fibre axes was found even for the as-extruded filaments without drawing. However, an improved alignment was obtained through optimizing whisker loading and by drawing the as-spun fibres. Drawing tends to improve the fibre mechanical properties considerably, rendering them easily handable or even useful as a ''composite fibre'' reinforcement in their own right. Although whisker alignment generally gets better with drawing, over-stretching leads to irregular fibre diameters. Preliminary experiments show that after some minor modifications, this technique may be applied to fabricate whisker reinforced ceramic composites.