Page 185 - Fiber Fracture

170 J.G. Lavin

Standard Disruption Gradual
Orientation

J.

Variable High High Thermal
Strength Strength Conductivity
Fig. 16. Influence of spinneret design on fiber morphology.

limits, appears to have minimal influence in changing the general 'structure' established
in the filament formation step. Subsequent heat treatment densifies the initial structure,
i.e., increases the packing to increase tensile and thermal properties and modulus.
The use of non-round pitch carbon fiber cross-section provides an alternate approach
to modify 'structure' with potential enhancement of fiber adhesion to matrices, improved
surface characteristics or improved conductivity. This forced filament geometry is
routinely practiced with several polymeric systems in melt spinning to control product
response. Ribbon and C-shaped carbon fibers have been provided to accomplish this, as

Radial Onion-sk in Random " Pac -man "

Flat -layer Radial -folded Line-or igin "Dog- bone"

Fig. 17. Summary of possible carbon fiber morphologies.