Figure 2-9. Techniques for using thermoplastics in textiles.
GPa GPa GPa
µ
m/m-K W/m-K MPa MPa kg/m
3
P100 Pitch 772 7 22 -0.44 520. 2440 700 2150
T300 PAN 231 14 22 -0.17 8.5 2970 2690 1770
AS4 PAN 248 13 21 -0.17 9.0 3490 2700 1800
IM6 PAN 276 12 19 -0.17 10.0 4500 2700 1770
IM7 PAN 276 12 19 -0.17 10.0 3940 2700 1740
S-2 Glass 90 90 36 0.50 9.0 2990 1570 2490
Kevlar-49 Aramid 112 7 3 -1.50 0.04 3040 1050 1440
A - Axial, T - Transverse,
σ
A
- Axial strength, k
A
- Axial thermal conductivity
The size of the yarn into which fibers are bundled is a very important parameter in a
textile composite. Yarn size is expressed as a filament count (the number of fibers, usually
in thousands or K); or as a linear density, either the denier (the number of grams in 9000 m
of yarn) or the yield (length per unit mass). Table 2.2 shows the relation between these
parameters for two carbon fibers and an aramid fiber. The nominal diameter of a circular
yarn is based by convention on an assumed packing fraction (area of fibers over area of the
circle) of 0.75. (This aasumption should not be carried into models of composite
properties. Fiber volume fractions should always be measured. See Sect. 5.)
