Lower heating value fiber

Absorption and Smelting Behavior. The absorption of moisture hy acetate and triacetate fibers generally depends on the relative humidity and whether equilibrium is approached from the dry or wci side. The percentage of moisture regain of commercial libers (ASTM Dl909-681. taken at 65% relative humidity for the ahsorplion cycle, is 6.5 lor acetate liber and 3.5 for triacetate. Heat treatment catt lower the ninislure regain of triacetate fiher. and values of 2.5-3.2% have heen observed. 

This is also true for PBT, as is shown by the study of as-extruded and heat-treated films of Feldman et al. [210]. The maximum values obtained for modulus and strength, 238 G Nm and 1.51 G Nm " respectively, are considerably lower than the largest fiber values, see Table 3. A study of the temperature and strain rate dependence of the deformation behaviour of these films revealed the onset of a structural reorganization near 300 °C, while the stress activation volume characterizing the activated rate process of the yield stress increased considerably above 200 °C [172]. 

As a result, the density of PAN based carbon fibers, ranging from 1.76 g/cm for HT fibers to 1.87 g/cm for HM fibers, is lower than that of mesopitch (MP) based carbon fibers, i.e., 2.0-2.20 glonf. As a result, the density of MP based carbon fibers approaches that of the ideal graphite single crystal, i.e., 2.278 g/cm [8]. Finally, a more preferred orientation of the coherent domains is achieved with MP based carbon fibers than with PAN based carbon fibers and it is improved for MP based fibers by raising the heat treatment temperature (HTT) and thereby reaching Z-values as low as 5°. 

Note RAYON-BASED CARBON FIBERS have a more isotropic structure than similarly heat treated polyacrylonitrile (PAN) or MESOPHASE PITCH (MPP) BASED CARBON FIBERS. Their Young s modulus values are, therefore, drastically lower (< 100 GPa). RAYON BASED CARBON FIBERS can be transformed into anisotropic CARBON FIBERS with high strength... 

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