2.7. X-ray diffraction analysis
The X-ray diffraction (XRD) patterns were measured for
raw wood fibers, chemical-purified cellulose fibers, and isolated
nanofibers with an X-ray diffractometer (D/max 2200, Rigaku,
Japan) using Ni-filtered Cu K radiation ( = 1.5406A˚ ) at 40 kV and
30 mA. Scattered radiation was detected in the range of 2 = 10–30◦
at a scan rate of 4◦/min. The crystallinity index (CI) was calculated
from the heights of the 2 0 0 peak (I200, 2 = 22.6◦) and the intensity
minimum between the 2 0 0 and 1 1 0 peaks (Iam, 2 =18◦) using the
Segal method (Eq. (1)). I200 represents both crystalline and amor-