X-ray Diffraction: An Efficient Method to Determine Microfibrillar Angle of Dry and Matured Cellulosic Fibers

Cellulose is a naturally occurring unbranched polymer containing microfibrils in the secondary cell wall of the plant fibers oriented at an angle called Microfibrillar Angle (MFA) with respect to the fiber axis. This important structural parameter influences the mechanical behavior and the tensile properties of these fibers and eventually their composites. This study discloses the technique to determine the mean MFA of dry and matured cellulosic fibers extracted from Cocos nucifera fruit by X-ray diffraction from the peak diffraction intensity and the values are compared statistically with the MFA obtained from the strain-induced during the tensile test. The mean MFA value of the fibers obtained using the X-ray diffraction technique is 27.32 ± 0.41°. This value is in accordance with the MFA value (29.91 ± 1.51°) obtained using the global strain equation and the slight disparity could be attributed to the non-uniformity of the fiber cross-section and the external pulling forces that could cause reorganization of amorphous and crystalline contents in the cell wall. This technique is simple, inexpensive, and fairly accurate with no cumbersome processing.