Coir Fibers - SWAXS Studies of Structural Changes Induced by Tensile Stress

Microfibril angle in coir fibers during tensile straining was studied by small-angle X-ray scattering in combination with the integrated TS 600 tensile stage. The experiment demonstrates the pos-sibility to characterize structural changes in complex materials during mechanical tests.


Natural fibers are used in a variety of textures which are used in many applications and products.

The microfibril angle (MFA) in lignocellulose, the es-sential structural feature of wood and natural fibers, represents the angle of helical windings of cellulose microfibrils in the secondary cell. Nature can tune the MFA in order to optimize mechanical tissue properties such as Young’s modulus, fracture stress and strain.

Coir fiber is obtained from the mesocarp of coconuts. It is a very common natural fiber consisting mainly of lignin and cellulose. The fiber is optimized for a maxi-mal fracture strain and therefore possesses also a maximal possible MFA of about 45°.

Previous studies of coir deformation behavior under tensile stress using synchrotron radiation have shown that the microfibril angle (MFA) of the cellulose fibers is directly proportional to the magnitude of the applied strain[1]. In this study the experiments were repeated using a laboratory small- and wide-angle system op-erated in point-collimation mode (Anton Paar SAXSpace and SAXSpoint systems). The fiber was measured with the integrated Tensile Stage (TS 600) which was used for applying tensile stress during the scattering experiment.


1. K. J. Martinschitz, P. Boesecke, C. J. Garvey, W. Gindl, J. Keckes, J. Mater. Sci. 43 (2008) 350

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