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Periodic disorder along ramie cellulose microfibrils.
Yoshiharu Nishiyama1, Ung-Jin Kim, Dae-Young Kim
1School of Agricultural and Life Science, The University of Tokyo, Tokyo 113-8657, Japan. nishiy@sbp.fp.a.u-tokyo.ac.jp
Biomacromolecules
|July 15, 2003
Summary
Small angle neutron scattering revealed a 150 nm periodicity in ramie cellulose fibers. This structural feature, linked to microfibril arrangement, was not observed in cotton wood fibers due to lower microfibril orientation.
Area of Science:
- Materials Science
- Biophysics
- Polymer Science
Background:
- Cellulose fibers are crucial natural polymers with complex hierarchical structures.
- Understanding the arrangement of cellulose microfibrils is key to optimizing their material properties.
- Neutron scattering offers a unique method to probe structural details in biological materials.
Purpose of the Study:
- To investigate the longitudinal periodicity of cellulose microfibrils in ramie and cotton wood fibers.
- To correlate structural periodicity with the degree of polymerization and microfibril organization.
- To elucidate the structural differences between ramie and cotton wood cellulose.
Main Methods:
- Small-angle neutron scattering (SANS) with deuterium labeling to enhance contrast.
- Electron microscopy for visualizing fiber structure.
- Acid hydrolysis, gel permeation chromatography, and viscosity measurements to determine polymer characteristics.
Main Results:
- A meridional Bragg reflection indicating a 150 nm longitudinal periodicity was observed in ramie fibers.
- This periodicity correlated precisely with the leveling off degree of polymerization (LODP) after acid hydrolysis.
- Cotton wood fibers did not exhibit a Bragg reflection, suggesting less ordered microfibril orientation.
Conclusions:
- Ramie cellulose microfibrils exhibit a distinct longitudinal periodicity of approximately 150 nm.
- This periodicity is attributed to the arrangement of crystalline and disordered regions within the microfibrils.
- The findings highlight differences in microfibril organization between ramie and cotton wood, impacting their structural characteristics.