Structural, Chemical And Physical Properties Of Palms Fiber

Now the Chinese government encourages people to develop low-carbon economy. The shortage of woody material is receiving considerable attention in the entire world, together with greenhouse effect. It is essential to find some other plants for usage except wood. PALMAE is one monocot family, which has about 210 genus and 2800 species, and most species of this family grow in tropical and subtropical area, especially in tropical Asian and America. Comparing with other plants from PALMAE, windmill palm (Trachycarpus fortunei) is a widely distributing monocot. Windmill palm grows in large parts of the world where few other palms do and it could serve there as a local source of fiber, wax, etc. From ancient time people already use its leaf sheath fibers for making ropes and the rope shows nice decay resistance. In tropical area people use palm trunks for building construction.By using polarization microscope and transmission electron microscope (TEM), the multilayered cell walls of palm fiber were observed and the cell wall of each fiber has 3 layers at least. The scanning electron microscope (SEM) showed that the whole fiber bundle's surface was covered by silica bodies. This can be a reason why palm fiber is decay resistance material.Several leaf sheaths were tested along its axial direction by FT-IR (ATR), the transformation of chemical contents in leaf sheath from bottom to top part was found. As fibers becoming matured, parenchyma detached from fibers. Without the connection of ground parenchyma, fibers were separated. The contents of cellulose and hemicelluloses tended to decrease gradually in each leaf sheath, while lignin increased.Palm's leaf sheath fiber has two styles:big vascular bundles and small fibrous bundles. And these fibers grow in different direction, which make them showing crisscross pattern in tangential sight of trunk. During tensile strength testing, typical stress-strain curves of the fiber bundles were obtained. They show yielding followed by plastic deformation until the breakage from 20-70% strain for each fiber. Fibers from every piece of leaf sheath were separated into three layers according to its direction and size. The mean diameters of fiber bundles from one sheet, which are separated into inside, middle and outside layers, are 202.1μm,418.0μm and 342.5μm. The diameter of fiber bundles ranged from 147 to 547μm. The smallest one was composed of 33 fiber cells, while the largest one 574 fiber cells. Although inner layer fibers are thinner, they have higher values of the mean tensile strength 113.9MPa and Young's modulus 1249.0MPa than other layers. Some specimens for tensile strength test were broken after test, while some just had a high strain and without fractured. By SEM observation, the fracture surface of broken fibers was checked.