| Abstrakt: |
This study investigates the relationships between the composition, cell wall microstructure, and mechanical properties of the abaca fiber. Raw abaca fibers have undergone a series of sequential chemical treatments (acetone/methanol, boiling water, EDTA, HCl, NaClO2, and NaOH) to selectively remove certain non-cellulosic components (NCCs) in the fiber, such as waxes, water-soluble fragments, pectin, and lignin in a step-by-step manner. Changes in composition, morphology, and mechanical properties were observed using FTIR spectroscopy and ion chromatography, digital microscope and SEM, and tensile tests, respectively. The raw fiber was composed of 23% NCCs, 18% hemicellulose, and 58% cellulose, and exhibited a 17.4 GPa Young’s modulus and a 444 MPa tensile strength. Furthermore, the raw abaca fibers demonstrated a linear tensile graph without yielding, and a planar fracture surface without fiber pull-outs, thus suggesting a highly elastic but brittle nature. At the end of the alkali treatment, the fibrillated fiber was 83% cellulose, yet the stiffness and strength dropped to 7.3 GPa and 55 MPa, respectively, as more components were removed, and microfibril relaxation and realignment have occurred. Load-bearing cellulose and hemicellulose accounted for 42% and 36% of the stiffness, respectively, due to –OH groups capable of hydrogen bonding. 63% of the strength was due to thenative NCC matrices, which contribute a significant role within the cell wall’s load-transfer activities. |
