Comparative mechanical and thermal study of chemically treated and untreated single sugarcane fiber bundle

- A systematic study on the properties of the single sugarcane fiber bundle was performed.
- Percentage of cellulose is increased in fibers through chemical treatments.
- Tensile strength, modulus, and strain were improved by 107%, 21% and 26%, respectively.
- Decomposition temperature is enhanced by about 50 °C due to chemical treatments.
- Treated fibers exhibited greater energy absorption ability during loading.

Natural fiber as a reinforcing constituent can play a dominant role in the field of fiber reinforced polymer composites (FRPC) due to its availability, eco-friendliness, renewability, CO2-neutrality, flexibility, low density, and low cost. Sugarcane fiber can be a potential candidate to replace the synthetic FRPC. The objective of this study is to evaluate the effect of chemical treatment on the tensile, thermal, and morphological properties of single sugarcane fiber bundles. Locally grown sugarcane was cut into specific lengths from the internode section and the single fiber bundles were extracted from the rind region. These fiber bundles were then dried in an oven to remove the moisture. Surface modification of fiber bundles was accomplished by performing alkali treatment and neutralized by acetic acid solution. The fiber bundles were then rinsed with water and dried at 80 °C for about 24 h in an oven. Optical Microscopy (OM) was employed to measure the diameter of the single fiber bundle which ranged from 0.260 mm (untreated) to 0.155 mm (treated). Tensile tests were carried out on single fiber bundles according to the ASTM standard. Correction factors were also applied for machine displacement and slippage of the fiber bundle. Data from tensile tests showed that maximum improvement in the tensile strength and modulus for the treated fiber bundles were observed to be 106.83% and 20.46%, respectively, compared to those of untreated ones. Strain to maximum strength was enhanced by 25.92% in the treated fiber bundles compared to that of the untreated one. Untreated fiber bundles were observed in Thermogravimetric Analysis (TGA) studies to start decomposing at around 200 °C compared to about 250 °C for treated ones. Differential Scanning Calorimetry (DSC) provided the amount of moisture content present in treated and untreated fiber bundles which matched with the TGA results. Fourier Transformed Infrared Spectroscopy (FTIR) revealed structural modification after treatment. Scanning Electron Microscopy (SEM) was used to evaluate the fracture morphology of failed samples. Fracture morphology of the treated fiber bundles revealed cleaner and rougher fracture surfaces compared to those of untreated ones.

Stress-strain curve for corrected untreated, 1% and 5% alkali treated fiber bundles, (2) comparison of Young's modulus for corrected and uncorrected one, (3) comparison of strain to maximum strength for corrected and uncorrected one, and (4) fracture surfaces of 5% alkali treated fiber bundle: (A) 200×, (B) 500×, (C) 1000×, and (D) 2000×.