A Study on Structural Changes During the Thermal Stabilization Stage of Hemp Fibers Impregnated with Phosphoric Acid Before Carbonization and Activation 


Vol. 26,  No. 2, pp. 685-696, Feb.  2025
10.1007/s12221-024-00835-7


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  Abstract

After being wet treated with 4% phosphoric acid (H3PO4) aqueous solution, industrial hemp fiber was subjected to thermal stabilization processes at temperatures of 160, 180, 200, 220, 240 and finally 250 °C and holding times of 30 min. Some basic analyses were used to determine the structural and characteristic changes of all samples for the thermal stabilization of hemp fibers in an oxygen environment before the carbonization and activation processes. These included linear density, fiber thickness, flame testing, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), infrared spectroscopy (IR), X-ray diffraction, and Scanning Electron Microscopy (SEM) measurements. DSC analysis showed that impregnation of the phosphoric acid (PA) mixture increased thermal stabilization and prevented the formation of volatile products by blocking the hydroxyl groups in the cellulose structure. TGA thermograms showed an increase in carbon yield at increasing stabilization temperature values. The results from XRD indicated that the cellulose II crystal structure disappears with the increase of the stabilization temperature and an amorphous structure appears. IR spectra show that the partial loss of intramolecular and intermolecular hydrogen bonds continues as a result of the simultaneous removal of hydroxyl groups and water removal reactions. After a 250 °C stabilization, the carbon yield at 900 °C was 42%. These findings highlight the importance of H3PO4 in accelerating the formation of an aromatic structure, which is critical for withstanding the high temperatures of subsequent carbonization and activation stages.

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  Cite this article

[IEEE Style]

A. Gül, "A Study on Structural Changes During the Thermal Stabilization Stage of Hemp Fibers Impregnated with Phosphoric Acid Before Carbonization and Activation," Fibers and Polymers, vol. 26, no. 2, pp. 685-696, 2025. DOI: 10.1007/s12221-024-00835-7.

[ACM Style]

Abdullah Gül. 2025. A Study on Structural Changes During the Thermal Stabilization Stage of Hemp Fibers Impregnated with Phosphoric Acid Before Carbonization and Activation. Fibers and Polymers, 26, 2, (2025), 685-696. DOI: 10.1007/s12221-024-00835-7.

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pISSN : 1229 - 9197
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