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Balsa and kapok fibers are by-products of community plantations. Both fibers have not been optimally utilized in Indonesia. The high holocellulose content and low lignin content of these fibers indicate the potential to be used as a nanocellulose raw material with a simple extraction. The objective of this study was to extract cellulose nanocrystals (CNCs) from balsa and kapok fibers through a direct extraction without pre-treatment. CNCs from balsa and kapok fibers were prepared by a one-step procedure with ammonium persulfate solution (APS) at concentrations of 1, 1.5, and 2 mol/L. The CNCs were characterized by determining their morphology, functional groups, crystallinity, and thermal stability using transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis, respectively. The results showed that the diameter of the CNCs was in the range of 1.25–11.87 nm depending on the APS concentration and the fiber type. APS dissolved the lignin and hemicellulose, which led to an increase in the CNCs crystallinity with an increasing APS concentration. The decrease in the thermal stability of the CNCs was thought to be due to the increase in the surface area of the particles and the presence of carboxyl groups in the CNCs. This research revealed that balsa and kapok fibers could be used as raw materials to produce nanocellulose in one-step using ammonium persulfate. [ABSTRACT FROM AUTHOR]

The fibers of oil palm empty fruit bunch (OPEFB) stalks were investigated to determine the changes in their basic properties after oven-heat treatment. The oven-heat treatment was conducted at 100℃ or 190℃ for 15 min. There were slightly noticeable morphological, chemical, and thermal alterations in oven-heat treated OPEFB stalk fibers for short duration. Scanning electron microscopy (SEM) revealed that the treated fibers had smooth surfaces and irregular heavy deposition of cementing agents. The highest cellulose content (41.68%) was present in OPEFB stalk fibers treated at 100℃ for 15 min, whereas the highest crystallinity index (48.74%) occurred in fibers treated at 190℃ for 15 min. The fibers comprised cellulose, lignin, and hemicellulose with a high percentage of C, O, K, and other elements. Based on differential scanning calorimetry (DSC) analysis, oven-heat treated and untreated OPEFB stalk fibers had similar thermal stability characteristics. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effect of ammonium persulfate's (APS) oxidation time on the characteristics of the cellulose nanocrystals (CNCs) of balsa and kapok fibers after delignification pretreatment with sodium chlorite/acetic acid. This two-step method is important for increasing the zeta potential value and achieving higher thermal stability. The fibers were partially delignified using acidified sodium chlorite for four cycles, followed by APS oxidation at 60 °C for 8, 12, and 16 h. The isolated CNCs with a rod-like structure showed an average diameter in the range of 5.5–12.6 nm and an aspect ratio of 14.7–28.2. Increasing the reaction time resulted in a gradual reduction in the CNC dimensions. The higher surface charge of the balsa and kapok CNCs was observed at a longer oxidation time. The CNCs prepared from kapok had the highest colloid stability after oxidation for 16 h (−62.27 mV). The CNCs with higher crystallinity had longer oxidation times. Thermogravimetric analysis revealed that the CNCs with a higher thermal stability had longer oxidation times. All of the parameters were influenced by the oxidation time. This study indicates that APS oxidation for 8–16 h can produce CNCs from delignified balsa and kapok with satisfactory zeta potential values and thermal stabilities. [ABSTRACT FROM AUTHOR]