Chemical extraction and its effect on the properties of cordleaf burbark (Triumfetta cordifolia A. rich) fibres for the manufacture of textile yarns

Impact of extraction methods on the properties of Carica papaya pseudostem fibers from Cameroon used as reinforcement in biocomposites

Carica papaya pseudostems are widely available as biomass waste in Cameroon. These agricultural wastes can be effectively used as natural fibers in the manufacture of biocomposites. In this study, Carica papaya fibers were extracted from papaya pseudostems by retting with water and an alkaline sodium hydroxide (NaOH) solution at different concentrations (2.5 %, 5 %, and 7.5 %). An experimental campaign is being conducted on the physical, chemical, thermal, mechanical, and morphological characteristics of Carica papaya fibers. Fourier transform infrared spectroscopy (FTIR) of Carica papaya fibers extracted by water retting and those extracted with NaOH indicates that the cellulose, hemicellulose, and lignin functional groups are present in the fibers and are dissolved considerably as the percentage of NaOH increases. Scanning electron microscopy (SEM) in the longitudinal plane gives a visual representation of the rough and irregular surfaces without the presence of impurities on the chemically extracted fibers compared to that extracted with water. In contrast to the decrease in diameter, the measured density of Carica papaya pseudostem fibers increased with NaOH concentration (0.633 - 1.522 g cm-3), all of which remained light fibers. Water absorption decreased from 159.36 % to 141.28 % with increasing NaOH, and relative humidity dropped to 6.41 %. The thermal stability of Carica papaya fibers extracted at concentrations of 2.5 % NaOH (215 °C), 5 % NaOH (200 °C), and 7.5 % NaOH (175 °C) showed a clear decrease compared to those extracted by water retting (220 °C). Fibers extracted at 2.5 % NaOH achieved a tensile strength of 287.55 ± 56 MPa, a tensile modulus of 8.271a± 1.62, and 3.505 ± 1.01 % elongation. The tensile properties of these fibers showed great variability, and an influence of diameter was observed, indicating the need to study the influence of technique and NaOH mass concentration. The results show that Carica papaya fiber extracted at a concentration of 2.5 % will be the most suitable for biocomposite applications.

The Influence of the Chemical Composition of Flax and Hemp Fibers on the Value of Surface Free Energy

The article presents the exploration of flax and hemp fibers' surface free energy depending on the chemical composition of the fiber, which is closely related to the plant variety and the method of extracting the fiber. For this purpose, tests of the surface free energy (SFE), evaluation of the percentage content of individual fiber components and FTIR analyses were conducted. The research was carried out with the use of fibrous materials prepared in three different ways: 1. To analyze the effect of subsequent stages of flax fibers refining process on chemical composition and SFE, 2. to explore the dependence of fiber SFE on hemp variety, the water-retting hemp fibers were used, 3. To evaluate the influence of the retting method of hemp fibers BIAŁOBRZESKIE variety on SFE, the fibers extracted with the use of dew and water retting were used as the research material. The study confirmed that the content of individual components in the fiber influenced its sorption capacity and therefore determined its hydrophilic properties. The values of Pearson's linear correlation coefficients determined in the statistical analysis proved that the surface free energy was strongly correlated with the content of individual components in the fibers. Understanding the wettability characteristics of bast fibers will allow modeling the properties of products made of these fibers and designing surface modification processes in order to obtain specific functionality of textile products, depending on their intended utilization.