The selection of a retting method for the extraction of bast fibers as response to challenges in composite reinforcement

Abstract

This article presents an evaluation of bast fiber properties conditioned by the selection of a retting method in terms of meeting requirements for the final application of the fibers as composite reinforcement. Two different methods of fiber extraction were used in the experiment: dew retting and osmotic degumming. The fibrous material was extracted from flax (Modran variety) and hemp (Bialobrzeskie variety). In addition, retted kenaf fibers (from China) were evaluated for the comparison of fiber properties. The properties of the retted and degummed fibers were evaluated according to relevant valid standards regarding color, linear mass, breaking tenacity, aspect ratio, microscopic images and chemical composition, which included the determination of wax and fat, cellulose, hemicellulose, lignin and pectin content and the thermogravimetric analysis coupled with Fourier transform infrared spectroscopy technique. The Attenuated Total Reflection FTIR spectroscopic technique was used for the characterization of the fibers. Also, fogging and volatile organic compound (VOC) emissions were tested in order to evaluate the suitability of the bast fiber for composite formation. The results of the study proved that osmotic degumming applied for bast fiber extraction improves significantly the fiber quality in terms of color, odor, aspect ratio and VOC emission. The aspect ratio of osmotically degummed flax fibers increased by about 46% and hemp fibers by about 22% in comparison with dew-retted fibers. VOC emission of osmotically degummed hemp decreased by about 35%, but in the case of flax fibers, increasing of VOC has been observed. For this reason, osmotically degummed fibers can be recommended as more suitable for composite reinforcement.

Antioxidant Potential of Hemp and Flax Fibers Depending on Their Chemical Composition

“…The infrared spectra of the tested fibers ( Figure 7 , Figure 8 and Figure 9 ) serve to identify the absorbance ranges that represent vibrations of such functional groups as: O-H, C=O, C=C, COO, C-H, CH 2 , CH 3 , COC [ 20 , 21 ]. The characteristics of the main absorbance spectra in the FTIR of the tested fiber are shown in the Table 5 .…”

“…Cellulose, hemicellulose and pectin all belong to the polysaccharides similar in terms of molecules bonded with glycosidic bonds within the absorbance range at 896 cm −1 [ 20 , 22 , 23 ]. In the cellulose, the molecules are bonded with (1,4)-β-glycosidic bonds, while in hemicellulose and pectin with (1,4)-β and (1,3)-β-glycosidic.…”

A Comprehensive Review on Bast Fibre Retting Process for Optimal Performance in Fibre‐Reinforced Polymer Composites

“…e finest fibre was obtained after 96 hours of osmotic retting with 40 °C working temperature. is fibre retting method claimed to be more suitable for fibre reinforcement applications [93]. On the contrary, Ruan et al [94] introduced radiofrequency treatment to improve retting efficiency in a variety of water-retting temperatures and durations.…”

Hemp Fibre Properties and Processing Target Textile: A Review

“…The percentage values of the share of the main chemical components in hemp fibres provided by different authors are shown in Table 1. The share of chemical components in the fibre depends on several aspects, e.g., hemp plant variety (Table 2), climatic conditions of growing, method of fibre extraction [30,42] and agricultural methods of plant cultivation including climatic conditions. 66.0-72.5 3 14-22 3 0.6-3.5 3 2.4-5.5 3 0.2-0.5 3 67-78 4 16-18 4 0.8 4 3.5-5.5 4 0.7 4 68 5 15 5 0.8 5 10 5…”