Research

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17 pages, 6298 KiB

Open AccessEditor’s ChoiceArticle

Novel Insight into the Intricate Shape of Flax Fibre Lumen

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Fibers 2021, 9(4), 24; https://doi.org/10.3390/fib9040024 - 06 Apr 2021

Cited by 21 | Viewed by 3555

Abstract

Plant fibres and especially flax can be distinguished from most synthetic fibres by their intricate shape and intrinsic porosity called lumen, which is usually assumed to be tubular. However, the real shape appears more complex and thus might induce stress concentrations influencing the [...] Read more.

Plant fibres and especially flax can be distinguished from most synthetic fibres by their intricate shape and intrinsic porosity called lumen, which is usually assumed to be tubular. However, the real shape appears more complex and thus might induce stress concentrations influencing the fibre performance. This study proposes a novel representation of flax fibre lumen and its variations along the fibre, an interpretation of its origin and effect on flax fibre tensile properties. This investigation was conducted at the crossroads of complementary characterization techniques: optical and scanning electron microscopy (SEM), high-resolution X-ray microtomography (µCT) and mechanical tests at the cell-wall and fibre scale by atomic force microscopy (AFM) in Peak-Force Quantitative Nano-Mechanical property mapping (PF-QNM) mode and micromechanical tensile testing. Converging results highlight the difficulty of drawing a single geometric reference for the lumen. AFM and optical microscopy depict central cavities of different sizes and shapes. Porosity contents, varying from 0.4 to 7.2%, are estimated by high-resolution µCT. Furthermore, variations of lumen size are reported along the fibres. This intricate lumen shape might originate from the cell wall thickening and cell death but particular attention should also be paid to the effects of post mortem processes such as drying, retting and mechanical extraction of the fibre as well as sample preparation. Finally, SEM observation following tensile testing demonstrates the combined effect of geometrical inhomogeneities such as defects and intricate lumen porosity to drive the failure of the fibre. Full article

(This article belongs to the Special Issue Plant Bast Fibers)

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13 pages, 8400 KiB

Open AccessArticle

Effect of Bitumen Emulsion and Polyester Resin Mixture on the Physico-Mechanical and Degradable Properties of Jute Fabrics

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Fibers 2018, 6(3), 44; https://doi.org/10.3390/fib6030044 - 25 Jun 2018

Cited by 19 | Viewed by 6539

Abstract

Jute fabric samples were treated, with different formulations, using various proportions of bitumen emulsion and polyester (PE) resin in combined solutions. Styrene monomer was used as solvent, methyl ethyl ketone peroxide as cross-linking agent and cobalt naphtha as curing agent. The fabric specimens [...] Read more.

Jute fabric samples were treated, with different formulations, using various proportions of bitumen emulsion and polyester (PE) resin in combined solutions. Styrene monomer was used as solvent, methyl ethyl ketone peroxide as cross-linking agent and cobalt naphtha as curing agent. The fabric specimens were immersed in the solution for 10–15 min, then pressed by a roller and dried at room temperature for 24 h. According to the percentage of bitumen emulsion and PE resin, the jute samples were obtained as J0 (untreated or raw jute), J1 (20% bitumen emulsion +10% PE), and J2 (10% bitumen emulsion +20% PE). It was revealed that tensile strength (TS) increased with bitumen emulsion and PE resin mixture treatment on both directions of jute fabrics where J2 showed the highest improvement of TS which were 61.4% and 44.7% for warp and weft direction respectively. Tensile strength (TS) decreased for all the samples in both directions after soil degradation. After 90 days, the untreated sample was totally degraded. Treated samples exhibited better stability than untreated ones in soil medium. Weight loss by soil degradation, moisture regain, moisture content and water uptake tests of the treated and untreated jute samples were also performed. Scanning electron microscopy (SEM) analysis was conducted to analyze the fiber surfaces of raw and treated jute fibers, finding significant differences as a result of treatment. Finally, the strategy of combining bitumen emulsion and PE resin for treatment, rather than using only PE resin, was found to produce a jute fabric which was not only better in all the above respects but also would be cheaper to produce. Full article

(This article belongs to the Special Issue Plant Bast Fibers)

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8 pages, 645 KiB

Open AccessArticle

Expression Analysis of Cell Wall-Related Genes in Cannabis sativa: The “Ins and Outs” of Hemp Stem Tissue Development

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Marc Behr

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Stanley Lutts

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Jean-Francois Hausman

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Gea Guerriero

Fibers 2018, 6(2), 27; https://doi.org/10.3390/fib6020027 - 01 May 2018

Cited by 3 | Viewed by 5434

Abstract

Textile hemp (Cannabis sativa L.) is a multipurpose crop producing biomass with uses in e.g., the textile, biocomposite, and construction sectors. It was previously shown that the hypocotyl of hemp is useful to study the kinetics of secondary tissue development, where primary [...] Read more.

Textile hemp (Cannabis sativa L.) is a multipurpose crop producing biomass with uses in e.g., the textile, biocomposite, and construction sectors. It was previously shown that the hypocotyl of hemp is useful to study the kinetics of secondary tissue development, where primary and secondary growths are temporally uncoupled. We here sought to demonstrate that the stem of adult hemp plants is an additional suitable model to study the heterogeneous lignification of the tissues and the mechanisms underlying secondary cell wall formation in bast fibres. A targeted quantitative PCR analysis carried out on a set of twenty genes involved in cell wall biosynthesis clearly showed differences in expression in the core and cortical tissues along four stem regions spanning from elongation to cell wall thickening. Genes involved in phenylpropanoid biosynthesis and secondary cell wall cellulose synthases were expressed at higher levels in core tissues at the bottom, while specific genes, notably a class III peroxidase and a gene partaking in lignan biosynthesis, were highly expressed in the cortex of elongating internodes. The two systems, the hypocotyl and the adult stem of textile hemp, are equally valid and complementary to address questions related to lignification and secondary cell wall deposition. Full article

(This article belongs to the Special Issue Plant Bast Fibers)

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18 pages, 7149 KiB

Open AccessFeature PaperArticle

Dynamic In-Situ Observation on the Failure Mechanism of Flax Fiber through Scanning Electron Microscopy

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Shabbir Ahmed

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Chad A. Ulven

Fibers 2018, 6(1), 17; https://doi.org/10.3390/fib6010017 - 19 Mar 2018

Cited by 19 | Viewed by 8897

Abstract

In order to develop and improve bio-inspired fibers, it is necessary to have a proper understanding of the fracture behavior of bio-fibers such as flax fibers from an individual fiber down to the constituent micro-fibrils and nano-fibrils. For investigating the failure mechanism of [...] Read more.

In order to develop and improve bio-inspired fibers, it is necessary to have a proper understanding of the fracture behavior of bio-fibers such as flax fibers from an individual fiber down to the constituent micro-fibrils and nano-fibrils. For investigating the failure mechanism of individual and technical flax fibers, a tensile test bench was placed within a scanning electron microscope, and the entire process of fiber failure was investigated through the capture of an SEM movie. Next, fractographic analysis was performed on the failure surface of single fibers as well as meso-fibrils that failed at a displacement rate of 0.25 mm/min, 0.75 mm/min, and 1.6 mm/min. The analysis also enabled visualization of a few internal details of flax fiber such as the arrangement of meso-fibrils and micro-fibrils (nano-fibrils). It was shown that the crack bridging mechanism and successive fiber pull-out contributed to the high work of fracture of flax fiber and the value may reach as high as

10^{6}

J / m^{2}

. Full article

(This article belongs to the Special Issue Plant Bast Fibers)

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16 pages, 2164 KiB

Open AccessArticle

Influence of Stem Diameter on Fiber Diameter and the Mechanical Properties of Technical Flax Fibers from Linseed Flax

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Fibers 2018, 6(1), 10; https://doi.org/10.3390/fib6010010 - 05 Feb 2018

Cited by 14 | Viewed by 6451

Abstract

The continued search for sustainable and eco-friendly materials has led to the integration of bio-fibers, such as flax fiber, as reinforcement in composite materials; however, a wide variation in their diameters and mechanical properties poses a considerable challenge for their incorporation in load [...] Read more.

The continued search for sustainable and eco-friendly materials has led to the integration of bio-fibers, such as flax fiber, as reinforcement in composite materials; however, a wide variation in their diameters and mechanical properties poses a considerable challenge for their incorporation in load bearing and structural bio-composite materials. In this paper, a rigorous experimental investigation was performed using two varieties of linseed flax from two growing locations to determine if the variations observed in ultimate tensile strength, Young’s modulus, failure strain and diameter could be attributed to the diameters of the stems that produced the fibers. Tests were performed in two different facilities and the results were compared and analyzed using Welch’s t-tests. Results showed that samples which differed by stem diameter had statistically significant positive correlation with fiber diameter and negative correlation with tensile strength. No correlations for tensile strength, Young’s modulus or fiber diameter were found in samples with the same stem diameter range that were grown in different locations or were of different varieties, that is the effect of location and variety is not statistically significant. Failure strain did not show any statistical significance with respect to differences in stem diameter and only showed one statistically significant result between both facilities for one of the two growing location comparisons. Full article

(This article belongs to the Special Issue Plant Bast Fibers)

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15 pages, 3359 KiB

Open AccessArticle

Interfacial Characterization by Pull-Out Test of Bamboo Fibers Embedded in Poly(Lactic Acid)

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Fibers 2018, 6(1), 7; https://doi.org/10.3390/fib6010007 - 19 Jan 2018

Cited by 25 | Viewed by 6488

Abstract

In this work, the apparent shear strength at the interface between a bamboo fiber and the surrounding poly(lactic acid) (PLA) matrix is quantified. A method for processing pull-out test samples within a controlled embedded length is proposed and the details of the test [...] Read more.

In this work, the apparent shear strength at the interface between a bamboo fiber and the surrounding poly(lactic acid) (PLA) matrix is quantified. A method for processing pull-out test samples within a controlled embedded length is proposed and the details of the test procedure are presented, along with a critical discussion of the results. Two series of samples are considered: untreated and mercerized bamboo fibers from the same batch, embedded in the same polyester matrix. Electron and optical microscopy are used to observe the fiber–matrix interface before and after the test, and to identify the failure mode of each sample, especially as regards the occurrence of fibrillation in the fiber bundles. The values of apparent interfacial shear strength are calculated only for regular fibers successfully pulled out from the matrix, and reported with their statistical variations. Mercerization, whose efficiency was proven by Fourier transform infrared (FTIR) spectroscopy, did not appear though to improve the quality of the interface (τ_app = 7.0 ± 3.1 MPa for untreated fibers and τ_app = 5.3 ± 2.4 MPa for treated fibers). Full article

(This article belongs to the Special Issue Plant Bast Fibers)

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9 pages, 2113 KiB

Open AccessFeature PaperEditor’s ChoiceCommunication

Investigation of the Mechanical Properties of Flax Cell Walls during Plant Development: The Relation between Performance and Cell Wall Structure

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Fibers 2018, 6(1), 6; https://doi.org/10.3390/fib6010006 - 17 Jan 2018

Cited by 38 | Viewed by 7159

Abstract

The development of flax (Linum usitatissimum L.) fibers was studied to obtain better insight on the progression of their high mechanical performances during plant growth. Fibers at two steps of plant development were studied, namely the end of the fast growth period [...] Read more.

The development of flax (Linum usitatissimum L.) fibers was studied to obtain better insight on the progression of their high mechanical performances during plant growth. Fibers at two steps of plant development were studied, namely the end of the fast growth period and at plant maturity, each time at three plant heights. The indentation modulus of the fiber cell wall was characterized by atomic force microscopy (AFM) using peak-force quantitative nano-mechanical property mapping (PF-QNM). Changes in the cell wall modulus with the cell wall thickening were highlighted. For growing plants, fibers from top and middle heights show a loose inner Gn layer with a lower indentation modulus than mature fibers, which exhibit thickened homogeneous cell walls made only of a G layer. The influence of these changes in the fiber cell wall on the mechanical performances of extracted elementary fibers was also emphasized by tensile tests. In addition, Raman spectra were recorded on samples from both growing and mature plants. The results suggest that, for the fiber cell wall, the cellulose contribution increases with fiber maturity, leading to a greater cell wall modulus of flax fibers. Full article

(This article belongs to the Special Issue Plant Bast Fibers)

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Review

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11 pages, 18662 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Key Stages of Fiber Development as Determinants of Bast Fiber Yield and Quality

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Fibers 2018, 6(2), 20; https://doi.org/10.3390/fib6020020 - 02 Apr 2018

Cited by 20 | Viewed by 11153

Abstract

Plant fibers find wide application in various fields that demand specific parameters of fiber quality. To develop approaches for the improvement of yield and quality of bast fibers, the knowledge of the fiber developmental stages and of the key molecular players that are [...] Read more.

Plant fibers find wide application in various fields that demand specific parameters of fiber quality. To develop approaches for the improvement of yield and quality of bast fibers, the knowledge of the fiber developmental stages and of the key molecular players that are responsible for a certain parameter, are vitally important. In the present review the key stages of fiber development, such as initiation, intrusive growth, and formation of thickened cell wall layers (secondary and tertiary cell walls) are considered, as well as the impact of each of these stages on the final parameters of fiber yield and quality. The problems and perspectives of crop quality regulation are discussed. Full article

(This article belongs to the Special Issue Plant Bast Fibers)

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Other

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6 pages, 4269 KiB

Open AccessBrief Report

Transcriptome Assembly of the Bast Fiber Crop, Ramie, Boehmeria nivea (L.) Gaud. (Urticaceae)

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Louay Al-Ani

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Michael K. Deyholos

Fibers 2018, 6(1), 8; https://doi.org/10.3390/fib6010008 - 01 Feb 2018

Cited by 3 | Viewed by 5006

Abstract

Ramie (Boehmeria nivea) is a perennial crop valued for its strong bast fibers. Unlike other major bast fiber crops, ramie fiber processing does not include retting, but does require degumming, suggesting distinctive features in pectin and the development and composition of [...] Read more.

Ramie (Boehmeria nivea) is a perennial crop valued for its strong bast fibers. Unlike other major bast fiber crops, ramie fiber processing does not include retting, but does require degumming, suggesting distinctive features in pectin and the development and composition of fibers. A comprehensive transcriptome assembly of ramie has not been made available, to date. We obtained the sequence of RNA transcripts (RNA Seq) from the apical region of developing ramie stems and combined these with reads from public databases for a total of 157,621,051 paired-end reads (30.3 billion base pairs Gbp) used as input for de novo assembly, resulting in 70,721 scaffolds (≥200 base pairs (bp); N₅₀ = 1798 bp). As evidence of the quality of the assembly, 36,535 scaffolds aligned to at least one Arabidopsis protein (BLASTP e-value ≤ 10⁻¹⁰). The resource described here for B. nivea will facilitate an improved understanding of bast fibers, cell wall, and middle lamella development in this and other comparative species. Full article

(This article belongs to the Special Issue Plant Bast Fibers)

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