Deformation of the compound middle lamella in spruce latewood by micro-pillar compression of double cell walls

Raghavan, R.; Adusumalli, Ramesh Babu; Buerki, Gerhard; Hansen, Silla; Zimmermann, Tanja; Michler, Johann

doi:10.1007/s10853-012-6531-y

Cited by 14 publications

(9 citation statements)

References 24 publications

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“…In addition, the images collected confirm the observations done by Zamil and Geitmann [13] and Raghavan et al [15] in the ML and S 1 -S 2 region. The authors reported that the middle lamella is stronger than the primary or secondary wall layers and not damaged from a mechanical stretch; on the contrary, fractures take place in the adjacent primary or secondary cell-wall layers.…”

Section: Resultssupporting

confidence: 88%

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The Middle Lamella of Plant Fibers Used as Composite Reinforcement: Investigation by Atomic Force Microscopy

et al. 2020

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Today, plant fibers are considered as an important new renewable resource that can compete with some synthetic fibers, such as glass, in fiber-reinforced composites. In previous works, it was noted that the pectin-enriched middle lamella (ML) is a weak point in the fiber bundles for plant fiber-reinforced composites. ML is strongly bonded to the primary walls of the cells to form a complex layer called the compound middle lamella (CML). In a composite, cracks preferentially propagate along and through this layer when a mechanical loading is applied. In this work, middle lamellae of several plant fibers of different origin (flax, hemp, jute, kenaf, nettle, and date palm leaf sheath), among the most used for composite reinforcement, are investigated by atomic force microscopy (AFM). The peak-force quantitative nanomechanical property mapping (PF-QNM) mode is used in order to estimate the indentation modulus of this layer. AFM PF-QNM confirmed its potential and suitability to mechanically characterize and compare the stiffness of small areas at the micro and nanoscale level, such as plant cell walls and middle lamellae. Our results suggest that the mean indentation modulus of ML is in the range from 6 GPa (date palm leaf sheath) to 16 GPa (hemp), depending on the plant considered. Moreover, local cell-wall layer architectures were finely evidenced and described.Molecules 2020, 25, 632 2 of 17 be found in Wambua et al. [8]. The authors studied several poly-(propylene) composites reinforced with different plant fibers (sisal, kenaf, jute, hemp, and coir), and their results showed that coir fibers, extracted from seeds, have lower longitudinal mechanical properties than the others but, on the other hand, they exhibit a higher impact strength, which was also confirmed in Reference [9]. This result follows the functional evolution of the different kinds of cells in a plant; for example, bast fibers are responsible for the stiff structure of a plant and this specific role also explains their high mechanical performance.Every bast fiber has a similar (ultra)structural model even if they originate from different plants. An elementary fiber is a single cell, and several fibers are linked to each other to form a bundle of several dozens of single fibers having a multilayer structure, as illustrated in Figure 1a: (1) the lumen is the central hollow part of the cell and its shape and diameter vary with the maturity of the plant and the environmental conditions during growth; (2) the secondary cell wall is the thickest layer, divided into two to three sub-layers (S 1 , S 2 or G, and S 3 ) rich in cellulose where the thinner and not always visible S 3 can also be assimilated to unmatured Gn layer instead of a real S 3 [10]; (3) the primary cell wall is the external layer enriched in hemicelluloses, pectins, and lignin [11]. Between the fibers, there is another layer called middle lamella (ML), which cements the primary cell walls of adjacent cells together and is mainly composed of pectic polysaccharides, lignin, and a small amou...

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Section: Resultssupporting

confidence: 88%

“…Between the fibers, there is another layer called middle lamella (ML), which cements the primary cell walls of adjacent cells together and is mainly composed of pectic polysaccharides, lignin, and a small amount of proteins [12][13][14]. This binder layer between two cells acts as a very thin and efficient interfacial matrix in the plant [13,15].…”

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The Middle Lamella of Plant Fibers Used as Composite Reinforcement: Investigation by Atomic Force Microscopy

et al. 2020

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“…The failure occurred either at the S 3 layer or in the ML (see Supplementary Figure S3). This represents a different failure mechanism from the one observed in Raghavan et al (2012) that consisted of a tearing of the interface between the S 1 and the S 2 layers of the CW.…”

Section: Resultsmentioning

confidence: 69%

“…As seen from Table 1, the average yield stress provided by MCo (183 ± 11.9 MPa) was higher than the values in the cited literature. For instance, Raghavan et al (2012) obtained a yield strength of about 125 ± 20 MPa and Adusumalli et al (2010) obtained 158 ± 20 MPa from five micropillars, both investigated for spruce latewood. The obtained higher strength and yield stress can be attributed to the fact that a species different from that in mentioned literature was measured and, moreover, to the fact that libriform fibers in late wood zone were measured.…”

Section: Resultsmentioning

confidence: 99%

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Micromechanical properties of beech cell wall measured by micropillar compression test and nanoindentation mapping

Klímek

Sebera

Tytko³

et al. 2020

Holzforschung

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Wood exhibits very different behavior and properties at different scales. One important scale is the cell wall (CW) that is commonly tested by nanoindentation. Common nanoindentation provides important insight into the material but has limitations because it does not apply uniaxial stress and provides data from single spots. Therefore, the aim was to examine beech CW using two stateof-the-art techniques: micropillar compression (MCo) and nanoindentation mapping (NIP). The mean strength of the beech CW was found to be about 276 MPa and the mean yield stress was 183 MPa. These values were higher than those in most cited literature, which was attributed to the fact that libriform fibers from beech late wood were measured. Mean E obtained from MCo was about 7.95 GPa, which was lower than the values obtained on a macrolevel and about 61% of the value obtained from NIP. NIP also showed that E of the CW around the middle lamella (ML) was about 64% of the value at the location attributed to the S 2 layer. Lower E from MCo may be caused by sinking of the micropillar into the wood structure under the load. Failure of the micropillars showed gradual collapse into themselves, with debonding at the S 3 layer or the MLs.

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Biotechnological and Biochemical Utilization of Lignin

Rais

Zibek

2017

Advances in Biochemical Engineering/Biotechnology

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This chapter provides an overview of the biosynthesis and structure of lignin. Moreover, examples of the commercial use of lignin and its promising future implementation are briefly described. Many applications are still hampered by the properties of technical lignins. Thus, the major challenge is the conversion of lignins into suitable building blocks or aromatics in order to open up new avenues for the usage of this renewable raw material. This chapter focuses on details about natural lignin degradation by fungi and bacteria, which harbor potential tools for lignin degradation and modification, which might help to develop eco-efficient processes for lignin utilization.

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Deformation of the compound middle lamella in spruce latewood by micro-pillar compression of double cell walls

Cited by 14 publications

References 24 publications

The Middle Lamella of Plant Fibers Used as Composite Reinforcement: Investigation by Atomic Force Microscopy

The Middle Lamella of Plant Fibers Used as Composite Reinforcement: Investigation by Atomic Force Microscopy

Micromechanical properties of beech cell wall measured by micropillar compression test and nanoindentation mapping

Biotechnological and Biochemical Utilization of Lignin

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