China
Africa
Explore chapters and articles related to this topic
Fibre reinforcements
Published in A.R. Bunsell, S. Joannès, A. Thionnet, Fundamentals of Fibre Reinforced Composite Materials, 2021
R. Bunsell, S. Joannes, A. Thionnet
Spiders produce silk from glands, called spinnerets, at the rear of the body and the chemical composition is similar to that of Nylon. Mass production of spider silk is made difficult by their small diameters and by the cannibalistic nature of spiders. There seems little willingness for spiders to collaborate amongst themselves. There have been attempts to produce man-made spider silk either by extruding silk, so emulating the natural process or by introducing some part of the spider DNA into other creatures, such as silk worms, or even mammals such as goats with the intention of spinning silk from the proteins found in the silk, called spideron, expressed in their milk. So far this has not been commercially successful even if some ersatz spider silk have been developed over the years and applied with varying degrees of success to hightech textile products.
Responsible Textile Design and Manufacturing: Environmentally Conscious Material Selection
Published in Ammar Y. Alqahtani, Elif Kongar, Kishore K. Pochampally, Surendra M. Gupta, Responsible Manufacturing, 2019
Ece Kalayci, Ozan Avinc, Arzu Yavas, Semih Coskun
However, these fibers may be harmful to the environment during their life cycle due to their petroleum-based structure. For that reason, researchers are investigating alternative natural or natural-based fibers with high-performance properties. Spider silk is the most commonly known natural protein-based high-performance fiber. Although natural spider silk exhibits extraordinary features, it is nearly impossible to farm and manufacture spider silk due to the cannibalistic characteristics of some kinds of spider (Eisoldt et al., 2011; Bunsell, 2009; Kalayci et al., 2015d). Therefore, spider silk is artificially produced using biotechnological spider silk recombinant protein production (Avinc et al., 2015; Chung et al., 2012). Hagfish slime fiber is another natural protein fiber that exhibits high-performance properties. The hagfish is a primitive sea animal that lives in burrows on the sea floor and releases a slime that contains thousands of fibers to defend itself when threatened (Kalayci et al., 2015d; Kalayci et al., 2015a). The production of hagfish slime fibers is also difficult, as with spider silk, due to the living conditions of the hagfish. Artificial hagfish slime fibers can be produced from regenerated proteins by biotechnological hagfish recombinant protein production (Fudge et al., 2010; Fudge et al., 2014).
Natural Materials – Composition and Combinations
Published in Graham A. Ormondroyd, Angela F. Morris, Designing with Natural Materials, 2018
Spider silk fibroin has a distinctive amino acid sequence of –(Gly-Ser-Gly-Ala-Gly-Ala-)n which takes up an anti-parallel β-sheet arrangement. Spider silk is produced for different functions, and has markedly different properties, between the strong stiff radiating frame of the web, and the dragline (both are formed by the major ampullate gland), and the more elastic-catching spiral (viscid spiral) of the web (Goseline et al. 1999, Chen et al. 2012). Two types of proteins have been identified in the dragline silk of Nephila clavipes and Argiope auranta, and shown to have different protein conformations (Brooks et al. 2005). MaSp1 contains segments of two protein types – a glycine-rich (Gly-Gly-X) repeat and polyalanine domains; the MaSp2 type also contains the polyalanine segments, but there is a higher proline content in the glyine-rich portions, with a Gly-Pro-Gly-X-X repeat. The combination of these two types of protein segment allows sheets of polyalanine to form highly aligned segments, with amorphous regions of the glycine-rich protein providing elasticity and flexibility (Keten and Buehler 2010). The catching spiral silk has a higher proline content, replacing much of the alanine and serine (Chen et al. 2012). The presence of proline induces a kink in the protein chain, reducing crystallinity, maintaining the amorphous properties required for this filament within the web (Szent-Györgyi and Cohen 1957).
Spider dragline silk fibres maintain rectangular columnar liquid crystalline phase
Published in Liquid Crystals, 2023
Kenjiro Yazawa, Kazuchika Ohta
Molecular assemblies of the spider silk fibres have previously depicted as a two-phase model in which spider silk fibres consist of crystal and amorphous regions [40]. It has long been believed that the crystal region contributes to the strength and that the amorphous region helps to the ductility of spider silk fibres [41]. The crystal region consists predominantly of β-sheet structures containing polyalanine sequence, while the amorphous region mainly formed by random coil and helical structures including polar amino acids with the bulky side chains [42]. In addition, semi-crystalline region is also proposed to express the intermediate of crystal and amorphous region, and the random coil and helical structures are partially oriented in the semi-crystalline region [43]. However, it is difficult to give a reasonable explanation for the mechanical strength of spider silk fibres based on these two- or three phase model because the amorphous regions can cause structural defects during deformation. On the other hand, a manmade high-performance fibre, Kevlar, is depicted as one phase model and consisted of oriented crystalline region with a minimum structural defect [44]. Kevlar fibre is produced by a wet spinning of liquid crystalline aramid compounds dissolved in a concentrated sulphuric acid [45]. Spider silk proteins are thought to be stored in the spinning dope as a liquid crystalline state [21]. Based on the fibre formation mechanism of Kevlar, it can be deduced that spiders form liquid crystalline polymers in the spinning dope and maintain the liquid crystalline structure during the fibre formation like Kevlar. In this study, we found using the X-ray liquid crystal structural analysis that the spider silk fibres do not contain any three-dimensionally crystalline parts, but they have a structure consisting of only a two-dimensionally rectangular columnar liquid crystal with a P21/a (p2gg) symmetry. The spider silk molecules are tightly packed into a two-dimensional rectangular columnar structure in the direction perpendicular to the fibre axis. On the other hand, the long columnar molecules can easily slide and fluctuate along the fibre axis, contributing to few structural defects. The liquid crystalline model can rationally explain the mechanical strength of the spider silk. Although the two-phase model consisting of the crystalline and amorphous region has long been believed, we have demonstrated in this work that the spider silk fibres don’t have any three-dimensional crystalline structure but only two-dimensional rectangular columnar liquid crystalline structure.