Ramie fibres

The microscopic appearance of ramie fibres is similar to that of flax but they are coarser and have a wider lumen as illustrated in Fig. 4.4. Bleached ramie is white and lustrous and is extremely durable but lacks flexibility and elasticity. It also has a peculiar hairiness which, whilst enabling it to... 

Fig. 4.5 (A) Single ramie fibre mercerized under full tension (B) Single ramie fibre mercerized without tension...

Ahmed, M. Chattopadhyay, S.K. Gaikwad, R.S. Dey, S.K. Characteristics of degummed ramie fibre and its cotton blended yarns., Indian Journal of Fibre Textile Research 29 (3) 362-365 (2004). 

In liquid water, cellulose shows limited swelling. The amount of water taken up depends on the kind of sample. Native cellulose, such as purified cotton-, and ramie fibres, take up about 0.5 g water per g of the dry material, artificial fibres 1.0 g or even more. The sorption isotherms of various samples show a similar difference at a given vapour pressure native fibres absorb less water than regenerated ones The shape of the isotherms is, however, the same in all cases. A very characteristic feature is. 

Good agreement with experiments has been established in series of regenerated cellulose fibres from isotropic up to highly oriented ones, for which the values of Tie and na> at ideal orientation were also computed with the aid of measurements on nearly perfectly oriented merceri2 ed ramie fibres . 

Fig. 84. X-ray photographs of a) native ramiefibres, b) mercerised ramie fibres (both highly oriented),...

Mater Bi SCONACELL A TPS blends with PCL, EVOH, etc. with at least 85% of starch Modified starch blends Novamont/Montedison BSL Non-woven of flax, hemp, ramie fibres [143]... 

In another vein, a recent report [95] describes the preparation of an all-cellulose composite by dissolving pretreated ramie fibres in DMAc/LiCl and introducing untreated fibres into the ensuing solution. The composites were then isolated by coagulation with methanol and dried. 

Menezes et al. [118] also extracted cellulose nanocrystals or whiskers of ramie fibres by acid hydrolysis. Acid hydrolysis of native ramie cellulose fibres leads to aqueous suspensions of elongated nanocrystals with high aspect ratio. The geometric average length and diameter were around 134 59 nm and 10.8 4.5 nm, respectively, giving rise to an aspect ratio around 12. A minimum of 228 and 70 measurements were used to determine the length and the diameter, respectively, of ramie whiskers. They noticed that more than 50% of the... 

The employment of natural fibres, such as cellulose pulp, sisal, bamboo, hemp, flax, jute, ramie fibres, etc., is restricted to countries where these fibres are easily available. They are important constituents of structural elements used for construction of inexpensive buildings in developing regions of the world (Coutts, 2005). In Africa, sisal fibre-reinforced concrete has been nsed extensively for making roof tiles, corrugated sheets, pipes, silos, and gas and water tanks. Subrahmanyam (1984) cited the application of elephant grass... 

Ramie fibre is classified chemically as a cellulosic, just like cotton, linen, etc. Leading producers of ramie are China, Taiwan, Korea, the Philippines and Brazil. Until recently ramie has been unknown in the ready-to-wear market, but it is appearing in more garments. It is often blended with cotton and available in woven and knit fabrics from those that resemble fine linen to coarse canvas. 

Ramie fibres are found in the bark of the stalk the fibre is very fine and silk-like, naturally white in colour and has a high lustre. The process of transforming ramie fibre into fabric is similar to processing linen from flax. 

Raw ramie fibre produced either by hand scraping or decortication contains a fairly large percentage of gums and non-fibrous cells, or parenchyma (30-35%). These gums and cells are, for the most part, insoluble in water and must be removed before the fibre can be mechanically spun in fine count yams. They are composed principally of arabans and xylans which are readily soluble in alkaline solutions. 

Although ramie fibre is usually degummed chemically, there have been promising developments in microbial degumming (retting). Additionally some researchers reports that the use of ultrasonic vibrations speeds up the degumming process. The enzymatic treatment seems to be promising. 

Table 2.15 Ramie fibre properties in comparison with other fibres...

Ramie fibre is very durable, but like linen and cotton, ramie has poor resiliency and wrinkles easily application of wrinkle-resistant finishes or blending with synthetic fibres can reduce the problem in woven fabrics. Because of its high absorbency, ramie is comfortable to wear, especially during warm weather. Other properties include resistance to alkali, rotting, light and mildew. Resistance to insects is good unless the fabric is heavily starched. Ramie is not harmed by mild acids but can be damaged by concentrated acids. 

Hoefer, T.H., The Ramie Fibre Today, Melliand Textilberichte, no. 47. 

More recently, cellulose fibres have been investigated as potential precursors for self-reinforced polymer composites, as well summarised in a review by Eichhom et al. [191]. Numerous authors have reported the use of cellulose fibres from various sources, including wood pulp fibres [192, 193], filter and Kraft paper [194-197], microcrystalline cellulose fibres [198-202], sisal fibres [203, 204], ramie fibres [205], cotton fibres [206], regenerated cellulose (Lyocell) and cellulose fibres spun from an anisotropic phosphoric acid solution (Bocell) [207], and fibres from bacterial cellulose [208]. Two main technologies have been presented to produce these so-called self-reinforced cellulose or all-cellulose composites, and these are, first, the conventional impregnation of cellulose matrix into cellulose fibres and, second, a novel selective dissolution method in which the cellulose fibre surfaces are partially dissolved to form a matrix phase that bonds fibres together. 

Ishikawa, A., Okano, T., and Sugiyama, J. (1997) Fine stmcture and tensile properties of ramie fibres in the crystalline form of cellulose 1, 11, IIII and IVl. Pdymer, 38 (2), 463-468. 

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