Vegetable fibres properties

As it is now possible by choice of suitable conditions to prepare most compounds in this form, the colloid state should be considered as a physical state in which all substances can be made to exist. Many ma terials such as proteins, vegetable fibres, rubber, etc. are most stable or occur naturally in the colloidal slate. In the colloidal stale the properties of surface are all-important. 

The common elements in the cited examples are the mechanical characteristics and the insulation properties. These advantages come, not only from macroscopic configuration of these materials (the hollow cylindrical structure of stubble for instance), but, mainly, from their microscopic structure. Most the vegetal fibres can be described by two models wood fibres and cotton fibres, which will be presented later. In order to better understand the mechanical properties of these fibres, let us first consider their molecular constitution, then their hierarchical structure. 

The properties of the so-called oxycellulose are also of interest from a tinctorial standpoint. On oxidation of vegetable fibre (cellulose) with chlorine, chromic acid, or similar agents, it undergoes a change, and becomes capable of fixing basic dyestuffs without a mordant. 

The tetrazo-compounds obtained from benzidine and similar bases combine -with phenols and amines to produce yelloiTj red, bluCj and violet dyestuffs. These have attained considerable importance on account of their remarkable property of dyeing (in form of alkali salts) on unmordanted vegetable fibres. 

These Congo dyes possess the noteworthy property of colouring vegetable fibres (cotton) directly, whereas, with all other azo dyes, the cotton must be mordanted before dyeing. 

Biagiotti, J., Puglia, D., and Kenny Jose, M. A Review on Natural Fibre-Based composites-Part I Structure, Processing and Properties of vegetable Fibres, J. Nat. Fibers, 1(2), 37-68, 2004 Italicized data from McGovern, J.N. Fibers, vegetable. In Polymers— Fibers and Textiles. A compendium. University of Wisconsin, Madison, WI, 1990. 

Biagiotti, J. Puglia, D. Kenny, Jose M. A review on natural fibre-based composites-Part I structure, processing and properties of vegetable fibres. Journal of Natural Fibers, 2004, Vol. 1 Issue 2, pp. 37-68. 

The chemical composition as well as the morphological microstmcture of vegetable fibres is extremely complex due to the hierarchical organisation of the different compounds present at various compositions. Depending on the type of fibre, the chemical composition of natural fibres varies. Primarily, fibres contain cellulose, hemicellulose and lignin. The property of each constituent contributes to the overall properties of the fibre. 

Mohanty AK, Parija S, Misra M (1996) Ce(IV)-A(-acetylglycine initiated graft copolymerization of acrylonitrile onto chemically modified pineapple leaf fibers. J Appl Polym Sci 60 931-937 Mohanty AK, Khan MA, Hinrichsen G (2000) Surface modification of jute and its influence on performance ofbiodegradable jute-fabric/Biopol composites. Compos Sci Technol 60 1115-1124 Mohanty AK, Misra M, Drzal LT, Selke SE, Harte BR, Hinrichsen G (2005) Natural fibers, biopolymers and biocomposites an introduction. In Mohanty AK, Misra M, Drzal LT (eds) Natural fibers, biopolymers and biocomposites. Taylor Francis, FL, Boca Raton Mukherjee PS, Satyanarayana KG (1986) Structure and properties of some vegetable fibres Part 2 pineapple fiber. J Mater Sci 21 51-56... 

Recently, some papers were published showing the need for conducting LCA of nanoproducts. A group of Brazilian researchers studied the LCA of cellulose nanowhiskers. Vegetal fibres are an important source of cellulose for the extraction of nanowhiskers, which can be used to enhance the mechanical properties of different polymers. The study contributes to the environmental performance of cellulose nanowhisker production processes in the development stage. Environmental aspects and related impacts of two cellulose nanowhiskers product systems are evaluated nanowhiskers extracted from unripe coconut fibres (EUC system) and from white cotton fibres (EC system). The comparison between the two systems showed that nanowhiskers produced in the EC system required less energy and water, emitted fewer pollutants, and contributed less to climate change, human toxicity and eutrophication than those produced in the EUC system. 

Vegetable fibres are also used to replace asbestos fibres, which are expensive and dangerous to health. Coconut fibres were tested for that purpose and their strength and deformability, as well as thermal and acoustic properties, and were proved comparable with those of asbestos fibres (Paramasivam et al. 1984). Similar tests on specimens reinforced with flax fibres from New Zealand and Australia also showed their ability to replace asbestos in thin cement sheets (Courts 1983). 

Table 4.4 Important physical properties of vegetable fibres used in geotextiles... 

Ramie (Boehmeria nivea) is one of the oldest fibre crops, principally used for fabric production, even mummy cloths, because of the non-fibrous material with antifungal and antibacterial properties. It is a bast fibre, and the part used is the bark (phloem) of the vegetative stalks. Unlike other bast crops, ramie requires chemical processing to de-gum the fibre (up to 25% mass loss). 

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