Natural cellulose fibres application

In tropical countries like India synthetic fibres blended with cellulosic fibres fabrics are very popular due to their excellent combination of aesthetic properties and easy care properties. Thus, bleaching of blended fibre fabrics before further processing is an important step. Many of the preparatory processes used for natural and synthetic fibres have little or no application in preparation of blended fibre fabircs. 

Graupner, N., Herrmami, A.S., Mussig, J. Natural and man-made cellulose fibre-reinforced polyflactic acid) (PLA) composites An overview about mechanical characteristics and application areas. Compos. A 40, 810-821 (2009)... 

The mercerizing is based on the action of cold strong alkali (usually NaOH) solution and concomitant application of a stretching force, followed by neutralization. As is shown in Figure 9.6.4, this allows cellulose fibre to pass from the meta-stable natural crystalline structure I to the stable cellulose II form. The mercerization produces effluents with very high pH, requiring further acidic treatment for discarding. 

This chapter first gives an overview of cellulose raw materials and their molecular and supermolecular structures. The principles of shaping cellulose into fibres, films, and nonwovens by means of solution techniques are then outlined followed by a section on properties and market applications of these materials. Derivatives of cellulose are presented with special emphasis on thermoplastic cellulose esters, typical plasticizers, and promising reinforcing materials. Finally, recent developments and future prospects of cellulose materials are reviewed as far as the above applications are concerned. This book does not cover the important applications of cellulose and ligno cellulose fibres for reinforcing thermoplastics, like wood plastic composites (WPC) and natural fibre reinforced plastics (NFRP), since in these cases cellulose does not substitute a thermoplastic. 

Natural fibres show many advantages over glass fibres when used as reinforcement of synthetic polymers (see Table 5.1) the relatively high density of glass fibres 2.5 g/cm ) compared to cellulose or ligno-cellulose fibres of 1.5 g/cm makes lightweight applications possible. 

Commonly used natural fibres are cotton and silk, but also included are the regenerated cellulosic fibres (viscose rayon) these are widely used in non-implantable materials and healthcare/hygiene products. A wide variety of products and specific applications utilise the unique characteristics that synthetic fibres exhibit. Commonly used synthetic materials include polyester, polyamide, polytetrafluoroethylene (PTFE), polypropylene, carbon, glass, and so on. 

Njuguna J, Wambua P, Piehchowski K, Kayvantash K. Natural fibre-reinforced polymer composites and nanocomposites for automotive applications, cellulose fibers bio- and nano-polymer composites. In Kaha S, Kaith BS, Kaur 1, editors. Cellulose fibres bio- and nano-polymer composites. Berlin, Heidelberg Springer 2011. 

Cellulose ethers have the polymeric backbone of cellulose, a natural carbohydrate that contains a basic repeating structure of anhydroglucose units. During the manufacture of cellulose ethers, cellulose fibres are treated with caustic solution, which in turn is treated with methyl chloride or propylene oxide. The chemical reaction yields a fibrous product, which is purified and ground to a fine powder. Commercial grades vary chemically and physically for matching the desired applicative properties. 

Fibrillar fines obtained from cellulosic fibres are known for their unique structure, material characteristics, and potential applications (Hubbe et al. 2008). An amorphous lignin and hemicellulose matrix separates the elementary nanofibrils in natural vegetable fibres. Based on raw material sources, pretreatment and subsequent defibrillation procedures will produce a broad spectrum of fibril structures as well as nomenclatures used to describe them. Thus, we find various terms adopted in the field, such as nanoscale-fibrillated cellulose, cellulosic fibrillar fines, cellulose aggregate fibrils, and microfibrillar cellulose. 

Research in ACF has attracted increasing attention in the last few years in terms of their synthesis, and their suitability in different applications that include solvent recovery, molecular sieving, gas storage and catalysis. Activated carbon fibres are usually prepared from precursors of low or intermediate crystallinity such raw materials include polyacrylonitrile (PAN) fibres, cellulose fibres, phenolic resin fibres, pitch fibres, cloth or felts made from them, and viscose rayon cloth. They are first pyrolysed and then activated at a temperature of 700-1000 C in an atmosphere of steam or carbon dioxide. Both the processing costs and the properties of the fibre products are dependent on the nature of the starting material. 

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