Mechanical fiber separation

Mechanical fiber separation may be carried out in different ways such as beating the fiber source with metal blades (scutching) or combing (hackling) [56]. When combined with other separation techniques, mechanical decortication, which is also known as scutching, leads to production of lighter, softer and finer fibers [8]. Although... 

There are several modifications of the sulfite method which are designated according to the pH of the cooking liquor (Table 7-1). For the production of chemical pulps, delignification is allowed to proceed until most of the lignin in the middle lamella is removed after which the fibers can be readily separated from each other. Semichemical pulps are often produced by the neutral sodium sulfite method followed by mechanical fiberization of the partially delignified wood. 

The lignin-removal and fiber-separation mechanisms involved in chemical pulping are alkaline hydrolysis (lignin bond cleavage) and the formation of soluble sulfur-containing... 

Semichemical Pulping. Various combinations of chemical and mechanical treatments have been used to produce pulps with specific properties. Mild chemical treatments to give partial delignification and softening are followed by mechanical means to complete fiber separation. 

Spinning processes are mostly involved with fiber separation, ventilation, and guidance that require mechanical and air movements. Production purposed, air conditioning and ventilation purposed machinery and systems of spinning lines are reported as electric energy-intensive processes. 

Semichemical or chemimechanical pulping procedures involve a mild chemical treatment aimed at weakening the lignin-carbohydrate complex of the fiber bond. The mechanical stage achieves the fiber separation to produce the pulp, which is followed by refining to develop improved properties. The yields of pulp obtained are between 65% and 90% depending on the extent of chemical treatment and on the wood species. 

Controlled mechanical film-to-fiber separation, performed by a needle roller equipped with teeth, by embossing or profiling techniques, or by slicing or cutting techniques. In these cases, more or less well-defined separation into regular network-like fibrous structures is achieved. Because of their relatively good uniformity, these processes compete with conventionally synthetic products (coarse multifilament yarns or staple fibers), and one should speak here of slit-film fibers or slit fibers [157]. 

In addition, as a typical failure mechanism, fiber/matrix debonding occurs due to the shear and tension type loading. If fiber/matrix debonding has taken place, the local separation initiates additional fiber cracking, wear debris formation, and a more intensive wear process. In the steady state wear process, a so-called compacted wear debris layer (CWDL) covers the surface it is composed of pulverized wear debris and matrix material. During the wear process, this layer is continuously formed and removed by the surfaces sliding over each other. 

Fibers for fiberboard are coarser and less refined chemically than those used for paper. Processes are used that bring about fiber separation with a minimum loss of chemical components and a maximum yield. The pulping processes used are generally the following mechanical, thermomechanical. 

Because an increasing amount of paper materials is being made from recycled fibers, a key consideration relative to surface modifications of paper surfaces is the chemistry of the bulk. When paper is recycled (with some virgin fiber content) by either mechanical or chemical pulping processes, the mixing of pulp with water and the application of mechanical techniques causes hydrogen bonds in the paper to be broken and create further fiber separation. Most recycled-content commercial... 

The main method for fiber separation from the flax is microbiological one in which vital activity of pectin degrading microorganisms degrade pectins linking bast batches to the stalk tissues. After that the fiber can be easily detached by mechanical processing. 

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