Insulation Materials Made with Vegetable Fibres - Nearly Zero Energy Building Refurbishment - page 418

Fig. 10 Illustrative
production diagram
through traditional or advanced techniques. Figure 11 shows some of the major
extraction methods which are detailed in (Satyanarayana et al. 2007 ).
Retting is the biological process of extracting natural fibres (Agriculture 2000 ). In
the retting process, the pectin and lignin between the fibre bundles are dissolved so
that the fibres can be extracted. The available retting process includes mechanical,
chemical retting, steam/vapour/dew retting and water or microbial retting.
Traditionally, bacteria and fungi are used in the retting process to remove
lignin, pectin and other substances (Sumere 1992 ). Dew or field retting by fungi
mainly is most commonly applied process using this method. Another commonly
applied process by this method is water retting which involves bacteria as the main
agent. Water retting produces better quality fibres than dew retting does generally
with more cost. Water retting has been largely abandoned in some countries due to
its cost and pollution.
Fig. 11 Extraction processes of some lignocelluosic fibres (Satyanarayana et al. 2007 ); reprinted
here with kind permission of Elsevier, 2013