The scope of the present investigation was to widen the experience regarding the suitability of non-wood fibre sources for pulp and paper. Three different non-wood fibre sources: elephant grass (Miscanthus sinensis), wheat straw (Triticum aestivium) and reed canary grass (Phalaris arundinacae) were pulped in the laboratory by four different pulping methods: kraft, ethanol-enhanced soda (ethanol-soda), bisulphite (pH 4.5) and autocatalysed acidic ethanol (ethanol-water). Scandinavian birch (Betula verrucusa) was used as short fibre wood reference.
Results from the preparatory pulping showed that fibre separation occurred at total yields specific to the species and almost regardless of pulping metod used (wheat straw = 60%, elephant grass Å 57%, reed canary grass Å 40 and birch Å 53% pulp yield), and that the pulp fibres of non-woods contained a higher content of residual lignin in than did birch. The content of residual lignin was higher in acidic than in alkaline media; intrinsic pulp viscosities were low; AcBr-lignin - kappa number relationships were rectilinar; fibre lengths were short (²1mm). Subsequent paper testing of the resultant 64 pulps (four species, four cooking methods and four levels of beating) showed that for the non-woods investigated the choice of pulping method seems to be decisive for the tensile strength that can be obtained, while the choice of species seems to be decisive for the levelof tear resistance that can be obtained. A remarkably high specific light scattering coefficient at low surface roughness was found for wheat straw and elephant grass bisulphite pulps, known to give brittle papers, unbeaten or at a low degree of beating. Finally results from mixing different wheat straw pulps with a commercial softwood kraft pulp showed the wheat straw bisulphite (pH 4.5) pulp, mixed and almost without any beating might be a very useful short fibre component in printing and writing papers. It remains however to be seen whether this unique feature is persistent and survives bleaching.
Other University of Karlstad reports within the subject area"Investigation of non-woods as a fibre source for pulp and paper".
1) Håkansson, H 1995 "Ethanol Pulping of Reed Canary Grass". University of Karlstad, Research Report 95:3.