Paper properties of grass and straw pulps

Abstract

Elephant grass, wheat straw and reed canary grass have been evaluated with regard to their paper properties after pulping according to four different cooking methods, namely conventional kraft, ethanol-enhanced soda, (ethanol–soda), conventional bisulphite (pH 4.5) and autocatalysed acidic ethanol (ethanol–water). Birch has been chosen as a short-fibre wood reference. Evaluated in general terms, the non-wood pulps were `weaker' than the birch pulps, especially in tear strength, and showed little response to beating. 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 tear level that can be obtained. The emphasis of the evaluation is then put on properties deemed relevant for printing and writing grades of paper. A remarkably high specific light scattering coefficient at low surface roughness were found for wheat straw and elephant grass bisulphite pulps, unbeaten or at a low degree of beating.