Permanence of paper 2: Correlation between permanence of paper made from straw pulps and ageing variables

Paper sheets from local Egyptian straw pulps (bleached soda rice straw- and kraft bagasse) were prepared. Different ageing variables, namely: pH of si zing system (3.65 -7.0) and time of accelerated ageing (0 - 12 days) were s tudied. The effects of pH and time of ageing on the chemical, optical and m echanical properties were correlated and compared with samples prepared fro m imported bleached wood pulp (kraft softwood) and its blend with a local p ulp. The results show that both pH of the sizing system and time of ageing are important for paper permanence. Relatively high permanent paper sheets were obtained from low level alum/rosin-sized bagasse pulp (pH 6.75) and so dium silicate-alum/rosin sized rice straw pulp (pH 7.0), i.e. by neutral si zing. Breaking length and burst factor of such a paper after 12 days ageing are comparable to the values of sheers made from wood and From mixed pulps under the same ageing variables. The results recommend the use of neutral sized paper from local agricultural wastes even for important documents - a ssuming appropriate environmental conditions are maintained.