| Abstract: | Summaries. Paper sheets from local Egyptian straw pulps (bleached soda rice straw- and kraft bagasse) were prepared. Different ageing variables, namely: pH of sizing system (3.65 -7.0) and time of accelerated ageing (0 - 12 days) were studied. The effects of pH and time of ageing on the chemical, optical and mechanical properties were correlated and compared with samples prepared from imported bleached wood pulp (kraft softwood) and its blend with a local pulp. 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 sodium silicate-alum/rosin sized rice straw pulp (pH 7.0), i.e. by neutral sizing. Breaking length and burst factor of such a paper after 12 days ageing are comparable to the values of sheets made from wood and from mixed pulps under the same ageing variables. The resuits recommend the use of neutral sized paper from local agricultural wastes even for important documents - assuming appropriate environmental conditions are maintained. |
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