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Nils-OlofNilvebrant,Niklas Garoff,Christer Fellers 한국펄프·종이공학회 1999 한국펄프종이학회 기타 간행물 Vol.- No.-
Friction was measured on filter paper sheets impregnated with model compounds representing wood extractives using an apparatus based on the horizontal plane principle. The best lubrication of paper surfaces was achieved when they were completely separated by a densely packed film of saturated long-chain amphophilic molecules, such as fatty acids. The fatty acids adsorbed with their polar ends on the paper surface, causing their hydrocarbon chains to be orientated perpendi-cularly to the paper surface. The saturated C 18-acid, stearic acid, was an efficient lubricator for paper surfaces. The introduction of a double bond in stearic acid eliminated its lubricating ability. The spatial length of the lubricating fatty acid thereby decreases from 24 A to II A. However the trans-isomer of oleic acid, elaidic acid, had the ability to lower friction due to an increased spatial length of the fatty acid. Both the spatial length of the hydrocarbon chain and the number of lubricating chains may be of importance for the paper-ta-paper friction caused by wood extractives. A hydrophilic head-group in the wood extractive and an ordered molecular layer of lubricating molecules seems also to be prerequisites for efficient lubrication. A chemical weak boundary layer between the paper sheets was suggested to cause the low friction when long chain saturated fatty acids were deposited on paper.