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J. Hemmingson, H. Wong (1989)
Characterization of Photochemically Degraded Newsprint Solubles by 13C NMR and IR Spectroscopy, 43
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Introduction Mechanical pulp products, such äs newsprint, go yellow, lose fibre strength and form a complex mixture of coloured and colourless, soluble and insoluble products when exposed to light (Fengel and Wegener 1984). Studies of the formation and composition of the soluble product mixture will assist the search for ways to prevent the degradation and discolouration processes. In the previous paper of this series (Hemmingson and Wong 1989), two acetone-water soluble (AWS) product mixtures were characterized using 13C NMR spectroscopy. The composition was found to differ for newsprint exposed to direct sunlight (DS), in comparison with indirect sunlight (IS), for 8.5 months. However, the yield was much lower, 4.5% compared to 11.0%, in the case of (IS) exposure. This paper reports a study of the Variation of AWS product composition with product yield and with (DS) äs opposed to (IS) exposure. One product mixture was fractionated to further elucidate product composition and the degradation process.The effect on degradation of pre-extracting the newsprint to remove extractives is also reported. Experimental Sample preparation ! j»· ' Sheets of commcrcial ncwsprint wcrc cxposcd to glass filtcrcd dircct sunlight (DS), or indirect sunlight (IS) äs dcscribcd prcviously (Hemmingson and Wong 1989). Thc
Holzforschung - International Journal of the Biology, Chemistry, Physics and Technology of Wood – de Gruyter
Published: Jan 1, 1990
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