Effect of increased levels of dissolved andudcolloidal substances from Pinus radiata onudnewsprint paper strength

摘要

The effect of increased levels of wood resins, salts and dissolved organics on newsprint tensile strength wasudevaluated. Significantly more Pinus radiata wood resins are adsorbed onto the fibre surface compared to reportedudresults for Norwegian spruce. Differences in chemical composition may explain this. Tensile strength was foundudto decrease significantly and reach a limiting value as the level of wood resins in the handsheets increased toudapproximately 5 mg/g acetone extractives. High levels of calcium ions were found to cause precipitation of the woodudresins onto the fibre surface and also reduced tensile strength. Increasing amounts of soluble polysaccharides, suchudas galactoglucomannans, were found to stabilize the wood resins in solution and reduce the amount adsorbed ontoudthe fibre surface, resulting in increased tensile strength. The addition of polymeric fixatives was found to reduce theudnegative effect of the higher levels of extractives attached to the fibres.