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|Last update : June 18, 2003|
|3 - Application of MorFi to pulp characterization|
R. Passas (EFPG)
The properties of paper are correlated with fiber or pulp characteristics. To determine them, a lot of devices are available on the market and some of them can be installed on-line. In this paper, some laboratory experiments made with the Morfi equipment are discussed and possible applications are given. The first part of this work consists in a brief description of a new equipment aiming at the morphological characterization of pulp fibers: the "MorFi" has been recently developed in order to ascertain some key parameters of fibers such as length, width, curl….
One of the most interesting results, which can be reached by this equipment, is the possibility to obtain a length/width repartition of fibers. This is a very time consuming task if one tries to carry out this calculation manually. This also allows to determine quickly what kind of wood fibers is present in the pulp. Moreover in some cases, species can be distinguished in a two components mixed pulp of hardwoods.
In a second part, mixed pulps containing hardwood and softwood fibers are studied. The average length and coarseness of different proportions of each component are measured. The experimental values show a good correlation with the theoretical ones.
Refining of pulp is important to develop fibers properties. This mechanical treatment induces changes in length and fine ratio. Based on the modification of the length distribution, it is possible to have a quite good prediction of the beating degree (°SR), for chemical bleached pulp of both hardwood and softwood species. Applying this method to hardwood/softwood pulp blends at 40 °SR, it is possible to show that hardwood fibers are less sensitive to beating than those of softwood, which is in good agreement with the literature.
MorFi can also be used to characterize mechanical pulps and more particularly the amount of shives. Two parameters could be established (number of shives per gram and shive area per gram) allowing to check the runnability of the screener. The mean shive area per gram is in correlation with the Sommerville Index but should be taken with care due to the shape of the shives.
In conclusion, some prospects are discussed like the relation between the fiber morphology and the physical properties of a handsheet or how to transform MorFi software to achieve information about weighted values.