Surface Structure of Thermomechanical Pulp Fibers Studied by Electron Microscopy
Abstract
Pulp samples were obtained from the Bauer pressurized refiner and from the Masonite process. The surface structure of these fibers was studied by light and electron microscopy and related to the defibering temperature.
It was found that refiner pulp produced at 110 C consists mainly of individual fibers and fiber bundles. These units expose mainly cellulosic S1 microfibrillar structure with intermittent areas of S2 and display rough surface structure with numerous surface "fibrillation."
The Masonite pulp produced at 254-298 C consists of about 60% fiber bundles and 40% fully separated fibers and fragments of fibers. In contrast to refiner pulp, Masonite pulp exposes smooth surface structure that consists of a continuous and intact envelope of primary wall. In addition, these fibers are coated with a thick layer of amorphous middle lamella substance over part of their surface and possess vertical ridges of middle lamella at the cell corners. The pulp is dark in color and is considerably degraded.
References
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