Bert Pettersson

Effects of Acidic Media Pre-incubation on Flax Enzyme Retting Efficiency

Overnight incubation of flax straw in a weakly acidic (pH 2) solution decreases the amount of enzyme needed for virtually complete retting by two to three orders of magnitude, as judged by a modified Fried test. This effect is probably based on removal of Ca2+ crosslinking pectin chains in the middle lamella. Washing the enzyme-retted fibers in ethanol and then in acetone or in 0.1 M KOH reduces their stickiness and matting, thus apparently eliminating dry-back. The methods show potential usefulness for the development of a commercial enzyme retting process.

Technical soda lignin dissolved in urea as an environmental friendly binder in wood fiberboard

The application of lignin as binder in wood composite panel is not only environmentally friendly but also commercially attractive. The dissolving of technical soda lignin is the most premier challenge in its application. In this study, the effect of different key factors on soda lignin solubility in urea was investigated. The maximum solubility of 60.16 g/L was obtained under the temperature 70 °C, urea concentration 8 M, lignin content 7%, and pH 8.8. Then, different kinds of wood fiber material were mixed with the dissolved lignin solution to make fiber board separately. The results showed that the lignin can enhance the tensile strength of particleboard and can be used as a binder in wood material, but the strength will be different with different materials. The optimal tensile strength obtained was 44.63 MPa with the sample made from oriented cotton linter sheet.

Characterisation of Wetting by Solidification of Agarose Solution Sessile Drops

A new method for characterising the wetting of structured surfaces is presented. Sessile drops of a warm agarose solution were placed on test surfaces and then removed after the gelation of the agarose solution caused by the cooling of the drop. By studying the base of the sessile drops using confocal microscopy and image processing it was possible to determine the wetting mode and general appearance of the liquid–gas interface beneath the drop. The method also shows potential to measure the wetted area, and local contact angles beneath the footprint of a sessile drop. The applicability of the method was also demonstrated by its application to periodically structured photopolymer plates and surfaces covered by microsized glass spheres.

Enzymic Mechanisms of Cellulose Degradation Caused by the Rot Fungus Sporotrichum Pulverulentum (Chrysosporium Lignorum)

Sporotrichum pulverulentum belongs to Fungi imperfecti and is characterized as a white rot fungus. It was originally isolated from pine pulp wood chips. Bergman and Nilsson (1) tentatively called the fungus Chrysosporium lignorum. However, no description of the fungus was published so this name must be regarded as a nomen nudum. We have, however, recently received information from Centraalbureau voor Schimmelcultures in Baarn, The Netherlands, that the organism is identical with Sporotrichum pulverulentum Novobranova.