PRESSURE-IMPREGNATION TECHNIQUE FOR WOOD CHIPS

In this paper the pressure impregnation of wood chips is analyzed and a pressure-impregnation method is suggested, whereby the chips are imp regnated at high pressures without causing the wood to collapse. This can be done by increasing the pressure slowly so that the pressure dif ference between the edge of the chip and the centre of the chip never exceeds the compression strength of the wood. To test the efficiency o f the suggested method, penetration of copper sulphate into dry Norway spruce wood blocks was studied with a colour reagent for copper and w ith SEM-EDXA. High pressures (1-10.5 MPa), which were reached by incre asing gradually the pressure (0.5-2.3 MPa/min), were tested in combina tion with short impregnation times (3-15 min). The experiments showed that the penetration was more thorough at a higher pressure than at or dinary pressure (1 MPa). After the impregnation, no collapsed wood cel ls could be observed.