SEM ANALYSIS OF THE WOOD-BASED COMPOSITES STRUCTURE AFTER EXPOSURE TO WATER AND VARIOUS CLIMATIC CONDITIONS

S pomočjo vrstičnega elektronskega mikroskopa smo preučevali spremembe na nivoju zgradbe gradnika kakor tudi lepilne vezi med gradniki ter korelacijo med debelinskim nabrekanjem, razslojno trdnostjo in tlačno strižno trdnostjo ivernih, MDF in OSB plošč ter strižno trdnostjo furnirne plošče. Debelinski nabrek smo določali z izpostavitvijo preizkušancev klimi s povišano zračno vlažnostjo, z izpostavitvijo suhi klimi in potapljanjem v vodo. Preizkušancem smo pred in po izpostavitvi različnim klimam določili tlačno strižno trdnost, razslojno trdnost in debelinski nabrek. Ugotovili smo, da imajo v normalnem stanju najboljšo tlačno strižno trdnost iverne plošče, najslabše so se obnesle OSB plošče. Pri izpostavitvi vlažni klimi so imele najboljšo tlačno strižno trdnost iverne plošče, najslabše pa MDF plošče. Pri potapljanju v vodo so se najbolje obnesle OSB plošče, najslabše so bile MDF plošče.. Opravili smo tudi analizo z elektronskim vrstičnim mikroskopom, s pomočjo katerega smo potrdili, da pri izpostavitvi vlažni klimi in vodi prihaja do spremembe v in med gradniki (obremenitev lepilne vezi) kakor tudi porušitve samih gradnikov.Changes in constituents, adhesive bond, and correlation between the thickness swelling, internal bond, compression shear strength of particleboards, MDF boards, OSB and plywood shear strength were studied. The thickness swelling was determined by exposure to a high humidity and dry and by immersion in water. Prior to and after mentioned exposures, we had determined the tensile shear strength, internal bond, shear strength and thickness swelling. The results have shown that while in normal state, particleboards have the best compression shear strength, whereas OSB showed lowest values. When exposed to humidity, particleboards had the highest values, while MDF the lowest. At immersion, the highest values were determined at OSB and the lowest at MDF. We have also performed an SEM analysis with where we confirmed changes in and between constituents (stresses in glue line) as well as constituents failures