The Structure and Adhesive Properties of Poly(vinyl acetate) Dispersion Modified with Organosilicon Compounds
Keywords:timber, polyvinyl acetate dispersion, bond strenght, splitting stresses, silica derivatives.
Among many polymeric adhesives used in wood processing industry polyvinyl acetate has a rather wide application. It is used to glue tenon joints, doors, windows and other wooden articles. Bond strength is much higher than that of the wood itself. However, polyvinyl acetate is nonresistant to moisture polymer and if such adhesive joints are exploited in moist environment its strength substantially decreases. Sufficiently moisture resistant adhesive joints are obtained by modifying PVA dispersion with special compounds characterized by high reactivity. Such monomers have chemically active groups with the aid of which spatial structures of molecules are formed. Halogensilans are known as having high reactivity with hydroxylic groups, including polyvinyl acetate, acting as netting agents. Unplasticizied poly(vinyl acetate) dispersions were modified with organosilicon compounds. The adhesive properties of the modified dispersions were evaluated after preparation of adhesive joints with birch strips according to requirements of EN205. Moisture resistance was evaluated by the experiment sequence according of EN 204. Strength of the adhesive joints were up to 2.5 time higher than EN204 requirements. IR spectra show formation of the new chemical bonds with some of the organosilicon compounds in the modified poly(vinyl acetate) dispersion
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