Adhesion Properties between Polyvinyl Acetate Dispersion and Ammonia Modified Oak Wood

It is known that PVA dispersion exhibits very good adhesion with natural wood. However, still remains unclear what adhesion-related changes occur, when the outside factor, i. e. ammonia, affects bonding or what the stability of bonding strength is, when the moisture content of ammonia modified wood increases. The aim of this work was to assess adhesive properties of ammonia modified oak wood and the bonding strength of PVA adhesive and modified wood, and to evaluate suitability and boundaries of PVA adhesive for bonding ammonia modified wood. To explore phenomena of adhesive interface of polyvinyl acetate (PVA) dispersion and modified wood ammonia treated oak was bonded using PVA dispersions manufactured by JSC “Achema”. Non-water resistant “Lipalas D2” and “Lipalas D3” with enhanced water resistance adhesives comparison allowed examining and comparing gluing performance at variable pH and ammonia content in PVA. In addition bonding strength between PVA adhesive and modified oak wood was evaluated and compared with the adhesive bondline properties for unmodified oak wood. Tests performed in accordance with the standard EN 205:2003 revealed remarkably contrasting effects at dry and wet gluing conditions especially for modified oak. The scanning electron microscope (SEM) enabled image confirmation and explanation changes in the PVA adhesive interfaces after contact with modified and untreated oak wood. DOI: http://dx.doi.org/10.5755/j01.ms.19.2.4433