Prediction of the Strength of Oakwood Adhesive Joints Bonded with Thermoplastic Polyvinyl Acetate Adhesives

Among the several kinds of thermoplastic adhesives, structured and non-structured polyvinyl acetate (PVA) adhesives have a rather wide application and are used currently for forming adhesive joints from different wood species, especially oakwood. To ensure proper conditions of oakwood adhesive joints use, it is important to have fast and accurate methods of predicting their strength and durability. The strength changes of the oakwood adhesive joints bonded with structured and non-structured PVA adhesives have been investigated by conducting long-term experiments. Based on the generalization of experimental data and theoretical predictions regarding the mechanism of the adhesive seam formation, equations that allow calculating theoretically the strength of oakwood adhesive joints bonded with non-structured and structured PVA adhesives have been proposed. The pro-posed equations reproduce experimental data with suffi-cient accuracy of ±3.5 % within the temperature range from 251 K to 306 K and humidity range from 40 % to 100 %, and therefore, are recommended for practical use.