Properties of the water-resistant plywood glued with pf resin with the addition of tannin filler and nanoclay
The conducted study was aimed at finding the phenol-formaldehyde adhesive formulation containing both the nanoclay and the tannin filler which allows to manufacture water-resistant plywood characterized by the improved properties. The research assumed the application of six experimental variants having a different proportions of the mentioned components which were compared with the mixture prepared according to the industrial recipe. Properties of liquid mixtures such as their gelation time and viscosity were investigated. Moreover, the differential scanning calorimetry (DSC) was performed. The manufactured plywood panels were tested in terms of bonding quality, bending strength and modulus of elasticity. Studies have shown that after the adjustment in components proportions it is possible to achieve the proper viscosity level of adhesive mixtures. The results also indicated that the suitable amount of nanoclay can contribute to the acceleration of resin gel time, however, the DSC analysis showed no effect on its reactivity. The nanoclay concentrations ranging from 2 to 4 pbw (parts by weight) per 100 g of adhesive positively influenced the bonding quality of plywood. Furthermore, there was no clear tendency in case of the effect of applied formulation on the modulus of elasticity and bending strength of plywood. The mixture containing 3 pbw of nanoclay and 5.3 pbw of tannin filler was distinguished as the most beneficial taking into account the improvement in the properties of manufactured plywood.