Determination of properties of stone pine bark tannin and valonia tannin based bioadhesives

In this master thesis, various performance properties of tannin based adhesives were comparetively was investigated with synthetic alternatives which contain formaldehyde. In this research, it is also aimed to reveal the use potential of bark and acorn cup (cupule) which are important non-wood forest products generally considered as waste. For this purpose, some properties of tannin based adhesives produced by using stone pine bark tannin and valex tannin obtained from cupule were determined. The cupules used in the study were obtained from "AR-TU Kimya ve Ticaret A.S." operating in Manisa province in Turkey and stone pine barks were obtained from the cut residues of forest enterprises in Bergama region of Turkey. Within the scope of the study, tannin extraction of acorn cup and bark samples with water was first carried out. The acorn cup and bark powders were then extracted by using ethyl alcohol and distilled water. The extraction solutions were filtered, and the resulting aqueous tannin solutions were evaporated to obtain an appropriate solid matter ratio. The obtained liquid tannin solutions were reacted with eight kinds of hardener at different ratios and bioadhesive production experiments were performed. The gelling time, viscosity, pH, density, solid matter content and bonding strenght parameters of the synthesized bioadhesives were compared with mimosa commercial tannin, valex commercial tannin and commercial urea formaldehyde adhesive. Lap-shear samples were prepared from beech veneers of 3 mm thickness to determine wet and dry adhesion strength values of all adhesive samples. Finally, TGA and FTIR analyses of bioadhesives were performed. As a result of the study, the highest pH value of the bioadhesives was seen in the adhesives produced from the samples used tris (hydroxymethyl) nitromethane as hardener. When viscosity values were examined, it was observed that high viscosity was found in hexamine formulations of valex tannin-based bioadhesives. Gelling of stonepine bark tannin-based bioadhesives was obtained by using high viscosity formaldehyde and paraformaldehyde. While the highest gelling time of 1800 sec. was obtained in stone pine bark tannin formulation with benzaldehyde, the lowest gelling time of 55 sec. was recorded for stone pine bark tannin bioadhesive with formaldehyde. Tests showed that the dry bonding strength closest to the commercial UF adhesive was in the formaldehyde formulation of stone pine. The wet strength of the stone pine bioadhesive sample prepared using paraformaldehyde is higher than UF adhesive. Valex bioadhesives don't have wet strength while the highest dry strength was observed in VCT. Finally, it was demonstrated by thermogravimetric analysis that the bioadhesives produced were thermally more stable than UF adhesive.