The characteristics of urea formaldehyde adhesive modified with red pine bark tannin

In this study, the performance characteristic of urea formaldehyde adhesive modified with red pine bark tannin was revealed. By obtaining tannin from red pine bark, the urea formaldehyde adhesive was modified by adding 5-50% tannin to the urea formaldehyde adhesive in proportion to the adhesive solid material, and the performance of the adhesive was revealed as a result of the studies. The red pine bark used in this study was supplied from Or-San Orman Ürünleri in Konya/Karatay district. Within the scope of this study, the extraction process was carried out using the bark powder sample of red pine (Pinus brutia)to obtain powder tannin. Modified adhesive groups were obtained by adding 5-50% tannin to urea formaldehyde adhesive in proportion to glue solid material. The viscosity, solid content, gel time, pH and free formaldehyde in the adhesive of the produced modified adhesive samples were assigned. To reveal the wet and dry strength values of all adhesive samples, lap shear tensile strength tests were carried out using beech veneer. At the same time, FT-IR analyses of the modified adhesives and microscopic images of the adhesion line were taken and analyzed. As a result of the study, it was observed that the viscosity of the adhesive increased as the tannin usage rate increased among the modified adhesive groups produced. It was observed that the viscosity increased to 3741cP, which is the highest value, in the U11 modified glue group with 50% tannin content. It was observed that as the amount of tannin increased in the modified adhesive, the gelation time also increased. The gelling time was recorded as 340 seconds in the U4 modified adhesive group with a tannin ratio of 15%. When the free formaldehyde determination results of the modified adhesive are examined, the increase in the tannin ratio shows that there is a decrease in the amount of formaldehyde in the adhesive in general. However, it is seen that the decrease in the amount of formaldehyde is not regular, but in the form of fluctuations. It is the urea formaldehyde glue with the highest dry strength value in the lap shear strength tests. It was observed that the modified adhesive groups that showed the closest dry strength to the urea formaldehyde adhesive were the U4, U2 and U3 groups, respectively. When we look at the wet strength values, the commercial urea formaldehyde adhesive has the highest wet strength value. It was observed that the modified adhesive samples that showed the closest performance to urea formaldehyde adhesive in wet strength values were U4, U2 and U3 adhesive groups, respectively. As a result, it was alleged that the free formaldehyde ratio of the modified adhesive was significantly lower than the urea formaldehyde adhesive. Keywords: Bark, formaldehyde, tannin, modified adhesive, red pine