Water resistance improvement by polyethyleneimine of tannin-furfuryl alcohol adhesives

In this research furfuryl alcohol (FA) and polyethyleneimine (PEI) in different ratio were added to a tannin based adhesive in order to improve its moisture resistance. In order to characterize the functional groups involved, Fourier-transform infrared spectroscopy (FTIR) was used. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to study the thermal behaviour of the formulations. FTIR spectroscopy indicated the reaction of quebracho tannin with FA and PEI. The results of the TGA showed that the added FA and PEI increased the resistance to thermal degradation. DSC analysis showed that the added FA and PEI reduced the heat absorption peak. According to the tensile shear strength of the formulations, the adhesive formulation T1 F0.75 P20 (mixing proportion: Tannin 1, FA 0.75, PEI 20%) was able to satisfy the standards requirements (BS 1204-2) as a moisture resistant adhesive. Furthermore, this formulation presented the best tensile shear tests results and the least number of delaminated samples.