Properties and bonding mechanism of konjak powder - chitosan - PVA blending adhesive

In order to enhance utilization value of konjak powder and develop environment-friendly wood adhesive, konjac glucomannan and chitosan were blended as main raw bonding materials with adding polyvinyl alcohols (PVA). Thermal characteristics of the blending adhesive were analyzed to determine the hot-pressing temperature parameters by differential scanning calorimetry (DSC). Then the orthogonal experiment was used to investigate the effects of the process parameters on the bonding strength of plywood. The bonding strength of plywood using the konjak powder - chitosan blending adhesive was compared with PVA and without PVA, and the microstructure of the blending adhesives were also analyzed by infrared spectroscopy (FTIR) and scanning electron microscope (SEM). Results showed that the plywood could reach the maximum value of bonding strength when the press temperature, press pressure, pressing time, and adhesive storage time was 130℃, 4 MPa, 15 min and 24 h, respectively. FTIR showed that there existed the strong interaction of hydrogen bond among the three kinds of molecular. SEM observations indicated that the blending adhesive with PVA had the net-like structure so as to increase its whole bonding strength. These results could provide scientific basis for accelerating process of the development of environmentally friendly wood adhesive and improving the processing condition.