Hot pressing technique for poplar plywood bonded with modified soybean protein adhesive

Using a single factor method,we investigated the influence of hot pressing parameters(temperature,time and pressure) and resin content on bonding strength of plywood glued with modified soybean protein adhesive.The results indicated that the bonding strength increased significantly when hot pressing temperature rose from 100 to 220 ℃.It also increased with prolonged hot pressing time ranging from 35 to 60 s /mm.When hot pressing time increased from 60 to 85 s /mm,the bonding strength did not change significantly.The plywood exhibited the maximum bonding strength at a pressure of 1.25 MPa.The bonding strength increased when resin content rose from 130 to 430 g /m2.The optimum process was therefore suggested as follows:The plywood is pressed at 180 ℃ with a pressure of 1.25 MPa;the pressing time is 60 s /mm and the amount of adhesives is 310 g /m2.