Effect of heat treatment on properties and interfacial compatibility of poplar veneer/polyethylene film composite plywood

This study aimed to enhance the properties and interfacial compatibility of poplar veneer/polyethylene (PE) film composite plywood using heat treatment by prolonging the hot-pressing time. The plywood was heat-treated (long time hot-pressed) at 160, 180, and 200 °C for 2 h. The results showed that after being heat-treated at 180 °C for 2 h, the shear strength of the plywood was effectively increased from 0.49 MPa to 0.94 MPa, which met the requirements of type I plywood according to the Chinese National Standard GB/T 9846–2015. The higher the treatment temperature, the better the water resistance and durability of the plywood. The Fourier transform infrared spectroscopy (FTIR) spectra indicated that the number of hydroxyl groups and carbonyl groups was reduced after heat treatment, thus decreasing the surface hydrophilicity of poplar veneer. The scanning electron microscopy (SEM) images showed that heat-treated plywood possessed more continuous and uniform glueline compared with untreated plywood.