Study On The Preparation And Performance Of Eucalyptus Veneer Plywood Glued By Thin Polyethylene Film

Eucalyptus is one of the main tree species of southern plantation in China with its relatively rich resources.Polyethylene is a kind of good performance thermoplastic material.The PE film/eucalyptus wood veneer composite panel made by hot-cold pressing is a kind of green,ecological and environmental panel with formaldehyde-free release,,which can be used for furniture,decoration and whose application has vast potential for future development.By comparing strength change under the environment of high,low temperature and hot-cold alternating cycle for the three kinds of panels(plywood glued by UF,plywood glued by PF and plywood glued by PE film),the high temperature tolerance,the low temperature resistance and the ability to resist cold and heat alternate cycle of panels were studied and the variation of dynamical mechanical properties of plywood glued by PE film and plywood glued by UF were compared.Also,the effect of temperature and pressure on preparation of plywood glued by PE film was studied and the optimized technological program in pilot plan test was acquired.The conclusion are as follows:(1)The moisture content of the panel glued by PE film had a significant effect on hot-pressing time;Polyethylene film with thickness between 0?0.08 mm will not obviously affect the heat transfer when hot pressure technology was applied to bond the plywood.(2)Increasing the pressure of hot press had not obvious effect on the improvement of bonding strength.Hot-pressing process with subsection,can accelerate the discharge of water inside the panels;Cold pressing pressure is the key to ensure that the bonding strength of the panels,in a certain pressure range,improving cold pressing pressure would not only be beneficial to improve the bonding strength of panels but also did not significantly affect the compression rate of panels.(3)Among the three boards,the best one with properties of resistant to high temperature is plywood bonded by urea formaldehyde,followed by plywood bonded by phenolic aldehyde and last one is plywood bonded by thin polyethylene film.Low temperature had a little effect on the strength of the three kinds of plywood;Dynamic storage modulus of plywood bonded by polyethylene film was related to the film melting temperature.(4)Combining the sectional type hot pressing process with hot pressing-cold pressing could not only increase the production efficiency but also save the time,manpower,finally improve the quality of products,which can be applied to production.