The Deformation Fixation And Physical Properties Of Diversification Of Heat-treated Bended Plywood

In order to solve the technological problems on recovery and deformation of Bended Plywood(BP),and to clarify its mechanism about fixation and deformation in molecular level, this paper illustrates proper technics and influential factors in manufacturing, and also analyses heat-treated BP in physical properties, such as its dimensional stability, stress relaxation, X-ray diffraction analysis and dynamic mechanical analysis. The main conclusions are as followings:(1) The recovery of BP's chordwise length decreases with the heating temperature and time increasing, and increases with shorter curvature radius. The compressing deformation recovery decreases and quality loss increased with heating temperature and time increasing.(2) The remaining stress in BP decreases and the dimensional stability increases with the heating temperature and time increasing. In the early measure time, the stress of heated BP sharply declines, of which the inflexion is respectively 1.67min,2.86min,3.3min after heat treatment with 140℃,160℃and 180℃. Meanwhile, the relaxation speed increases.(3) BP's degree of crystallinity increases with heating temperature, especially beyond 160℃.(4) There are four absorption peaks of untreated BP from -80℃to 300℃when heating, and the center temperatures are respectively 48.2℃, 118.6℃, 248.6℃and 326.7℃, which respectively due to movement of absorbed water molecule,and decomposition of hemicellulose,lignin,cellulose.(5) The change of E″of treated BP is little, while that of untreated BP decrease obviously. E′increases with measuring frequency, but the increasement is little.