Study On Dimensional Stability Of Cotton-stalk Reconsolidated Square Material

In this paper, cotton-stalk reconsolidated square material was chosen as the basic rawmaterials. The paper investigated the effect of different technical parameters and treatmentmethods on dimensional stability of cotton-stalk reconsolidated square material, explored thepossibility of using cotton-stalk reconsolidated square material to make furniture. The purposeis to explore the regulation of dimensional changes of cotton-stalk reconsolidated squarematerial, using reasonable methods to improve the dimensional stability of cotton-stalkreconsolidated square material. And to provide the technical basis for improving thedimensional stability of cotton-stalk reconsolidated square material. The results weresummarized as followings：(1) The dimension of cotton-stalk reconsolidated square material changed with themoisture content. During the range of experiment, the shrinkage and hygroscopic expansionexhibited strong directionality; the shrinkage and hygroscopic expansion rate of the verticaldirection were less than the anteroposterior direction’s. Shrinkage and hygroscopic expansionrate of vertical and anteroposterior direction increased with the increase of density, anddecreased with the increase of resin content, hot-pressing temperature and time.(2) During the range of experiment, from65%humility to oven, the shrinkage rate ofdifferent concentration alkaline pretreated cotton-stalk reconsolidated square material in thevertical and anteroposterior direction was less than the test block without pretreatment, thedimensional stability of cotton-stalk reconsolidated square material was enhanced. Theshrinkage rate of the vertical direction decreased from1.76%to1.41%, and decreased by19.9%, and the anteroposterior direction decreased from3.14%to2.14%, and decreased by31.8%, when the concentration increased from0.5%to1.5%and the density was0.7g/cm3.With the increase of the concentration of lye, cotton-stalk reconsolidated square materialdifference shrinkage reduced.(3) During the range of experiment, the shrinkage rate of cotton-stalk reconsolidatedsquare material whose density was0.7g/cm3, decreased after post heat treatment at differenttemperatures. At170℃,190℃and220℃, when the treatment time was increased from 10min to30min, the shrinkage rate of the vertical direction of cotton-stalk reconsolidatedsquare material decreased from1.849%,1.180%and0.708%to0.954%,0.690%and0.211%,decreased by48.4%,41.5%and70.2%; And the anteroposterior direction decreased from3.028%,2.129%and1.395%to1.767%,1.214%and0.411%, decreased by41.6%,43.0%and70.5%. This suggested that post heat treatment could enhance the dimensional stability ofcotton-stalk reconsolidated square material.(4) During the range of experiment, hygroscopic and hygroscopic expansion rate ofcotton-stalk reconsolidated square material whose density was0.8g/cm3, from oven dry to65%humidity reduced apparently after Liquid paraffin high temperature treated. When theparaffin processing temperature was165℃,180℃and195℃,and the processing timeincreased from1.5h to2.5h,the hygroscopic rate of cotton-stalk reconsolidated squarematerial decreased by23.44%，33.45%，54.40%;The vertical directions’ hygroscopicexpansion rate of cotton-stalk reconsolidated square material from oven dry to65%humidity decreased by52.47%,17.96%,92.21%, and the anteroposterior direction decreasedby64.92%,79.22%,47.26%;The vertical direction’ s hygroscopic expansion rate ofcotton-stalk reconsolidated square material from65%to95%humidity decreased by35.42%,16.67%,43.30%; and the anteroposterior direction decreased by48.57%,62.18%,64.95%.Liquid paraffin treatment could obviously enhance the dimensional stability ofcotton-stalk reconsolidated square material.(5)Cotton-stalk reconsolidated square material could be sawed, planed, drilled and sanded.The three small square stools made by cotton-stalk reconsolidated square material, proved that cotton-stalk reconsolidated square material could be used in the furniture product development.The cotton-stalk reconsolidated square material should be pressed in a clear direction and aside a certain margin under the existing conditions.