Study On The Softened Process And Flattened Board Performance Of Maso Bamboo Tube

The development of bamboo flattening board is a kind of environmental and high added-value products recently.The technical content of this technology in the bamboo processing field is high,but the basic theory still needs to be studied.The Phyllostachys edulis was used in this study as the research object.The temperature of softening process is judged through studying the bamboo glass transition temperature(Tg).The high temperature and rapidly softening method was carried out on investigating bamboo softening process and studying the influences of different factors on the open groove size and flattening characteristics of bamboo.Last,the physical and mechanical properties of bamboo flattening board were studied.It will provide the theoretical basis for the bamboo softening and flattening,accelerating industrialized production of the bamboo softening and flattening.Research showed that:(1)With an increase of moisture content(MC)at 50.0-250.0 ?,Tg decreased from 217.3 ? to113.0 ?.The changement of initial MC at lower levels had a greater effect on Tg than moisture content changes at higher levels.The Tg for the outer,median,and inner layers of bamboo along the radial direction showed little differences.Maximum difference in Tg was 12.0 ? and minimum was 0.5 ?.With identical radial positions and initial MC,different ages and the heights did not affect bamboo Tg which had differences of less than 5.0 ?.This study showed that an increased initial MC was good for bamboo softening and will,thus,help make full use of materials in the production process.(2)The softening temperature,time and initial moisture content of specimens have significant effects on bamboo softening.The modulus of elasticity(MOE)of bamboo decreased with the increasement of softening temperature and MC.And with the increasment of softening time,MOE reduced first and then increased.The most significant drop was at 160 ? and 6 min and fell to 48.5%and 45.5%,respectively.The MOR and compressive strength of bamboo decreased with the increasement of the softening temperature,time and MC.FTIR and XRD showed that with the extension of the softening temperature,time and MC were good for bamboo softening and dimensionalstability of bamboo products.Within the scope of the test,the higher the softening temperature,the longer the softening time and the higher the initial moisture content,the easier softening the bamboo.(3)The optimal experiment of softening process showed that softening temperature has an important effect on MOE and MOR,the effect of softening time on MOE is efficient and MOR is unconspicuous,the influence of initial moisture content on the both is not significant.Take the bamboo flattening characteristics and actual situation of enterprise production into consideration,the best softening process combination is softening temperature as 180 ?,softening time as 6 min,and MC beyond the fiber saturation point.(4)Whether remove bamboo green or not and the number of bamboo knot have an excellent influence on the open groove size and flattening characteristics of bamboo.Removing bamboo green can increase the open groove size and the success rate of flattening,it also helps to reduce the board crack.The more the number of bamboo knot,the smaller the open groove size,the more difficult the flattening,and the bigger the probability of cracks.Height has less effect on the open groove size and flattening characteristics.Wall thickness has less effect on the open groove size while influences flattening characteristics.The crack rate of bamboo board increased with the bigger of wall thickness.Initial moisture contents below the fiber saturation point had a greater effect on the open groove size and flattening characteristics than moisture contents below the fiber saturation point.(5)As the consequences of the research,the processing on softening and flattening of bamboo is that: the distortion of bamboo parenchyma cells after softening was smaller than the bamboo after flattening.Compared with the original bamboo,the physical and mechanical properties of board are unchangeable after softening and flattening and have no influence on its subsequent processing and utilization.