Study On Dimensional Stabilization Of Poplar Wood Based On Superhydrophobic And Thermal Modification Techniques

As one of the four major raw materials,wood is a green,environmentally friendly material that is renewable,recyclable,and naturally biodegradable.However,the primary and high quality forest resources in China are seriously scarce.Although the quantity of fast-growing plantation wood is large,its material quality is poor and easy to deform.therefore,It is difficult to meet the requirements of wood quality in the fields of architecture and household.Poplar is the most widely planted tree species in Shandong Province,but its material is soft and easy to deform and lead to poor dimensional stability,which affects the efficient utilization of poplar resources.Therefore,this study selected poplar as raw material,focusing on exploring the bionic superhydrophobic self-cleaning technology and high-temperature thermal modification technology to improve the dimensional stability of poplar,in order to obtain the key technology of poplar wood size stabilization.On the basis of the above,the optimum technology was selected to stabilize the compressed poplar which is easy to deform,to further verify the effectiveness and practicability of the optimal selection technique.The results of the study were as follows:(1)Inspired by the superhydrophobic self-cleaning properties of natural lotus leaves,the ethanol loaded nano-silica superhydrophobic emulsion was synthesized by sol-gel method.Its particle size was about 110 nm,and it can be suspended in ethanol solvent for more than one year and be green and inexpensive.After spraying the stable suspension on the wood surface,the nano-silica distributed uniformly on the surface of the wood micro-scale rough structure,forming a homogeneous micro/nano hierarchical structure,making the wood obtain a superhydrophobic surface with a static water contact angle greater than 150° and a roll angle less than 10°.The coating did not affect the visual effect of the wood surface.The modified wood obtained excellent dimensional stability.The water was continuously soaked for 24 hours and the size hardly swells,which indicates the improved wood had excellentdimensional stability.However,the superhydrophobic surface had poor wear resistance.Under the weight of 200 g,the abrasion resistance of 240-grit sandpaper did not exceed 20times(10cm each time),which affected the wide application of the technology.(2)Using high-temperature thermal modification technology,poplar was treated under vacuum conditions.The dimensional stability of poplar was studied under different conditions at 170°C,180°C,190°C,200°C,and 210°C.The results show that,At 90? for 10 hours,the physical properties of poplar decreased relatively low(bending strength,compressive strength,wear resistance and impact toughness of wood decreased in varying degrees,and obtained better dimensional stability.The decrease of hydroxy group in the chemical component may be the reason for the improvement of the dimensional stability of wood.(3)Comparing two kinds of dimensional stabilization technologies,the high-temperature thermal modification technology was preferred in terms of the perspective of cost-effectiveness and easy promotion.And in this way,it was further processed into compressed wood,so as to test the effect of the thermal modification technology with high temperature on dimensional stability of the compressed wood which is easy to deform.And more,the compressed technology can solve the drawbacks of high temperature thermal modified wood that the mechanical properties are normally reduced.The results show that the compressed wood can significantly improve its dimensional stability under the conditions of different compression ratios(30%,50%,and 70%),and the improved compressed wood has higher mechanical properties than those of unmodified poplar wood,which proves the effectiveness of this technique.