铺装结构及密度对玉米秸秆轻质复合板性能的影响

为充分利用玉米秸秆并制备性能优越的轻质复合材料,通过对玉米秸秆内外表面特性的分析,采用机械疏解重组其胶合结构单元,以脲醛树脂为胶黏剂,制备定向和均向2种玉米秸秆轻质复合板。本文研究了不同铺装方式和密度对板材静曲强度(MOR)、弯曲弹性模量(MOE)、内结合强度(IB)、吸水厚度膨胀率(TS)、吸水率(WA)的影响。结果表明:定向铺装结构可以增强复合板材的MOR、MOE、IB,相同密度下定向玉米秸秆复合板(OCSB)的纵向静曲强度(MOR∥)和纵向弹性模量(MOE∥)约为均向玉米秸秆复合板(HCSB)的3倍,IB约为4~5倍。OCSB的MOR∥、MOE∥明显大于横向静曲强度(MOR#x22A5;)、横向弹性模量(MOE#x22A5;);OCSB密度为0.3 g/cm3时,MOR∥约为MOR#x22A5;的3.5倍,MOE∥约为MOE#x22A5;的5倍。OCSB的MOR#x22A5;均大于HCSB的MOR(密度0.3 g/cm3除外),OCSB的MOE#x22A5;均小于HCSB。OCSB和HCSB的MOR、MOE在试验范围内都随着密度的增加而增加;当OCSB密度为0.6 g/cm3时,MOR∥为25.24 MPa,MOE∥达到4 216 MPa,其物理力学性能够满足在民用建筑中的使用。此外,OCSB的TS、WA均小于HCSB。 

Effects of formation structure and density on properties of lightweight cornstalk composites

In order to make full use of the cornstalk and prepare the lightweight composites with superior properties, the cornstalk was splited into filamentous structure units according to the analysis of both internal and external surface of it. Then these filamentous structure units were used to fabricate the composite by different formation modes of orientation and non-orientation, and urea formaldehyde resin was used as adhesive. The density of the fabricated composites was 0. 3, 0. 4, 0. 5, 0. 6 g/cm3 , respectively. The influence of formation structure and density on the physical and mechanical properties of the lightweight composites with cornstalk was explored, including the modulus of rupture ( MOR ) , modulus of elasticity ( MOE ) , internal bond strength ( IB ) , thickness swelling ( TS ) and water absorption ( WA ) . The results showed that MOR, MOE and IB of the lightweight composites were enhanced by the formation mode of orientation. The MOR// and MOE// values of OCSB were about 3 times, and the IB value was about 4--5 times as much as HCSB with the same density. The MOR//, MOE// were significantly greater than transverse static bending strength ( MOR^) and transverse elastic modulus ( MOE^) . When the density was 0. 3 g/cm3 , MOR// was about 3. 5 times as much as MOR^, MOE// was about 5 times as much as MOE ^;The MOR ^of OCSB was larger than MOR of HCSB ( except 0. 3 g/cm3 ) , the MOE ^of OCSB was smaller than MOE of HCSB. The MOR and MOE increased with the increasing of density. When the density was 0. 6 g/cm3 , the MOR//of OCSB was 25. 24 MPa, the MOE// of OCSB reached 4 216 MPa, the physical and mechanical properties can satisfy the civil buildings. In addition, the WA and TS of OCSB were smaller than HCSB.