劈裂率对定向结构麦秸板物理力学性能的影响

Effects of Splitting Rate on the Physicomechanical Properties of Oriented Structural Straw Board

通过比较4种不同劈裂率(100%、90%、70%、50%)的原料压制定向结构麦秸板,探究劈裂率对板材主要物理力学性能的影响。结果表明:随着劈裂率的降低,平行向的抗弯强度与抗弯弹性模量呈增大趋势,当劈裂率为50%,平行向的抗弯强度为59.38 MPa,比劈裂率100%时(51.75MPa)提高了15%;平行向的抗弯弹性模量为6.65GPa,比劈裂率100%时(5.40GPa)提高了23%。垂直方向的抗弯强度与抗弯强度模量差异不显著。劈裂率100%、90%、70%间内结合强度差异不显著,劈裂率为50%时,内结合强度显著下降,50%劈裂率时的内结合强度为0.31MPa,比劈裂率100%时(0.36MPa)下降了14%。随着劈裂率的降低,2h吸水厚度膨胀率和24h吸水厚度膨胀率呈增大趋势,24h吸水率差异不显著。劈裂率50%时的2h吸水厚度膨胀率为5.46%,约为劈裂率100%时(1.80%)的3倍,24h吸水厚度膨胀率为17.97%,为劈裂率100%(10.83%)的1.7倍。

Oriented structural straw boards were prepared by using wheat straws with four（100%,90%,70%,and 50%）different splitting rates（SR）to examine the SR on physicomechanical properties of the board.The results demonstrated that with the decrease of SR,parallel-aligned bending strength（PBS）and bending modulus（PBM）tended to increase.For example,when SR was 50%,PBS was 59.38Mpa,15%higher than that of 100%SR,the PBM was 6.65Mpa,23%higher than that of 100%SR.The bending strength and bending modulus in vertical direction were not significantly different among different splitting rates.The differences in internal bonding strength（IBS）among the splitting rates of 100%,90%,and 70% were not significant.However,with 50% SR,IBS significantly decreased.For example,IBS was 0.31Mpa with 50%SR,14%lower than that of 100%SR.Two-hour and 24hthickness swelling rates（TSR）increased along with the decrease of SR,and the differences in 24hTSR among different SRs were not significant.For example,with 50%SR,2hTSR was 5.46%,3times higher than that of 100%SR,and 24hTSR was 17.97%,1.7times higher than that of 100% SR.