螺杆蒸汽爆破预处理对稻秆结构及其无胶板性能的影响

摘要

The rice straw ( RS) was pretreated by continuous screw-extrusion steam explosion to obtain steam explosion pretreated rice straw for the preparation of binderless board. The pretreated rice straw was washed by distilled water and filtered to obtain washing solution and filter residue ( steam explosion pretreated rice straw fiber, SE-RS ) . The structure and properties were investigated by scanning electron microscopy ( SEM ) , ultraviolet-visible absorption spectrum ( UV-Vis ) , Fourier transform infrared spectroscopy ( FT-IR) , X-ray diffraction ( XRD) , thermogravimetric analysis ( TGA) , components testing and moisture absorption testing respectively. The SEM images show that after pretreatment the surface structure of rice straw was destoried and the fiber bundle was separated to slender fiber and fragment. The UV-Vis , FT-IR and TG analyses showed that the hemicellulose and lignin of RS were degraded during the pretreatment and there was no significant change in the structure of fiber. Comparing to the raw material, the content of benzene-alcohol extract and the ash of SE-RS were decreased by 36. 91% and 23. 13%respectively;The crystallinity of cellulose was increased by 10.61% and the moisture absorption rate was decreased by 17.02%after washing. Binderless boards were then prepared from rice straw and pretreated rice straw. The modulus of rupture ( MOR) and modulus of elasticity ( MOE) of the binderless board was increased by 142. 02% and 196. 78% compared to the control respectively, and the thickness expansion rate of water absorption for 2 h( 2 h TS) was only one-third of the control′s.%采用连续式螺杆蒸汽爆破对稻秆(RS)进行预处理得到汽爆预处理稻秆,用于制备无胶板;汽爆预处理稻秆经蒸馏水洗涤,过滤后得洗涤液和滤渣(汽爆预处理稻秆纤维,SE-RS),用于扫描电镜(SEM)、紫外-可见吸收光谱(UV-Vis)、红外光谱(FT-IR)、X射线衍射(XRD)、热重分析(TG)、成分测试和吸湿性测试,分析稻秆预处理前后结构与性能的变化.分析结果表明:SEM显示预处理后的稻秆表面结构被破坏,纤维束分离形成了细长的纤维和碎片;UV-Vis、FT-IR和TG分析表明在预处理过程中稻秆的木质素和半纤维素发生了降解,纤维素结构未发生明显变化;与未处理稻秆相比,水洗后的预处理稻秆的苯醇抽提物和灰分分别降低了36.91%和23.13%,纤维吸湿率下降了17.02%,纤维素结晶度提高了10.61%.用预处理前后的稻秆分别制备无胶板,预处理稻秆制的无胶板的静曲强度(MOR)提高了142.02%,弹性模量(MOE)提高了196.78%,2 h吸水厚度膨胀率(2 h TS)为39.32%,仅为未处理无胶板的1/3.