PFI及超声波预处理对阔叶木溶解浆纤维性能及其黄化过程的影响

本研究对阔叶木溶解浆纤维进行PFI(磨浆)预处理和超声波(破碎)预处理,考察预处理前后对纤维长度和宽度、孔隙结构、表面形貌、纤维素结晶度和Fock反应性能的影响。结果表明,PFI预处理对纤维孔容、比表面积、纤维素结晶度和Fock反应性能影响较小,而超声波预处理(540 W/10 min)后,纤维的孔容由1.0×10-2cm3/g增加至2.2×10-2cm3/g,比表面积由5.358 m2/g增加至9.503 m2/g,纤维素结晶度从82.57%下降至76.38%,Fock反应性能由38.82%增加至49.80%。纤维在黄化试剂体系中的溶解历程主要是"鼓泡式"润胀-溶胀-溶解的过程,随着黄化反应的进行,纤维二重质均长度先下降后上升,二重质均宽度持续增加;细小纤维含量先增加后降低,纤维素结晶度不断降低,纤维素部分溶解;在黄化反应3 h过程中,纤维二重质均宽度由17.6μm增加至34.3μm,纤维素结晶度由76.38%下降至57.53%;纤维的二重质均长度在0~2 h时由0.826 mm下降至0.547 mm,3 h后增加至0.766 mm;细小纤维含量在0~2 h时由1.2%增加至6.2%,3 h后则降低至3.4%。

Effect of PFI and Ultrasonic Wave Pretreatments on the Fiber Morphology and Xanthation Characteristics of Hardwood Dissolving Pulp

In this study,the hardwood dissolving pulp fibers were respectively pretreated by the PFI mill and the ultrasonic wave,and the influences of both pretreatments on the fiber length,width,porosity,surface morphology,cellulose crystallinity and Fock reactivity were investigated.The results showed that PFI pretreatment had little effects on pore volume,specific surface area,cellulose crystallinity and reaction property,while after the 540 W/10 min ultrasonic wave pretreatment,the pore volume of fibers increased from 1.0×10-2cm3/g to 2.2×10-2cm3/g,the specific surface area increased from 5.358 m2/g to 9.503 m2/g,the crystallinity degree decreased from 82.57% to 76.38%and the Fock reactivity increased from 38.82%to 49.80%.The dissolution of the pulp fiber in xanthation reagent system was mainly a process of"bubble-shape"swelling-swelling/dissolution-dissolution.As the xanthation reaction went on,the fiber weight-weight length first decreased and then increased,while the fiber weight-weight width continued to increase.The fines content first increased and then decreased,and the cellulose crystallinity continued to decrease and the cellulose partially dissolved.During 3 h xanthation reaction,the fiber weight-weight width increased from 17.6μm to 34.3μm and the cellulose crystallinity degree decreased from 76.38%to 57.53%.The fiber weight-weight length decreased from 0.826 mm to 0.547 mm during the period of 0~2 h and then increased to 0.766 mm after 3 h.Fines content increased from 1.2%to 6.2%during the period of 0~2 h,and then decreased to 3.4%after 3 h.