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Title
Influence of pressing and drying on the microstructure of recycled plant fibers
Authors
Jinquan Wan Yan Wang Yongwen Ma and Qing Xiao
Received
October 21, 2008
Published
Volume 43 Issue 1-3 January-March
Keywords
pressing, drying, cellulose crystallinity, pore structure, recycled fiber
Abstract
The influence of pressing and drying on the microstructure of wheat straw fiber during reuse processes was studied. The results showed that, at an applied pressure below 4 MPa, the WRV loss rate was of 7.96%, while, at pressures over 4MPa, it was of 25.90%. When pressure increased from 1MPa to 5 MPa, cellulose crystallinity increased also, and the fiber cell wall pores closed to a great extent. With increasing pressure from 1 to 5 times, WRV decreased. However, cellulose crystallinity increased with increasing the number of pressings. Fiber pores were irreversibly and significantly closed after the first pressing while, with an increasing number of pressings, the changes observed in pore size and distribution of fibers were insignificant. When the drying temperature increased from 60 to 120 ºC, cellulose crystallinity increased to 84.6% and the average pore volume corresponding to the mesopore decreased by 5.42 × 10-5 cm3/g. In addition, WRV decreased, cellulose crystallinity increased and the degree of non-reversible closure was enhanced, when increasing the drying time at 100 ºC. Electronic microscope photographs evidence no non-restorable collapse deformation and folds on the fiber cell wall after pressing and drying, which modified the sizes and shapes of the fiber cell wall.
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