Study The Influences Of Physical Process On The Decay Mechanism Of Plant Fibers

Due to the complexity of the supra-molecular structure and the decay of the cellulosefibers’ properties, which restrict the paper recycling, resulting in a waste of resource. In thispaper, the eucalyptus wood as the raw material, different analysis methods were used tocharacterize the macroscopic and microscopic performance of eucalyptus fiber during thepapermaking process, which is aimed to explore the mechanisms of hornification and providea theoretical guidance to ease the decay of plant fiber performance further.The effects of the beating, pressing and drying on the macroscopic properties ofeucalyptus fibers were studied. The results showed that the WRV of the beaten fiber with30min was increased by31.51%compared with the virgin fiber. The WRV was significantlydeceased with increasing the squeezing time or drying time. To explore the effect of physicalprocess on the performance fiber into paper further, the characteristics of the fiber surfacewere analyzed. The fiber surface wass fibrillated and then rendered fibrillated difficulty. Withthe increase in compression pressure the fiber surface become compacted, smooth, stiff, andflat. Further, the drying time increases, the fiber surface and the edge portion wass burnedcracks, fiber surface become smooth, stiff, almost there is no fine fibers on the surface fibers,and the obviously gap between fibers pressed flat.Effects of physical processes on fiber hydrogen bonding models were studied. Themaximum rate of changes about the total content of the intra-molecular hydrogen bondO(2)H O(6) and O(3)H O(5) decreased by27.33%, the content of inter-molecularO(6)H O(3′) increased by26.65%during beating. In addition, the inter-molecular hydrogenbonding of cellulose is dominant, and it manifests itself as a force between fibers to combinethe chains of cellulose, while intra-molecular hydrogen is just in position within the auxiliary.The results show that the content of inter-molecular hydrogen bond O(6)H O(3′) waspresented after the first increase and then decrease, while the total relative content of theintra-olecular hydrogen bond O(2)H O(6) and(3)H O(5)was opposite with the increase ofpressure. Specifically, compared with the virgin fibers, the content of inter-molecularhydrogen bond increased by15.65%, while the intra-molecular hydrogen bond O(2)H O(6)and (3)H O(5) reduced by23.34%within the press pressure of0.3MPa. The content ofinter-molecular hydrogen bond O(6)H O(3′) showed an increasing trend, increased by16.51%when the drying time was in range from0min to10min; continuing to increasing thedrying time the content of inter-molecular hydrogen bond declined, which indicating that thecell wall collapse with the force drying, narrowing the distance between the cellulose chains is good for the formation of partially reversible hydrogen bond O(6)H O(3′), making thestructure of fiber more regular and compact; while increasing the drying time cellulose isunable to form intermolecular hydrogen bonds because of the destruction of the molecularstructure, thus reducing the content of the intermolecular hydrogen bonds.Influences of physical processes on the fiber crystalline structure were analyzed. Thecellulose crystal type (cellulose I) did not change, but the average width of crystal plane andthe cross-sectional area of eucalyptus cellulose fibers have significant changes, and themaximum rate of change about the crystallinity and size of the crystal plane were29.2%and33.2%, respectively, during beating. The results of the spectral fitting for the cellulose C4region of the13C NMR spectra of the pulps with different beating times were shown that therewas a degree of conversion between different forms of crystalline cellulose, while cellulose Iβis predominant in the eucalyptus fiber. However, the only significant difference is the changeof the fibrils aggregate dimensions ranges from22.2nm to27.8nm. Cellulose crystal type didnot affected, but the average width of crystal plane and the cross-sectional area of eucalyptuscellulose fibers have significantly been changed by pressing. In addition, with the increase insqueeze pressure, the degree of crystallinity showed a tendency to increase after the firstdecrease, which was consistent with infrared detection. Compared with virgin pulp, the degreeof crystallinity of the fiber dried25min increased by6.58%; the crystallinity of the fiberincreased as increasing the drying time. The reason is that the water of the fiber wall pores iscompletely evaporated and the fibers are excessively dried, causing aggregation of thecellulose molecular chains, that is increase the degree of fiber hornification. In addition,changes in the size of the crystal surface causing changes in the cross-sectional area of thecrystal surface, which is a parameter to measure the degree of microcrystalline aggregate.