| As important renewable biomass of forest rejectamenta and agricultural residues, salix psammophila can substitute fossil resource and be used to produce biology fuel and other industrial products. But its utilization is not still developed adequately today. In order to improve efficiently the utilization of salix psammophila, the biological structure, fiber characteristics and chemical components were analyzed. The optimal pulping and bleaching technology of salix psammophila in soda-AQ and kraft pulping process were discussed. Pulp of salix psammophila was mixed with other pulp to produce paper and the optimal ratio of the mixed pulp obtained in this thesis.Cross-section, longitudinal section and string section of salix were observed by optical microscope, and, the observation confirmed salix is a diffuse porous hardwood, and its texture was uniform, which was composed mainly by the catheter, wood fiber, wood ray parenchyma cells, boundary between growth rings was clear,. Fiber morphologic of salix were analyzed, and the results showed that Salix fiber length ratio closed to 45, the wall cavity was less than 1, and fiber morphology was better, and these analysis confirm salix can used to produce paper. But the fiber length of salix was shorter, and its cell walls were thinner, and it would influence the strength of paper in certain extent. The analysis results of the chemical components of salix stalk showed that cellulose content was 52.63%, hemi-cellulose content 23.34%, lignin content 19.19%, ash content 2.1%, and alcohol benzene extractive content 3.13%. Compared with salix stalk, ash and extractive content in salix skin was high, and it would cause colophony obstacle in the pulping process, and affect the pulping properties of salix.Soda-AQ pulping of salix were discussed by using the orthogonal L9(34) test of four-factor and three-level were. The variable parameter were NaOH dosage (based on the oven dry salix material) 22%, 24% and 26%, the highest cooking temperature 160℃, 165℃and 170℃, the maximum temperature holding time 60min, 90min and 120min. Its influence on yield, kappa values and viscosity were analyzed and the optimal technology of salix in soda-AQ pulping process was obtained. The results showed that the optimal pulping technology were NaOH dosage 24%, the maximum temperature 165℃, and the highest temperature holding time 90min.The optimal technology of salix in kraft pulping process was discussed. The main parameter influenced salix pulping including NaOH dosage (based on the oven dry salix material as Na2O) 16.3%, 17.8%, 19.3% and 20.9%, sulidity 21%, 23 %, 25%, 27% (as Na2O), H factor 600, 900, 1200 and 1500 were studied. The results showed that the optimal pulping parameters were alkali dosage 17.8%, sulfidity 25%, and H factor 900.In these pulping parameters, properties of pulp were breaking length 7.81 km, tear index 8.20 mN·m2·g-1, and burst index 4.63 kPa·m2·g-1 at 40oSR beating degree.Bleach ability of salix kraft pulp was studied. The results showed that the optimal bleaching conditions in DP sequence were ClO2 dosage 1.0% and H2O2 dosage 2.5%, in which brightness of the bleached pulp was 79.5 %ISO. The optimal bleaching conditions in HP sequence were hypochlorite dosage 7% and H2O2 dosage 3%, in which brightness of the bleached pulp was 78.5 %ISO. Compared with the HP bleaching sequence, strength properties of the bleached pulp in DP bleaching sequence were better and yield were higher.Properties of salix kraft pulp mixed with other pulp to produce paper were studied. The results showed that the optical and physical properties of salix kraft pulp mixed with poplar APMP were changed, and bulk and opacity of the mixed pulp were improved significantly physical properties of the mixed pulp decreased slightly. The strength properties of salix bleached kraft pulp mixed with hardwood bleached kraft pulp improved remarkably especially tear index of the mixed pulp.
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