The Research On The Pulpability And Mechanism Of E.urophylla×grandis

Using E.urophylla×grandis as the material,this research systematically studied the pulpability with different pulping methods,bio-pretreatment and bleaching sequence,by adding surfactant and reinforcing agent,which can be very useful for the industry application of E.urophylla×grandis.The study of the physical properties of E.urophylla×grandis and APMP pulping process showed that E.urophylla×grandis contained more homocellulose(75.75%),had lighter color and lower base density(0.487g/cm³) with the length-width ratio of 61.0 and a fairly large flexibility index.The appropriate APMP chemical pretreatment conditions for E.urophylla×grandis were as follows:for the 1^st stage presoak,5.5%of NaOH,1%of H₂O₂,1%of Na₂SiO₃,0.5%of MgSO₄,0.3%of EDTA,were added,and the process lasted 45min at 75℃with the wood to liquor ratio at 1:4;for the 2^nd stage presoak,2.5%of NaOH,5%of H₂O₂,3%of Na₂SiO₃,0.5%of MgSO₄,0.3%of EDTA were added,and the process lasted 45min at 75℃with the wood to liquor ratio at 1:5.The brightness of E.urophylla×grandis APMP pulp reached 66%ISO,NOSA statistic software was applied to analyze the variance of data,the regression equation of breaking length,brightness,and presoak condition were obtained.The study of the pulpability of E.urophylla×grandis KP-AQ was studied at different planted distance.It was found that the physical properties of Dongmen E.urophylla×grandis and Leizhou E.urophylla×grandis were almost same.So the KP-AQ cooking condition of E.urophylla×grandis Dongmen and Leizhou E.urophylla×grandis in southern China was quite similar.The study of the bleachability of Leizhou E.urophylla×grandis KP-AQ showed that after D₁-E-D₂-P bleaching,pulp brightness was 81.1%and the viscosity was 972mL/g.Brightness increased to 83.2% after it was extracted treatment by acetone.Pulp brightness reached 81.0%and its viscosity was 931mL/g when NaOH was replaced by Mg(OH)₂.GE brightness reached 58.4%,viscosity was 914mL/g and Kappa number was 7.76 after the D₁-E-D₂-P bleaching.Brightness and viscosity became 86.0%and 872mL/g respectively after the O-D₁-E-D₂ bleaching.After O-D-E-P bleaching,they were 85.4%and 883mL/g respectively.The optimum conditions to pretreat Leizhou E.urophylla×grandis by using T lanuginosus were:10 U xylanase/g pulp,reaction time 90 min,temperature 60℃,pH 6.0 and consistency 10%.Pulp brightness was 55.2%,its kappa number decreased to 8.38 and the viscosity rose slightly.The strength properties increased slightly after bleaching.After studying bleaching mechanism,it was found that xylan in pulp decreased by 3.51%,and its acid indissoluble lignin decreased by 0.12%.XRD did not show considerable change in crystallinity.The SEM study showed the pulp had a more compact structure and smoother surface without xylanase pretreatment.IR and UV spectra proved that free hydroxyl may increase hydrogen bonding.Xylanse degraded some xylan and dissolved small bit of lignin.Compared with other xylan,the viscosity of the pulp increased after the treatment of T lanuginosus,and the amount of the xylan decreased.KMnO₄ charge was 0.6%in TCF(O-X-Mn-P) bleaching of Leizhou E.urophylla×grandis KP-AQ. The pulp brightness reached 80%and viscosity was more than 800mL/g.Light(superlight) ECF bleaching of KP-AQ had better effect by O-X-A-D₁-Ep-D₂.The pulp brightness reached over 85%at a total chlorine charge of 0.95%,which saved 60%and 40%ClO₂ respectively compared with the O-D₁-E-D₂ and O-D₁-Ep-D₂.The study of the effect and mechanism of surfactants in AS-AQ pulping and bleaching showed that the optimum conditions by adding LAS were as follows:12-13%of NaOH(as NaOH),16-18%of Na₂SO₃(as NaOH),0.06-0.1%of AQ,0.2-0.3%of LAS,120-140 min at maximum temperature.Pulp yield,brightness,viscosity and WRV were increased by adding LAS,while benzene-alcohol extractives were decreased.The addition of LAS did not decrease the particle size of anthroquinone in cooking liquor.The concentration of anthroquinone whose diameter is smaller than 0.45μm is 35%lower at room temperature than the cooking liquor without LAS.The amount of anthroquinone increased tremendously by adding LAS,which led to the increasing of sulfite at 100℃and 120℃.The best additive in oxygen bleaching was compound surfactants(0.25%LAS and 0.25%AEO-9), which can increase brightness by 3.6%and decrease kappa number and viscosity by 1.3 and 36mL/g respectively.Xylanase activity reached its maximum value and increased by 27%at the presence of 20mg/mL Tween80.NP series was the best additives for peroxide bleaching;the maximum effect was reached with an addition of 0.25%NP-10 and 0.75%NP40 with a 16.1 of HLB value.Pulp brightness increased by 5.1%and the hand sheets had better physical strength properties by adding the additive in the different stages of O-X-Q-P.The effects of different strength agents were studied.Grafting copolymer with chitosan was applied in KP-AQ pulping.The results showed that the pulp properties improved more appreciably with the application of CTSAD than CTS,and the amount of CTSAD used was smaller than that of CTS. Microscopic graph showed more compact fiber interweaving after the application of these additives, especially the application of CTSA.The density of the fiber interweaving increased dramatically compared with the control samples.The study of the strength enhancing effect of Starch-PAM bi-copolymer,CTSAD tri-copolymer and their mixture showed that the better strength enhancing effect achieved when grafting ratio of starch-PAM was 35.59%.At a dosage of 0.8%and 46oSR of beating degree,the tearing index increased from 4.7mN·m²/g to 9.5mN·m²/g,folding endurance enhanced from 229 to 278 times,tensile index rose from 74.70N·m/g to 147.94N·m/g.As for their mixture,tearing index increased by 14.9%,the folding times enhanced by 96.0%;the tensile index improved by 82.7%when the reaction temperature was 40℃,pH8.5,and starch-PAM grafting bi-copolymer to CTSAD grafting tri-copolymer ratio was 5:5,which will be very helpful to the basic and low weight papermaking.