Study On The Chemical Modification Of Liaoning Poplar’s CMP

This paper discusses the optimal condition of pretreatment and refining on Liaoning poplar’s CMP, the results showed that temperature and NaOH’s amount are the most important factors influencing the pretreatment. The optimal pretreatment condition is:liquid ratio1:4,6%NaOH, temperature130℃, holding time35min; After pretreatment with the optimal condition, three segments refining the chips according to the gaps:0.2mm,0.08mm,0.08mm. Then chose20mesh screen to screening the pulp after refining. Among all the fiber, the proportions of long fiber and short fiber are53.7%and46.3%respectively.In order to improve the pulp quality and paper performance, long fiber component is treated by alkaline peroxide in the paper. The results show that the softness, length, swelling properties and hydrophilcity improved after long fiber treated; amount of hydrophilic group carboxyl generated on the surface of fiber after treated by alkaline peroxide. The content of carboxyl group is1.3times of that untreated, increase130.25mmol/kg to172.31mmol/kg; modified by peroxide, pentosan and acid in soluble lignin content decrease slightly, while acid soluble content increase slightly. The crystallinity of long fiber increases from0.68to0.76by alkaline hydrogen peroxide treatment, by the way, the physical properties of the paper has been improved. The optimum treatment condition is determined by test:2.5%NaOH,4%H2O2,75℃,65min; the treated long fiber corresponded relative short fiber could improve the paper strength compared with modified molo-pulp to some extent:tensile index increase from32.45N·m/g to39.56N·m/g, tear index increase0.2mN·m2/g.In order to get better mechanical pulp and paper with sound mechanical properties, long fiber component is treated by ozone in the paper. The results show that Liaoning poplar long fiber treated by ozone can improve the surface hydrophilcity performance, and stripping happened on the fiber surface, improved the roughness and fibrillation performance. The content of lignin and pentosan decreased to some extent by ozone treatment. The crystallinity of long fiber increases from0.68to0.81by ozone treatment, by the way, the physical properties of the paper has been improved. The optimum treatment condition is determined by test:ozone usage2.52%(relative to dry component), pH4, pulp concentration0.4%; paper attained in the optimum treatment condition, which shows a better performance in brightness, tear index and tensile index compared with holo-pulp:brightness increase about1%ISO, tensile index increase from25.36N·m/g to31.99N·m/g, tear index increase1.93mN·m2/g. By determining the ozone usage in each experiment and analyzing the data, it is conclude that lower pulp concentration, higher pH and longer suitable reaction time will improve the effect of ozone treatment.