Study On The Mechanism Of Bleaching And Yellowing Of Bambusa Chungii APMP Pulp

In the thesis, the mechanism of pulping and bleaching of APMP of Bambusa Chungii was researched. And then we studied the properties and mechanism of light-induced yellowing of bleached APMP bamboo pulp.Firstly, we studied the changes of chemical ingredients and fiber morphology of Bambusa Chungii during APMP pulping and supplementary bleaching. The results showed that there is a high content of extractions in bamboo chemical components. For example, the alcohol-benzene extractive content is 3.19%, and l%NaOH extractive content is 29.85%. Most extractions in initial bamboo material were dissolved away during the APMP pulping and supplementary bleaching, and it was of great benefit to pulp brightness but a disadvantage for the yield of pulp. The SEM observation revealed that the bamboo fibers were divided completely and a large amount of fragments stuffed around fibers. We promoted the pulp brightness while these fragments which must be middle lamella remainders were removed from pulp by supplementary bleaching. Meanwhile, fiber surface properties were also improved.Secondly, the modern spectrum analytical technologies were applied to study the changes of lignin structure of Bambusa Chungii during pulping and bleaching. The results indicated that the lignin of Bambusa Chungii is a GSH style lignin with a large amount of condensed G style. There were also many ester bond linkages in bamboo Ugnin. By measuring the molecular weight distribution, it was found that after APMP pulping the macromolecule structure of bamboo lignin was broken down, and the average molecular weight of lignin decreased, also the polydispersity of it increased. FTIR and H-NMR analysis...