Analysis Of Bamboo Bark Composition And Its Effect On SCMP Pulping And Yellowing From Bambusa Chungii

China has abundant bamboo resources,and bamboo fiber is a good raw material for non-wood fiber.It is an important way to solve the shortage of paper materials for replacing wood resource with bamboo resource.However,high-yield bamboo pulp are hard to bleach and easy to yellow,which limits its application range.This paper mainly studies that effect of the composition of bamboo bark（such as wax,pigment,sterol,fatty acid,glycerol resin and so on）on SCMP pulping and yellowing from bambusa chungii.The experimental results show that:1.There was a dense layer of wax on the surface of bamboo bark by SEM.Wax is extracted by solvent extraction,the composition of wax contains acids,hydrocarbons,acids,phenols,ketone,aldehydes and other substances by GC-MS,these substances may remain in the SCMP pulp,consume H₂O₂ and affect the bleaching.2.Bamboo bark pigment is extracted by ultrasonic extraction,extraction solvent for ethanol.The optimum extraction conditions:ethanol concentration 90%,solid-liquid ratio 1:35,ultrasonic time 40 min,ultrasonic temperature 55℃,twice-extraction under the condition of optimum extraction,crude extraction rate of pigment about 3.49%and chlorophyll extraction rate about 0.39%.The crude extractives contains chlorophyll and carotenoids,and may contain sterols,fatty acids,glycerol resins,aromatic hydrocarbons and alkanes from bamboo bark by column chromatography,NMR and FITR analysis.The chemical composition of bamboo bark was analyzed,the content of 1%NaOH extractives,benzene-alcohol extractives and lignin of bamboo bark are higher,and the extractives contains O-H,C=C,C=O,N=N,C-O and other groups.3.The composition of raw materials,SCMP pulp and bleached SCMP pulp were analyzed before and after removal of bamboo bark.The compositions of the benzene-alcohol extractives of SCMP pulp before and after removal of bamboo bark were analyzed By GC-MS,surface morphology and surface elements of SCMP pulp fibers before and after removal of bamboo bark by SEM and XPS.It can be seen that the bamboo bark prevents the penetration of the chemical solution and consumes the chemical solution during sulfonating,refining and bleaching.Bamboo bark has an effect on SCMP pulping.4.The residual H₂O₂ concentration and the pH value of SCMP pulp after one-stage bleaching before and after removal of bamboo bark were analyzed,showed that the extractives can hinder the permeation of the chemical solution,and affect bleaching effect.The one and two-stage bleaching and bleaching after benzene-alcohol extraction of SCMP pulp before and after removal of bamboo bark.Brightness increased by 24.47%ISO,34.62%ISO,25.46%ISO respectively before removal of bamboo bark.Brightness increased by 24.91%ISO,36.40%ISO,25.06%ISO respectively after removal of bamboo bark,showed that SCMP pulp has good bleachability after removal of bamboo bark,benzene-alcohol extractives had an effect on bleaching.Heat-induced and Light-induced yellowing were analyzed,SCMP pulp after removal of bamboo bark has good bleaching performance,the yellowing value decreases greatly after two-stage bleaching.