The Chromophoric Study In Situ On High Yield Pulp Of Fast-growing Wood During The Pulping And Bleaching Process

To explore the effects of pulping, bleaching with different bleaches and aging on the CTMP of fast-growing wood, the changes of ISO brightness, CIELa*b*value, and Ultra-violet Reflectance Diffuse Spectra of CTMP made from eucalyptus and the admixture of eucalyptus and poplar wood during pulping, bleaching with hydrogen peroxide, sodium borohydride, sodium hydrosulfite and aging through heating and irradiation affected with different temperature, time and moisture content were studied. And the changes about amounts and structures of chromophores during the different peocesses were also discovered, deriving the relevant mechanisms. In addition, electronic spectras of model compounds of quinone, stilbene and stilbene quinone were calculated with a quantum method, analysised and predicted the mechanism of coloring, and the extents of their effects on pulp.Through study on the pulping process of Eucalyptus CTMP, it was found that pulping destructed the coniferyl aldehyde structure of lignin, which made the ISO brightness and Lightness go up.After Dealing the wood powder, unbleached and bleached pulp which was with or without water with put in the shadow, heated in the drying oven and irradiated under the sunlight, it was found that put in the shadows had no effect on the absolutely dry materials, and a little on the wet. Irradiation had severe effects on the materials, and chromophore contents increased a lot. The chromophores in the wet pulp increased apparently more than that in the dry pulp.The ISO brightness was in order of unbleached pulp< sodium dithionite bleached pulp