| The lignin rich in plant is a natural degradable hydroxybenzene macroraolecule. It can be used in the synthesis of raacroraolecule material, in order to promote the high-valued utilization of lignin in industry. By the means of the research of synthesis of lignin based epoxy resins, we can not only help to reduce the natural pollution from pulping industry, but also find a new way of utilizing lignin .This paper is to discuss the isolation and extraction of bagasse lignin from alkali-oxygen pulping waste liquor and the method of synthesis of lignin based epoxy resins. Meanwhile the lignin based epoxy resins are analyzed by means of FTIR and 1H-NMR .The experiments were constituted of three main parts as followed.1. The isolation and extraction of bagasse alkali-oxygen lignin (OLG). The content of bagasse material were analyzed and the data of result- are shown in table 2-1. The new clean pulping method, alkali-oxygen pulping, is used for the pulping of bagasse. By the method of single-factor-three-level, the optimal conditions are the initial Oz pressure 0. 6 MPa, the temperature 130"C and the amount of NaOH 14% (by o. d. soaked material), when the Kappa number of the pulp is 18.9. The lignin is isolated from the pulping waste liquor by the means of acid-precipitation and extracted by centrifuge.2. FTIR and 1H-NMR analyses of lignin. The OLG and the hydrogenolysis wheat alkali-oxygen lignin (HLG) are compared. By the means of FTIR and 1H-NMR, it is cleared that the total hydroxyl of HLG is more than that of OLG. HLG has more Al-OH and Ph-OH too, which can increase reaction activity of lignin (for example , the synthesis of epoxy resins ).3. The synthetical method and analyses of lignin based epoxy resins. Prior to the synthesis of lignin based epoxy resin, lignin is to be modified, then reacted with epichlorohydrin.a. The synthesis of lignin based epoxy resins from phenol. The conditions of lignin modification are the ratio of lignin and phenol 4:6 (lignin, 5 g: phenol 7.5 g), the time of reaction 3 hours, temperature 95C, catalyst 20 ml of 2mol/L H2S04. The conditions of synthesis of epoxy resin are the catalyst 50ml NaOH (20%, by weigh); 20 ml epichlorohydrin, the temperature 80 C, reaction time 3 hours. The synthesis mechanism is also discussed by the means of FTIR and 'H-NMR, and shown in the chemical equation 1.b. The synthesis of lignin based epoxy resin from 2, 2-di(4-hydroxy phenyl)propane(ab. DA). The modification conditions are the ratio of lignin and DA is 5:5 (lignin 5 g: DA 5 g); the reaction time 1.5 hours; the temperature 90 C, the catalyst 10ml NaOH (20%, by weigh). The conditions of synthesis of epoxy resin are epichlorohydrin 10 ml, the catalyst 20 ml NaOH (20%, by weigh); the temperature 75癈, the reaction time 1.5 hours. The synthesis mechanism is discussed by the means of FTIR and 'H-NMR, and shown in the chemical equation 2.c: The synthesis of hydrogenolysis lignin based epoxy resins from DA. The method is the same as that of the synthesis of lignin based epoxy resins from DA. The synthesis mechanism is discussed too and is shown in the chemical equation 2.According to the results, we can know that the bagasse alkali-oxygen lignin is well fit for the synthesis of macromolecular material. The bagasse alkali-oxygen lignin is modified by phenol or DA and then synthesized into lignin based epoxy resins whose characteracations are equal to or even beyond those from saled epoxy resins. OLG or HLG can replace about 40% phenol or DA or more. After hydrogenolysis of wheat alkali-oxygen lignin, the lignin has more hydroxyl, which can easily promote the reaction activity of synthesis of macromolecular material. |
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