【作者】 郑菲；

【导师】 周晓燕；

【作者基本信息】 南京林业大学 ， 木材科学与技术， 2012， 硕士

【摘要】 来源于生物质的燃料乙醇作为最直接最有效的石油基液体燃料替代品正越来越受到人们的重视。利用木质纤维原料制取生物燃料乙醇时，原料首先经过预处理，破坏原料中纤维素，半纤维素和木质素之间的结构，从而提高原料中纤维素对纤维素酶的可及度。经过预处理的物料在酶的催化下水解成单糖，单糖继而被酵母菌发酵成乙醇，在此过程中会产生大量废弃物，即主要成分为木质素的酶水解残渣。随着纤维素燃料乙醇工业的发展，酶解木质素必将成为一类丰富的可再生资源。本文采用冷等离子体对酶解木质素进行改性处理，以显著提高酶解木质素的反应活性，从而使之可直接作为胶粘剂用于制备不含游离甲醛的环保型木质纤维复合材料。文中系统研究了冷等离子体处理工艺对酶解木质素表面化学结构及热特性的影响，探索了冷等离子体强化酶解木质素胶合力的机理。研究结果对于推进我国纤维素燃料乙醇的工业化进程和推动我国人造板工业的科技进步具有重要的现实意义。研究结果表明：1、随着氧冷等离子体处理时间的延长，羧基含量显著增加，羰基含量略有增加，碳元素含量呈逐渐下降趋势，但是降低幅度不大；氢元素含量也逐渐降低；氧元素含量则是增加的，酶解木质素的自旋数也随着处理时间的延长而增加。2、随着氧冷等离子体处理功率的增大，羧基含量显著增加，羰基含量略有增加，碳元素含量逐渐下降，氢元素含量也逐渐下降，氧元素则呈上升趋势，酶解木质素的自旋数随着处理功率的增加而增加，但是增加幅度不大。3、经各种冷等离子体处理后，羧基含量显著增加，羰基含量都有略微的增加，碳元素含量都是降低的，氢元素含量也有显著下降，氧元素含量则都是增加的。经冷等离子体处理后，酶解木质素的自旋数都是增加的。4、酶解木质素的Tg值为168.2℃，而经氧冷等离子体处理后，酶解木质素的Tg值下降至161.5℃。经氧冷等离子体处理后的Tg值下降，因为木质素的结构发生了变化，其含氧官能团含量增加；木质素上含有很多苯丙烷单元和较大的支链，经氧冷等离子体处理后，这些主支链上会生成较多的羟基、羰基、羧基等含氧官能团，这些极性官能团含量的增加使酶解木质素的分子运动更活跃；也可能是酶解木质素大分子中的醚键发生断裂，从而降低了分子量，使玻璃态转化温度下降。5、添加了酶解木质素对纤维板的物理力学性能有较大的影响。氧冷等离子处理对酶解木质素的活化作用极大的改善了纤维板的性能。在光谱分析中表明，当氧冷等离子处理时，含氧官能团如—OH、—C—O—、—C=O、—COO能引入到酶解木质素的表面。这些基团和自由基都有助于粘结性能的改善。更多还原

【Abstract】 Increasing environmental and energy concerns have been the driving force of bio-ethanolresearch. Both cellulose and hemicelluloses in lignocellulosic biomass can be converted tosimple sugars that can be subsequently fermented to ethanol. The conversion of even a smallportion of this renewable resource into ethanol could substantially reduce gasoline consumptionand our dependence on petroleum. Therefore, related research and development has beenfocused on producing ethanol from wood and agricultural residues. However, lignin, which isone of the major three components of lignocellulosic biomass, is a barrier to enzymaticsaccharification of cellulose in wood and agricultural biomass. In cellulosic ethanol processes,lignin is considered as a waste product. For example, nearly one ton of residues are generatedfor every ton of bio-ethanol produced from corn stover;30-35%of these residues areEnzymatic hydrolysis lignin (EHL). Value-added utilization of EHL not only can help offset thecost of bio-ethanol production and boost the economic viability of the bio-ethanol industry butalso provide a source of renewable materials.The work described here explored the feasibility of using enzymatic hydrolysis lignin(EHL) as a natural binder for biocomposites manufacture and proposed an effective approach toactivating EHL. The effects of plasma treatment on the surface chemical changes and thermalcharacteristic of EHL were evaluated and the modification mechanism of the plasma wasinvestigated.The results are showed as following:1. With prolonging oxygen plasma treatment time, carboxyl content increasedsignificantly and a slight increase in carbonyl content. At the same time, carboncontent showed a gradual downward trend, hydrogen content also decreased with thetreatment time reduction. The oxygen content gradually increased with prolonging theprocessing time. The spin concentration of the enzymatic hydrolysis lignin (EHL)increased with prolonging the processing time.2. With increasing oxygen plasma treatment power, carboxyl content increasedsignificantly and a slight increase in carbonyl content. After oxygen plasma treatment,the carbon content in the enzymatic hydrolysis lignin (EHL) decreased gradually withthe increase of processing power but the range is not big. The hydrogen contentdecreased gradually with the increase of processing power, but it is not evident. Theoxygen content increased gradually with the increase of processing power. The spinconcentration of the enzymatic hydrolysis lignin (EHL) increased with the extension of the processing power, but the range is not big.3. After plasma treatment of different gases, carboxyl content increased significantly.Among these gases, the carboxyl content increased the most after the oxygentreatment, followed by air, nitrogen and argon. Carbonyl content all has slightlyincreased. After different plasma treatment, the carbon content of enzymatichydrolysis lignin (EHL) decreased. Among them, carbon content decreased the mostafter oxygen plasma treatment, followed by argon, nitrogen and air. Hydrogen contentalso decreased the most after oxygen plasma treatment, followed by nitrogen and air.The oxygen content is all increased and it increased the most after oxygen plasmatreatment, followed by air, nitrogen and argon. The spin concentration of theenzymatic hydrolysis lignin (EHL) increased the most after oxygen plasma treatment,followed by air，nitrogen and argon.4. The Tg value of enzymatic hydrolysis lignin (EHL) decreased after oxygen plasmatreatment under the same heating rate. Because the structure of lignin changed and thecontent of oxygen functional groups increased. The lignin contained a lot ofphenylpropanoid units and larger branched-chain after oxygen plasma treatment.These branched chains would generate many oxygen-containing functional groupssuch as hydroxyl, carbonyl, and carboxyl. The extension of the content of polarfunctional groups made the molecular motion of enzymatic hydrolysis lignin moreactive. May be it is because the ether bond of hydrolysis lignin macromoleculesruptured which reduced the molecular weight and made the glass transitiontemperature dropped.5. Adding EHL has a beneficial effect on the physicomechanical properties of thefiberboards. Oxidative activation of EHL with oxygen plasma treatment improves theproperties of the fiberboards significantly. The spectroscopic analyses indicate thatoxygen-related functional groups such as–OH, C–O,–C=O,–COO had beenimplanted efficiently onto the surface of EHL in the course of oxygen plasmatreatment. These groups and the free radicals generated have probably contributedsynergistically to the bonding improvement.更多还原