【作者】 苏勇；

【导师】 张洋；

【作者基本信息】 南京林业大学 ， 木材科学与技术， 2012， 硕士

【摘要】 本论文以麦秸为研究对象，研究了化学法结合纤维素酶处理方法分离纤维素微纳纤丝的优化工艺条件。论文对所制备的微纳纤丝进行了TEM分析、红外分析、XRD分析和DSC分析，探索了微纳纤丝改性脲醛树脂后制造胶合板的工艺。本研究的结论归纳如下：（1）蒸煮和氧化可以去除麦秸中大部分的半纤维素和木素，分离出较高纯度的麦秸纤维素，能够有效地作为纤维素酶的酶解底物。蒸煮优化工艺条件：用碱量12%，蒸煮温度150℃，蒸煮时间为4h。氧化优化工艺条件：温度为70℃，时间为6h，过氧化氢浓度为5%。经过蒸煮和氧化两个步骤后能够得到绝干含量为88.32%的纤维素，适合作为纤维素酶的酶解底物。（2）本论文所使用纤维素酶的固体酶活为148.45FPU/g。为了加快酶解反应和节省酶用量，选择加酶量为35FPU/g。当加酶量小于35FPU/g时，增大加酶量后，纤维素酶对所制纤维素的酶解效果显著增加；但是当加酶量大于35FPU/g时，增大加酶量后，纤维素酶的酶解效果增加不显著。在酶用量为35FPU/g条件下，酶解效率随着时间的延长而降低，试验结果表明：酶解的最佳时间为48h。通过对酶解后的产物进行分离及超声分散处理可以制得微纳纤丝，该微纳纤丝在水中团聚后的平均粒径为31.192μm。（3）通过微纳纤丝的TEM分析表明：单根麦秸微纳纤丝的长度在100-300nm之间，直径在10-20nm之间，达到了微纳纤丝的要求。红外分析结果显示通过酶解制得的微纳纤丝以纤维素为主。经过XRD分析可知，酶处理能够提高麦秸微纳纤丝的结晶度；超声波处理时间过长，微纳纤丝的结晶度会降低。DSC分析显示纤维素经过酶处理和超声波处理后，其热性能没有明显的变化，所制备的微纳纤丝在300℃内热稳定性非常好。（4）添加3%的微纳纤丝有助于脲醛树脂的固化,并能在一定程度上降低脲醛树脂的固化温度。在热压温度为105-135℃之间时，微纳纤丝添加量对压制的杨木胶合板的胶合性能有显著影响。结果表明：在试验区间内，当微纳纤丝的添加量为3%时，改性脲醛树脂的胶合性能最好。更多还原

【Abstract】 In this thesis, wheat straw was selected as research object to study on the optimumtechnology conditions of cellulose micro/nano fibrils separated by the method of chemicalcombined with cellulase treatment. This thesis characterized the micro/nano fibrils which wasseparated in the experiment by TEM, FTIR, XRD and DSC analysis, and then explored thetechnology of produce three-ply plywood using UF resin modified by micro/nano fibrils.Conclusions based on this thesis were shown as follows:(1) Most hemicellulose and lignin in the wheat straw was wiped off by digesting andoxidation, and isolated high purity wheat straw cellulose would be a good substrate ofenzymolysis of cellulase.The optimum digesting technology conditions: alkali dosage was12%, digesting temperature was150℃and digesting time was4hours. The optimumoxidation technology conditions: oxidation temperature was70℃, oxidation time was6hoursand hydrogen peroxide concentration was5%. After digesting and oxidation, the cellulosewhose dry content was88.32%was obtained, and it was a good substrate of enzymolysis ofcellulase.(2) The solid enzyme activity of cellulase used in this thesis was148.45FPU/g. In orderto accelerae the enzymolysis and save the enzyme dosage, the added enzyme dosage wasselected as35FPU/g. When the added enzyme dosage was less than35FPU/g, enzymolysiseffect of cellulase would improve observably with the increase of dosage. But when the addedenzyme dosage was more than35FPU/g, enzymolysis effect of cellulase would not improveobservably with the increase of dosage. In the condition of35FPU/g enzyme dosage,enzymolysis efficiency would decrease with the enzymolysis time prolongation, the studyshowed that the optimum enzymolysis time was48hours. By separating the enzymolysisproduct and ultrasonic dispersing treatment, Micro/nano fibrils would be prepared. Themicro/nano fibrils would aggregate in the water, and the mean diameter of micro/nano fibrilsaggregate is31.192micrometer.(3) TEM analysis showed that the length of a single fibril is between100-300nm and thediameter of a single fibril is between10-20nm, met the requirement of micro/nano fibrils.FTIR analysis illustrated the dominated component of micro/nano fibrils generated byenzymolysis was cellulose. According to XRD analysis, enzyme treatment could improve thecrystallinity of wheat micro/nano fibrils, and the crystallinity would decrease if the ultrasonictime was excessive. DSC analysis showed that thermal property of cellulose had not changedobviously after enzyme treatment and ultrasonic treatment, its thermal stability was very good when the temperature under300degree centigrade.(4) Adding3%micro/nano fibrils was beneficial to UF curing in only one time and itcould decrease the curing temperature in some extend. When hot-press temperature was within105-135degree centigrade, the effect of added amount of micro/nano fibrils on the bondingproperty was significant. The result manifested that the bond strength of the modify UF resinwould be the best in the test interval when the added amount of micro/nano fibrils was3%.更多还原