【作者】 漆小华；

【导师】 蒲俊文；

【作者基本信息】 北京林业大学 ， 林产化学加工工程， 2009， 硕士

【摘要】 醋酸纤维用途广泛,所用原料为高纤维素含量的棉浆或高级针叶木浆粕,而目前木浆粕仍需进口。研究开发木浆粕,己成为我国醋酸纤维行业能否实现可持续性发展的关键问题,桉木作为一种重要的速生阔叶材种,如能用于生产纯度高的醋酸纤维浆粕,对我国醋酸纤维工业具有重要的意义。论文以尾叶桉为原料,研究了制浆、漂白、木聚糖酶处理和碱精制工艺,得到了满足醋酸纤维要求的浆粕,再进行活化、醋酸化、水解等处理,并对其反应机理进行了探讨。实验的主要结果如下:（1）桉木浆粕采用KP+AQ法制得,条件为:用碱量17%（Na₂O计）,硫化度16%,AQ 0.05%,液比1:4,空转30 min,升温90 min至130℃;再次升温90 min至170℃,保温60 min。（2）为了得到高白度浆粕,又不造成环境污染,对D₁ED₂常规漂白条件进行了探讨,D₁段用氯量必须控制在3.6%以内;碱处理的条件需要强烈些,以去除半纤维素,提高浆粕的α-纤维素含量和平均平均聚合度。但是想要通过提高用碱量来大幅提高α-纤维素含量是不可行的。桉木制醋酸纤维浆粕的漂白条件为:D₁段用氯量3.6%,70℃,90 min,浆浓10%,pH 3.5;E段NaOH 2.0%,75℃,60 min,浆浓10%;D₂段用氯量0.9%,70℃,90 min,浆浓10%,pH 3.5;P段NaOH用量与H₂O₂用量一致为2.5%,70℃,90 min,浆浓10%。（3）木聚糖酶处理最佳条件为:酶用量120 IU/g,60℃,时间2h,浆浓3%,pH6.0;碱精制中,NaOH除了可以去掉部分半纤维素,而且可以溶解掉部分短链纤维素,当碱浓度为4%时,平均聚合度增至1163,白度增至90.0%,α-纤维索含量为96.78%,达到了醋酸纤维浆粕国际标准。（4）对木聚糖酶处理前后的浆粕进行红外扫描。发色基团和助色基团如C=O伸展振动(1058cm^-1)、木素-烷基醚基C-O-C伸展振动(1164cm^-1)、芳基-烷基醚键(1240cm^-1)、木素羰基伸展振动C=O(1637cm^-1)、木素芳环振动(1430 cm^-1)处的吸收峰在木聚糖酶处理后,强度有所减弱,这或许是木聚糖酶处理后浆粕白度提高的原因。（5）桉木浆粕最佳活化条件:活化时间为3.0 h、活化温度50℃,醋酸用量为500%;醋酸化最佳条件为:醋酸酐用量400%,催化剂硫酸用量7.5%,温度60℃,时间2h;水解最佳条件为:醋酸含量为80%,水解温度为60℃,制得醋酸纤维取代度为2.51。（6）对活化后的浆粕进行X-射线衍射扫描,并结合红外图谱。活化处理仅仅是一个物理溶胀的过程,确实改变了纤维素的结晶结构,使得可及区增加,有更多的羟基为醋酸化剂可及,有利于醋酸化反应的进行,用醋酸对浆粕的活化处理,为醋酸化做足准备,其他并无明显化学反应发生。（7）对醋酸纤维红外扫描。1752cm^-1为C=O的伸缩振动,3348 cm^-1为-OH伸缩振动,其强度明显减弱,说明浆粕醋酸化产物的主要成分是醋酸纤维;对醋酸纤维进行X-射线衍射扫描,醋酸化使纤维素氢键作用减弱,同时醋酸基的引入使纤维素结晶结构受到一定程度的破坏,从而导致纤维素结晶度的降低。更多还原

【Abstract】 Cellulose acetate is used widely,its raw materials is cotton of high-cellulose content or senior coniferous wood pulp,which is needed to import from abroad.Therefore,the research and development of wood pulp become the key issues of sustainable development of cellulose acetate,Eucalyptus is an important fast-growing hardwood species,which has importance to ease the cellulose acetate industry in China.Eucalyptus is studied as raw materials in this paper,including pulping、bleaching、xylanase and alkaline purification process,the product meet the requirements of cellulose acetate pulp,and then activation、acetic anhydirde、hydrolysis process and its mechanism explore.The main experimental results:（1） The pulp is cooked by means of KP+AQ,conditions:alkaline 17%（Na₂O）,sulphidity 16%,AQ 0.05%,liquid ratio 1:4,idling about 30 min,heating to 130℃within 90min;then warming up to 170℃in 90min,holding temperature about 60min.（2） In order to increase brightness without causing environmental pollution,it’s needed to research the conditions of D₁ED₂ conventional bleaching,the amount of chlorine must be controlled within 3.6% at D₁ stage;in order to improve a-cellulose content and degree of polymerization,alkaline conditions is needed more stronger to remove the hemicellulose.But it is not feasible to increase a-cellulose content by increasing the amount of alkaline.Eucalyptus wood pulp bleaching conditions for cellulose acetate: D₁,the amount of chlorine 3.6%,70℃,90 min,plup consistence 10%,pH 3.5;E paragraphs NaOH 2.0%,75℃,60 min,pulp concentration 10%;D₂,the amount of chlorine 0.9%,70℃,90 min,plup consistence 10%,pH 3.5;P,the amount of NaOH and H₂O₂ are the same amount of 2.5%,70℃,90 min, plup consistence 10%.（3） Pulp’s xylanase purification conditions:enzyme dosage 120 IU/g,60℃,time 2h,plup consistence 3%,pH 6.0.Alkali purification,NaOH can not only remove part of hemicellulose,also dissolve some short-chain cellulose,when the alkali consistence is 4%,the degree of polymerization 1163,brightness 90.0%,a-cellulose content 96.78%,cellulose acetate pulp achieve international standards.（4） Scanning the pulp before and after purification treatment by 1R.It’s found that:the chromophoric group and color auxochrome group,such as the C=O stretching vibration(1058cm^-1), lignin-alkyl ether-based C-O-C stretching vibration(1164cm^-1),aryl-alkyl ether bond(1240cm^-1), lignin carbonyl stretching vibration C=O(1637cm^-1),lignin aryl ring vibration(1430 cm^-1),their absorption peak intensity has weakened after purification,and this is why the pulp’s brightness increased after purificationt.（5） The activation of eucalyptus pulp’s conditions:time 3.0 h,temperature 50℃,the amount of acetic acid 500%;acetic anhydride conditions:the amount of acetic anhydride 400%,the amount of catalyst sulfate 7.5%,temperature 60℃,time 2.0 h;the hydrolysis conditions:80%acetate content, temperature 60℃,degree of substitution of CA is 2.51.（6） Scanning pulp before and after activation by means of X-ray diffraction and IR.The activation is just a physical process,change the crystalline structure of cellulose,making available district increased,more hydroxyl can be reached by acetic anhydride.The activation processing is a preparation for next step,there is no obvious chemical reaction occurred.（7） Scanning the CA by IR.1752cm^-1 C=O stretching vibration,3348 cm^-1 -OH stretching vibration,which intensity decreased significantly,it’s proved that the product is CA.X-ray diffraction of CA:hydrogen bonds weaken,the introduction of acetic group make crystal structure damaged to a certain extent,which result in the reduction of cellulose crystallinity.更多还原