The Improvement in the Determination Method of Hydroxyl Value for Lignin

以聚醚多元醇羟值测定方法——邻苯二甲酸酐-吡啶法为基础建立了木质素样品中活性羟基官能团数目测定方法,针对木质素磺酸钠和玉米秸秆酶解木质素样品的特性,改进了羟值校正时酸值和碱值的测定方法:在确保酸值测定精确度的同时成功采用乙醇-水替代了高毒性吡啶溶剂,在碱值测定时率先采用邻苯二甲酸氢钾替代盐酸溶液,使测定碱值的相对标准偏差小于1％,精确度得以显著提高.     

低游离甲醛羟甲基化木质素磺酸盐-酚醛复合胶黏剂研究

以工业木质素为原料,采用羟甲基化反应提高木质素反应活性,确定了羟甲基化反应木质素和催化剂的最佳配比:木质素与甲醛质量比为3:1、催化剂用量为0.25%(以木质素原料计).并用FT-IR和13C NMR对羟甲基化反应结果进行了分析.通过羟甲基化木质素磺酸盐(HLF)与酚醛树脂(PF)共混制得木质素酚醛树脂(LPF)胶黏剂.实验结果表明,该胶具有制备工艺简单、游离甲醛低的特点,用HLF替代40%的PF时,其胶合强度达到国家Ⅰ类胶合板的要求.     

木质素胺基多元醇的合成及其化学结构表征

以木质素、二乙醇胺及甲醛为原料,通过Mannich反应合成木质素胺基多元醇,研究了反应温度、时间、pH值及物料配比等因素对产物羟值的影响。实验结果表明,反应物料按质量比m(二乙醇胺)∶m(木质素)为0.35∶1、物质的量比n(甲醛)∶n(二乙醇胺)为1.1∶1时,在反应体系pH值为11条件下,80℃反应2.5~3 h,产物的羟值最高,为279 mg/g。通过FT-IR及元素分析方法表征了木质素胺基多元醇的化学结构。     

棉秆木质素的光谱分析

采用球磨方法分离并提纯出棉秆全秆磨木木质素(MWL)和棉秆秆芯MWL.采用紫外光谱和红外光谱对上述分离出的木质素进行分析.并用 13 C NMR 作了进一步分析研究.从分析结果看出:棉秆木质素属于愈疮木基-紫丁香-对羟苯基(GSH)型.棉秆秆皮和秆芯木质素结构不同,在秆皮中存在较多的紫丁香基结构单元和少量的对羟苯基结构,而秆芯中以紫丁香基结构单元和愈疮木基结构单元为主.     

造纸黑液磺化改性及改性产物性能研究

采取了先提木质素再将木质素磺化的方案进行造纸黑液的磺化,由分段正交试验(先羟甲基化再磺化)确定最佳磺化工艺,制备出磺化木质素.利用红外光谱表征产物,并测定了产物的磺化度、净浆流动度和重均分子质量(Mw).最佳磺化工艺:酸析木质素4 g,水40 g,甲醛溶液5 g,pH值11,75℃下反应2h,再调pH值为7,加亚硫酸钠2 g于140℃下反应4h,所得磺化木质素的净浆流动度为232 mm.红外分析表明磺化木质素中引入了较多的磺酸基;磺化木质素的磺化度为0.821 mmol/g,Mw为22.97 ku,均优于市售木质素磺酸钠,从而导致水灰比值0.35时其净浆流动度亦优于同掺量下的木钠.     

红外光谱技术快速预测杨木中木质素含量的研究

采用傅里叶红外光谱技术对杨木木质素含量进行预测,通过偏最小二乘法(PLS)和完全交叉验证方式建立校正模型,对原始光谱进行一阶导数二阶导数等不同预处理后,建立样品木质素含量和光谱数据之间的相关性,并与化学测定方法进行了对比。模型决定系数(R~2)为0.887 1,偏差为-0.44%~1.73%,结果表明红外光谱技术可用于杨木木质素含量的快速预测。     

酸木质素改性酚醛树脂胶粘剂的研究

分别用硫酸、硝酸和盐酸从造纸黑液中提取木质素,用酸木质素来替代部分苯酚合成酚醛树脂胶粘剂,对产物进行了固体含量、游离甲醛含量和胶合强度的测定,并用红外光谱对其进行了结构表征。作者考察了酚醛比(物质的量比)和酸木质素的替代量对胶粘剂性能的影响。结果表明:当n(苯酚):n(甲醛)=1:1.5,硝酸木质素的替代量为20%时,胶粘剂的综合性能最优。     

中国与巴西蓖麻油化学性质的测定

本实验的酸值、皂化值采用中和法,碘值用碘量法.酸值的测定是用乙醇、乙醚的混合液溶样,以氢氧化钾(氢氧化钠)中和游离脂肪酸.皂化值的测定是用碱的乙醇溶液水解样品,分解出来的脂肪酸与碱中和,以标准盐酸滴定剩余的碱.碘值的测定是用惰性溶剂氯仿溶样,加入过量的溴化碘标准溶液,使卤素起加成反应,再加碘化钾,使与未起反应的卤素作用,以硫代硫酸钠滴定释放出的碘.此法比较简单、准确.     

四种算法用于近红外测定制浆材材性的对比研究

采集了常见制浆材(桉木、相思木及杨木)样品的近红外光谱,测定了样品的基本密度、综纤维素、木质素和苯醇抽出物含量,用人为控制水分的方法测定了样品的水分含量。对原始光谱进行预处理后,分别运用偏最小二乘法(PLS)、LASSO算法、支持向量机法(SVR)和人工神经网络法(BP-ANN)建立基本密度、水分含量、综纤维素、木质素和苯醇抽出物含量的预测模型。对预测模型进行独立验证,结果显示:LASSO算法建立的基本密度和综纤维素模型性能最优,其预测均方根误差(RMSEP)分别为0.006 3 g/cm~3和0.49%,绝对偏差(AD)范围分别为-0.008 8~0.009 6 g/cm~3和-0.85%~0.87%;PLS建立的水分含量模型及苯醇抽出物模型最优,RMSEP值分别为1.21%和0.24%,AD范围分别为-1.99%~2.03%和-0.35%~0.38%;SVR建立的木质素模型最优,RMSEP值为0.43%,AD范围为-0.76%~0.74%,均满足制浆造纸工业中对误差的要求。     

支持向量机结合近红外光谱法测定杉木木质素的含量

采用支持向量机(SVM)结合近红外光谱(NIR)技术建立测定杉木中木质素的定量分析模型。以47个杉木样品作为实验材料,用常规方法测定了样品中木质素的含量,用近红外光谱仪采集相应的光谱,对光谱数据进行平滑、求导、小波压缩以及归一化,结合支持向量机,以径向基(RBF)作为核函数,建立了测定杉木中木质素含量的模型。校正相对误差的平方和为0.007433,预测相对误差的平方和为0.001219。结果表明,该方法测量比较准确,可以用于杉木中木质素含量的预测。     

响应面优化酶解木质素酚化工艺研究

利用响应面法分析碱性条件下木质素酚化工艺中,木质素取代量、酚化时间、酚化温度、催化剂用量对响应值酚羟基含量的影响,以及各因素之间的交互作用,在给定的条件范围内,建立了各因素与响应值之间的数学模型,优化得到木质素酚化的理想工艺:木质素取代量达到63%,酚化温度为109℃,酚化时间为1.4h,催化剂用量为苯酚用量的3.4g。在此条件下,其酚羟基含量可达4.498mmol/g。分析等高线图及响应曲面图详细描述了各个因素之间的交互关系,得出各个因素的影响主次顺序为酚化温度>酚化时间>催化剂用量>木质素取代率;各因素交互作用中,酚化温度与酚化时间的交互作用对酚羟基含量影响最显著。     

二乙醇胺基木质素非离子表面活性剂的制备及表征

依据酸沉淀法对碱木质素进行了分级,分级后pH值4 ～ 6的木质素与环氧氯丙烷、二乙醇胺反应,制备了木质素基非离子表面活性剂.通过红外光谱、含氮量的测定对产物的结构进行了表征,通过表面张力测定对产品的表面活性进行了分析.结果表明:木质素基非离子表面活性剂固含量为32.6%,含氮量为1.99%,红外光谱分析可确定在木质素上引入了环氧氯丙烷和二乙醇胺,水溶液表面张力降低到53.27mN/m,表明二乙醇胺基木质素非离子表面活性剂(DLNS)具有良好的表面活性.另外通过与十二烷基磺酸钠(SDS)复配后浊度的测定,表明产品在SDS与DLNS的体积比为20: 3 ～ 20: 20范围与SDS复配,浊度较低,复配效果较好.     

CaO/MgO复合固体碱催化剂催化降解木质素的研究

在氧化镁载体上浸渍醋酸钙后烧结制备了CaO/MgO复合固体碱催化剂,所制固体碱催化剂的表面碱度与催化剂制备条件有关:当CaO/MgO比值为0.08、在700℃下煅烧时间24 h时制得的催化剂表面碱度可达到30.2 mmol/g。以该固体碱催化剂催化木质素中醚键断裂反应,测试结果表明木质素降解产物重均相对分子质量(Mw)可从3 000降低至800以下,羟值由200 mg/g增加至480 mg/g左右。FT-IR表征结果表明降解产物中醚键含量明显减少,羟基含量增多。     

New method to determine the hydroxyl value in liquefied bark as Polyurethane material

Conclusions When the hydroxyl values of materials containing phenolic 3 or sterically hindered hydroxyl groups were determined by the esterification method, the values were considerably smaller than the theoretical values. In contrast, the NCO method provided hydroxyl values much closer to the theoretical values for such materials, though the values varied depending on the kinds and amounts of catalysts.The quantity of hydroxyl groups reacting with the NCO group could be directly determined by the NCO method using a catalyst mixture consisting of DABCO and DBTDL in a molar ratio of 21. Therefore, this method can be considered useful for determining the hydroxyl value before preparing polyurethane from liquefied wood or bark.Part of this paper was presented at the 51st Annual Meeting of the Japan Wood Research Society, Tokyo, April 1988     

Bromination of different morphological parts of spruce wood (Picea abies)

Summary It has been found that the lignin in a middle lamella fraction isolated by a sieving technique has the same reactivity to bromine as the whole wood lignin. A plataue value of 1 mole bromine/mole C₉-unit was obtained for both samples. The lignin in compression wood had a considerably lower reactivity to bromine than the normal wood lignin. A plataue value of 0.68 mole bromine/mol C₉-unit was obtained with such lignin. The discrepancy between this and earlier results from the bromination of middle lamella and the implication of the results for lignin determination by the SEM- and TEM-EDXA technique are discussed.     

“I-214杨”心材、边材木质素的红外光谱、质子和碳-13核磁共振波谱特征研究

对从杨树心、边材提取的磨木木质素进行了元素分析和红外光谱（FTIR）质子和碳－13核磁共振波谱（^1H,^13C NMR)等化学特征研究。研究结果表明：杨树心、边材木质素的经验式分别为C9H7．16O2．38（OCH3）1．99和C9H8．61O2．73（OCH3）1．33。心材木质素甲氧基含量28．16％,比边材高8．73％。两种木质素均具有典型阔叶材的特征,化学结构类型基本一致,碳骨架结构基本相同,但化学官能团和键型的组成上存在差异。     

Variation of the phenolic hydroxyl group content in wood lignins

Summary The phenolic hydroxyl group content of wood lignin has been determined in situ by a periodate oxidation method for four softwood and six hardwood species. Hardwood lignins, in contrast to softwood lignins, showed a significant variation among different species in this functional group content which decreased with an increase in the proportion of syringyl units in the wood lignin.Financial support from the Empire State Paper Research Associates is greatly appreciated     

Evaluation of the quantitative assay of lignin distribution by SEM-EDXA-technique

Summary A method has been developed for the determination of lignin distribution in wood cell walls by studying bromine concentrations in 0.5 m sections with scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM-EDXA) technique. Evaluation of backscattering, absorption and fluorescence effects on quantitative assay of lignin distribution indicated that these effects may all be ignored, if relative comparisons are made. Thus, a relative ratio of the measured Br-L X-ray intensities directly provides bromine concentration ratio, from which the ratio of lignin concentrations in different morphological regions can be estimated. Additionally, the effect of electron beam bombardment on bromine was found to be negligible. Therefore, the SEM-EDXA technique provides quantitative information of lignin distribution with relatively high accuracy. The potential and limitations of this technique were also elucidated.Paper No. 6861 in the Journal Series of the North Carolina Agricultural Research Service, Raleigh, North Carolina. This paper is an excerpt from the Ph.D. dissertation of Shiro Saka     

氧漂过程中脱木质素与木质素氧化之间定量关系的研究

对氧碱漂白过程中木质素氧化进行定量分析,分析方法是基于氧化前后高锰酸钾消耗量的变化。该方法对溶出残余木质素的氧化结果分析发现其呈明显3个阶段：第一段木质素氧化的当量电荷数约4～5／木质素单元;木质素总氧化电荷数大约为9／木质素单元。这些数据以及甲氧基的脱除（75％）均表明：木质素的氧化不仅发生在酚型木质素单元,同时也发生在非酚型结构单元上。只有第一阶段氧化反应是木质素与氧气直接反应,而在第二、三阶段主要是协同氧化作用,氧化反应过程中产生的活性氧基团扮演了一定角色。通过对低浓度针叶材硫酸盐浆的氧漂研究发现：当卡伯值下降一半（25．4至13．4）时平均每个木质素单元氧化3当量电子,氧漂后的纸浆中仍然有大量未被氧化的残余木质素。定量地证明了在氧漂过程中木质素氧化是脱木质素反应的实质。     

Quantifying lignin and holocellulose content in coniferous decayed wood using near-infrared reflectance spectroscopy

To determine the independent decomposition rates of lignin and cellulose of decayed woody debris, a technique for the rapid analysis of lignin and cellulose is required. We applied a near-infrared spectroscopy (NIRS) technique to measure the lignin and holocellulose content in decayed wood. We succeeded in creating partial least-squares (PLS) models to estimate the lignin and holocellulose content in the decayed wood of five species using NIR spectra. Although the accuracy was acceptable for the estimation of a five-species mixed model (R ² = 0.970 for lignin and R ² = 0.962 for holocellulose), it was further improved when the model was applied to each species independently. This combination of NIRS and a PLS model is a valuable tool for the determination of the lignin and holocellulose content in decayed wood. The technique is time efficient (3 min per sample) and non-hazardous (no acid treatment is required).