纤维素经液氨预处理对其结构和晶型的影响

棉短绒纤维素在室温和工1.03MPn压力下用无水液氢进行预处理,并经蒸发除去大部分氨,研究液氮处理前后纤维素微细结构和结晶形态的变化,讨论氛对纤维素的作用机理。结果表明,液氮处理后纤维素的侧序分布、结晶度、微晶尺寸、晶格形态都发生深刻的变化。X-射线结晶度下降21％,微晶横向尺寸减少20％-40％,晶格由纤维素I转化为纤维素I。纤维素结构中较高序态区向低序和无序部分转移,这种物理结构的变化将增进纤维素的可及度,提高纤维素在制备行生物时的反应性。     

超声波处理对纤维素纤维形态结构的影响

用扫描电镜和光学显微镜研究超声波处理对纤维素纤维形态结构及超微结构的影响。探讨了超声波处理时间、超声波功率、浆浓度等因素对处理效果的影响。研究发现在超声波作用下纤维素纤维形态结构和超微结构变化明显,细纤维化作用显著;其变化程度与处理时间、超声波功率有关,随着超声波处理时间的增加,超声波对纤维素纤维的作用程度提高,更多的次生壁 S2 层微纤维暴露,并发生分丝帚化现象;随着超声波功率的增大,超声波强度提高,空化泡崩溃时产生的微射流对纤维素纤维的冲击作用加强,对纤维形态结构和超微结构产生影响的效应随之增大;确定了超声处理时适宜的浆浓度范围为 1%～3%。纤维素纤维在超声波作用下发生细胞壁层的脱除,使高反应性能的 S2 层微纤维暴露,对提高纤维素的可及度和化学反应性能非常有利。     

纤维素氨基甲酸酯的合成研究

以微晶纤维素和尿素为原料 ,二甲苯为溶剂合成了纤维素氨基甲酸酯。考察各种影响因素 ,得到优化的反应条件为 :微晶纤维素在质量分数为 2 0 %的氢氧化钠水溶液中预处理 4～ 6h ,尿素与微晶纤维素质量比为 ( 3～ 4)∶1,反应温度为 137℃ ,反应时间为 4h。元素分析测得产品氮的质量分数约为 8%     

天然纤维素蒸汽闪爆改性对其长支链酯合成影响

采用蒸汽闪爆技术对天然纤维素进行改性,并利用改性后的纤维素、乙酸酐和脂肪酸合成长支链纤维素酯。结果表明,蒸汽闪爆处理后纤维素葡萄糖环单元三个羟基的可及性及相对反应性能得到提高,同时缩短了反应周期。     

可反应性纳米SiO_2对PVC颗粒结构、性能的影响

以VCM和可反应性纳米SiO2(RNS)为原料,采用原位聚合方法合成了PVC/RNS复合材料,考察了RNS对PVC树脂颗粒结构和性能的影响,并利用FTIR和XPS等分析了RNS与PVC之间的相互作用机制。结果表明:①PVC/RNS颗粒内部结构较为疏松多孔,可见较多的初级粒子;②与PVC树脂相比,PVC/RNS复合材料的黏数略有增加,增塑剂吸收量提高,表观密度略有降低,颗粒粒度分布变化不大,维卡软化温度小幅增加,热降解速率降低;③RNS与部分PVC分子链之间形成了强化学键结合。     

蒸汽爆破预处理对植物纤维素性质的影响

用研制的植物纤维素连续所爆破机对植物纤维素原料的预处理进行了研究,利用扫描电镜（ＳＥＭ）,红外光谱（ＩＲ）和Ｘ－射线衍射仪对汽爆处理后物料的形态结构,物理特性及化学组成的变化进行了分析,研究结果表明,汽爆预处理方法对 物料的物理结构及化学组成有一系列蝗影响,汽爆使物料的粒度变小,Ｘ－射线衍射峰变明显,处理物料红外光谱的某些峰强度减弱,半纤维素变化较大,处理后的物料易于酶解。     

木素的存在对纤维素水解反应性能及其产物结构的影响

对木素含量为0.9％—8.3％的速生杨硫酸盐浆进行了X—射线分析研究。利用多相水解方法测定了其反应性能。研究结果确定,浆中结晶纤维素含量取决于木素脱出程度并随着木素含量的降低而增加。木屑和浆中的纤维素结晶度相当高,而在脱木素过程中只呈微小变化。木素存在于多相水解反应过程中起着阻碍纤维素水解的作用,降低其反应速度常数。基于研究结果,提出了木素与纤维素结晶部分外表面联结的结论.并探讨了这种联结键的可能形式。     

液氨管线带压开孔技术

介绍了在液氨管线上进行不停输带压开孔的具体实施步骤,并对安全施工要点作了总结。     

液氨流量计的选用分析

针对工业生产过程中液氨流量计测量不准确的问题,为了能够正确的选择与使用液氨流量计,通过对几种流量计工作原理进行分析,找出影响测量误差的原因,对影测量误差的因素进行判断和调效,从而实现工业生产中对液氨流量的准确监控。     

The effect of sulphur present in coal on the course of its reduction in the potassium/liquid ammonia system

Two low-rank coals of high content of sulphur and low sulphur content orthocoking coal were chosen as the subject of study. The process of reduction was carried out twice, for raw and demineralised, by the Radmacher method, coals. Elemental and spectral analyses of the initial coals and the products obtained from them were made. The solubility of the coals in dichloromethane and the average molecular weight of the extracts were determined. The degree of conversion of the coals studied to the products soluble in dichloromethane was found to be surprisingly high regarding the low-rank coals. A hypothesis is put forward that the high content of sulphur in low-rank coals can endow them with certain properties typical of coking coals.     

不同碱金属氢氧化物对纤维素羧甲基化的影响

以不同碱金属氢氧化物(NaOH,KOH)为碱化剂,利用淤浆法合成CMC,对纤维素的碱化及羧甲基化进行了研究。结果表明,NaOH质量分数为25%,纤维素达到最大的润胀,KOH质量分数在20%~35%,纤维素的润胀率出现平台区;同一质量分数下,纤维素在NaOH溶液中的润胀率和吸附碱量都比在KOH中高;CMC的取代度随NaOH用量的增加急剧增加,而随KOH量的增加较为缓慢;取代度相近时,羧甲基纤维素钾的耐酸性和耐盐性比羧甲基纤维素钠差。     

Homogenous carboxymethylation of cellulose in the NaOH/urea aqueous solution

In this work, the carboxymethylation of cellulose in the alkaline cellulose solvent, 7 wt% NaOH/12 wt% urea aqueous solution, was investigated. Carboxymethyl cellulose (CMC) samples were characterized with FT-IR, NMR, HPLC, and viscosity measurements. Water-soluble CMC with DS = 0.20–0.62 was prepared from both Avicel cellulose and cotton linters. Thus, carboxymethylation of cellulose in NaOH/urea leads to a polymer with the lowest DS value for water solubility (0.20) of CMC known. The total DS of CMC could be controlled by varying the molar ratio of reagents and NaOH to AGU and the reaction temperature. Structure analysis by means of HPLC after complete depolymerization showed that the mole fractions of the different carboxymethylated repeating units as well as those of unmodified glucose follow the simple statistic pattern. A distribution of the carboxymethyl groups at the level of the AGU in the order O-6 > O-2 > O-3 was determined. The results were similar with findings for CMC obtained by totally homogeneous reaction of cellulose in aqueous solvents such as Ni[tris(2-aminoethyl)amine](OH)₂.     

球形棉纤维素的制备

脱脂棉花经碱化和磺化得粘肢液，用热溶胶转相法制得球形纤维素珠体。在粘胶液的制备过程中，棉与碱的质量比为2：1，老化时间60h，磺化温度23℃、磺化时间3h,CS2的用量为碱纤维素中纤维素质量的35．6％；在成球过程中，分散介质为V（泵油）：V（氯苯）=2：1，上升至温度为80～90℃后恒温2h。     

吡啶类离子液体的合成及对纤维素溶解性能的研究

采用一步法合成N-烯丙基吡啶氯盐离子液体([APy]Cl),测定其相溶性和吸水率,利用核磁共振氢谱(1H-NMR)、傅里叶变换红外光谱仪(FT-IR)、质谱(MS)和热分析系统(DSC-TGA)对其化学结构和热稳定性进行分析;并测定对纤维素的溶解能力。结果表明,[APy]Cl为纤维素的优良溶剂,在120℃时对棉浆粕纤维素(聚合度DP=556)的溶解度可达到19.71%,脱脂棉纤维素(DP=1971)可达15.29%。利用FT-IR、X射线衍射仪(XRD)和DSC-TGA对再生前后纤维素进行表征,结果表明该离子液体为纤维素的直接溶剂,可将晶型由Ⅰ型转变为Ⅱ型。     

雏议我国第一条长输液氨管道的设计

作者通过工作实践，介绍了我国第一条长输液氨管道的概况以及设计中应注意的问题和输氨管道的防护．     

离子液体法制备再生细菌纤维素纤维

以离子液体(氯化1-甲基-3-正丁基咪唑)溶解高聚合度细菌纤维素(BC),采用湿法纺丝制备再生细菌纤维素(RBC)初生纤维;通过红外光谱分析(FTIR)、广角X射线衍射(WAXD)分析、热失重(TG)分析、扫描电镜( SEM)、单丝强度拉伸等表征了RBC初生纤维的结构和性能.结果表明:该溶剂体系通过10 h的快速搅拌溶...     

Moisture induced plasticity of amorphous cellulose films from ionic liquid

Amorphous cellulose films were created by regeneration from 1-Ethyl-3-methylimidazolium acetate (EmimAc) solutions. Their mechanical properties were analyzed as a function of water content. Cellulose with different molecular weights, i.e. microcrystalline cellulose (Avicel), Spruce cellulose and bacterial nanocellulose (BNC), were used for film preparation. All the regenerated films were free from EmimAc residues as shown by Fourier transform infrared spectroscopy (FTIR), amorphous as shown by wide angle X-ray spectroscopy (WAXS) and optical transparent. The equilibrium water content (w/w) was measured at different relative humidities. The plasticizing effect of water on the films was evidenced by both tensile tests and dynamical mechanical analysis (DMA) with humidity scans. The mechanical properties were clearly related to the proportional water uptake of the films. The sample with the longest cellulose chains, i.e. BNC, showed significantly larger elongation to brake at high moisture content which was owed to chain entanglements.