N,O—羧基壳聚糖制备及其保温性能研究

阐述了制备Ｎ，Ｏ－羧甲基壳聚糖的工艺路线和方法，并测定其保温、吸湿性能。结果表明：制备Ｎ，Ｏ－羧甲基壳聚糖最佳工艺条件为ＮａＯＨ：ＣｌＣＨ２ＣＯＯＨ＝０．９：１，异丙醇：壳聚糖＝１２：１（质量比）；反应温度６５℃，反应时间２．５ｈ，得到的产品在保湿、吸湿方面明显优于甘油。     

壳聚糖微球制备方法的专利技术进展

壳聚糖,通过甲壳素脱除部分乙酰基得到,结构中含有大量的氨基和羟基,是天然多糖中唯一的碱性多糖。由于壳聚糖分子中含有大量的配位基团,且其具有优异的包埋和缓释性能,大量的研究将壳聚糖及其复配的组合物制备成微球形态。近几年对于壳聚糖的制备方法的专利越来越多,对原有的壳聚糖微球制备方法做了各种优化。壳聚糖微球的制备技术不断地进步,使壳聚糖微球在多个领域的产品中使用。     

酶载体壳聚糖制备的研究

本文分别采用电热法、连续微波法和问歇微波法制备了几种性能不同的壳聚糖,并对产品的脱乙酰度和分子量进行了比较.结果表明,间歇微波法制备的壳聚糖具有制备时间短、产品脱乙酰度高和分子量大等特点,能更好地满足酶载体的要求.     

微波技术提取高脱乙酰度高黏度壳聚糖的实验研究

壳聚糖作为一种具有独特性能的天然高分子生物材料，其应用越来越广泛，并且对壳聚糖品质的要求也越来越高。高脱乙酰度和高黏度是壳聚糖的二个重要质量指标，传统制备工艺中，通过提高反应温度和延长反应时间，能得到高脱乙酰度的壳聚糖产品，但由于过长的反应时间使黏度大大降低。本文采用微波技术和传统工艺相结合，通过正交试验确定了从虾壳中提取高脱乙酰度高黏度壳聚糖的较优工艺条件。     

羧甲基壳聚糖的合成

以壳聚糖原料，采用氟乙酸途径制备方式，得到制备羧甲基壳聚糖最佳工艺路线，并对产物进行了性能测定．其取代度达到90％以上。     

壳聚糖可纺性能的探讨

主要介绍壳聚糖的性质、壳聚糖纺丝原液的制备工艺，并对壳聚糖的可纺性能进行探讨。     

纳米纤维素晶须-壳聚糖/聚乙烯醇复合膜性能与细胞相容性

以椰壳纤维为原料，制备了纳米纤维素晶须，用硅烷偶联剂对纳米纤维素晶须进行改性，将改性后纳米纤维素晶须与壳聚糖、聚乙烯醇共混，采用溶液浇铸法制备了改性纳米纤维素晶须-壳聚糖/聚乙烯醇复合膜。采用FTIR、DSC、TG、XRD和SEM对改性纳米纤维素晶须-壳聚糖/聚乙烯醇复合膜的结构、热性能、结晶行为和形貌进行表征与分析，对复合膜的力学性能和水接触角进行测试，将成纤维细胞L929接种到复合膜上，对其进行细胞相容性实验。结果表明，添加改性纤维素晶须，能够使壳聚糖/聚乙烯醇复合膜的热性能、结晶行为和力学性能提高，成纤维细胞在复合膜上具有较好的黏附和生长，制备的纳米纤维素晶须-壳聚糖/聚乙烯醇复合膜具有良好的综合性能和细胞相容性。     

甲壳素及壳聚糖最新研究进展

综合我国近十年有关甲壳素及壳聚糖的研究文献，概述了甲壳素及壳聚糖的制备与加工方法，基本性能与应用现状，同时提出了我国目前在甲壳素及壳聚糖的研究与应用中存在的问题及今后的发展方向。     

壳聚糖膜的制备及其性能测试

以天然高分子材料壳聚糖为原料,采用流延法制备了壳聚糖膜。研究了N-乙酰化和交联壳聚糖膜的制备方法及性能特性等。通过FTIR、XRD和SEM方法表征结构,并测试了力学性能。试验结果表明交联和乙酰化可以增加壳聚糖膜的拉伸强度提高膜的性能。     

海藻酸钙/改性壳聚糖混纺亲水性纤维敷料的制备及其性能研究

本文以海藻酸钙纤维和改性壳聚糖纤维为原料,通过针刺无纺布工艺制备含有不同比例的改性壳聚糖纤维的海藻酸钙/改性壳聚糖混纺敷料,同时,对制备的复合敷料的吸液性能、抗菌性能、止血性能进行研究。结果显示,海藻酸钙/改性壳聚糖混纺敷料具有很好的吸液性能、抗菌性能以及止血效果,有效的改善了海藻酸钙敷料的性能。     

酸、碱溶液对脱脂蚕蛹的解剖结构影响

将脱脂蚕蛹分别置于清水、1%盐酸溶液和1%氢氧化钠溶液中,100℃浸泡处理20 min,采用电子光学显微分析技术观察脱脂蚕蛹的解剖结构。结果表明:①清水浸泡,蛋白质、甲壳素膨胀;②盐酸溶液浸泡,在蛋白质、甲壳素膨胀的同时,有蛋白的部分分解;③氢氧化钠溶液浸泡,蛋白质、甲壳素膨胀,蛋白质溶解,并伴有部分蛋白的分解。碱对蛋白层与甲壳层的层间有劈开作用。碱液能实现蛋白层与甲壳层的剥离。     

可再生甲壳质吸附特性研究进展

本文综述了可再生甲壳质吸附特性研究的概况,介绍了可再生甲壳质吸附阴离子染料、有机酸、Cr~(6 )、低浓度无机酸等特性。     

Synthesis and FTIR spectroscopic studies on shear induced oriented liquid crystalline chitin/poly(acrylic acid) composite

Liquid crystalline chitin/poly(acrylic acid) composite, with its unique optical properties, was fabricated by the free‐radical photopolymerization of acrylic acid in an aligned mesophase. Alignment of the mesophase was achieved by unidirectional shearing. The developed composites, coated on calcium fluoride (CaF₂) substrate, were transparent, and the alignment was retained depending on the mesophase composition of the ternary dispersion (chitin microfibrils, water, acrylic acid). According to studies from polarized FTIR spectroscopy, both the degree of orientation and the molecular interactions were strongly affected by respective mesophase behavior. The average molecular chains of chitin microfibrils were oriented along the shear direction. A high dichroic ratio value of about 25, observed in composites of chitin/poly(acrylic acid) with a w/w ratio of 55:45, opens an interesting avenue to prepare a new chitin‐based optically anisotropic composite. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1932–1940, 2003     

利用金蝉制备甲壳素

从金蝉中提取甲壳素,对制备工艺、脱色条件、酸碱浓度及用量等进行研究。结果表明,金蝉中含有较多的蛋白质,甲壳素含量为10％～12％。     

丁酰甲壳素的制备及表征

甲烷磺酸体系中,均相酰化制备了丁酰甲壳素,红外、X-射线衍射、元素分析和DSC等测试结果标明,甲壳素丁酰化后结晶结构被破坏.丁酰甲壳素易溶于二氧六环、四氢呋喃、丙酮、甲醇、乙腈、二甲基乙酰胺和乙酸等普通有机溶剂.在碱性条件下,丁酰甲壳素可以水解成甲壳素.     

Removal of endocrine disrupting chemicals from contaminated industrial groundwater using chitin as a biosorbent

BACKGROUND: The removal of endocrine disrupting chemicals (EDCs) from drinking water is of great importance. Chitin isolated from crab shells was used as a biosorbent for removal of three EDCs—benzo(a)antracene, β‐estradiol and bisphenol A—present in contaminated groundwater. Fourier transform infra‐red (FTIR) spectroscopy, porosimetry and scanning electron microscope (SEM) were used for structural elucidation of chitin. Experiments were conducted using batch adsorption mode under different conditions of initial EDCs concentration, solution pH and adsorbent dose. The effect of chitin particle size was also investigated. Batch adsorption data were fitted to Langmuir and Freundlich isotherms and pseudo‐first‐ and second‐order models for kinetic study. RESULTS: The maximum adsorption capacity of chitin by the three EDCs, calculated using the Langmuir equation, ranged from 42.9 to 84 mg g^?1. The adsorption of EDCs by chitin was due primarily to electrostatic forces. The measurement of zeta potential indicated that chitin has higher surface charge in alkaline pH, resulting in reduction in removal of EDCs with increasing pH. Complementary to the experimental results molecular simulations were also performed on HyperChem software to understand the adsorption mechanism between chitin and EDCs in aquesous solutions. Chitin was regenerated after washing with methanol/acetic acid (1/3, v/v) and the regeneration process was repeated for 10 cycles, which showed 90% adsorption capacity retained by chitin. CONCLUSIONS: The experimental results suggest that chitin could be employed as an adsorbent in the removal of EDCs from aqueous solutions, and the adsorption potential of used chitin can be recovered by methanol/acetic acid solvent washings. The reusable biosorbent chitin would be cost‐effective and a better option for future water remediation endeavours. Copyright © 2010 Society of Chemical Industry     

Adsorption of humic acid onto chitin and chitosan

The adsorption of humic acid onto chitin and chitosan has been investigated. The uptake of humic acid from aqueous solution was determined from changes in concentration, as measured by ultraviolet-visible spectroscopy. The decrease in humic acid removal was observed with the increase in pH. A significant uptake of humic acid on both chitin and chitosan was observed. The uptake of humid acid on chitosan was greater than that on chitin. Adsorption isothermal data could be interpreted by the Langmuir and Freundlich equation. Langmuir and Freundlich constants have been determined. The experimental data of the adsorption equilibrium from humic acid solutions correlate well with the Langmuir isotherm equation, as compared to the Freundlich isotherm equation. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2305–2310, 1998     

Chitin nanofibers: preparations, modifications, and applications

Chitin nanofibers are prepared from the exoskeletons of crabs and prawns by a simple mechanical treatment after the removal of proteins and minerals. The obtained nanofibers have fine nanofiber networks with a uniform width of approximately 10-20 nm and a high aspect ratio. The method used for chitin-nanofiber isolation is also successfully applied to the cell walls of mushrooms. They form a complex with glucans on the fiber surface. A grinder, a Star Burst atomization system, and a high speed blender are all used in the mechanical treatment to convert chitin to nanofibers. Mechanical treatment under acidic conditions is the key to facilitate fibrillation. At pH 3-4, the cationization of amino groups on the fiber surface assists nano-fibrillation by electrostatic repulsive force. By applying this finding, we also prepared chitin nanofibers from dry chitin powder. Chitin nanofibers are acetylated to modify their surfaces. The acetyl DS can be controlled from 1 to 3 by changing the reaction time. An acetyl group is introduced heterogeneously from the surface to the core. Nanofiber morphology is maintained even in the case of high acetyl DS. Optically transparent chitin nanofiber composites are prepared with 11 different types of acrylic resins. Due to the nano-sized structure, all of the composites are highly transparent. Chitin nanofibers significantly increase the Young's moduli and the tensile strengths and decrease the thermal expansion of all acrylic resins due to the reinforcement effect of chitin nanofibers. Chitin nanofibers show chiral separation ability. The chitin nanofiber membrane transports the d-isomer of glutamic acid, phenylalanine, and lysine from the corresponding racemic amino acid mixtures faster than the corresponding l-isomer. The chitin nanofibers improve clinical symptoms and suppress ulcerative colitis in a DSS-induced mouse model of acute ulcerative colitis. Moreover, chitin nanofibers suppress myeloperoxidase activation in the colon and decrease serum interleukin-6 concentrations.     

甲壳素酰化改性的研究进展

甲壳素作为一种来源广泛的生物质材料,具有良好的生物相容性和抑菌性,可用于药物缓释、伤口包覆、组织植入、生物分离、重金属吸附等高附加值领域,但强烈的氢键作用使其不熔难溶,需经改性以促进其加工和应用。本文简要回顾了甲壳素酰化改性的发展历程,重点介绍均相条件下甲壳素的各种酰化方法,如在甲磺酸、氯化锂/二甲基乙酰胺、离子液体、三氟乙酸酐中进行反应,以及在非均相条件下提高酰化效率的各种方法,如优选催化剂、结构活化等,比较了各种方法的优缺点,并简述了甲壳素酰化产物的性能特点和应用。目前甲壳素非均相酰化工艺较成熟,已实现工业化,但仍有一定的局限性和缺点。最后展望了均相和非均相酰化可能的改进方向。     

间接法生产甲壳素纤维

由于天然甲壳素结晶度高,在湿法纺丝过程中溶解甲壳素时需要使用价格较高的有机溶剂。甲壳素脱乙酰基后得到的甲壳胺可以很方便地溶解在稀醋酸水溶液中,经喷丝孔挤出后用稀碱中和沉淀即可得到甲壳胺纤维。在甲壳胺纤维上加上乙酰基后可以得到再生甲壳素纤维。介绍了在用乙酸酐处理甲壳胺纤维制备再生甲壳素纤维过程中,反应时间、反应温度、乙酸酐用量对乙酰化的影响。