Improved mechanical properties of chitosan fibers

A highly deacetylated chitosan from shrimp with a degree of deacetylation of 95 ± 3% was prepared and spun into a monofilament fiber using a solution of 5% by weight chitosan in 5% by volume aqueous acetic acid. Samples of the spun fibers were immersed in separate solutions containing phosphate ions and phthalate ions, and subsequently washed and dried. The various solutions ranged in pH from 4.12 to 7.75. The highest dry mechanical properties resulted from solutions containing phthalate ions between 4.5–5.5 pH, and from solutions containing phosphate ions at pH 5.4. Immersion time was varied between 1 and 60 min at 25.8°C, and temperature was varied between 25.8 and 70.0°C, in the phosphate ion solutions at a pH of 5.8. Dry mechanical properties were highest at 25.8°C and after 1 h of treatment. Chitosan films were subjected to similar treatments in phosphate and phthalate ion solutions. Fourier transform infrared data (FTIR) on the films suggest that some interaction is occurring between the phosphate ions and the amine group on the chitosan backbone. An additional experiment was performed whereby the same chitosan was used to prepare a dope of 4% by weight chitosan in 4% by volume aqueous acetic acid with 30% by volume methanol. This solution was spun into fibers, but was subjected to a “final draw” by increasing the speed of the winder. With increasing the final draw, denier and elongation‐at‐break decreased, while the other mechanical properties showed a marked increase. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1721–1732, 1999     

壳聚糖-丙烯酰胺接枝共聚高分子絮凝剂研究

为改进壳聚糖化学性质不活泼、溶解性差等缺点,采用壳聚糖中胺基、羟基可生成多功能基团的性质,研究了壳聚糖（CTS）-丙烯酰胺（AM）接枝共聚的反应规律,及产物的结构性能。由反应的接枝率、接枝效率表明,在氮气的保护下,以硝酸铈铵为引发剂,控制m（CTs）：m（AM）=1：5,于60℃下接枝共聚的反应2h,可制得一类新型壳聚糖改性絮凝剂,并用IR、SEM对产物结构进行了表征,同时用某印染厂废水进行了絮凝实验,结果表明,其废水中COD去除率可达到60％左右。     

Chitosan–Polyelectrolyte complexation for the preparation of gel beads and controlled release of anticancer drug. I. Effect of phosphorous polyelectrolyte complex and enzymatic hydrolysis of polymer

Enzymic hydrolyzed chitosan was employed to prepare chitosan–tripolyphosphate and chitosan–polyphosphoric acid gel beads using a polyelectrolyte complexation method for the sustained‐release of anticancer agent, 6‐mercaptopurine (6‐MP). pH responsive swelling ability, drug‐release characteristics, and morphology of the chitosan gel bead depends on polyelectrolyte complexation mechanism and molecular weight of the enzymic hydrolyzed chitosan. The complexation mechanism of chitosan beads gelled in pentasodium tripolyphosphate or polyphosphoric acid solution was ionotropic crosslinking or interpolymer complex, respectively. The drug‐release patterns of all chitosan gel beads in pH 6.8 seemed to be diffusional based, which might be in accordance with the Higuchi model, whereas release profiles of the chitosan–tripolyphosphate gel beads in pH 1.2 medium seemed to be non‐Fickian diffusion controlled due to the swelling or matrix erosion of the beads. The rate of 6‐MP releasing from chitosan–tripolyphosphate or chitosan–polyphosphoric acid gel matrix were significantly increased with the decreased molecular weight of enzymic hydrolyzed chitosan. However, the dissolution rates of 6‐MP entraped in chitosan–tripolyphosphate and chitosan–polyphosphoric acid gel matrix were significantly slower than the dissolution rate of the original drug. These results indicate that the chitosan–polyphosphoric acid gel bead is a better polymer carrier for the sustained release of anticancer drugs in simulated intestinal and gastric juice medium than the chitosan–tripolyphosphate gel beads. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1868–1879, 1999     

壳聚糖絮凝剂处理水源水中有机物的试验研究

研究了壳聚糖絮凝剂的絮凝特性,进行了壳聚糖絮凝剂跟无机絮凝剂复合絮凝对水源水中浊度和有机物去除的试验。实验结果表明,复合絮凝能够相互促进各自的絮凝性能,显著提高有机物的去除效果,并使除浊和去除有机物得到了统一。在壳聚糖絮凝剂分别与三种常用无机絮凝剂(硫酸铝、氯化铁和聚合铝铁)的复合絮凝的效果的实验表明,其中聚合铝铁跟壳聚糖的复合絮凝剂的效果最好,在最佳条件下,其浊度、CODMn和UV254的去除率分别达到了97％、44％和55％。     

5-溴水杨醛改性壳聚糖的制备及吸附性能

制备了两种不同形态的改性壳聚糖希夫碱：微粒化的壳聚糖希夫碱（P-CTSS）,未微粒化的壳聚糖希夫碱（CTSS）,并研究了它们分别对Cu^2＋,Pb^2＋,Cd^2＋及Zn^2＋的吸附性能,考察了pH值、时间等因素对吸附性能的影响。结果表明,P-CTSS较CTSS易于粉碎,且吸附性能较好。CTSS对Cu^2＋,Pb^2＋,Cd^2＋及Zn^2＋的吸附容量分别为：15．21、10．35、12．13、9．28mg／g,而P-CTS对Cu^2＋,Pb^2＋,Cd^2＋及Zn^2＋的吸附容量分别为：37．46、15．84、16．34、13．67mg／g,P-CTSS对Cu^2＋的吸附率在2．5h内达到84．5％左右,具有一定的选择性吸附。     

壳聚糖的粘流性及织物表面固着的研究

探讨了壳聚糖乙酸胶液在不同状态下的粘度特征,分析了其流体动力学的稳定性,比较了超声波、加热、微波等物理方法促进壳聚糖固着时对织物透气性的影响,确定了壳聚糖向织物组织内部渗透并固着的工艺条件。     

壳聚糖脱乙酰度的测定及其应用研究进展

壳聚糖是自然界中存量巨大的多糖类物质,在食品、医药、农业、环保等领域发挥着许多重要的作用.其脱乙酰度是评判其性能的重要指标之一,这使得在实际应用中对脱乙酰度检测方法的便利性和准确性提出较高的要求.本文综述了化学分析方法、光谱学分析方法、破坏性分析方法和电特性分析方法,探讨各种分析方法及其改进方案的优缺点,发现化学分析法...     

EDTA对磁性壳聚糖的改性及对Mn2+的吸附性研究

目的 为解决现有水体除Mn²⁺技术条件苛刻、成本高、传统吸附剂回收利用难等问题,通过交联反应和乳化反应分别制备了磁性壳聚糖(CMS)和EDTA改性磁性壳聚糖(EDTA-CMS)两种Mn²⁺吸附剂。方法 采用SEM、FT-IY、XRD等对CMS、EDTA-CMS进行了表征,并考察了CMS、EDTA-CMS在不同实验条件下对Mn²⁺的吸附性能。结果 与CMS相比,在温度为25 ℃、pH值为6、吸附剂用量为1 g/L、吸附时间为720 min时, EDTA-CMS对Mn²⁺ 的吸附率更高;CMS、EDTA-CMS对Mn²⁺的吸附过程符合准二级动力学模型,表明化学吸附主要控制着吸附速率;且吸附过程符合Langmuir等温模型,最大吸附容量分别可达95.638 mg/g、119.363 mg/g;循环吸附5次后, EDTA-CMS对Mn²⁺的吸附率为71.47％,仍高于CMS对Mn²⁺的初次吸附率。结论 EDTA-CMS不仅对Mn²⁺的吸附效果较好且重复利用率高,是处理含Mn²⁺废水的潜在可回收吸附剂。      

High-speed CO2 transport channel containing carboxymethyl chitosan/hydrotalcite membrane for CO2 separation

A comprehensive understanding of carboxymethyl chitosan (CMC)-based mixed matrix membrane (MMM) has been critically investigated. The present work elaborates the compatibility of hydrotalcite (HT) and CMC in terms of CO₂ separation application. Various spectroscopic and microscopic techniques have been utilized to characterize the respective properties of the prepared membrane. The temperature stability and moisture retention behavior of the membrane recognized itself as the flue gas separation membrane. The CO₂/N₂ separation experiment was performed on the MMM at different temperature (60–110 °C) and sweep/feed water flow to the saturator ratio (0.33 to 3). The membrane exhibited the optimum CO₂ permeance of 70 GPU at 90°C pertaining to water flow ratio of 2.33 (sweep/feed). The CO₂/N₂ selectivity observed at that same operating condition was 13. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48715.     

Chitinous polymers: extraction from fungal sources,characterization and processing towards value-added applications

Chitin, chitosan and their complexes with β-glucan (chitin–glucan complex, CGC, and chitosan–glucan complex, ChGC) are value-added polysaccharides extracted from the cell-walls of many fungi. Commercial chitin and its deacetylated form, chitosan, are currently obtained from marine waste material, mostly animal sources (crustaceans and marine invertebrates), through harsh chemical procedures that have low reproducibility due to the variability of the composition of the sources and their seasonal character. These disadvantages are overcome by using fungi as sources of chitinous polymers. The extraction of chitin/chitosan from fungi cell-walls has the great advantage of yielding products with stable composition and properties, using simpler procedures, with the added benefit of also generating CGC and ChGC, two copolymers that combine the proven properties of chitin/chitosan with those of β-glucans. Over the last decades, fungal chitinous polymers have been the focus of extensive research that included optimization of the cultivation conditions of a wide range of species and the development of optimized extraction, purification and characterization techniques, as well as the demonstration of the biopolymers' biological properties, which include immunomodulatory, anticancer, antioxidant and antimicrobial activity. Given these properties, several attempts were made to develop applications for them in areas ranging from biomedicine and pharmaceuticals to food and agriculture. Despite their wide range of proven functional properties that include the ability to form different polymeric structures, as well as biological activity, fungal chitinous biopolymers are still underexplored. Nevertheless, these biopolymers hold great potential for development into valuable products or applications that are surely worth further investigation. © 2019 Society of Chemical Industry