纤维素/离子液体溶液流变行为的研究

以离子液体1-丁基-3-甲基咪唑氯盐（[BMIM]Cl）为溶剂,制备了不同质量分数的纤维素/[BMIM]Cl溶液,利用ARES-RFS旋转流变仪研究了溶液的稳态流变行为,讨论了剪切速率、温度和纤维素含量等因素对溶液粘度和非牛顿指数的影响。结果表明：纤维素/[BMIM]Cl溶液属于非牛顿假塑性流体,呈现切力变稀行为;溶液的表观黏度随着剪切速率的升高而降低;随着温度的升高,溶液的结构黏度下降,而非牛顿指数增加;纤维素含量的增加可使溶液的结构黏度、零切黏度和黏流活化能增大,使非牛顿指数降低。     

离子液体中胶原纤维的溶解和再生

天然胶原纤维被成功地溶解于1-丁基-3-甲基咪唑氯化物([BMIM]Cl)离子液体中,并且在不同的沉淀剂中再生。在偏光显微镜中观察,发现胶原纤维的晶体结构在加热过程中已经被[BMIM]Cl破坏了。利用变温红外光谱法检测溶解过程中胶原/[BMIM]Cl的结构变化。利用FTIR和XRD表征再生胶原的结构。结果表明,胶原蛋白的三螺旋结构在溶解与再生过程中一定程度上被破坏了。沉淀的处理很大程度上决定了再生胶原的成膜能力和热稳定性,提出了胶原在[BMIM]Cl中溶解以及在沉淀剂中再生的可能机制。利用[BMIM]Cl作为介质可以成功制备不同形态(薄膜,纤维,凝胶)的胶原蛋白/纤维素复合材料。     

基于棉秆的离子液体溶解及其全纤维素复合材料的制备与性能研究

采用离子液体1-丁基-3-甲基咪唑氯盐{[BMIM]Cl}溶解棉秆纤维(CSF)制成溶剂,将棉秆皮纤维作为增强材料与所制得的溶剂复合制备全纤维素复合材料(ACC)。考察了温度、纤维素质量分数对纤维素/[BMIM]Cl体系黏度和复合材料力学性能的影响。采用偏光热台显微镜、扫描电镜(SEM)、X射线衍射(XRD)、FT-IR对棉秆纤维的溶解及复合材料结构进行表征。结果表明:在同一温度下,纤维素/[BMIMI]Cl体系黏度随着纤维素质量分数的增加呈现剧增趋势;在同一质量分数下,其黏度随着温度的升高呈下降趋势。当温度为105℃、纤维素溶液质量分数为8%时,全纤维素复合材料的拉伸强度达到最大值,为45.23 MPa。     

多种预处理方法对纤维素结晶结构的影响

分别采用丙三醇、NaOH、乙二胺（EDA）、H₃PO₄以及离子液体[BMIM]Cl对不同来源的纤维素进行预处理，通过X射线衍射（XRD）、固体核磁共振（CP/MAS ¹³C NMR）及傅里叶变换红外光谱（FT-IR）研究了这几种预处理方法对纤维素结晶结构的影响。结果表明，16.5 wt%的NaOH及60 wt%的H₃PO₄预处理可将天然纤维素结构从I型转化为II型，EDA预处理可将天然纤维素结构转化为III型，85 wt%的H₃PO₄以及离子液体[BMIM]Cl预处理可将纤维素转化为无定形结构。[BMIM]Cl预处理比85 wt%的H₃PO₄预处理更有利于无定形纤维素的产生。结构转化过程中，纤维素的羟甲基构象相应地发生变化。结晶度方面，低质量分数NaOH预处理有利于获得低结晶度的纤维素，EDA预处理对纤维素结晶度的影响与原料结构关系较小，而NaOH与离子液体[BMIM]Cl预处理对纤维素结晶度的影响与原料有关，纤维素原料结晶度高，预处理后纤维素的结晶度也相应较高。     

离子液体法纤维素薄膜的制备及性能的研究

以离子液体1-丁基-3-甲基咪唑氯盐([BMIM]Cl)为溶剂,溶解棉浆粕得到均匀透明的纤维素溶液,采用湿法工艺制备纤维素薄膜,并研究了凝固浴浓度对纤维素薄膜微孔结构和力学性能的影响。结果表明,选用质量分数为20%的离子液体水溶液作凝固浴可得到具有一定强度的均匀透明的纤维素薄膜。     

离子液体对羊毛纤维的改性及其性能研究

为了改善羊毛的亲水性,提高羊毛的染色性能,采用[BMIM]Cl、[EMIM]Br、[BMIM]Br 3种不同的离子液体对羊毛纤维进行处理,筛选出处理效果最佳的离子液体,同时分析处理温度、离子液体质量分数和处理时间的影响。研究结果表明:用离子液体处理羊毛纤维,其表层结构遭到破坏,而且用[BMIM]Cl离子液体处理效果最好,处理的最佳工艺为:[BMIM]Cl离子液体的质量分数为30%、染色温度为70℃、处理时间为10 min。经过处理后,明显提高了羊毛的亲水性,色牢度达到要求,改善了羊毛的染色性能,还可以实现低温染色。     

离子液体纺丝溶剂[BMIM]Cl蒸馏动力学研究

离子液体[BMIM]Cl作为纤维素溶解纺丝的优良溶剂,文章通过莫尔滴定法研究了蒸馏温度和蒸馏时间对离子液体浓度的影响,并离子液体纺丝溶剂[BMIM]Cl减压蒸馏过程进行了动力学研究,结果表明离子液体减压蒸馏过程符合二级动力学模型,这为离子液体蒸发器设计提供依据.     

纤维素在咪唑基离子液体中的降解行为

为了解纤维素在咪唑类离子液体中的降解行为,用正交试验法分析了温度、转速、时间对纤维素降解程度的影响,并比较了纤维素在四种离子液体中的降解行为。结果表明,纤维素在1-乙基-3-甲基咪唑醋酸盐（[EMIM]Ac）中的最佳溶解条件为,温度80℃,时间1h,转速230r/min。温度对纤维素降解程度影响最大,其次为时间和转速。同条件下,纤维素在[EMIM]Ac中的降解最轻,在1-烯丙基-3-甲基咪唑氯盐（[AMIM]Cl）中降解最严重。没食子酸丙酯可显著缓解纤维素在离子液体中的降解程度。[EMIM]Ac、1-丁基-3-甲基咪唑醋酸盐（[BMIM]Ac）遇没食子酸丙酯显紫红色,并在纤维素溶解后颜色消失。     

蛋白质在离子液体中的溶解特性研究

合成了离子液体-1-丁基-3-甲基氯代咪唑([BMIM]Cl),以此作为溶剂,研究了3种不同蛋白质:明胶、酪素、皮胶原在其中的溶解行为及再生前后的结构与热稳定性的变化。结果表明:明胶、酪素、皮粉在[BMIM]Cl中均能溶解,在相同温度下,不同蛋白质在[BMIM]Cl中的溶解度不同,且蛋白质在[BMIM]Cl中的溶解度随温度的升高增大;所得蛋白质-[BMIM]Cl溶液的黏度随浓度的增加而逐渐增大;FT-IR、XRD、TG分析结果表明,明胶、酪素溶解前后其结构和热稳定性能都未发生明显变化,皮胶原的热稳定性能略有下降。     

离子液体预处理/硫酸水解协同制备纳米纤维素及其稳定Pickering乳液初步研究

以微晶纤维素(microcrystalline cellulose, MCC)为原料,利用离子液体预处理/硫酸水解协同制备纳米纤维素,通过Zeta电位分析、原子力显微镜(atomic force microscope, AFM)、红外光谱、X-射线衍射(X-ray diffraction, XRD)和热分析探究不同质量分数的硫酸溶液(10%～40%)对纳米纤维素结构的影响,并对其稳定Pickering乳液性能进行初步研究。结果表明,经过离子液体预处理后,随着硫酸溶液质量分数增加(10%～40%),纳米纤维素得率逐渐下降,但Zeta电位绝对值逐渐增加;AFM结果表明纳米纤维素形态从长纤丝状网络结构逐渐变为短棒状结构,其长度逐渐减小但直径增加。XRD结果表明纳米纤维素同时具有纤维素I型和Ⅱ型晶体结构,结晶度降低。MCC制备纳米纤维素过程中,经离子液体预处理后氢键结构遭到破坏,热稳定性随着硫酸溶液质量分数的增加也逐渐降低。经不同质量分数硫酸溶液水解制备的纳米纤维素在不同颗粒质量浓度(1～5 g/L)和油相比例(30%～70%,体积分数)下均能稳定Pickering乳液,但40%硫酸溶液制备的...     

Dissolution of fir powder and its graft copolymer in ionic liquid

Ionic liquid of 1-(2-hydroxylethyl)-3-ethyl imidazolium chloride ([HeEIM]Cl) was synthesized and its chemical structure was examined by FTIR and ¹HNMR. Dissolution of the fir powder which was activated with 25% NaOH under different conditions in the ionic liquid was studied. Acrylamide (AM) was grafted onto the dissolved fir powder in [HeEIM]Cl and aqueous medium, respectively. Technologic conditions for graft copolymerization were optimized by orthogonal test. The results showed that the ionic liquid exhibited good solubility for the fir powder, the dissolution rate was as high as 18.3%. The graft copolymer prepared in [HeEIM]Cl had higher grafting degree and grafting efficiency than in aqueous medium. The most suitable conditions for graft copolymerization were: mass fraction of AM 25%, fluid ratio of [HeEIM]Cl to wood 30:1, and mass proportion of wood to AM 1:4. FTIR and SEM suggested that AM had been grafted onto the fir powder. XRD and TG indicated that the crystalline structure of the wood fiber had been destroyed thoroughly after being grafted, and the thermal stability of graft copolymer had been improved.     

Degumming of Tasar silk using imidazolium-based ionic liquids

Abstract

In the present work, degumming of Tasar silk was carried out using novel reagents, the ionic liquids (ILs), 1-butyl-3-methylimidazolium chloride [BMIM]Cl and 1-butyl-3-methyl-imidazolium hydrogen sulphate [BMIM]HSO₄.The results on weight loss, tensile strength loss and absorbency were compared with soda ash-H₂O₂ method. These treatments were carried out under conventional heating, sonication and microwave irradiation as different techniques of energy input. The ILs showed higher weight loss and absorbency with negligible strength loss as compared to the soda ash-H₂O₂ method, [BMIM]Cl being the most effective with further advantage of working at nearly neutral pH. The treatments under sonication and microwave showed increasingly higher efficiency as compared to the conventional heating. The chemical structure of Tasar silk, as estimated by FTIR spectroscopy, and the crystalline structure, as elucidated by X-ray diffraction, remained unchanged. SEM images showed that the surface of Tasar silk degummed with ILs was smoother. The dye uptake was nearly the same for all degummed samples. A further advantage is accrued by recyclability of ILs, which makes the process cost effective.     

离子液中蔗渣纤维素的硫酸酯化及抑菌效果研究

从蔗渣中分离出蔗渣纤维素(BC),以离子液[BMIM]C1为反应介质对BC进行均相硫酸酯化得到蔗渣纤维素硫酸酯(BCS),采用13CNMR光谱对产物BCS进行结构表征,通过体外抑菌试验考察BCS的抗菌活性.结果表明,BCS结构中硫酸酯取代基分布随反应时间的变化而不同,硫酸酯化取代首先发生在C6位,然后在C2位、C3位;BCS对大肠杆菌和金黄色葡萄球菌均有一定的抑制作用,抑菌圈直径随BCS浓度的升高而增大.     

1-丁基-3-甲基咪唑氯盐/二甲基亚砜溶剂体系对棉的溶解及再生性能

采用1-丁基-3-甲基咪唑氯盐([BMIM]CI)/二甲基亚砜(DMSO)溶剂体系溶解脱脂棉.将溶解的纤维素溶液制成纤维素膜,测试了纤维素膜的厚度、断裂强力、透光率、接触角及水中溶胀性等性能,利用SEM、XRD及FTIR对纤维素膜的结构进行表征.结果表明:当[BMIM]CI与DMSO质量比为15:85,脱脂棉1 g,在...     

两种离子液体溶剂干湿纺纤维素纤维的力学性能及孔结构研究

以离子液体氯化1-丁基-3-甲基咪唑([BMIM]Cl)和醋酸1-乙基-3-甲基咪唑([EMIM]Ac)为溶剂,通过干喷湿法纺丝工艺成功制备了高强型、高抗原纤化型和普通型3种典型的再生纤维素纤维,采用纤度-强伸度仪、湿摩擦和小角X射线散射法对再生纤维素纤维的力学性能、孔尺寸及其取向分布进行了表征,并探讨了其成型机制。结果表明:纺丝成型时的溶剂种类、原料聚合度、原液挤出胀大、拉伸应力、取向效应等因素决定了再生纤维素纤维的聚合度和取向度,进而促进具有不同力学性能、孔径及孔取向分布再生纤维素纤维的形成。     

Weight reduction of polyester fabric using sodium hydroxide solutions with additives cetyltrimethylammonium bromide and [BMIM]Cl

Polyethylene terephthalate (PET) fibre is largely used in the textile apparel industry. Treatment of PET fibres by sodium hydroxide solution is a well-known process giving smooth surface with decrease in the fibre diameter. Hydrolytic scission of ester linkages of the polyester chains on the fibre surface takes place. Appropriate effects are achieved through monitoring of alkali concentration, time and temperature of the process without any significant deterioration of important fibre characteristics. Addition of various chemicals enhances the hydrolytic action of alkali. PET fabric was treated with aqueous as well as methanolic solutions of sodium hydroxide in the presence of additives namely, a quaternary ammonium compound, cetyltrimethylammonium bromide (CTAB) and an ionic liquid, 1-butyl-3-methylimidazolium chloride ([BMIM]Cl). The process parameters were optimized for desired level of treatment and the effect evaluated in terms of reduction in fabric weight and SEM images of the samples. Weak methanolic NaOH showed greater effect than aqueous NaOH solution. Also, the addition of [BMIM]Cl enhanced the effect better than CTAB. Results of ANOVA analysis showed that temperature played very significant role and time was of less significance for treatment using [BMIM]Cl. Both the parameters were insignificant for the conventional and CTAB treatments. Thus, the use of novel eco-friendly additive [BMIM]Cl can cause conservation in terms of time and temperature in this commercially important process.     

Nanocellulose preparation via a dissolution and regeneration process and application to wood‐plastic composites as toughness enhancement

In this work, nanocellulose (NC) was prepared by a new route consisting of dissolution of cellulose in phosphoric acid followed by regeneration in water. To facilitate the dissolution, the cellulose was pre-treated with aqueous solution of urea. Although the regenerated cellulose from water had been in nanoscale, its size could be further reduced through ball milling. The composition, structure, and morphology of the materials from different preparation stages were studied by infrared spectroscopy (FTIR), X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. NC was then incorporated into the HDPE based wood-plastic composites (WPCs) in a skillful way to guarantee its good dispersion. The influence of addition content of NC on the mechanical and thermal properties of WPCs was investigated comprehensively. WPCs incorporated with NC exhibited an obvious increase in impact strength compared with those without NC. In addition, the Rockwell hardness, Vicat softening temperature and thermal stability of WPCs incorporated with NC were also correspondingly improved. The effect of ball milling on the size of nanocellulose was also investigated. The application results showed that the NC prepared without ball milling was more efficient in enhancing the toughness of WPCs.

     

天然彩色棉纤维在1-丁基-3-甲基咪唑氯盐离子液体中的溶胀与溶解

为避免使用非生态染料和助剂对人体造成伤害,利用热台偏光显微镜研究天然彩色棉纤维在[BMIM]Cl（1-丁基-3-甲基咪唑氯盐）离子液体中的溶胀与溶解性能。比较不同预处理方式、温度和时间对纤维溶胀和溶解性能的影响。结果发现天然彩色棉纤维在[BMIM]Cl溶剂中均产生横向的不匀性溶胀继而溶解,但溶解性能存在差异。棕棉和绿棉纤维比白棉纤维更易溶解。碱处理和酶处理提高了纤维溶胀速率和溶胀尺寸,酶处理后纤维在[BMIM]Cl溶液中变为均匀溶胀。棕棉在溶解过程中色素物质分布相对稳定,绿棉纤维色素物质随纤维溶解而向外扩散。温度对棉纤维的溶胀有很大影响。随着温度升高,棉纤维的溶胀度增大,达到最大的溶胀尺寸时间缩短。