Determination of the Viscosity in Cadoxen Solvent of Cellulosic Materials Dyed with Reactive Dyes

A modified cadoxen solvent was used to determine the viscosity of reactive-dyed cellulosic materials. The conditions for completely dissolving cellulosic materials dyed with different types of reactive dyes were standardised. Reactive-dyed cotton materials showedno anomalous viscosity behaviour in the cadoxen solvent. With viscose rayon samples dyed with bifunctional reactive dyes, higher viscosity values were observed when measurements were carried out immediately after dissolution. However, on storing the solutions for a further 24 h, the viscosity values became independent of the type or the amount of dye andwere identical with those of undyed rayon. Thus, measurements of the viscosity of reactive-dyed materials can be conveniently carried out in cadoxen solvent.     

Estimation of Dye Content of Dyed Wool

Different types of wool fibres dissolved satisfactorily in cadoxen solvent, but the solutions were coloured owing to the formation of cadmium sulphide and complexes of cadmium with the decomposition products of wool. Zincoxen solvent, however, gave stable colourless solutions, although the time required for dissolution was longer. Estimation of dyeings with most direct, acid, metal-complex acid and reactive dyes could be conveniently and accurately carried out by measurement of the absorbance of solutions in cadoxen. For certain yellow and orange dyeings, however, it would be advisable to use zincoxen solvent.     

Studies in swelling of cotton. I. Neutral salt technique to determine the true swelling parameters in cadoxen

This paper describes the swelling of cotton fiber in cadoxen containing 4.6% cadmium (w/w) and 30% ethylenediamine (w/w). A special neutral salt technique is described involving the analysis of extract as well as mother liquor which enables the determination of mechanically held liquor and hence the values of true absorption. The percentage true weight swelling values are much lower than the percentage apparent weight swelling as measured by centrifuge technique. The effect of variation in material-to-liquor ratio on the true absorption of cadmium and ethylenediamine is also investigated.     

The effect of crosslinking on the swelling of cotton in solutions of sodium hydroxide and cadoxen

This paper describes the effects of prior crosslinking in dimethylol ethyleneurea (DMEU) on the swelling of cotton fiber in aqueous solutions of sodium hydroxide and in cadoxen solutions (solutions of cadmium oxide in mixtures of ethylenediamine and water). The degree of swelling in the weaker swelling solutions is markedly reduced by the crosslinking, but in the stronger solutions (particularly in concentrated sodium hydroxide) the effect of prior crosslinking is only small; this is accounted for in terms of a fibril-tearing mechanism in these stronger solutions. Crosslinking cotton reduces the mercerizing effect of strong alkali solutions (i.e., the disordering and the cellulose I → II lattice change), and also reduces the solubility of the fiber in solutions of cadoxen and cuprammonium hydroxide.     

The swelling of cotton in cadoxen,ethylenediamine, and cuprammonium hydroxide

This paper describes the swelling of cotton fiber in solutions of cadoxen, ethylenediamine, and cuprammonium hydroxide. The absorption of swelling agent and the increase in width of the fiber were measured. The degree of swelling in cadoxen solutions, in relation to the composition of these solutions, is complex; very high degrees of swelling can be attained. The effects of these swelling treatments on the fine structure of cotton, as measured by the infrared-deuteration method, density, acid hydrolysis, and an acetylation technique, are described and discussed in relation to the swelling behavior.     

Flow birefringence and viscosity of cellulose solutions in semi-dilute regime

An attempt was made to study the flow birefringence and the viscosity of the systems of cellulose in aqueous sodium hydroxide and cadoxen solutions. For this purpose alkali-soluble cellulose samples with crystal form I (simply denoted as cellulose I sample), prepared from conifer wood pulp by the steam-explosion method, and alkali-soluble cellulose samples with crystal form of cellulose II (cellulose II sample), regenerated from cuprammonium cellulose solution under specific conditions, were used. The extinction angle χ of aqueous alkali solutions of the cellulose I sample is significantly less shear rate (γ) dependent as compared with that of the cellulose II sample. In the latter system the χ versus γ relations for a given cellulose sample shifted to the higher γ side with decrease in the average molecular weight. The viscosity of the cellulose II sample in aqueous sodium hydroxide solutions is approximately twice that of the cellulose I sample in the same solvent if compared at the same molecular weight, same concentration, and same temperature. The latter solution showed a non-Newtonian property at relatively smaller γ than the former solution did. Spin-lattice relaxation time T₁ (by ¹³C-NMR) of cellulose in cadoxen solution was smaller in cellulose I, suggesting the existence of intra- and intermolecular hydrogen bondings at the C₆ position of cellulose molecules in cellulose I solution. A dynamic light scattering study on cellulose in cadoxen showed that in a 5 wt % solution of cellulose I cellulose particles are dispersed with time into smaller particles and the larger particles could be excluded by ultracentrifuge and in cellulose II solutions the cellulose particles had almost the same size during storage. The above findings indicate that in 5 wt% cellulose I solutions in aqueous alkali or in cadoxen, cellulose I is not dissolved molecularly, but a supra-molecular structure of the solid is at least partly reserved in the above solutions.     

Investigations in modified alkaline iron-tartrate complex solvent for cellulose

A simple method of preparing a stable alkaline iron-tartrate complex solvent (FeTNa (NaCl)) solvent starting from anhydrous ferric chloride was developed. The solvent having the composition: 300 g/l complex, 2N free alkali and 37.5 g/l sodium tartrate as stabiliser, dissolves cotton samples of a high degree of polymerization under higher ambient temperature conditions like those in India. In contrast to solutions in other solvents, cellulose solutions in FeTNa (NaCl) solvents are practically non-sensitive to air exposure. Intrinsic viscosity values were determined for a large number of cellulosic samples. The influence of the viscosity gradient on several viscosity functions was found to be of the same order as in other FeTNa solvents of similar compositions. Fractional precipitation of cellulose dissolved in this solvent was investigated by adding different quantities of aqueous solutions of mannitol.     

Characterization of nonderivatized cellulose by gel permeation chromatography

The development of a gel permeation chromatography (GPC) system for the analysis of nonderivatized cellulose in the DP range of technical cellulose products is reported. In contrast to traditional GPC, where cellulose derivatives have to be prepared, in this work the cellulose solvent cadoxen was applied for the determination of the molecular weight distribution using a special analysis system. Nuclear magnetic resonance studies of cadoxen solutions indicated no complex formation between cadoxen and cellulose. Therefore, to avoid precipitation of cellulose from the prepared solution, cadoxen was also used as eluent in the chromatographic system. For this reason a stationary phase had to be found which is stable under the given strong alkaline conditions. The utilization of Fractogel TSK as column material resulted in the separation of dissolved cellulose showing a DP_v between 400 and 2000 with good reproducibility. The application of very sensitive detectors together with a GPC program allows the characterization of unknown cellulose samples of different origin within a few hours.     

Adsorption behavior of heavy metal ions on cellulose graft copolymers

The adsorption behavior of cadmium, copper and lead ions on holocellulosic materials containing various levels of polyacrylonitrile and poly(acrylic acid) grafts was examined. The amount of metal ions adsorbed per gram of the modified cellulosic substrate depended on the metal ion type, the nature and level of the incorporated graft polymer. In all cases grafting increased the metal ion-binding capacity of the cellulosic materials (by up to 50% for Cu (II) ions). The influence of temperature and initial metal ions concentration on the sorption behavior of the metal ions on the composite materials was investigated.     

新型无卤阻燃剂乙二胺双磷酸二苯酯的合成

报道了一种新型无卤双磷酸酯阻燃剂乙二胺双磷酸二苯酯(ENDP),其分子结构中含有膨胀型阻燃剂的酸源和气源,具有磷氮协效作用,阻燃效率高且兼具增塑功能。其合成采用氯化磷酸二苯酯(DPCP)和乙二胺为原料,以4-(N,N-二甲基)氨基吡啶(DMAP)为催化剂,以三乙胺为缚酸剂,并考察了溶剂、反应温度、反应时间和催化剂用量对ENDP产品收率的影响。得到的最佳反应条件为:以四氢呋喃(THF)为溶剂,反应温度45℃,反应时间8 h,催化剂DMAP与DPCP的质量比为3%,反应收率可达88.0%。产品结构经红外图谱(FT-IR)、核磁氢谱(1H NMR)和质谱(MS)等进行了确证;热分析表明,产品具有很高的热稳定性,其初始热分解温度为265℃,最大热分解温度为365℃,并在450℃以上时仍有20%的质量残余。     

碘促进合成杂环醌类化合物

采用分子碘促进合成杂环醌类化合物,首先以二氯萘醌和乙二胺反应得到杂环醌类化合物,研究了工艺条件对反应的影响。结果表明,二氯萘醌、乙二胺、碘和NaOH的摩尔比为1:1.2:1.1:1,溶剂为氯仿时收率大于80%,目标产物结构经核磁共振仪确认。虽然二氯萘醌和1,6-己二胺反应时并没有得到预期的产物,但是该方法具有操作方法简单,大大缩减操作步骤,反应条件温和,收率较高等优点。     

New approach to aqueous gel permeation chromatography of nonderivatized cellulose

A novel approach to the gel permeation chromatography (GPC) of nonderivatized cellulose is reported using Sepharose CL-6B as the column packing material, 0.5N NaOH as the eluent, and cadoxen as the cellulose solvent. The traditional approach to GPC of cellulose has been to convert the cellulose to its nitrate thereby making it soluble in the solvent tetrahydrofuran. The circumvention of the need to derivatize the cellulose in the new system results in considerable saving of time. The new system gives good fractionation for cellulose. It also provides excellent separation of polystyrene sulfonate and dextran standards thereby making the system amenable to calibration. The effect of the particle size distribution of the column packing material on the efficiency of separation is discussed. Potential applications for this new method include studies on both acidic and enzymatic hydrolysis as well as fine structure of cellulose, starch, and other polymers capable of forming stable alkaline solutions.     

Fine structural changes in native and mercerized fibrous cellulose brought about by ethylenediamine and methyl alcohol

X-Ray diffraction (XRD) studies were made on native as well as mercerized ramie and cotton fibers after swelling them in ethylenediamine (EDA) solutions and washing out the swelling agent using methyl alcohol (MeOH). These treatments are shown to convert the cellulose I and II lattices into cellulose III_I and III_II type lattices, respectively. Treatment of the III_I and III_II samples in boiling water or hydrochloric acid results in reconversions of their crystal lattices into the respective parent types. Alkali treatment causes a III → II type conversion. Studies using alkali-swollen fibers as well as fibers of different lateral order as starting materials indicate the importance of the structural organization in the cellulosic materials in the production of the cellulose III lattices. Possible mechanisms involved in the lattice transformations in cellulose brought about by the EDA and MeOH treatments are discussed.     

Solvent Extraction Studies of Zinc and Cadmium with Aliquat 336-S in Aqueous Chloride Solutions

Abstract

New solvent extraction systems have been developed for the extraction of zinc and cadmium from aqueous chloride solution using Aliquat 336-S dissolved in the nonpolar solvents heavy aromatic naphtha and xylene as the extractant. Moderately high concentrations of the metalions (1 mg/ml zinc and 2 mg/ml Cd) can be extracted quantitatively from acid solutions with an equal volume of 5% Aliquat 336-S solution in 15 sec. Both zinc and cadmium can be stripped from the organic phase with a series of aqueous stripping solutions. When comparing zinc and cadmium, cadmium is the easier to extract and the more difficult to strip under the same experimental conditions.     

N-乙基乙二胺的合成研究

以乙二胺和氯乙烷为起始原料,甲醇为溶剂,甲醇钠为缚酸剂,合成N-乙基乙二胺,通过精馏分离得到高纯度目标产物并回收甲醇和过量的乙二胺。实验优化了反应条件:乙二胺∶氯乙烷摩尔比=1.5∶1,反应温度40℃,反应时间4h,产品收率达到70.7%。通过气质联用(GC-MS)对目标产物N-乙基乙二胺进行了定性确认。     

Spectroscopic investigation of hydrocellulose phenylosazones in cadoxen solution

Solutions of hydrocellulose phenylosazone in cadoxen are stable when oxygen is excluded. In the presence of oxygen, the absorption spectrum changes, but the change is partially reversible when nitrogen is bubbled through the oxidized solution. It is probable that a hydroperoxide of the hydrocellulose phenylosazone is formed initially and is then decomposed by the basic solvent. The work indicates the importance of using deoxygenated solvents and working in an oxygen-free atmosphere when preparing cadoxen solutions of hydrocellulose phenylosazone.     

Preparation and characterization of transparent cellulose films using an improved cellulose dissolution process

Effective dissolution of cellulosic macromolecules is the first predominant step to prepare functional bio‐based materials with desirable properties. In this study, we developed an improved dissolution process using a freeze‐drying pretreatment to promote the dissolution of cellulose. Rheological measurements of cellulose solutions and physicochemical characterization of regenerated cellulose films (scanning electron microscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, and thermogravimetric analysis) were performed. Cellulose solution prepared from 5% microcrystalline cellulose (w:v) in the solvent exhibits a Newtonian fluid character while cellulose solutions at higher concentrations show a pseudo‐plastic fluid behavior. Results from physicochemical characterization indicate that a freeze‐drying pretreatment step of cellulose leads to a complete dissolution at 5% concentration while only part of cellulose is dissolved at 10% and 15% concentrations. The results obtained indicated that the use of a freeze‐drying pretreatment step under mild conditions lead to a complete dissolution of cellulose at 5% concentration. The cellulose films prepared from 5% concentration exhibited desirable properties such as good optical transparency, crystallinity, and thermal stability. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44871.     

Evidence for cholesteric morphology in films of cellulose acetate butyrate by transmission electron microscopy

Summary Transmission electron microscopy provides direct evidence of helicoidal cholesteric morphology in films of cellulose acetate butyrate prepared by solvent casting from liquid crystalline solutions in dimethylacetamide. We believe this is the first observation reported of cholesteric structure in a mixed cellulosic ester. Cholesteric morphology was also observed in solvent cast blended films of cellulose acetate butyrate and lignin from liquid crystalline solutions. There are indications that lignin particles may be serving as nucleating surfaces or sites of direct termination for some of the observed cholesteric fingerprint pattern.     

胺端基型超支化乙二胺三嗪聚合物对PLA/PPC的增韧改性研究

以乙二胺和三聚氯氰作为原料,以丙酮为溶剂,通过“一步法”合成了胺端基型的超支化乙二胺三嗪聚合物(HBETP)。以HBETP作为改性剂,采用双螺杆挤出机熔融共混和注射成型法制备了聚乳酸(PLA)/聚碳酸亚丙酯(PPC)共混物,并用差示扫描量热仪(DSC)、 热失重分析仪(TGA)、电子万能试验机、扫描电字显微镜(SEM)等测试手段对共混物的热性能、力学性能以及断面形貌等进行表征与测试。结果表明,与PLA/PPC共混物相比,当HBETP含量为0.6份时,PLA/PPC/HBETP共混体系在保持拉伸强度基本不变的基础上,断裂伸长率和冲击强度分别提高了266.0 %和122.9 %;HBETP是一种增韧PLA/PPC共混物的有效助剂。     

Graft copolymerisation of vinyl monomers on modified cottons. VII. Grafting by chain transfer

Grafting of methyl methacrylate on cellulosic materials by chain transfer under the catalytic influence of azobisisobutyronitrile (AIBN) was extensively studied. The graft yield is influenced by reaction time, temperature, monomer and initiator concentration, reaction medium and nature of the substrate. In general, the grafting reaction shows an induction period after which the polymerisation proceeds rapidly. The graft yield increases and the induction period decreases by rising the reaction temperature from 50 to 70°C. This is also the case when the monomer concentration was increased from 2 to 6%. Increasing the AIBN concentration up to 0.01 M causes a significant enhancement in grafting while further increase brings about a marked fall in the graft yield. Among the reaction media studied, a water/solvent mixture containing 25% of either methanol, ethanol, propanol, butanol or acetone seems to constitute a reaction medium where the monomer and initiator are completely miscible and the swelling of cellulose by water is not hindered by the presence of these solvents. Increasing the solvent ratio in the water/solvent mixture causes a considerable decrease in the graft yield. The polymer content of the cellulosic materials, i. e. the graft yield, follows the order: partially carboxymethylated cotton > cotton treated with 12N sodium hydroxide > cyanoethylated cotton > cotton treated with 0.5 N sodium hydroxide > purified cotton. In addition, proof of grafting was provided by the fractional precipitation method.