The chelate molecule, ethylenediamine, was incorporated onto the surface of ramie fiber via sequential reactions of the hydroxyl groups on ramie fiber with epichlorohydrin followed by the chelating agent. The performance of the modified material (CelNH) was characterized by Fourier transform infrared spectroscopy (FI-IR), X-ray diffraction (XRD), scanning electron micrographs (SEM), thermogravimetry analysis (TGA), UV–Vis, and elemental analysis. Results show that the excellent characteristics of the raw fiber were still remained after modification although the crystallinity of the modified fiber decreased. The modification parameters were optimized as the concentration of ethylenediamine of 0.75 mol/l, the temperature of 50 C, and the reaction time of 5 h. Meanwhile, the dye of C.I. reactive red 2 was used to study the dyeability of the raw and the modified fibers. The color strength and the dye uptake of the modified fiber increased obviously with an increase in the nitrogen contents in CelNH. The color strength and the dye uptake of the modified fiber can be controlled by changing the extent of surface modification of raw ramie fiber.

The typical polymerization process in supercritical fluids (SCFs) was improved through modifying the reaction system and designing and using sampling tubes. The efficacy of the newly developed procedure was demonstrated by the free radical homopolymerization of 2,2,2-trifluoroethyl methacrylate (TFEMA) and coplymerization of TFEMA and N-vinylpyrrolidone (NVP) in supercritical carbon dioxide (scCO2). Results indicate that the newly developed procedure has the characteristics of minimum loss of reactants and polymerization starting at the desired temperature and pressure. Furthermore, the polymerization process can be well tracked by analyzing the reaction mixtures online sampled from the reactor at certain reaction times by FT-IR, 1H NMR, and GPC. The reaction time and the product properties can be optimized based on the tracking results. For the first time, block copolymers by free radical polymerization in scCO2 was successfully synthesized by sequential addition of TFEMA and methyl methacrylate (MMA) into the reactor at different reaction stages. The synthesized polymers were characterized by FT-IR, 1H NMR, 13C NMR, GPC, TGA, and DSC, respectively. It was proved that the losing of monomer, pollution to the environment, and distribution of the molecular weight of the synthesized polymers decreased while the yield of product, the reproducibility, and the controllability of polymerization increased after improvement of the polymerization process.

Dyeing of ramie fiber with C.I. disperse red 74 (DR74) at the temperatures from 343.15 to 403.15 K and under the pressures of 12-20 MPa has been thoroughly investigated using supercritical carbon dioxide (scCO2)as a solvent. Ramie fiber was first treated with alkali and then with benzoyl chloride to improve the affinity and interaction between disperse dye and ramie fiber. The morphological and structure transformations in fiber induced by pretreatment were determined by a Fourier transform infrared spectrometer (FT-IR),X-ray diffraction (XRD),scanning electro-microscopy (SEM),differential scanning calorimetry(DSC),and thermogravimetry analysis (TGA).The modification of ramie fiber with benzoyl chloride was characterized by a degree of substitution (DS).The damage to ramie fiber caused by pretreatment and scCO2 dyeing was determined by stress-strain measurements. The color strength of the fiber was evaluated by K/S measurements. The dyeing effects have been studied by means of time, pressure,temperature,and concentration of dye.

The multi-walled carbon nanotubes (MWCNTs) having different outer diameters but similar inner diameters were loaded with 3.0 wt.% Pt via the reduction of H2PtCl6 by formaldehyde in the solution of ethanol and water. For both the MWCNT supports and catalysts, the BET surface areas and pore size distributions determined by N2 adsorption and desorption were varied significantly although type II adsorption isotherms with closed hysteresis loops were observed. The 3.0 wt.% Pt/MWCNT catalysts were investigated for the selective hydrogenation of cinnamaldehyde (CALD) in a batch reactor under the conditions of 80 8C and 2.0 MPa of hydrogen. All the catalysts showed reasonably high catalytic activity but significantly different product selectivities. The highly selective hydrogenation of C C bonds into hydrocinnamaldehyde (88% selectivity at 100% conversion) occurred over Pt-supported MWCNT4 with the biggest outer diameters (>50 nm). In the case of the other three catalysts, however, C O bonds were selectively hydrogenated showing about 60–80% selectivities to cinnamyl alcohol (CA) depending on the catalysts and CALD conversions. Irrespective of the catalysts, the results of X-ray diffraction and highresolution transmission electron microscopy indicated that the metallic Pt particles with an average size of about 11 nm were overwhelmingly deposited on the outer surface of the MWCNTs. The binding energies of Pt and the surface atomic ratios of oxygen to carbon determined by X-ray photoelectron spectroscopy were slightly varied for different catalysts. Based on these characterization results together with the hydrogenation results of CA, the different selective behaviors of the Pt/MWCNTs catalysts were discussed. Besides other factors, the electronic effects induced by the significantly varied tube diameters of the MWCNTs played the major role in determining the selective behaviors of different catalysts.

近年来,超临界二氧化碳(sc-CO2 ) 在聚合反应中的应用受到了越来越多的关注。本文主要综述了以sc-CO2 为反应介质的自由基聚合、阳离子聚合、过渡金属催化聚合、热致开环聚合、溶胶2凝胶聚合以及氧化耦合聚合的研究概况。一系列研究结果表明sc-CO2 是非常有前途的反应溶剂,在高分子合成领域将会有更加广阔的应用前景

A series of AOT (aerosol-OT) analogue surfactants (sodium salt of dibutyl-2-sulfosuccinate, sodium salt of dipentyl-2-sulfosuccinate, sodium salt of dihexyl-2-sulfosuccinate, and sodium salt of dioctyl-2-sulfosuccinate) were synthesized and characterized by 1H NMR and elemental analysis. A static method coupled with gravimetric analysis is developed to measure the solubility of the surfactants in 1,1,1,2-tetrafluoroethane (HFC-134a) and supercritical CO2 (scCO2). The solubilities of the surfactants in HFC-134a and scCO2 are affected by the temperature, pressure, and carbon atom number of the surfactant. The solubility of the same surfactant in HFC-134a solvent is approximately two times that in the most commonly used supercritical solvent CO2. The pressuretemperature phase diagrams for water/HFC-134a microemulsions stabilized by the surfactants were determined using cloud-point measurements for a concentration range of the surfactant from (1.85 _ 10-3 to 5.60 _ 10-3) M, temperature up to 338 K, and pressure up to 40 MPa in a high-pressure vessel. At a fixed temperature, the cloud-point pressure increased with increasing water-to-surfactant molar ratio (Wo). At a fixed Wo, the cloudpoint pressure decreased with increasing temperature. The surfactant with the longest hydrocarbon chain has the highest cloud-point pressure even at lower surfactant concentrations.

zing cellulose acetate particles from ramie fiber was developed. The optimum conditions for preparing cellulose acetate (CA) by reaction of ramie fiber with acetic anhydride under an acidic condition were determined. Reaction was carried out in a ratio of ramie fiber to acetic anhydride of 1:6 (w/w) at 80 _C for 0.5–1 h. When CA was added to a mixture of water and acetone, CA particles with a well-distributed diameter ranging from 5 to 15 lm were obtained. The difference of the CA particle surface was resulting from different washing methods of CA particles with water or aqueous sodium bicarbonate. The highest degree of substitution (DS) of 2.50 for CA by titration method was achieved. A new adsorbent was prepared from CA, which is an excellent sorption regent for organic waste in water. The scanning electron microscopy (SEM) and particle size distribution results showed that the average size of CA particles is about 5–15 lm in diameter. The thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to determine the stability of ramie fiber and CA particle. 2006 Elsevier B.V. All rights reserved.

The catalytic synthesis of methyl acrylate by hydroesteri cation of acetylene with methyl formate was studied under various conditions. Mixtures of nickel acetate tetrahydrate, copper sulfate pentahydrate and sodium iodide dihydrate were used as catalysts, and N,N-dimethylformamide as solvent. The experimental results concerning the effects of the reaction condition on selectivity to methyl acrylate, methanol and methyl propionate suggested the synthesis of methyl acrylate through the carbonylation reaction of acetylene. When the reaction was carried out under the total initial pressure of 6.0 Mpa and the CO initial partial pressure of 3.0 MPa at the temperature of 1808C with the catalyst composition of 0.040 M Ni(OAc)2_4H2O and 0.054 M NaI_2H2O, 86% selectivity to methyl acrylate and 64% conversion of methyl formate were achieved. # 1998 Elsevier Science B.V. All rights reserved.

The surface hydrophobicity/hydrophilicity of ramie fiber was regulated through the atom transfer radical polymerization of methyl methacrylate from initiators immobilized on the fiber. The optimal reaction conditions for preparing the macroinitiated ramie fiber were determined to be a temperature of 608C and a reaction time of 24 h. The grafted copolymers were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive analysis of X-rays, gel permeation chromatography, and thermogravimetric analysis. The results indicate that poly (methyl methacrylate) was covalently bonded onto the surface of the ramie fiber, and the polymerization of methyl methacrylate was a living/controlled process under the investigated conditions. The results of the contact angle measurements indicate that the wettability of the ramie fiber could be widely regulated by control of the grafted ratios of poly(methyl methacrylate) from 26 to 33 wt %.

The effects of pretreatment conditions, including the addition of a phase-transfer catalyst, on the benzylation of ramie fiber were investigated in this study. Raw and benzylated ramie fibers were dyed in supercritical carbon dioxide, and the color strength (K/S) of the ramie fiber was measured by ultraviolet–visible spectroscopy. An obviously improved dyeing capability of the benzylated ramie fiber, that is, a better level-dyeing property and a higher K/S, was achieved. Moreover, the color strength of the ramie fiber, indexed as the value of K/S, increased significantly with the degree of substitution of the benzylated ramie fiber. The raw and modified ramie fibers were characterized with Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry.