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 %.

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.

在35～55 ℃、7～15 MPa条件下,利用果胶粗酶液和木聚糖酶液,对苎麻韧皮进行超临界CO2 处理及其脱胶试验,考察了超临界CO2 处理苎麻韧皮前后酶液中的活菌数、酶活和脱胶效果。实验结果表明,经超临界CO2 处理1 h左右,苎麻脱胶菌的致死率在99 %以上;不同类型非纤维素降解酶,在超临界条件下的稳定性不同,木聚糖酶比较稳定,酶活仅降低1.6 % ,而果胶粗酶液的稳定性较差,酶活降低23.79 %；超临界CO2 介质有利于加速苎麻酶的脱胶催化反应进程,使苎麻脱胶效果提高60 %～100 %。

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.

对亚麻快速生物脱胶和温水沤麻过程中的果胶酶、木聚糖酶、纤维素酶、微生物、pH 值和还原糖等进行了动态变化研究。结果表明,2 种脱胶过程中果胶酶和木聚糖酶的变化趋势基本相似,酶活性脱胶前期均增加缓慢,中后期迅速增加;纤维素酶活性的变化趋势有明显的区别,快速生物脱胶的纤维素酶酶活性增加幅度小,酶活性低(0105 IUPmL左右) ,温水沤麻的纤维素酶在发酵72 h后迅速增加,脱胶完成后酶活性达0. 337 9 IUPmL ;微生物的变化趋势基本相似,在脱胶前期迅速增加、脱胶完成时开始下降;pH值和还原糖量的变化趋势分别呈“U”型和“M”型。