Structure and properties of regenerated cellulose films coated with polyurethane–nitrolignin graft‐IPNs coating

A regenerated cellulose film (RC) was coated with a graft‐IPNs coating, which was composed of castor oil‐based polyurethane and 2.8 wt % nitrolignin (NL), to obtain water‐resistant films. The effects of NCO/OH molar ratio and different polyols, such as 1,4‐butanediol (BDO) and trimethanol propane (TMP), on the structure and properties of the coated RC films were investigated. With an increase of the NCO/OH molar ratio, the tensile strength of the coated films increased, but the water resistivity and size contraction hardly changed. The coated films with TMP exhibited the higher breaking elongation at 1.5 of the NCO/OH molar ratio, while those with BDO have more excellent tensile strength, water resistivity, and dimensional stability. The coated films with the graft‐IPNs coating exhibited superior water resistivity and dimensional stability. The light transmittance of the coated films was more excellent than that of the RC film. Moreover, the results from the IR and electron probe microanalysis (EPMA) showed that the chemical bonding occurred between cellulose and coating, and the introduction of NL plays an important role in the enhancement of the interface adhesion of the coated films. Atomic force microscopy (AFM) depicted the flat and dense surface of the coated films, which restricted the water vapor penetration and the size contraction, resulting in the enhancement of water resistivity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1799–1806, 2002     

乙醇生产集成工艺流程的环境与经济性评价分析(英文)

乙醇是一种非常重要的可再生燃料,在本文中,从环境影响和经济效益的角度对不同的原料玉米、纤维素和乙烯生产制乙醇的工艺过程进行了评估,并利用AspenPlus模拟软件中的严格物料和能量平衡模块对典型的生产工艺进行了设计、模拟和优化。基于模拟的结果,提出了定量的环境影响方法一绿色度理论,并通过综合对比文献中报道的数据和模拟数据表明,纤维素制乙醇具有更强的环境影响优势,但在经济效益方面仍需要进一步改进。     

羧甲基纤维素阳离子化衍生物的研究现状

羧甲基纤维素阳离子化改性是制备性能优良的天然两性高分子的重要方法之一。文章综述了迄今为止羧甲基纤维素阳离子化改性所用的阳离子单体的主要类型及其接枝的若干主要途径,其中包括自由基型接枝共聚、高分子侧基反应、聚合后功能化等三大类。     

高压静电场纺丝法制备羟丙基甲基纤维素邻苯二甲酸酯超细纤维

通过高压静电场纺丝法制备了羟丙基甲基纤维素邻苯二甲酸酯(HPMCP)的超细纤维,并详细研究了溶液浓度、纺丝电压及混合溶剂的配比对纤维形态和直径的影响。当混合溶剂中的无水乙醇与二氯甲烷为1∶1(V/V)时,在纺丝电压为30kV的条件下,HPMCP可纺丝的浓度范围为7%～16%(wt)。溶液浓度为7%时,电纺得到珠状纤维;浓度大于8%时,得到表面光滑的圆柱状纤维。随着纺丝溶液浓度的增大,所得纤维的平均直径逐渐增大。在HPMCP溶液浓度(8%)和溶剂组成(无水乙醇/二氯甲烷=1∶1)保持一定时,随着纺丝电压的增大,所得纤维的平均直径呈下降的趋势。而在纺丝浓度和电压一定的情况下,随着混合溶剂中二氯甲烷体积分数的增大,所得纤维的平均直径先增大后减小,无水乙醇与二氯甲烷体积比为1∶1和1∶2时,所得纤维的直径分布相对集中。     

亚砜基改性纤维素膜的SO2气体渗透性能研究

分别使用二甲基亚砜浸泡的物理方法及苯基乙烯基亚砜加成的化学方法对纤维素膜进行了改性,并对改性膜的性能进行了测试.结果表明改性后纤维素膜仍为致密结构,SO2的渗透性能及其对N2的分离性能明显提高,其中改性液中添加二甲基亚砜的均相化学加成反应所得的改性膜具有较好的SO2渗透稳定性.     

含硫纤维素衍生物的研究进展

简述了近年来在含硫纤维素衍生物方面的研究进展。将含硫纤维素衍生物分为巯基纤维素与费原酯棉、水溶性含硫纤维素衍生物和聚硫醚纤维素三大类，对含硫纤维素衍生物的合成、应用及其与金属离子作用机理作了论述。     

Water flux,DSC, and cytotoxicity characterization of membranes of cellulose acetate produced from sugar cane bagasse,using PEG 600

Summary In this article, cellulose acetate produced through the homogeneous acetylation of sugar cane bagasse cellulose was used to produce membranes, using poly(ethyleneglycol) 600 (PEG 600) as an admixture. The membranes were characterized using water flux measurements (Payne’s cup), differential scanning calorimetry (DSC) and neutral red uptake (cytotoxicity). The results showed that PEG 600 acts as a crystallinity inductor and/or pore former in the cellulose acetate matrix. The induction of crystallinity is important for this system since it had not been reported on the literature yet. The results also demonstrated that the studied membranes present a nontoxic behavior.     

纤维素醋酸酯接枝己内酯的聚合研究

以冰醋酸为溶剂,浓硫酸为催化剂,将取代度为2 4的二醋酸纤维素水解为取代度为1 4的醋酸纤维素(CA)。以此醋酸纤维素为接枝骨架,ε 己内酯(ε CL)为接枝单体,在辛酸亚锡的引发下,合成了醋酸纤维素/聚己内酯接枝共聚物(CA g PCL)。研究了反应物纯度、原料配比、引发剂与单体摩尔比、反应时间、反应温度对单体转化率(C%)、接枝率(G%)、接枝效率(GE%)的影响。结果表明,当反应温度为140℃,单体ε 己内酯与醋酸纤维素的质量比为4∶1,引发剂辛酸亚锡与单体ε 己内酯的摩尔比为0 005,反应时间为16h,C%,GE%和G%分别为46 8%,65 2%和122 1%。     

尿素嵌入法制备纤维素氨基甲酸酯的研究

探讨了尿素嵌入法制备纤维素氨基甲酸酯(CC)的生产工艺。指出:选用聚合度为450~625、α-纤维素含量大于90/的纤维素浆粕,用14/~16/的氢氧化钠溶液,于40~50℃条件下活化处理30~40min后,与尿素以1∶2~3的比例混合,在137℃的二甲苯体系中反应2~3h,便可得到含氮量为2.4/~3.5/的纤维素氨基甲酸酯产物。该产物在氢氧化钠溶液中可形成良好的稳定溶液,过滤性好,可直接用于纺丝。     

Degradation of cellulosic and hemicellulosic substrates using a chelator‐mediated Fenton reaction

The involvement of catechol and hydroxamate chelators, along with hydrogen peroxide and Fe³⁺, in the degradation of cellulosic and hemicellulosic substrates was examined with the purpose of improving our current knowledge of the non‐enzymatic mechanisms involved in wood biodegradation by fungi. It could be demonstrated that a catechol chelator‐mediated Fenton reaction not only clearly degraded hemicellulosic substrates but also significantly accelerated and increased the effectiveness of degradation reactions. On the other hand, when a hydroxamate chelator‐mediated Fenton reaction was used, an inhibitory effect was observed. When cellulosic substrates underwent a chelator‐mediated Fenton reaction, no significant difference in degradation was observed between catechol and hydroxamate chelator‐mediated reactions. However, a catechol‐mediated reaction did accelerate the degradation of cellulosic substrates at the beginning of reactions. In addition, it was observed that with a chelator‐mediated Fenton reaction, oxidation of cellulose proceeds depolymerization. Copyright © 2005 Society of Chemical Industry