共查询到16条相似文献,搜索用时 93 毫秒
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高取代度羟乙基纤维素可利用异丙醇溶液进行精制,根据高取代度HEC中灰分及其在异丙醇中的溶解速度和溶解度不同,通过实验确定了最佳的精制工艺条件:洗涤次数为2次,每次洗涤时间为20min,洗涤液用量为每克HEC需10mL异丙醇溶液,每次洗涤时洗涤液的用量均相同。本实验还设计了产品及废洗涤液中异丙醇回收的实验装置,具有很好的工业参考价值。 相似文献
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探讨多种无机和有机添加剂的分子量、用量、溶剂用量及蒸发时间,确立了氰乙基纤维素/三醋酸纤维素共混膜的制膜参数。实验表明,共混膜的渗透选择性、耐酸、耐碱和耐微生物分解性能优于单一膜材料。 相似文献
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先以NaOH/H2O2水溶液对蔗渣进行预处理,再用预冷至-12℃的7%NaOH/12%尿素水溶液对预处理蔗渣进行分离,获得结构蓬松的蔗渣再生纤维素。以蔗渣再生纤维素为原料,以氯乙酸钠为醚化剂,在85%乙醇水溶液中,采用一次碱化、二次醚化的工艺,制备了羧基取代度达1.45的羧甲基纤维素钠(CMC)。利用红外光谱(FTIR)、扫描电镜(SEM)、X-射线衍射(XRD)、热重分析(TGA)等手段对样品的结构进行了表征,并研究了羧甲基纤维素钠样品的黏度性能。 相似文献
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The high performance liquid chromatography method (HPLC) with ethyl cellulose/cellulose acetate (EC/CA) blends and EC as column packing material, and small molecular weight compound as probe molecules was employed to measure the retention volume (VR) and equilibrium distribution coefficient (K) of both inorganic and organic solutes. The interfacial separation properties of EC/CA blends were characterized by the HPLC data. The effects of the blends on the interfacial adsorption properties, hydrophilicity, affinity, polar and non-polar parameters of EC membrane materials were studied subsequently. The research results indicate that the interfacial adsorption properties and hydrophilicity of EC have been improved by solution blending with CA. The alloys are superior to EC in the separation efficiency for non-dissociable polar organic solute. The EC/CA alloy (80:20, w) is suitable for desalting and desaccharifying. 相似文献
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The effect of physical ageing on the electrical properties, such as thermally stimulated discharge currents (TSDC) and conduction currents, of ethyl cellulose (EC) has been analysed. The TSDC thermograms of EC samples, poled with 100kVcm-1 at different poling temperatures (i.e. 50, 70 and 90°C) consist of two peaks located at 70±5°C and 110±5°C, respectively. The conductivity measurements were made over a time period of 101–103min in the temperature range 30–125°C with a poling field of 100kVcm-1. It has been observed that physical ageing considerably affects the magnitude of the thermally stimulated depolarization and conduction currents of EC films. This ageing effect, which has been attributed to continuous vitrification of a polymer, is considered to enhance the life-time of a polymer electret. © of SCI. 相似文献
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在过氧化氢和亚铁离子组成的氧化还原体系中加入第三组分二氧化硫脲(TD),将单体甲基丙烯酸乙酯(EMA)接枝于纤维素纤维上。探讨了单体EMA用量、过氧化氢用量、TD用量、反应温度、反应时间、去离子水用量等因素对接枝率、接枝效率的影响。结果显示纤维素接枝EMA的最佳工艺条件为:纤维8 g,EMA 6 g,过氧化氢0.02 g,TD 0.5 g,去离子水150 mL,反应温度50℃,反应时间1 h。红外光谱、扫描电镜分析均表明EMA接枝到了纤维素结构上。 相似文献
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采用纤维素与过量的氯乙烷及氢氧化钠反应 ,以甲苯为稀释剂 ,用一步法成功地合成了乙基纤维素。通过元素分析、红外光谱和核磁共振氢谱对产物的分子结构进行表征 ,确定所合成的化合物即为目标产物。该法所得乙基纤维素产品的乙氧基含量为 4 3 98%。 相似文献
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以乙基纤维素(EC)为载体材料,萘普生为包埋药物,采用O/W型乳化-溶剂挥发法制备了包封率较高的EC/萘普生复合载药微球,利用正交试验优化制备工艺,得出当EC与萘普生的质量比为3:1,EC用量2.5%,聚乙烯醇用量0.8%,吐温-80用量0.4%时是复合微球的最佳制备工艺,在该工艺条件下药物包封率达到88.97%。通过扫描电子显微镜(SEM)、激光粒度分析、傅里叶变换红外光谱(FT-IR)对复合微球的形态和结构进行了分析表征。SEM显示复合微球的形态顺滑,激光粒度分析表明复合微球平均粒径为14.014μm,复合微球的FT-IR谱图中既有EC的特征峰,又有萘普生的特征峰,但没有新基团产生,表明EC包覆萘普生过程中未产生新化合物。体外释放实验表明复合微球的累积释药率随溶出介质pH值的增大而增大,在溶出介质pH值为9时,复合微球的累积释药率最大,达到82.5%,缓释性能较好。 相似文献