液晶显示屏用三醋酸纤维素的合成及性能

采用高温酯化、低温水解方法,制备了用于液晶显示屏的三醋酸纤维素(CTA)。采用IR、化学滴定等手段对产物的结构进行了表征,并对膜的透光率以及力学性能等进行了测试。结果表明,自制的CTA结合醋酸含量达到60%以上,透光率高达95%以上,双折射值极低,力学性能良好,基本符合液晶显示屏起偏振片保护膜的使用要求。     

均相与非均相法制备醋酸纤维素的性质比较

以DMAc/LiCl为溶剂在均相体系中不加任何催化剂合成了醋酸纤维素(CA),运用化学滴定、1H-NMR、X射线衍射、DSC等手段对均相与非均相合成产物的结构及性质进行了对比.结果表明,在总取代度相同条件下,均相法制备的CA中乙酰基在葡萄糖环上C-2,C-3,C-6的分布更均匀;与纤维素相比,非均相法制备的CA结晶度降低为40%,而均相法制备的CA完全变为无定型态;均相法制备的CA的Tg比非均相法有明显下降;均相法制备CA溶液的透光率比非均相法制备CA的高.     

三醋酸纤维素中空纤维纳滤膜的研制

采用三醋酸纤维素 (CTA)为膜材料 ,环丁砜作溶剂 ,以聚乙二醇 (PEG)为主、加入适量其它添加剂组合成多元型致孔剂 ,通过冻胶法纺丝 ,制得中空纤维纳滤 (NF)膜 .该膜在给水质量浓度 2 0 0 0mg/L、操作压力 1.0MPa、水温 2 5℃条件下 ,对MgSO4 、NaCl的脱除率分别大于 96%和小于 5 0 % ,透水量均大于 2 .5mL/ (cm2 ·h) .还讨论了纺丝配方、热处理温度和操作条件等因素对膜性能的影响     

三醋酸纤维素正渗透膜用于大豆低聚糖浓缩的研究

<正>渗透(FO)过程是近些年发展起来的一种新型渗透驱动膜分离过程,它具有低能耗、高分离、低膜污染、常温常压下运行等优点,使其在诸多领域,特别在浓缩领域中有着很好的应用前景.通过相转化法制备三醋酸纤维素(CTA)正渗透膜,采用此正渗透膜对大豆低聚糖进行了浓缩,并研究了浓缩过程中膜的污染及清洗.结果表明,所制备CTA正渗透膜以去离子水为原料液,0.1mol/L NaCl为汲取液时的水通量为13.6L/(m2·h),对NaCl的截留率为94%~99%.在用于浓缩大豆低聚糖的过程中,累计浓缩150min,膜水通量由12.0L/(m2·h)降低到5.9L/(m2·h),总可溶物从1.0°Brix上升到8.0°Brix.在浓缩过程中正渗透膜表现出污染轻,易清洗等优点.     

铂粒子修饰的聚苯胺/醋酸纤维素复合膜电极对甲醛的催化氧化

采用循环伏安法在酸性溶液中成功的制备出聚苯胺(PANI)/醋酸纤维素(CA)复合膜,原子力显微镜显示:复合膜具有不对称的微孔结构,正面是不规则微孔结构的聚苯胺层,反面是海绵状的醋酸纤维素层.用电沉积法将铂沉积到PANI/CA复合膜上,研究发现Pt修饰的PANI/CA复合膜电极对甲醛有较高的催化活性和稳定性.     

醋纤基载药纳米纤维药物活性评价

采用静电纺丝制备了载药量均为20%的单层结构醋酸纤维素(CA)纳米纤维膜、多层结构醋酸纤维素/聚乳酸(CA/PLA)纳米纤维膜,药物选用具有抗凝血药理作用的姜黄素(CM)、阿司匹林(AS)。以复钙化凝血时间、溶血、动态凝血、血小板粘附实验对醋纤基载药纳米纤维复合体系的抗凝血药物活性进行了评价。结果表明,载药膜复钙化时间延长大于27s,溶血率均小于5%,内源性凝血因子被激活程度低,醋纤基载药纳米纤维复合体系的抗凝血性良好,纯CA纳米纤维膜的血液相容性得到了显著改善,药物在经过高压静电纺丝后,仍保留药物活性。     

以纳米Al2O3为添加剂CA/PAN共混超滤膜的制备

以纳米Al2O3为添加荆,采用相转化法制备了醋酸纤维素/聚丙烯腈(CA/PAN)共混超滤膜.采用扫描电镜(SEM)及透射电镜(TEM)观察不同条件下制备的CA/PAN共混超滤膜的表面、截面及内部的微观结构.结果表明,纳米Al2O3可有效的控制大孔的形成,不同的凝固浴温度时膜的表面及截面结构有很大影响.     

高性能醋酸纤维素正渗透膜的制备

以醋酸纤维素(CA)为正渗透膜成膜材料,以亲水性聚醚砜膜作为支撑材料,利用相转化法制备正渗透膜,考察了正渗透膜制备过程中的影响因素,包括铸膜液中聚合物的浓度、热处理温度、热处理时间及涂膜次数对正渗透膜性能(膜通量和截盐率)的影响。结果表明,当聚合物质量分数为3.57%,热处理温度为60℃,热处理时间为20min,涂膜次数为1次时,所制备的正渗透膜的膜通量为14.8L/(m2·h),截盐率在99.97%以上。     

添加剂对醋酸纤维素膜结构和性能的影响

以纳米二氧化钛为添加剂,N,N-二甲基甲酰胺(DMF)和N-甲基-2-吡咯烷酮(NMP)为溶剂,通过相转化法制备了醋酸纤维素(CA)/纳米Ti O2复合超滤膜。用扫描电镜SEM观察了制备的CA及CA/Ti O2复合超滤膜的表面结构,讨论了纳米Ti O2的加入对膜的孔隙率、水通量、截留率的影响,结果表明:在一定溶剂比例下,随着纳米Ti O2的加入使膜的孔隙率增加并且抗菌性增强。     

聚丙烯腈/醋酸纤维素共混超滤膜的研制与改性

研究了聚丙烯腈 /二醋酸纤维素 (PAN/CA)共混超滤膜的性能与聚合物共混比、聚合物质量分数等的关系 .结果表明 ,加有氯化锂 (LiCl)的二甲基乙酰胺 (DMAC)是PAN/CA共混体系的良溶剂 .当聚合物的质量分数为 14 % ,PAN/CA共混比为 5 0 / 5 0时 ,所制得的共混超滤膜的性能较好 .对共混超滤膜进行水解改性的实验发现 :膜的截留率上升 ,水通量下降 .用酱油、药酒为料液的超滤实验表明 :共混膜和水解改性膜的耐污染性能优于聚丙烯腈 (PAN)、聚砜 (PS)和磺化聚砜 (SPS)膜     

Controlled release of drugs from cellulose acetate matrices produced from sugarcane bagasse: monitoring by square-wave voltammetry

In this paper, cellulose triacetate (CTA) was produced from sugarcane bagasse and used as matrices for controlled release of paracetamol. Symmetric and asymmetric membranes were obtained by formulations of CTA/dichloromethane/drug and CTA/dichloromethane/water/drug, respectively, and they were characterized by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Different morphologies of membranes were observed by SEM, and the incorporation of paracetamol was confirmed by lowering of the glass transition temperature (T_g) in the DSC curves. This indicates the existence of interactions between the matrix and the drug. The evaluation of drug release was based on the electrochemical monitoring of paracetamol through its oxidation at a glassy carbon electrode surface using square-wave voltammetry (SWV), which provides fast, precise and accurate in situ measurements. The studies showed a content release of 27% and 45% by the symmetric and asymmetric membranes, respectively, during 8?h.     

Biopolymer-based nanocomposites: effect of lignin acetylation in cellulose triacetate films

We have prepared all-biopolymer nanocomposite films using lignin as a filler and cellulose triacetate (CTA) as a polymer matrix, and characterized them by several analytical methods. Three types of lignin were tested: organosolv, hydrolytic and kraft, with or without acetylation. They were used in the form of nanoparticles incorporated at 1 wt% in CTA. Self-supported films were prepared by vapor-induced phase separation at controlled temperature (35–55 °C) and relative humidity (10–70%). The efficiency of acetylation of each type of lignin was studied and discussed, as well as its effects on film structure, homogeneity and mechanical properties. The obtained results are explained in terms of intermolecular filler-matrix interaction at the nanometer scale, for which the highest mechanical resistance was reached using hydrolytic lignin in the nanocomposite.     

Biopolymer-based nanocomposites: effect of lignin acetylation in cellulose triacetate films

Abstract

We have prepared all-biopolymer nanocomposite films using lignin as a filler and cellulose triacetate (CTA) as a polymer matrix, and characterized them by several analytical methods. Three types of lignin were tested: organosolv, hydrolytic and kraft, with or without acetylation. They were used in the form of nanoparticles incorporated at 1 wt% in CTA. Self-supported films were prepared by vapor-induced phase separation at controlled temperature (35–55 °C) and relative humidity (10–70%). The efficiency of acetylation of each type of lignin was studied and discussed, as well as its effects on film structure, homogeneity and mechanical properties. The obtained results are explained in terms of intermolecular filler-matrix interaction at the nanometer scale, for which the highest mechanical resistance was reached using hydrolytic lignin in the nanocomposite.     

霉菌对银盐黑白胶片影响的实验研究

本文通过实验研究了霉菌对醋酸片基和聚酯片基银盐黑白胶片的危害及其程度 ,表明在适宜霉菌生长的温湿度环境下 ,霉菌对胶片的危害远远大于“醋酸综合症”等自然衰变 ,是除自然灾害和人为破坏之外对银盐黑白胶片档案安全的最大威胁 ,应予以高度的重视。     

Ultrafine porous fibers electrospun from cellulose triacetate

Ultrafine porous cellulose triacetate (CTA) fibers were prepared by electrospinning with methylene chloride (MC) and a mixed solvent of MC/ethanol (EtOH) and their intra- and inter-fiber pore structures was investigated. Ultrafine porous CTA fibers electrospun with MC had isolated circular shape pores with a narrow size distribution in the range of 50–100 nm. In the case of ultrafine CTA fibers electrospun with MC/EtOH (90 / 10 v/v), they had interconnected larger pores in the range of 200–500 nm. These porous structures were induced by phase separation resulting from the rapid evaporation of solvent during the electrospinning process. However, non-porous corrugated fibers were obtained from MC/EtOH (85 / 15 v/v) and MC/EtOH (80 / 20 v/v) due to their lower vapor pressure. The pore sizes in ultrafine CTA fibers electrospun with MC showed a bimodal distribution centered at ∼17 and ∼64 nm. CTA fibers electrospun with MC/EtOH (90 / 10 v/v) showed the greatest porosity due to their larger intra-fiber pores and fiber diameter.     

关于电影影片档案保存的技术问题

电影影片档案是一个国家极为珍贵的档案，主要分为两类，第一类是电影原始素材，即电影原底片和中间片，第二类是电影拷贝片，为电影标准拷贝片。我国电影原始素材资料档案库位于西安，而电影拷贝档案库则建在北京。本全面探讨了电影资料档案保存方面的一些重要技术问题，如：电影影片档案保存环境的国际标准，易燃易爆的硝酸纤维片基胶片的保存，三醋酸纤维片基在影片保存期间的醋酸综合症问题．外借的电影档案影片保存环境不佳和长期不还所造成的损害问题等等。     

长链纤维素酯在DMAc／LiCl中的均相制备及表征

采用75%乙二胺水溶液对纤维素进行预处理后,以DMAc/LiCl为溶剂,高级脂肪酸为酯化剂,对甲苯磺酰氯为共反应剂在均相状态下合成了纤维素棕榈酸酯和硬脂酸酯。运用红外光谱1、H-NMR、X射线衍射、DSC等手段对产品的结构及性质进行表征,研究了反应时间和反应温度对产物取代度的影响。结果表明,纤维素棕榈酸酯的取代度随反应时间延长和反应温度升高而增大。与纤维素相比,纤维素棕榈酸酯的结晶度下降,而玻璃化转变温度也远低于醋酸纤维素和醋酸丁酸纤维素。纤维素棕榈酸酯和硬脂酸酯分子结构中取代基支链起到了内增塑作用,可改善材料的加工工艺性。     

Plasticization of cellulose esters used in the coating of sustained release solid dosage forms

Plasticizer/polymer interactions have been studied by measuring intrinsic viscosity of six cellulose esters in a series of dialkyl phthalates and glyceryl triacetate. Mechanical properties (tensile strength and modulus of elasticity) of cast films were also measured. In general, high values for the reciprocal of modulus of elasticity and low tensile strength correlated with high intrinsic viscosity values. Among the plasticizers tested, dimethyl phthalate and glyceryl triacetate were most efficient.     

Plasticization of cellulose esters used in the coating of sustained release solid dosage forms

Abstract

Plasticizer/polymer interactions have been studied by measuring intrinsic viscosity of six cellulose esters in a series of dialkyl phthalates and glyceryl triacetate. Mechanical properties (tensile strength and modulus of elasticity) of cast films were also measured. In general, high values for the reciprocal of modulus of elasticity and low tensile strength correlated with high intrinsic viscosity values. Among the plasticizers tested, dimethyl phthalate and glyceryl triacetate were most efficient.