聚砚基纤维素填充复合超滤膜材料的研究

以聚砜为原材料,通过向铸膜液中混入纤维素微纳晶体,采用浸没沉淀相转化工艺制备了纤维素填充聚砜基复合超滤膜材料。测定了超滤膜的水通量、截留率、平均孔径、孔隙率等性能,通过单因素影响试验分析了各个工艺因素对产品性能的影响;考察了膜的化学稳定性以及运行压力对性能的影响;通过扫描电镜观察了膜孔的结构;并通过浊点滴定实验得到膜液的三元相图,分析了纤维素的加入对成膜过程的影响。     

黏胶纤维酶水解反应工艺研究

将黏胶纤维水解成糖类物质,是利用废弃黏胶纤维制备燃料乙醇的关键步骤.采用正交试验的方法,对纤维素酶催化黏胶纤维水解反应中的主要因素的影响进行了综合研究.结果表明,影响因素的显著性大小依次为:催化剂用量、固-液比、温度、pH值.对反应时间、温度、催化剂用量等影响因素进行的详细研究结果表明,酶的用量适当,反应温度选择在纤维素酶的适用温度上限,反应时间约为2 h是比较适宜的反应条件,黏胶纤维水解率约达87%.     

废棉布制备高粘度羧甲基纤维素

为纺织废料的再利用,本文以废棉布为原料制备高粘度羧甲基纤维,采用碱醚同釜法及正交实验,通过测试粘度得到最佳反应条件为:浴比为1∶3,氢氧化钠质量分数为30%,氯乙酸乙醇质量分数为30%,醚化时间为2 h,碱化时间为2 h,碱化温度为35~40℃,醚化初期温度为40~45℃,后期温度为70℃,羧甲基纤维素的的粘度值为932.6mPa.s。     

原花青素/醋酸纤维素可降解包装薄膜的结构与抗氧化性能

将原花青素(PC)添加到醋酸纤维素(CA)制膜溶液中,制得具有抗氧化性的可降解包装薄膜。通过红外光谱、X射线衍射和原子力显微镜对薄膜表面形貌、膜结构和结晶情况进行表征。以新鲜猪油为内装物、采用油脂氧化稳定性的检测方法Schaal烤箱法,测试薄膜在不同PC添加量时的抗氧化性。结果表明:当添加质量分数为2%PC时,薄膜的抗氧化性最佳,其对油脂的抑制率达到了37.65%,可在常温下延长油脂保质期两个多月。     

以离子液体为溶剂制备纤维素微球

将天然纤维素溶于离子液体中,制成纤维素/离子液体溶液,并以纤维素/离子液体溶液为原料采用悬浮聚合法制备了纤维素微球.讨论了纤维素种类和质量分数、纤维素/离子液体溶液与导热油体积比、搅拌速度和制备温度对纤维素微球粒径分布的影响.结果表明,质量分数为2％的棉纤维素/离子液体溶液,以导热油为分散相,V(纤维素/离子液体溶液)...     

碱处理棉纤维结构及其在LiCi/DMAc中的溶解特性

采用NaOH溶液对棉纤维进行处理.通过X射线衍射研究了不同碱处理条件下棉纤维的晶面结构变化,表征了棉纤维的结晶度和晶粒尺寸.考察了碱处理棉纤维在LiCl/DMAc中的溶解性和溶解稳定性.结果表明碱处理后,棉纤维的晶面结构明显变化,棉纤维衍射峰发生明显的变化,结晶度和晶粒尺寸也有变化,且随碱的质量分数的变化非常明显,而处...     

酵母多基因表达载体在纤维素生物转化中应用

构建含酿酒酵母组成型强启动子PGK、G418抗性基因及rDNA片段的整合型载体pScIKP,利用rDNA多个同源重组位点,将外源基因以多拷贝整合到酵母染色体上,无需诱导即可持续表达;利用载体位于表达盒两端同尾酶,可插入多个基因表达盒,实现多基因稳定共表达.为检验共表达情况,反转录从绿色木霉中获得纤维素酶基因eg3和cbh2, 克隆并转化获得重组酵母菌株S.cerevisiae-ec. 该重组酵母能降解羧甲基纤维素形成水解圈;用羧甲基纤维素还原糖法和滤纸酶活力法测定酶活力,其最适温度和最适pH值与所表达单酶相似,表明共表达未影响两种酶的生物学特性;且双酶具有协同作用,能更有效降解非结晶纤维素.pScIKP载体能成功用于多个外源基因共表达和产物协同作用的研究,为构建能直接降解纤维素的酿酒酵母菌株,实现纤维素可再生能源的生物利用奠定了基础.     

Study on volume ratio and plasticizer screening of free coating membranes composed of ethyl cellulose and chitosan

The aim of this study was to optimize the formula of free blended coating membrane of ethyl cellulose (EC) and chitosan (CS), including their suitable ratio range and the best plasticizer used. The dry films were produced by a casting/solvent evaporation method, with different volume ratio of EC and CS solution plasticized by various plasticizers, respectively. The wet films were prepared by immersing dry films in pH 6.8 phosphate buffer saline (PBS) for 24 h. The promising ratio range of EC/CS was below 20/5 or 20/6 with various plasticizer, which was determined by comparing the viscosity of the blended solutions and the morphology of the blended films. The efficiency of plasticization was evaluated by measuring glass transition temperature (T_g). All the testing plasticizers have good compatibility with EC or CS and dibutyl phthalate (DBP) have the strongest efficiency inducing the lowest T_g (39.9°C) of the film. Mechanical properties were evaluated by the ratio of tensile strength (T) to elastic modulus (E). In the wet state, the films with DBP had the highest T/E value (1.2). The results of leaching of plasticizers also verified that DBP was the most stable plasticizer in the films. The release rates of tetramethylpyrazine phosphate (TMPP) through the pellets coated with the blended films of EC/CS (20 : 6 v/v) plasticized by various plasticizers showed that the more water‐soluble the plasticizer was, the more quickly TMPP dissolved from the coated pellets, which further indicated that the water‐insoluble plasticizers (such as DBP) could be more applicable to keep the sustained or controlled release property of the blended films in wet state. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1932–1939, 2006     

Study of the influence of reaction conditions on the degree of substitution,intrinsic viscosity,and yield of oxidized cellulose acetate by factorial experimental design

A half‐fraction, two‐level, four‐factor factorial experimental design was used to study the effects of the acetic anhydride concentration, reaction temperature, reaction time, and sulfuric acid concentration on the degree of substitution, intrinsic viscosity, and yield of oxidized cellulose acetate (OCA). Oxidized cellulose containing 20% (w/w) carboxylic acid was used as the starting material. The data were fitted by multiple regression analysis with SAS software. The correlation coefficients obtained from plots of the predicted and observed values for the degree of substitution, intrinsic viscosity, and yield were 0.985, 0.993, and 0.991, respectively. Residual normal plots of the regression models showed a linear relationship. Lenth and main‐factor‐effect plots revealed an increase in the degree of substitution of OCA with an increasing concentration of acetic anhydride. The latter had no effect on the intrinsic viscosity and yield of OCA. An increase in the reaction temperature led to an increase in the degree of substitution and a decrease in the intrinsic viscosity and yield of OCA. The influence of the reaction time on the degree of substitution and intrinsic viscosity followed a trend similar to that observed with the reaction temperature, but the yield of OCA was unaffected. Increasing the concentration of sulfuric acid reduced the degree of substitution, intrinsic viscosity, and yield of OCA. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 696–705, 2005     

聚合度对纤维素表面性能的影响

根据Washburn浸渍理论和van Oss-Good-Chaudhury组合理论及应用柱状灯芯技术测试了具有不同聚合度(DP)的纤维素的表面性能,同时与已报道的纤维素的表面能进行了比较。结果表明:纤维素的表面能随分子量的增加而增大,但主要是其Lifshitz-van der Waals力在起主导作用。研究还发现纤维素的表面能γS与聚合度DP之间的关系大致可以描述为:γS=37.56+0.02 DP,而纤维素的极性率P与聚合度DP之间的关系则是一种非线性关系,如:P=11.88-0.02 DP+9.10 DP2。