二氧化碳-环氧丙烷共聚物电纺纤维形貌研究

利用电纺丝技术制备了二氧化碳环氧丙烷共聚物超细纤维,研究了喷丝口电势、纺丝距离、浓度、溶剂等因素对纤维形貌、直径及均一性的影响.实验结果表明,利用电纺丝法可以制备直径在小于200nm到7μm二氧化碳环氧丙烷共聚物纤维;喷丝口电势和浓度对于共聚物电纺丝纤维是否形成串珠结构有重要影响;电势、距离和纺丝液浓度都对纤维直径及分散系数有较大影响,在一定范围内,随着喷丝口电势增加,纤维平均直径变大而分散系数变小;纺丝距离增大使得纤维平均直径变小,分散系数变大;浓度的增大使得纤维平均直径变大,分散系数变小;不同溶剂配制的溶液体系制备的电纺丝纤维形貌有很大差异,在二氯甲烷和丁酮的体系中,分别观察到了两组较为集中的直径分布.     

聚丙烯腈纳米纤维的再细化

通过电纺丝法研究了溶剂种类、溶液浓度、纺丝倾斜角、聚合物分子量对纳米纤维形态和直径的影响,寻找到最佳工艺条件,并得到了平均直径为20nm的超细纤维.     

磁场辅助静电纺有序聚丙烯腈纳米纤维的研究

磁场辅助静电纺丝方法能够制备有序纳米纤维,但是其参数之间的匹配关系很少被研究。本文通过正交实验,对影响磁场辅助静电纺丝制备聚丙烯腈纳米纤维的四个工艺参数(溶液浓度、磁铁间距、纺丝电压和注射速度)在3个水平上进行优化筛选。以纤维直径大小、均匀度和纤维有序度为考察目标,同时考虑溶液浓度、磁铁间距与纺丝电压这三个因素之间的两两交互作用,结合极差分析、方差分析,发现溶液浓度是影响纤维直径和均匀度的高度显著因素,溶液浓度和纺丝电压的交互作用对直径均匀度有显著影响,纺丝电压是影响纤维有序度的显著因素。     

再生丝素蛋白水溶液的干法纺丝

以高浓度再生丝素蛋白水溶液为纺丝液,采用自制毛细管纺丝装置制备了再生丝素蛋白纤维.探讨了丝素蛋白分子量、pH、金属离子及纺丝工艺参数对溶液可纺性及纤维力学性能的影响.结果表明:当pH为5.2～6.0时,纺丝液表现出良好的可纺性,尤其以pH=6.0、Ca2+浓度为0.3 mol/L的纺丝液可纺性最佳.在最佳纺丝条件下(纺丝管长径比为133;卷绕速率为30mm/s)制得的纤维力学强度最高约为45.5 MPa.     

静电纺丝法制备聚醚酰亚胺纤维膜的结构和介电性能研究

采用静电纺丝法制备了聚醚酰亚胺(PEI)纤维膜,通过扫描电子显微镜(SEM)和偏振红外对PEI纤维膜的微观结构进行研究.实验结果显示纺丝液溶剂决定了PEI的可纺性,以N-甲基吡咯烷酮(NMP)为溶剂时,空气湿度显著地影响纺丝过程以及纤维的形态.在相同纺丝工艺条件下,随着纺丝液浓度的增加,所得PEI取向纤维沿辊筒收集方向的排列规整性提高,纤维平均直径由405 nm增加到3.25 μm.PEI纤维膜介电性能的研究表明,取向纤维膜的介电常数很小,最低可达到1.1,其介电损耗也维持在较低的水平,纤维膜的接收方式以及热牵伸处理会对PEI纤维膜的介电性能产生影响.     

静电纺丝法制备聚甲醛纳米纤维

以六氟异丙醇为溶剂, 用静电纺丝的方法制备了聚甲醛纳米纤维. 利用场发射扫描电镜对纤维形貌进行了表征, 纤维的直径为0.3~1.2 μm. 讨论了溶液浓度、接收距离、电压和温度等纺丝参数对纤维形貌的影响. 用DSC方法对电纺纤维膜的结晶性能进行了研究, 并与溶液浇铸膜的进行了比较. 结果表明, 电纺纤维膜的熔点与溶液浇铸膜的相同, 与溶液的浓度无关, 但结晶度比溶液浇铸膜的低. 力学性能用拉伸试验进行了测试, 观察到很长的断裂伸长率.     

壳聚糖修饰纳米纤维膜表面对氧化还原酶行为的影响

采用静电纺丝法制备了丙烯腈/丙烯酸共聚物(PANCAA)纳米纤维膜, 研究了纺丝液浓度对纤维形态的影响, 以扫描电子显微镜观察纤维形貌, 遴选得到最佳纺丝条件. 以1-乙基-3-(N,N-二甲基氨基丙基)碳二亚胺/N-羟基丁二酰亚胺(EDC/NHS)为偶联剂, 在纤维膜表面引入壳聚糖修饰层, 采用衰减全反射傅里叶变换红外光谱(ATR/FTTIR)、水接触角和称重法考察了修饰前后膜的变化. 通过戊二醛将过氧化氢酶固定到壳聚糖修饰的PANCAA纳米纤维膜上, 研究了壳聚糖及戊二醛浓度对固定化过氧化氢酶的影响, 结果表明, 在壳聚糖浓度为25 mg/mL及戊二醛质量分数为5%条件下, 壳聚糖修饰膜的固定化酶活性比空白膜提高了41.7%, 稳定性也得到了不同程度的提高.     

聚苯撑苯并二噻唑的纺丝工艺研究

对聚苯撑苯并二噻唑（PBZT）的纺丝采用了“干喷湿纺”新技术，连续纺出了高强度、高模量的PBZT纤维。研究了PBZT的溶液浓度、PZT分子量、纺丝时空气层高度、纺丝温度和拉伸比对所纺出PBZT纤维力学性能的影响，找到了最佳纺丝工艺条件。     

PHBV电纺纤维结构与形态的研究

利用电纺丝法制备了超细聚 β 羟基丁酸戊酸酯 (PHBV)纤维 ,通过扫描显微镜 (SEM)、差热分析(DSC)、宽角X射线衍射和偏振红外吸收光谱对产品进行了结构与形态的表征 .研究了纺丝过程中溶液浓度、电压和接收距离 3个参数对纤维形态的影响 .结果表明 ,溶液浓度是决定性的 ,只有高于一个定值才能获得单一的纤维产品 .与流延成型的PHBV相比 ,电纺丝具有较高的取向度和结晶度 .原因可能是 ,电场力下喷丝震荡过程中带来的拉伸作用从而引起分子链的规整排列     

静电纺丝法制备超细聚苯乙烯纳米纤维

采用静电纺丝方法制备了超细聚苯乙烯纤维, 通过向溶液中添加有机胺盐并降低溶液浓度将纤维的平均直径降至100 nm, 并研究了盐的添加量对纤维直径的影响.     

聚乳酸蜂窝状多孔膜的形成与控制

以单一组分聚L-乳酸(PLLA)为成膜材料,利用水辅助法制备了聚乳酸(PLLA)蜂窝状多孔膜.利用扫描电镜(SEM)和原子力显微镜(AFM)观察多孔膜形貌.研究溶剂、溶液浓度、环境温度和湿度等因素对所成多孔膜结构的影响.实验结果表明,高湿度环境和具有一定浓度的聚合物溶液是制备蜂窝状多孔膜的必要条件.溶剂的挥发性是形成规整蜂窝状孔结构的关键因素.环境相对湿度由43%增加到91%,PLLA多孔膜的孔径由(1.75±0.24)μm增加到(11.50±1.43)μm,且孔呈现六边形的蜂窝状结构.扫描电镜断面和AFM表明:膜表面形成了深度约为1.8μm的单层孔结构.通过控制溶液浓度、环境温度和湿度等因素来控制膜的表面形貌及其所成蜂窝状孔的大小.最佳的成膜条件为溶剂CH2Cl2,湿度75%RH,温度34℃,浓度3 wt%.讨论了蜂窝状多孔膜的形成机理.     

漆酚醛胺聚合物多孔膜的制备

以漆酚醛胺聚合物(UFDP)为成膜材料,利用水辅助自组装的固体基板展开法和水面展开法制备了漆酚醛胺聚合物多孔膜.研究了在静态(即不在聚合物表面吹扫氮气)高湿度环境下聚合物溶液浓度、环境湿度和固体基板等因素对多孔膜形貌的影响.结果表明,水面展开法更有利于形成单层的多孔膜而固体基板展开法得到的是多层的多孔膜.当UFDP聚合物浓度为6.0 mg/mL,环境相对湿度为90%时,用水面展开法制得的单层多孔膜的孔径分布较均匀.     

具有不同层间距、比表面和孔径大小的氧化硅柱层状铌酸的制备

层柱金属氧化物是近年来被开发的新型无机多孔材料［１～６］．水合铌酸是一类独特的固体酸催化剂,通常是非孔性的,且经较高温度热处理后比表面和酸性均很小,从而限制了其在催化领域中的应用［７］．我们［３］曾报道了氧化硅柱层状铌酸的制备,本文则通过进一步改变制备过程中所用氨基丙基三乙氧基硅烷（ＡＰＳ）溶液的浓度、反应温度和时间,获得了一系列具有不同层间距、比表面和孔径的氧化硅柱层状铌酸．１　实验部分ＨＮｂ３Ｏ８·Ｈ２Ｏ的制备见文献［８］．将１ｇＨＮｂ３Ｏ８·Ｈ２Ｏ加入７０ｍＬ不同浓度的ＡＰＳ水溶液中,所得…     

Membrane formation by water vapor induced phase inversion

The membrane formation by the phase inversion process was studied by coagulating a polysulfone/N-methyl-2-pyrrolidone solution with water vapor as a coagulant. The phase separation occurred when the relative humidity in the membrane casting atmosphere was higher than about 65%. The pore size was strongly affected by the relative humidity as well as the concentration of the polymer solution. It increased as both the relative humidity and the polymer concentration were decreased. The membranes produced showed a uniform structure composed of closed pores. The pure water flux measurement confirmed the closeness of the pores. The information on the late stage phase separation was obtained in situ by an optical microscope due to the slow phase separation. The pores seemed to grow very much at the late stage by coarsening which was observed to occur mainly by coalescence of polymer-lean droplets. As the relative humidity was lower, the coarsening continues longer ending up to a larger droplet size. The coarsening seems to enhance the interconnectivity of pores when the polymer concentration was low enough.     

水热提质对褐煤理化结构及复吸水特性的影响

选取云南昭通褐煤进行了水热提质处理,依托傅里叶变换红外光谱技术和氮气等温吸附模型分析研究了不同提质温度(150-300℃)下煤样表面含氧官能团和孔隙结构的演化行为,考察了复吸水特性的变化规律。结果表明,随着提质温度的不断升高,主要亲水性含氧官能团(-OH、-COOH、C=O)不断减少;煤样的孔隙结构发生显著改变,比表面积和总孔容积先增后减,在250-300℃水热条件下有焦油产生;受理化结构协同影响的复吸水特性得到了有效遏制,复吸水率随着提质温度的升高不断下降;对提质褐煤进行储存时,环境湿度是影响褐煤复吸水的关键因素,高温水热、低温低湿度储存更能提高褐煤的提质效果。     

无氧下低浓度硫化氢在浸渍活性炭上的吸附研究

为了考察常温、无氧下浸渍Na2CO3改性、原料气相对湿度对活性炭吸附硫化氢的促进作用，用动态吸附法分别测试了不同湿度下原活性炭和浸渍活性炭对低浓度硫化氢的吸附，同时考察了温度对该吸附过程的影响。结果表明，吸附平衡数据均符合Freundlich吸附等温方程。与原活性炭相比，浸渍活性炭的孔容和比表面积略有降低，但对硫化氢的吸附能力却显著提高，说明硫化氢与浸渍剂在活性炭表面上发生了化学反应。相对湿度增加，活性炭和浸渍活性炭对H2S的吸附能力均显著增强。温度升高，平衡吸附量均略有下降。     

Porous polymer films and honeycomb structures based on amphiphilic dendronized block copolymers

Fabrication of honeycomb patterned films from our synthesized amphiphilic dendronized block copolymer by "on-solid surface spreading" method and "on-water spreading" method was reported for the first time in this paper. The comparison of the two methods indicated honeycomb-patterned films with smaller size, and larger surface density of micropores can be fabricated by spreading on water but with lower regular arrangement. Furthermore, several influencing factors on the formation of the honeycomb structure and the different morphologies, such as the concentration of the copolymer solution and the relative humidity in the atmosphere and the substrates, were investigated. The results showed that comparably high relative humidity from 80% to 95% was needed, and the mica plate as a spreading substrate was suitable to form orderly porous films for such a copolymer. The best ordered pattern could be formed from the copolymer with concentration of 1.00 mg/mL at the relative humidity of 85% using a mica plate. Besides, strong periodicity, regularity, and a large, defect-free area were notable, which made this structure extremely interesting for applications for templated molecular objects formed via intramolecular metal or metal oxide synthesis.     

Kinetics of Degradation of Biapenem

The kinetic and thermodynamic analysis of biapenem degradation was conducted during acid–base hydrolysis, under the influence of buffer components and in the solid state at increased temperature (dry air) and relative air humidity (RH > 50%). The effects of the initial concentration of biapenem and the formation of degradation products on its stability were investigated.     

Functionalization of cotton with poly-NiPAAm/chitosan microgel. Part I. Stimuli-responsive moisture management properties

Stimuli-responsive microgel, based on synthetic polymer (poly-NiPAAm) and biopolymer (chitosan), was incorporated onto cotton fabric surface by pad-dry-cure method using 1,2,3,4-butanetetracarboxylic acid (BTCA) as crosslinker. In order to assess the moisture management properties of cotton functionalized with responsive microgel, the effects of temperature, relative humidity and concentration of microgel on water vapour transmission rate (WVTR) and moisture content (MC) were quantified. Since the use of experimental design is considered as a highly attractive feature in dealing with experiments and variables of this nature, the effects were quantified by using a central composite design. The regression equations obtained from the statistical analysis allowed the prediction of WVTR and MC at different ambient conditions. Material properties such as crease recovery and whiteness were also measured. The results indicate that both relative humidity and temperature significantly influence studied responses (WVTR and MC), showing that good perspiration can be achieved at lower humidity levels and at higher temperatures. The observed phenomena are attributed to controlled expansion (or contraction) of the surface incorporated microgel, which acts as a sensor of temperature and as a valve to regulate the water vapour permeability of functionalized cotton.     

Formation of microcrystals, micropuddles, and other spatial inhomogenieties in surface reactions under ambient conditions: an atomic force microscopy study of water and nitric acid adsorption on MgO(100) and CaCO3(104)

In this study, atomic force microscopy (AFM) is used to image freshly cleaved MgO(100) and CaCO3(104) as these surfaces undergo reaction with water and nitric acid under ambient conditions of temperature, pressure, and relative humidity. The reaction of water and nitric acid results in the formation of hydroxylated and nitrated surfaces, respectively. It is clear from the AFM images that there are spatial inhomogenieties and surface features that form on micrometer and nanometer length scales as these reactions proceed. These features, which include hillocks, patches, microcrystallites, and micropuddles, are due to surface and phase segregation as a result of facile ion mobility in the presence of adsorbed water. In addition, instabilities and oscillations in the AFM images provide an indication of liquid formation and the deliquescence (i.e., a solid to liquid-phase transition) of nitrate salts as a function of relative humidity.