静电纺丝法制备多孔五氧化二钒纳米管

静电纺丝法制备多孔五氧化二钒纳米纤维,在经过后续的高温处理得到多孔洞的五氧化二钒纳米管结构。本文以商用五氧化二钒粉末,苯甲醇和异丙醇为原料制备氧化钒溶胶,添加聚乙烯吡咯烷酮(PVP)以增加前驱体的粘性,并以此为前驱体通过静电纺丝法制备超长五氧化二钒纳米纤维。于是我们得到静电纺丝法制备的五氧化二钒纤维,通过改变热处理的时间来实现对纤维形貌的控制。我们所添加的PVP在整个溶液中的质量分数为10%。使用扫描电子显微镜(SEM)、投射电子显微镜(TEM)以及X射线衍射仪(XRD)来表征所制备的多孔五氧化二钒纳米管的形貌和结晶度。由热重分析仪(TGA)来测试静电纺丝设备制备得到的五氧化二钒纳米纤维的热分解,并以此选择高温处理温度。静电纺丝得到的超长五氧化二钒纳米纤维的直径在400-700纳米间,长度为2-10微米。经过不同时间的高温处理后,所获得结构为不同完整程度的多孔洞五氧化二钒纳米管。     

Modeling and optimization of electrospun PAN nanofiber diameter using response surface methodology and artificial neural networks

Response surface methodology (RSM) based on a three‐level, three‐variable Box‐Benkhen design (BBD), and artificial neural network (ANN) techniques were compared for modeling the average diameter of electrospun polyacrylonitrile (PAN) nanofibers. The multilayer perceptron (MLP) neural networks were trained by the sets of input–output patterns using a scaled conjugate gradient backpropagation algorithm. The three important electrospinning factors were studied including polymer concentration (w/v%), applied voltage (kV) and the nozzle‐collector distance (cm). The predicted fiber diameters were in agreement with the experimental results in both ANN and RSM techniques. High‐regression coefficient between the variables and the response (R² = 0.998) indicates excellent evaluation of experimental data by second‐order polynomial regression model. The R² value was 0.990, which indicates that the ANN model was shows good fitting with experimental data. Moreover, the RSM model shows much lower absolute percentage error than the ANN model. Therefore, the obtained results indicate that the performance of RSM was better than ANN. The RSM model predicted the 118 nm value of the finest nanofiber diameter at conditions of 10 w/v% polymer concentration, 12 cm of nozzle‐collector distance, and 12 kV of the applied voltage. The predicted value (118 nm) showed only 2.5%, difference with experimental results in which 121 nm at the same setting were observed. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

纳米纤维微孔型聚合物隔膜的研究

采用高压静电纺织法制备了适用于锂离子电池用的多微孔聚合物隔膜。通过改变不同的纺丝电压,能够得到一系列不同直径的聚合物纤维组成的聚偏氟乙烯(PVDF)电纺微孔膜。运用扫描电子显微镜技术(SEM)观测了电压对PVDF电纺膜形态结构的影响;DSC测试结果表明电纺后材料的结晶度被削弱,有助于提高微孔膜基体对电解液的亲和性。同时,得益于纳米纤维网状结构,电纺PVDF膜显示了高孔隙率和高电解液吸附的特点,样品室温电导率均在10-3S/cm以上,能够满足实际电池的要求;组装的扣式电池也显示了良好的循环性能和倍率放电性能。