低引燃倾向卷烟的研究进展

低引燃倾向卷烟作为一种安全型卷烟,能有效降低卷烟引起火灾的风险。本文介绍了卷烟的引燃倾向,对低引燃倾向卷烟制备技术的研究进展、卷烟纸特性及涂布方式进行了综述,并提出研究中存在的一些问题。     

生物柴油的制备及发展趋势

生物柴油是一种对环境友好可再生燃料,对解决日益枯竭石油资源和由石化柴油燃烧而带来环境问题有重要意义。本文简要介绍了生物柴油的发展现状、定义、特点及其原料,主要论述了生物柴油的制备方法,并且指出了生物柴油的发展趋势。     

磁控溅射制备Cu1-xCoxO复合氧化物的催化析氧

采用直流反应磁控溅射法制备了Cu1-xCoxO(0.02≤x≤0.14)复合氧化物电极。利用XRD、EDS和SEM分析技术对沉积氧化物的晶体结构、化学组成及表面形貌进行了表征,并利用循环伏安、线性扫描及电化学交流阻抗对沉积氧化物电极的电化学性能进行了测试。XRD分析结果显示复合氧化物Cu1-xCoxO具有CuO单斜晶体结构,不存在氧化钴独立相。电化学测试结果表明Cu1-xCoxO复合氧化物电极对水氧化反应的催化活性远高于CuO和Co3O4电极,更好的催化活性、较低的电阻和高的表面粗糙度是Cu1-xCoxO复合氧化物电极催化活性提高的主要原因。生成最优Cu1-xCoxO(0.02≤x≤0.14)复合氧化物的溅射功率为45W(Co)、100W(Cu)。     

Crystallization kinetics of cis‐1,4‐polybutadiene

The isothermal and nonisothermal crystallization kinetics of cis‐1,4‐polybutadiene has been investigated with respect to the content of cis units and the linearity of the main chain. The rate of spherulite growth increases with chain regularity as the presence of branches as well as segments with different configurations slows the crystallization rate. The major parameter that determines the crystallization rate is the presence in the formulation of heterogeneities that favor the formation of primary nuclei and determine an anticipated onset of crystallization. As the activity of the heterogeneous nuclei depends more on the type and number of foreign particle than on any chain parameter, no straightforward information on the influence of the chain structure on the crystallization rate can be derived by mere calorimetric analysis, at least for analyzed samples. It is only with combined analysis by optical microscopy that comprehensive information on the crystallization kinetics of cis‐1,4‐polybutadiene can be derived. The results reported in this contribution point out the importance, in polymer science, of preferring complementary instrumentation and not limiting experimental investigations to a single technique of analysis. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

On polyethylene chain generation through chemical crosslinking of isotactic polypropylene

Crosslinked isotactic polypropylene (iPP) was prepared by reactive blending using dicumyl peroxide and active sulfur. The modified material was characterized by means of several techniques: dynamic mechanical thermal analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy, and nuclear magnetic resonance (¹³C solid state NMR). Analysis of results using the above techniques confirms that, during the crosslinking process, new ethylenic chains are generated at expenses of the initially present iPP. Furthermore, a balance between the amount of missing iPP and the proportion of newly created polyethylene (PE) is observed. The newly formed PE is semicrystalline, having a degree of crystallinity of about 30%. The amorphous component of the generated PE is thought to contribute to the high impact strength of the crosslinked samples when compared to the unmodified iPP. In light of the results obtained by the different techniques, an attempt to describe the emerging structure of the new crosslinked iPP material is proposed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Evolution of dielectric properties in BaZrxTi1−xO3 ceramics: Effect of polar nano-regions

BaZr_xTi_1?xO₃ (x = 0.2, 0.25, 0.3) ceramics were prepared by a citrate method. The ferroelectric phase transition behavior and bias electric-field-induced dielectric nonlinearity of the ceramics were investigated. With increasing zirconium content, the phase transition behavior of the ceramics changed from a diffusion phase transition to relaxor-like behavior. Applying bias electric field in diverse manners led to differing effects on the dielectric nonlinearity, depending on the zirconium content of the ceramics. These dielectric phenomena were related to the polarization response of polar nano-regions (PNRs) embedded in the ceramics, which are macroscopically in the paraelectric state at room temperature. The characteristic parameters of PNRs were determined by fitting the dielectric constants under bias electric field to a multipolarization mechanism model. It was found that the size of PNRs was decreased with increasing zirconium content. The evolution of the phase transition behavior and dielectric nonlinearity with zirconium content was interpreted in relation to the size change of PNRs.     

内蒙古地区万寿菊植株营养成分分析

对内蒙古地区种植的万寿菊进行了营养成分分析。结果显示,本地区万寿菊含有丰富的粗蛋白、粗脂肪以及粗纤维等多种营养成分,除此之外还含有2种半必需氨基酸、7种必需氨基酸和8种非必需氨基酸。