Effect of Fe3O4‐doped sepiolite on the flammability and thermal degradation properties of epoxy composites

As‐received sepiolite/epoxy systems and Fe₃O₄‐doped sepiolite/epoxy systems were prepared, and the contents of sepiolite and Fe₃O₄‐doped sepiolite were kept as 2 and 4 wt%, respectively. Compared with sepiolite, the effect of Fe₃O₄‐doped sepiolite on the flame retardancy, combustion properties, thermal degradation, thermal degradation kinetics and thermomechanical properties of epoxy resin was investigated systematically by limiting oxygen index (LOI), cone calorimeter (Cone), thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). Some interesting results had been acquired. The addition of sepiolite decreased heat release rate, total smoke production and smoke production rate, and obviously improved LOI values of epoxy composites. Compared with sepiolite, the addition of Fe₃O₄‐doped sepiolite further reduced parameters mentioned above of epoxy composites, and further enhanced LOI values and char residues after cone test. There might be a synergistic effect between sepiolite and Fe₃O₄ on flame retardant epoxy composite. TGA results indicated that the addition of sepiolite had a slight effect on the thermal degradation of epoxy composites; however, the addition of Fe₃O₄‐doped sepiolite accelerated the thermal degradation of epoxy composites. DMA results showed that the addition of both sepiolite and Fe₃O₄‐doped sepiolite increased the glass transition temperature (T_g) of epoxy composite. The results obtained in this paper supplied an effective solution for developing excellent flame retardant properties of polymeric materials. Copyright © 2015 John Wiley & Sons, Ltd.     

Global weak solutions to one-dimensional compressible viscous hydrodynamic equations

In this article, we are concerned with the global weak solutions to the 1D compressible viscous hydrodynamic equations with dispersion correction δ~2ρ((φ(ρ))xxφ′(ρ))x withφ(ρ) = ρα. The model consists of viscous stabilizations because of quantum Fokker-Planck operator in the Wigner equation and is supplemented with periodic boundary and initial conditions. The diffusion term εu xx in the momentum equation may be interpreted as a classical conservative friction term because of particle interactions. We extend the existence result in[1](α =1/2) to 0 α≤1. In addition, we perform the limit ε→ 0 with respect to 0 α≤1/2.     

Dimension of Slices Through Fractals with Initial Cubic Pattern

In this paper, the Hausdorff dimension of the intersection of self-similar fractals in Euclidean space R~n generated from an initial cube pattern with an(n-m)-dimensional hyperplane V in a fixed direction is discussed. The authors give a sufficient condition which ensures that the Hausdorff dimensions of the slices of the fractal sets generated by "multirules" take the value in Marstrand's theorem, i.e., the dimension of the self-similar sets minus one. For the self-similar fractals generated with initial cube pattern, this sufficient condition also ensures that the projection measure μVis absolutely continuous with respect to the Lebesgue measure L~m. When μV《 L~m, the connection of the local dimension ofμVand the box dimension of slices is given.     

新型双杂环修饰的酰胺硫醚衍生物的合成和生物活性

首次设计并合成了16个新型1,2,4-三唑与1,3,4-噻二唑双杂环修饰的酰胺硫醚衍生物,并对其进行了结构表征。分别评价了目标分子对蛋白酪氨酸磷酸酶1B(PTP1B)和细胞分裂周期25磷酸酶B(Cdc25B)抑制活性,结果发现:16个目标分子对PTP1B具有良好的抑制活性,其中8-C-d和8-D-c的抑制作用最佳,半抑制浓度(IC_(50)值)分别为(1.19±0.22)mg/L和(1.08±0.09)mg/L,优于阳性参照物齐墩果酸(IC_(50)=(1.27±0.19)mg/L),有望作为抗糖尿病药物先导物;对Cdc25B抑制活性测试中,11个目标分子表现出良好的活性,其中8-A-d、8-C-d和8-D-c抑制活性的IC_(50)值分别为(0.97±0.05)、(1.06±0.03)和(0.94±0.11)mg/L,低于阳性参照物Na_3VO_4(IC_(50)=(1.25±0.14)mg/L),有望作为抗肿瘤药物先导物。     

聚乳酸/壳聚糖季铵盐皂石纳米复合材料的原位插层聚合及性能表征

通过两步法将2,3-环氧丙基三甲基氯化铵接枝壳聚糖合成了水溶性壳聚糖季铵盐(HTCC),以其为插层剂对稀有的新疆皂石(Saponite)黏土矿物进行有机改性,制备了壳聚糖季铵盐皂石(HTCC-saponite),并以其为助剂,以丙交酯为单体,通过原位插层聚合法制备了聚乳酸(PLA)/HTCC-saponite纳米复合材料.最优化合成条件:聚合反应温度150℃,辛酸亚锡加量2%(质量分数),HTCC-saponite加量1%(质量分数)、聚合反应时间16 h.微观结构分析表明HTCC-saponite具有插层与剥离共存的结构.采用X射线衍射(XRD)、透射电子显微镜(TEM)、热重分析(TG-DTG)和差示扫描量热仪(DSC)等对PLA/HTCC-saponite纳米复合材料的微观结构、形貌及热稳定性进行了表征和分析.结果表明,HTCC-saponite有效改善了PLA的结晶性能,提高PLA的热稳定性.抗菌测试结果表明,HTCC-saponite具有良好的抗菌性,并赋予PLA/HTCC-saponite复合材料较强的抑菌能力.     

堆肥中亲水性有机物还原容量表征及影响因素研究

还原容量(RC)是衡量水溶性有机物(DOM)还原特性的重要指标。分别取未腐熟和腐熟后筛分的堆肥样品提取DOM并分离亲水性组分(Hy I)作为电子供体及电子穿梭体,以3种不同形态的铁作电子受体测定其还原容量。结果表明,对于3种形态的电子受体Fe2(SO4)3,Fe(NO3)3和柠檬酸铁(FeCit),腐熟筛分后Hy I的还原容量值分别为15.88,13.41和51.45 mmol e-/mol C,均大于未腐熟阶段的Hy I还原容量值13.45,11.77和43.16 mmol e-/mol C。同时还发现不同电子受体对Hy I的还原能力影响明显,FeCit条件下测得的RC值明显高于在Fe2(SO4)3和Fe(NO3)3条件下的RC值。而且Hy I的微生物还原容量低于本底还原容量。通过紫外-可见光谱特征值(包括SUVA254和SUVA280)、特征值比值(包括A250/A365和A465/A665)及面积积分比值分析发现,芳香族、不饱和共轭双键结构、芳化度和有机质分子量都会对Hy I氧化还原能力产生影响;结合三维荧光光谱体积积分值及百分比分析发现,类腐殖质(包括类富里酸和类胡敏酸)相对含量是Hy I还原容量主要影响因素。本研究为科学表征亲水性组分的氧化还原特性、揭示其在堆肥体系污染物降解转化中的作用提供了科学依据。     

Flame-retarded mechanism of SEBS/PPO composites modified with mica and resorcinol bis(diphenyl phosphate)

The flame retardancy of styrene-b-ethylene/butylene-b-styrene triblock polymer (SEBS)/poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) blends was greatly improved by the combined use of mica and resorcinol bis(diphenyl phosphate) (RDP). The limiting oxygen index (LOI), vertical burning and cone calorimeter test were performed to evaluate the flame-retarded effect. The composite of SEBS/PPO/maleic anhydride grafted SEBS (SEBS-g-MAH) with a mass ratio of 11/11/3 passed a V-0 rating in the UL94 test by the addition of 10–15 wt% mica and 15–10 wt% RDP with total amount of 25 wt%. The synergism was confirmed by the mathematical evaluation of the synergistic effect index (SE) in LOI, the residue, the peak heat release rate (PHRR) and the total heat evolved (THE) per mass loss (THE/ML). The flame-retarded mechanism of the composite was also proposed on the results of cone calorimeter test, TGA-FTIR, SEM micrographs and SEM/EDS analysis of the residues. It was found that the degradation rate of SEBS/PPO/SEBS-g-MAH matrix was slowed down, a more consolidated char layer with higher residue was promoted by the combination of RDP and mica. The flame-retardancy of RDP with mica in SEBS/PPO/SEBS-g-MAH matrix was synergistic through gas and condensed phase action.     

Temperature Dependence in the Synthesis of SBA-16-Type Mesoporous Silica with Pluronic F68 Block Copolymer

By adjusting the local effective surfactant packing parameter through synthesis temperature, highly ordered SBA-16-type mesoporous silica materials have been synthesized by templating with a nonionic triblock copolymer Pluronic F68 in strongly acidic conditions at temperature 30～40°C with the addition of K₂SO₄. The prepared SBA-16-type mesoporous silica materials having Im3m cubic mesostructure were proved by the well-defined x-ray diffraction patterns combined with transmission electron microscopy. Scanning electron microscopy indicated that a transformation from faced-sphere to faced-polyhedron shape morphologies could be induced with increasing of the synthesis temperature. The nitrogen adsorption–desorption analysis revealed that the mean pore size (5.50～6.13 nm) of the prepared materials increased with increasing synthesis temperature. However, when the synthesis temperature exceeded 46°C, only disordered mesoporous silca was obtained. Our synthesis strategies by adjusting the local effective surfactant packing parameter through synthesis condition, even in a narrow range, would be used not only to optimize the synthesis conditions of reported mesoporous silca, but also to fabricate new mesoporous silica materials with well-ordered channel and anticipated morphologies.     

微波快速萃取-荧光衍生化HPLC-MS测定不同品种金银花中游离脂肪酸

建立了金银花中游离脂肪酸的微波快速萃取方法,采用柱前荧光衍生化法,测定了金银花中16种长链饱和与不饱和游离脂肪酸的含量。微波萃取功率800 W,溶剂V(氯仿):V(甲醇)=1:1,70℃萃取8 min,萃取率>98.8%。采用酸性乙腈/水流动相在反向C8色谱柱上进行梯度洗脱,HPLC荧光检测波长为505 nm,在线联用质谱辅助鉴定(APCI-MS),提高了检测的准确度。方法检出限在0.366~2.58μg/L之间,回收率88.3%~107.6%。     

Methyl β-(Benzotriazol-l-yl) vinyl Ketone: A New p-Acetylvinyl Cation Equivalent

A simple and efficient two-step approach to methyl β-(benzotriazol-1-yl)vinyl ketone 7 is described. The synthetic utility of compound 7 has been demonstrated by nucleophilic substitutions of the benzotriazolyl group with a range of nucleophiles. Thus, methyl β-(benzotriazol-1-yl)vinyl ketone provides a new β-acetylvinyl cation equivalent.