Preparation of POE/PS blends with fine particle sizes by diffusion and subsequent polymerization of styrene in POE pellets

Ethylene-α-octene copolymer(POE)/polystyrene(PS) blend pellets with fine particle sizes were prepared by diffusion and subsequent polymerization of styrene in POE pellets through a one-pot procedure.The effects of the amounts of styrene and BPO on PS content,monomer efficiency and monomer conversion were investigated.The blend pellets were characterized by Micro-FTIR and FESEM,showing homogeneous diametrical distributions of PS and particle size.After melt-processing into rods,the average particle sizes are almost doubled,but still in submicron scale.Compared to neat POE rods,the blend rods with PS content higher than 15% exhibit improved tensile modulus and tensile strength without significantly losing ductility,being attributed to the small sizes,complex nature of particles and the existence of POE-g-PS copolymer that result in good interfacial adhesion.POE/PS pellets were compared with the previously reported PP/PS pellets,and the differences between the two systems are attributed to the different morphology of the two matrices: POE is completely amorphous at the diffusion and polymerization temperature,while i PP is semicrystalline.Without efficient impediment of the crystal lamellae in POE pellets,styrene diffuses easily in POE pellets.     

THERMAL DEGRADATION AND FLAME RETARDANCY OF CALCIUM ALGINATE FIBERS

Calcium alginate fibers were prepared by wet spinning of sodium alginate into a coagulating bath containing calcium chloride.The thermal degradation and flame retardancy of calcium alginate fibers were investigated with thermal gravimetry(TG),X-ray diffraction(XRD),limiting oxygen index(LOI) and cone calorimeter(CONE).The results show that calcium alginate fibers are inherently flame retardant with a LOI value of 34,and the heat release rate(HRR),total heat release(THR),CO and CO_2 concentrations during ...     

采用离子对试剂同时测定啤酒中异α-酸和还原异α-酸

建立了使用离子对试剂同时检测啤酒中异α-酸、二氢异α-酸、四氢异α-酸和六氢异α-酸的反相高效液相色谱法。实验采用四丁基氢氧化铵-磷酸缓冲液(pH调至7.2)-乙腈为流动相,Xterra RP C18(4.6×150 mm,5μm)色谱柱,等度洗脱,实现这4种异构化α-酸的所有组分的有效分离测定。各组分色谱峰保留时间的RSD为0.1%～0.3%,峰面积的RSD为0.5%～1.7%(n=7),重现性和线性关系较好;4种异构化α-酸的加标回收率为96%～108%。该方法无需样品处理,简便易行,可用于分析啤酒中所含异构化α-酸的种类和含量。     

分散液相微萃取-高效液相色谱法测定水和土壤中多环芳烃

以二硫化碳为萃取剂,丙酮为分散剂对水样和土壤样中残留的多环芳烃进行分散液相微萃取。提取液供高效液相色谱仪的二极管阵列检测器和荧光检测器测定。选用LiChrospherPAH色谱柱作为固定相,用乙腈和水以不同比例混合的溶液作为流动相进行梯度淋洗。在优化的试验条件下,对合成水样中多环芳烃的富集倍数达220～560倍,16种多环芳烃可有效分离并测定。16种多环芳烃的检出限(3S/N)在0.002～0.05μg.L-1之间。用标准加入法测得回收率在64%～108%之间,测定值的相对标准偏差(n=7)在2.0%～7.8%之间。     

Poly(ethylene terephthalate)/carbon black composite fibers prepared by electrospinning

Poly(ethylene terephthalate)(PET)/carbon black(CB) composite fibers with improved mechanical properties in tensile modulus and tensile strength are prepared by eletrospinning. Stable dispersions suitable for electrospinning are obtained by dispersing melt pre-compounded PET/CB composites in hexafluoroisopropanol. The fiber morphology and CB dispersion are investigated by FESEM and TEM. The addition of CB has no obvious effect on fiber diameter, and the average fiber diameters for all the samples are around 2-3 μm. CB in the fibers is in the form of submicron-sized clusters. The thermal properties of the PET/CB composite fibers are evaluated by DSC, showing almost unchanged melting temperature and crystallinity. Uniaxial tensile tests are used to measure the mechanical properties of the PET/CB composite fiber mats. The fiber mats containing 1 wt%-8.5 wt% CB have significantly improved tensile modulus compared to neat PET fiber mat, showing reinforcing effect of CB. The electrical conductivity of the fiber mats has also been tested.     

新型双苯基型季铵盐Gemini表面活性剂的合成及其表面活性

以水杨醛和1,2-二溴乙烷为原料,经Williamson反应、氧化反应、酰氯化反应和酰胺化反应制得酰胺化合物（3）; 3与溴代正癸烷经季胺化反应合成了新型双苯基型季铵盐Gemini表面活性剂（4）,其结构经¹H NMR和IR表征。表面活性测试结果表明：4具有优异的抗酸、抗盐性能。在0.1 mol·L^-1NaCl溶液中, γ＝36.8 mN·m^-1, CMC＝0.20 mmol·L^-1;在HCl（pH 1）溶液中, γ＝32．5 mN·m^-1, CMC＝0.16 mmol·L^-1。     

β-丙氨酸-银复合膜修饰电极用于循环伏安法测定对乙酰氨基酚

制备了β-丙氨酸-银复合膜修饰电极(Ag-Ala/GCE),采用循环伏安法研究了对乙酰氨基酚在修饰电极上的电化学行为。结果表明:在pH 4.0的磷酸盐缓冲液中,对乙酰氨基酚在修饰电极上呈现一对灵敏的氧化还原峰,提出了用循环伏安法测定对乙酰氨基酚的含量。对乙酰氨基酚浓度在6.0×10-7～7.0×10-4 mol.L-1范围内与氧化峰电流呈现线性关系,检出限(3S/N)为2.0×10-7 mol.L-1。修饰电极用于药剂中对乙酰氨基酚的测定,并用标准加入法测得方法的回收率在95.1%～101.6%之间。     

石墨烯/聚苯胺复合材料的制备及超电容性能研究进展

近年来,石墨烯/聚苯胺复合材料由于自身优异的电化学性能引起了国内外学者的广泛关注,石墨烯具有大的比表面积和双电层电容特性,聚苯胺具有高赝电容特性,二者协同作用使其复合材料的超电容性能大大提高.主要介绍石墨烯/聚苯胺复合材料的制备方法及电容性能的影响因素,总结三维石墨烯/聚苯胺复合材料的构筑方法,并对复合材料未来在超级电容器领域的发展趋势进行了展望.     

青蒿素与氯化血红素作用的荧光研究及分析应用

介绍了吡罗红为指示剂通过荧光降低法研究青蒿素与氯化血红素之间的相互作用。实验发现两者为酶和底物作用模型,作用位点为药物的过氧基团和氯化血红素活性中心的金属离子,其动力学催化常数K_m, V_max和K_cat分别为8.4×10-5 mol·L-1, 7.4×10-6 mol·L-1·s-1及50.23 s-1,催化活性分别受去激活剂和高温影响。在最佳条件下, 荧光降低值ΔF(F₀-F)与青蒿素浓度在0.0～1.27×10-6 mol·L-1范围内成线性关系, 检测限为2.3×10-8 mol·L-1, 该方法已用于测定血浆和尿液介质中的微量青蒿素。     

在MOCVD系统中用预淀积In纳米点低温下合成生长InN

利用低压金属有机化学气相淀积(LP-MOCVD)系统,在(0001)蓝宝石衬底上采用预淀积In纳米点技术低温合成制备了立方相的InN薄膜.首先以TMIn作源在蓝宝石衬底表面预淀积了一层金属In纳米点,然后在一定条件下合成生长InN薄膜.X射线衍射谱(XRD)和X射线光电子发射谱(XPS)显示适当的预淀积In不仅能够促进InN的生长,同时还能够抑制金属In在InN薄膜中的聚集.原子力显微镜(AFM)观察表明,金属In纳米点不仅增强了成核密度,而且促进了InN岛的兼并.自由能计算表明预淀积的In优先和NH3分解得到的NH与N基反应生成InN.我们认为这种优先生成的InN为接下来InN的生长提供了成核位,从而促进了InN的生长.