微波萃取气相色谱-质谱法测定塑料中的增塑剂

建立了利用微波萃取气相色谱-质谱法同时测定塑料中18种增塑剂的方法。该方法以乙酸乙酯为萃取溶剂,采用微波萃取法提取塑料中邻苯二甲酸酯类、己二酸酯类、磷酸酯类、柠檬酸酯类等四种不同类型的18种增塑剂,采用气相色谱-质谱法对萃取液中的增塑剂同时进行测定。对色谱条件和样品前处理条件进行了优化,四种不同类型增塑剂的平均回收率为93.96%~101.20%,精密度实验相对标准偏差为1.09%~5.82%,检测限(S/N=3)为0.3~10mg/L。该方法简便、准确,灵敏度高,可满足塑料中多种类型增塑剂的检测要求。     

Microparticles and latexes prepared via suspension polymerization of a biobased vegetable oil and renewable carboxylic acid

Novel bio-based microparticles and latexes are synthesized using green chemistry principles through the reaction of aconitic acid (a sugarcane byproduct) and epoxidized linseed oil (ELO). No volatile solvents have been used, and no initiators are present in this polymerization. Using different agitation techniques, we investigate the particles and latexes formed via suspension polymerization in contrast to bulk dispersion polymerization. With the addition of water and a small amount of surfactant to the ELO and aconitic system, a thermally stable material up to 250°C is created that exhibits adhesive and hydrophobic properties. These microparticle latexes are anticipated for applications in hydrophobic coating and personal care products.     

Correction to: Nitrogen balance in paddy fields under flowing-irrigation condition

The article Nitrogen balance in paddy fields under flowing-irrigation condition, written by Makoto Saiki, Thi Phuong Mai Nguyen, Junko Shindo, Kei Nishida, was originally published Online First...     

扩孔时间变化对铝电解电容器用铝箔孔洞生长的影响

铝电解电容器高压用阳极箔一次腐蚀发孔后,经200 V以上电压化成后容易填没孔洞,需要通过二次腐蚀来增大孔径。在保持扩孔腐蚀电流密度不变的条件下,随着扩孔时间的延长,腐蚀箔孔洞深度加长,芯层减薄,孔洞密度减少,孔径增加。从腐蚀以及化成静电折弯分析,并非芯厚较薄的强度就一定差,化成后强度与扩孔后的孔径大小和规则性有一定的关联。     

Synthesis of EPDM-g-MAN by suspension graft copolymerization and its toughening effect on SAN resin

Suspension graft copolymerization of methyl methacrylate and acrylonitrile onto ethylene–propylene–diene terpolymer (EPDM) was carried out under different reaction conditions. A series of graft products of EPDM-graft-methyl methacrylate and acrylonitrile (EPDM-g-MAN), characterized by Fourier-transform infrared spectroscopy, was blended separately with styrene–acrylonitrile (SAN) resin to investigate their toughening effect on SAN matrix. The relationship between the polarity of EPDM-g-MAN and toughness of EPDM-g-MAN/SAN resin blends (AEMS) was evaluated. The compatibility and morphologies of AEMS were probed by dynamic mechanical analysis, transmission electron microscopy, and scanning electron microscopy to determine the toughing mechanism of the blends. Thermogravimetry results showed that the thermal stability of AEMS was enhanced with the incorporation of EPDM-g-MAN graft copolymer.     

Self-assembly of silver–graphene hybrid on electrospun polyurethane nanofibers as flexible transparent conductive thin films

A method of integrating hybrid thin films of graphene nanosheets (GNSs) and silver nanoparticles (AgNps) by in situ chemical reduction to prepare transparent conductive films (TCFs) is studied. The surface functional groups of graphite oxide (GO) serve as nucleation sites of silver ions for adsorption of AgNps. To fabricate conductive films with high transmittance, polyurethane (PU) nanofibers are introduced to help construct two-dimensional conductive networks consisting of AgNps and GNSs (AgNps–GNSs). This method requires only a low percentage of conducting AgNps–GNSs covering the transparent substrate, thereby improving the transmittance. The flexible GNSs serve as nanoscale bridges between conductive AgNps and PU nanofibers, resulting in a highly flexible TCF. The optical transmittance can be further increased after melting the PU nanofibers at 100 °C. A fused film obtained after electrospinning (ES) a PU solution for 120 s and immersion in 0.05 wt.% AgNp–GNS (5:1) solution has a surface resistance of 150 Ω/sq and 85% light transmittance. Mechanical testing shows that AgNps–GNSs on flexible substrates yield excellent robustness. Thus, TCFs with a 3:1 ratio of AgNps:GNSs have high conductivity, good mechanical durability, and barely one order of magnitude increase of surface resistance when bent to an angle of 90°.     

水源水中的遗传毒性检测技术研究进展

介绍了近几年常用的检测水源水中有机污染物遗传毒性方法,分别阐述了各项技术的机理,并从遗传终点、灵敏度和费用等方面对其进行了评价。拟提出一套快速、全面和实用的水源水遗传毒性检测的方法体系,并提出了水源水中有机物的遗传毒性检测技术的发展方向。     

Toughening of recycled poly(ethylene terephthalate) with a maleic anhydride grafted SEBS triblock copolymer

Toughening of recycled poly(ethylene terephthalate) (PET) was carried out by blending with a maleic anhydride grafted styrene‐ethylene/butylene‐styrene triblock copolymer (SEBS‐g‐MA). With 30 wt % of the SEBS‐g‐MA, the notched Izod impact strength of the recycled PET was improved by more than 10‐fold. SEM micrographs indicated that cavitation occurred in just a small area near the notch root. Addition of 0.2 phr of a tetrafunctional epoxy monomer increased the recycled PET melt viscosity by chain extension reaction. Different from the positive effect of the epoxy monomer in toughening of nylon and PBT with elastomers, the use of the epoxy monomer in the recycled PET/SEBS‐g‐MA blends failed to further enhance dispersion quality and thus notched impact strength. This negative effect of the epoxy monomer was attributed to the faster reactivity of the epoxy group with maleic anhydride of the SEBS‐g‐MA than with the carboxyl or hydroxyl group of recycled PET. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1462–1472, 2004     

Crystallization and melt behavior of magnesium hydroxide/polypropylene composites modified by functionalized polypropylene

The crystallization and melting behavior of Mg(OH)₂/polypropylene (PP) composites modified by the addition of functionalized polypropylene (FPP) or acrylic acid (AA) and the formation of in situ FPP were investigated by DSC. The results indicated that addition of FPP increased crystallization temperatures of PP attributed to the nucleation effect of FPP. The formation of in situ FPP resulted in a reduced crystallization rate, melting point, and degree of crystallization because of the decreased regularity of the PP chain. For the Mg(OH)₂/PP composites, addition of Mg(OH)₂ increased the crystallization temperatures of PP attributed to a heterogeneous nucleation effect of Mg(OH)₂. Addition of FPP into Mg(OH)₂/PP composites further enhanced the crystallization temperatures of PP. It is suggested that there is an activation of FPP to the heterogeneous nucleation effect of Mg(OH)₂ surface. The addition of AA also increased the crystallization temperatures of PP in Mg(OH)₂/PP composites, but crystallization temperatures of PP were not influenced by the AA content, a phenomenon explained by the heterogeneous nucleation effect of the Mg(OH)₂ surface activated by FPP and AA. A synergistic effect on crystallization of PP in Mg(OH)₂/PP composites further increased the crystallization temperatures of PP. However, the crystallization temperatures of Mg(OH)₂/PP composites modified by in situ FPP were lower than those of Mg(OH)₂/PP composites modified by the addition of FPP or AA. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91:3899–3908, 2004