多环芳烃在贵金属催化剂上竞争加氢反应的研究

采用水蒸汽脱铝获得了超稳Y载体, 并用离子交换法制备了金属含量约为0.8 wt%的双贵金属催化剂. 用NH₃程序升温脱附、X射线衍射、N₂吸附-脱附等方法表征了载体和催化剂. 以萘、蒽、芘加氢为模型反应, 在高压反应釜中研究了催化剂的加氢活性以及它们之间竞争加氢的反应. 结果表明, 催化剂具有深度加氢的能力. 萘与蒽竞争加氢的结果表明, 蒽的加氢活性高于萘加氢活性, 并且蒽抑制萘加氢, 萘抑制了八氢蒽向全氢蒽的转化. 说明对于分子动力学直径相当的混合体系中, 多环物质抑制少环物质的加氢. 分子动力学直径不同的萘与芘加氢结果表明, 萘的转化率始终高于芘的转化率, 并且单和混合体系中萘和芘的转化率变化程度不大, 说明分子能否扩散进入分子筛孔道内也是影响加氢活性的重要因素.     

三维荧光光谱总体积积分法同时测定多环芳烃

提出了三维荧光光谱总体积积分法并应用于多环芳烃萘、芘、Ｂｅｉ的同时测定，结果表明，三维荧光光谱总体积积分法不仅可以同时测定萘、芘、Ｂｅｉ而且灵敏度（信噪经）常规法分别提高２２、３３和２６倍同时并考察了积分区域对灵敏度的影响。     

GC–MS法同时测定聚氨酯塑胶跑道中16种多环芳烃

建立气相色谱–质谱法同时测定聚氨酯塑胶跑道中16种多环芳烃如萘、苊、二氢苊、芴、菲、蒽、荧蒽、苯并[b]荧蒽、芘、苯并[a]蒽、屈、苯并[k]荧蒽、苯并[a]芘、茚并[1,2,3-cd]芘、1-甲基奈、2-甲基萘的检测方法。样品采用甲苯为提取剂,经超声提取和硅胶柱净化后,用气相色谱–质谱法测定16种多环芳烃残留量。16种多环芳烃的质量浓度在0.2~10.0 mg/kg范围内与色谱峰面积呈良好的线性,线性相关系数r20.998,检出限为5.0~60.0μg/kg。回收率为72.4%~101.6%,测定结果的相对标准偏差为0.9%~7.2%(n=6)。该方法准确度高、精密度好,适用于聚氨酯塑胶跑道中多环芳烃多残留检测。     

Pluronic嵌段共聚物F127和P123胶束对萘、蒽、芘的增溶

35℃时F127和P123在ccm后可生成内核PO成分分别为92.7%和94.5%的胶束,后者胶束内核体积为前者的2.8倍.稠环芳烃和空胶束的第一步缔合平衡常数K₁值均随萘、蒽、芘顺序逐渐增大.萘、蒽、芘在每个F127和P123胶束中的增溶量均随胶束内核体积增大而线性增加,每个PO基团对应的增溶量比十二烷基磺酸胶束内核中相同体积对应的增溶量约大近2倍.Pluronic胶束除与稠环芳烃间具有强相互作用力外,所形成的大内核是导致大增溶量的重要因素.     

气相色谱质谱法测定化妆品中9种多环芳烃

建立了气相色谱质谱法测定化妆品中9种多环芳烃的分析方法。化妆品中的萘、苯并[a]蒽、、苯并[b]荧蒽、苯并[j]荧蒽、苯并[k]荧蒽、苯并[e]芘、苯并[a]芘、二苯并[a,h]蒽等9种多环芳烃用甲醇超声提取后,用环己烷液-液萃取后浓缩,经硅胶-中性氧化铝柱净化后,采用气相色谱-质谱测定。多环芳烃浓度在0.05～2 mg/L范围内,质量浓度与其峰面积呈良好的线性关系。在低、中、高3个添加水平下,9种多环芳烃化合物的平均回收率为81.6%～100.2%,相对标准偏差为1.3%～5.8%。方法可用于化妆品中多环芳烃的检测。     

固相膜萃取-超高效液相色谱-荧光法测定极地水体中多环芳烃

采用C<,18>固相膜萃取对样品进行富集净化,以二氯甲烷洗脱目标化合物,采用UPLC荧光可变波长进行分离分析.可在5min内实现15种多环芳烃分析,方法检出限分别为:萘为0.3ng/L,苊、芴、菲和苯并(a)蒽为0.26ng/L,蒽、荧蒽、苯并(b)荧蒽和茚并(1,2,3-cd)芘为0.28ng/L;芘、屈、苯并(k)荧蒽、苯并(a)芘和二苯并(a,h)蒽为0.24ng/L;苯并(g,h,i)苝为2.6ng/L.加标回收率在67%～87%之间,RSD均小于10%.可应用于极地环境中痕量多环芳烃样品的检测分析.     

用GC/MS研究含α-活泼氢芳烃与硝基苯的反应

在常温常压下，研究了苊、蒽、萘、芴、1-甲基萘（1-MN）、2,6-二甲基萘（2,6-DMN）、苯酚、α-萘酚与PhNO2(硝基苯)在Lewis酸AlCl3催化作用下的反应。结果发现，蒽、萘和苯酚与PhNO2不反应，苊、芴、1-MN、2,6-DMN和α-萘酚与PhNO2都能反应生成相应的苯胺基芳烃。GC/MS分析表明反应活性顺序为苊＞1-MN＞2,6-DMN＞芴，根据超共轭效应可以合理解释含α-活泼氢芳烃反应活性顺序。控制AlCl3与苊的摩尔比值为1.2和2.4左右，重结晶苊与PhNO2的反应产物分别得到联苊和5-苯胺基苊纯品，利用GC、GC/MS、FTIR和UV等分析测试手段对其进行了结构鉴定。     

原油空气氧化前后多环芳烃组分的气相色谱-质谱分析

采用柱层析法对空气氧化前后的原油进行族组分分离,利用气相色谱-质谱(GC-MS)分离测定其芳香烃组分,分析多环芳烃组分的变化.结果表明,随着氧化过程的进行,烷基化多环芳烃占多环芳烃的含量从氧化前的71.5%增加到92.0%(175℃)和90.2%(225℃).轻质组分萘和菲的优势逐渐被重质组分艹屈取代.侧链少的多环芳烃比侧链多的更易氧化.氧化后,其他稠环化合物蒽、萤蒽、芘、苯并蒽含量降低,苯并萤蒽含量增加;苯并芘在175℃氧化后含量降低,而在225℃氧化后含量增加.与此同时,175℃氧化后生成了原油所不含有的三芳甾烃、联苯和苯并呋喃.     

飞行时间质谱仪在线检测多环芳烃

采用实验室自行研制飞行时间质谱仪对二(口恶)英常见的关联产物多环芳烃进行了在线检测,选取二环至四环的多环芳烃芴、菲、蒽、萘、芘进行了测量并分析了仪器检测得到的信号.结果表明,该仪器对实验选取的多环芳烃具有良好的响应特性,检测浓度可达到25 nmol/L(即体积浓度500 ppbv),检测结果与实际物质浓度间具有良好的线性关系.使用最小二乘法拟合了浓度和信号强度的线性方程,实现了25～500 nmol/L(体积浓度0.5～10 ppmv)之间检测物质浓度的标定,为进一步发展烟气中的实际多环芳烃测量和浓度标定提供了参考.     

超高效合相色谱快速分析塑料制品中的18种多环芳烃

建立了一种超高效合相色谱-二极管阵列检测器快速分析塑料制品中萘、苊烯、苊、芴、菲、蒽、荧蒽、芘、苯并(a)蒽、(屈艹) 、苯并(b)荧蒽、苯并(k)荧蒽、苯并(j)荧蒽、苯并(e)芘、苯并(a)芘、茚并(1,2,3-cd)芘、二苯并(a,h)蒽、苯并(g,h,i)苝(二萘嵌苯)的方法。以甲苯为溶剂,超声萃取实际塑料制品中的多环芳烃,经超高效合相色谱分析。采用Daicel IB-3手性色谱柱,以CO₂为流动相,甲醇/乙腈(25:75, v/v)为流动相助溶剂,在柱温为40 ℃,背压为15.17 MPa的条件下,18种多环芳烃在8.5 min之内实现基线分离。18种多环芳烃的线性范围为0.05~50 mg/L(r≥0.9995),定量限(S/N> 10)为0.05 mg/L。加标回收率为78.3%~117.6%,相对标准偏差(RSD, n=5)小于5%。该方法具有分析速度快、分离效率高、节约有机溶剂的优点。     

Novel Epoxy Resins Derived from Biomass Components

Biomass has received considerable attention because it is renewable and offers the prospect of circulation of carbon in the ecological system. The concept “Biorefinery” has been developed rapidly in order to establish sustainable industries. Recently, new types of epoxy resins with polyester chains, which can be derived from saccharides, lignin and glycerol, have been investigated. In the above studies, the relationship between chemical structure and physical properties was investigated. In the present review, the features of the preparation system and the action of biomass components in epoxy resin polymer networks are described. The glass transition temperatures of the epoxy resins increased with increasing content of biomass components in epoxy resin polymer networks. Thermal decomposition temperatures were almost constant regardless of the content of biomass components contents in epoxy resins. Mass residue at 500 °C increased with increasing contents of biomass components in epoxy resins. It was found that the thermal properties can be controlled by changing the contents of biomass components.     

电子束辐射固化环氧树脂的动态力学分析——树脂化学结构、分子量及其分布的影响

应用不同化学结构、分子量及其分布的环氧树脂进行了电子束辐射固化实验 ,对固化物进行了动态力学分析 ,研究了不同样品凝胶含量、内耗tanδ及动态模量的变化规律 .分析结果表明环氧树脂辐射反应活性与其化学结构有很大关系 ,酚醛型环氧树脂的辐射反应活性高 ,固化后高温模量及玻璃化温度较高 ,而脂环族环氧树脂反应活性小 .在低辐射剂量下 ,环氧树脂的固化度随分子量增大略有下降 ,但固化物的玻璃化温度随分子量增加而升高 .增大辐射剂量 ,树脂固化度的提高受分子量大小的影响很小 ,分子量较大样品的网络均匀程度有所提高 ,在较高反应程度下 ,玻璃化温度主要受固化度影响 .树脂固化程度也是决定其模量高低的主要因素 ,而在固化程度相近的情况下 ,分子量的影响作用很大 .在同样辐射剂量下 ,分子量分布宽的树脂固化反应程度高 ,但交联网络均匀性低 .     

化学结构变化对刚棒状环氧树脂相行为和热力学性能的影响

用线性酚醛树脂(PN)和4-氨基苯基氨基砜(SAA)作为固化剂, 与刚性棒状环氧树脂联苯环氧(DGEBP)、四甲基联苯环氧(DGETMBP)和传统双酚A环氧树脂(DGEBA)分别进行固化. 研究了固化剂和环氧树脂化学结构的改变对热固网络相行为和热力学性能的影响. 结果表明, 刚性环氧网络比传统的DGEBA具有更好的热力学性能. DGEBP可形成不同类型的取向网络, 而取向态的类型也直接影响了热固网络的热力学性能. 用扫描电镜(SEM)观察不同网络体系的断裂面结构, 发现取向的刚性棒状环氧网络的断裂面呈韧性断裂, 而其它无定形环氧网络则呈典型的脆性断裂.     

Effect of fluorine functional groups on surface and mechanical interfacial properties of epoxy resins

To improve the surface and mechanical interfacial properties of epoxy resins, fluorine-containing epoxy resin (FEP) was prepared and blended with a commercially available tetrafunctional epoxy resin (TGDDM). As a result, when the fluorine content increased, the total surface energy of TGDDM/FEP blends was gradually decreased, while the water repellency of the blends was increased. The glass transition temperature and thermal stability factors of the blends showed maximum values at 20-40 wt% FEP compared with neat TGDDM epoxy resins. And the mechanical interfacial properties of the blend specimens were significantly increased with increasing the FEP content, which could be attributed to the intermacromolecular interactions in the cured TGDDM/FEP blends. These results indicate that the water repellency and toughness improvements have been achieved without significantly deterioration of the thermal properties in the TGDDM/FEP blends.     

Multifunctionality in Epoxy Resins

Abstract

Epoxy resin will continue to be in the forefront of many thermoset applications due to its versatile properties. However, with advancement in manufacturing, changing societal outlook for the chemical industries and emerging technologies that disrupt conventional approaches to thermoset fabrication, there is a need for a multifunctional epoxy resin that is able to adapt to newer and robust requirements. Epoxy resins that behave both like a thermoplastic and a thermoset resin with better properties are now the norm in research and development. In this paper, we viewed multifunctionality in epoxy resins in terms of other desirable properties such as its toughness and flexibility, rapid curing potential, self-healing ability, reprocessability and recyclability, high temperature stability and conductivity, which other authors failed to recognize. These aspects, when considered in the synthesis and formulation of epoxy resins will be a radical advance for thermosetting polymers, with a lot of applications. Therefore, we present an overview of the recent finding as to pave the way for varied approaches towards multifunctional epoxy resins.     

Prediction of Heat Shield Performance in Terms of Epoxy Resin Structure

Abstract

High-strength, readily processable, char-forming, insulative materials are being sought for application in ablative heat shields for re-entry vehicles. Toward this end, the family of epoxy resins has been evaluated. The structure of epoxy resins and curing agents in terms of their functionality, aromaticity, and chemical nature is discussed in relation to its effect on ablative properties. The concept of controlled, constructive thermal degradation is extremely important in ablative epoxide compositions. Bridged Diels-Alder adducts based upon cyclic dienes and maleic anhydride perform well as epoxy resin curing agents in this respect. The mechanism of thermal ablative degradation of these systems is discussed in terms of in situ thermal control and char-forming reactions. The position of attachment of glycidyl groups, as well as the nature and position of other sub-stituents around the aromatic nucleus, has little effect in general upon the ablative properties of epoxy resins. Thermal and ablative data of both benzene and naphthalene derivatives are given. A new epoxy resin based upon 2-nitro resorcinol has been synthesized. This resin gives significant char increases, both quantitatively and qualitatively, over conventional epoxides. The unusual mechanism of polymerization and thermal degradation of this resin is discussed.     

The effect of nanoparticles on structural morphology, thermal and flammability properties of two epoxy resins with different functionalities

The effect of layered silicate nanoclays, nano-silica and double-walled carbon nanotubes (DWNTs) on the thermal stability and fire reaction properties of two aerospace grade epoxy resins (a high temperature curing tetra-functional and a low temperature curing bi-functional resin) has been investigated using thermal analysis, cone calorimetry, LOI and UL-94 techniques. The morphology of the polymer-clay nanocomposites, determined by X-ray diffraction and transmission electron microscopy indicated intercalated structures. The addition of nanoclays (5-wt%) to both resins had a thermal destabilisation effect in the low temperature regime (<400 °C), but led to higher char yield at higher temperatures. The inclusion of nano-silica at 30-wt% significantly improved the thermal stability of the resins while DWNTs had an adverse effect due to their poor dispersion in the matrix. The nanoclays and carbon nanotubes significantly increased the fire resistance of the tetra-functional epoxy resin while a minimal effect was observed for the bi-functional resin.     

Oligo-fluoropolymer Modified Cycloaliphatic Epoxy Resins with Excellent Compatibility,Waterproof and Mechanical Properties for LED Encapsulation

An oligo-fluoropolymer(PFM) with functional cycloaliphatic epoxy and fluorinated groups was obtained via free radical polymerization and applied to the modification of cycloaliphatic epoxy resins(CE). The chemical structure of PFM was characterized by Fourier transform infrared(FTIR) spectroscopy, gel permeation chromatography(GPC) and nuclear magnetic resonance(NMR) spectroscopy, and the effects of different PFM concentrations(0.5%—6%, mass fraction) on the thermal resistance, mechanical properties, surface dewettability, light transmission, refractive index and various cured polymer properties were studied in detail. The DSC and TGA results demonstrate that the modified epoxy resins possess a higher thermal resistance than the neat epoxy resin. The improvements in the surface dewettability and water resistance are caused by the high crosslinking density and the enrichment of the oligo-fluorinated random copolymers dispersed in the matrix. The fracture surface morphologies of the thermosets were investigated by scanning electron microscopy(SEM) and transmission electron microscopy(TEM). It was observed that the optical transmittance of the composites was maintained even though microphase separation occurred during the curing process. With respect to the corresponding properties of the neat epoxy resins, the 2 phr(parts per hundreds of resin) PFM thermoset exhibited relatively better comprehensive properties, making the cured material a good candidate for light-emitting diode(LED) encapsulation.     

EPOXY RESINS TOUGHENED WITH CARBOXYL TERMINATED POLYETHERS

Carboxyl terminated polyethers, the adducts of hydroxyl terminated polytetrahydrofuran and maleic anhydride, were used as toughener for epoxy resins. The morphology of the toughened resins was investigated by means of turbidity measurement, dynamic mechanical testing and scanning electron microscope observation. It turned out that the molecular weight and the carboxyl content of the polyether and the cure conditions are important factors, which affect the particle size of the polyether-rich domains and, in turn, the mechanical properties of the cured resin. Carboxyl terminated polytetrahydrofurans have a low glass transition temperature, and in appropriate amount they do not affect the thermal resistance of the resin. These advantages make them preferable as toughener for epoxy resins.     

Imidazole‐type thermal latent curing agents with high miscibility for one‐component epoxy thermosetting resins

Epoxy resins are important thermosetting resins widely employed in industrial fields. Although the epoxy–imidazole curing system has attracted attention because of its reactivity, solidification of a liquid epoxy resin containing imidazoles proceeds gradually even at room temperature. This makes it difficult to use them for one‐component epoxy resin materials. Though powder‐type latent curing agents have been used for one‐component epoxy resin materials, they are difficult to apply for fabrication of fine industrial products due to their poor miscibility. To overcome this situation and to improve the shelf life of epoxy–imidazole compositions, we have developed a liquid‐type thermal latent curing agent 1 , generating an imidazole with a thermal trigger via a retro‐Michael addition reaction. The latent curing agent 1 has superior miscibility toward epoxy resins; in addition, it was confirmed that the epoxy resin composition has both high reactivity at 150 °C, and long‐term storage stability at room temperature. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2680–2688