反相高效液相色谱法测定一种口腔炎喷雾剂中绿原酸和咖啡酸的含量

取1mL口腔炎喷雾剂样品,用甲醇-水(1+1)溶液定量稀释至10mL,分取此溶液25μL供反相高效液相色谱法测定其绿原酸和咖啡酸含量。采用Shim-packVP-ODS色谱柱分离,以甲醇-0.012mol·L-1磷酸(27+73)混合溶液为流动相,柱温为30℃,流量为0.8mL·min-1,紫外检测器波长为323nm。结果表明:绿原酸在0.51～91.80mg·mL-1,咖啡酸在2.0～360.0mg·mL-1范围内呈线性关系,用标准加入法测定方法的回收率,结果依次在95.9%～97.4%和100.1%～100.9%范围内,检出限(3S/N)依次为0.10,0.40mg·mL-1,测定下限(10S/N)依次为0.36,1.40mg·mL-1。     

Thermal cured epoxy resins using certain calixarenes and their esterified derivatives as curing agents

The acetyl esterified calixarene (CA) derivatives were prepared from calix[4]resorcinarene (CRA), and p‐tert‐butylcalixarene (BCA[n], n = 4, 6, 8), respectively. Using these CA derivatives as curing agents, the thermal curing reactions of two multifunctional epoxy resins (jER 828, 186 g/equiv., and ESCN, 193.7 g/equiv.) were investigated. The temperatures of glass transition (T_g) and decomposition (T) were measured by DSC and TGA, respectively. Based on the yields, T_gs, and T_ds of the thermal cured jER 828 epoxy resin with CRA‐E100, the curing conditions were optimized to be tetrabutylphosphonium bromide (TBPB) as catalyst in NMP at 160 °C for 15 h. Under this curing condition, the cured materials of jER 828 or ESCN using various CA derivatives as curing agents were prepared. Except for BCA4 derivatives, the yields of thermal curing reaction were higher than 90%. T_gs and Ts of the resultant cured materials were in the range of 113–248 °C and 363–404 °C, respectively. These results mean that the cured epoxy resins with excellent T_gs were successfully formed by using CA derivatives as curing agents. It was also found that the T_gs of cured epoxy resins were strongly affected by the degree of esterification of CA derivatives. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1931–1942, 2010     

Non-extractable photoinitiators based on thiol-functionalized benzophenones and thioxanthones

Non-extractable photoinitiators could be advantageous for use in biological, electronic, and food packaging applications. Therefore, thioxanthone and benzophenone derivatives were synthesized from 1,6-hexane dithiol and chlorinated benzophenone or thioxanthone. The efficiency of thiol-functionalized photoinitiators in combination with amine co-initiators was compared to benzophenone and isopropylthioxanthone with amine co-initiators, and the cleavage of photoinitiator 2,2-dimethoxy-1,2-diphenylethan-1-one in acrylic resins. The reaction kinetics were analyzed using photo-differential scanning calorimetry and real-time FTIR. Coating physical properties were evaluated by pendulum and pencil hardness, steel-wool scratch and mandrel bend tests. The non-extractable photoinitiators had higher absorbance than their benzophenone or isopropylthioxanthone counterparts due to the sulfide substitution on the phenyl ring, and the free thiol groups reacted with the acrylate by either an amine catalyzed Michael addition or a free-radical chain process. The combination of thiol-functionalized photoinitiators with secondary amines provides an efficient photoinitiator system that is locked into the photopolymerized network and cannot be extracted with typical solvents.     

Preparation and Characterization of Graphite‐Epoxy Composite Modified with Zinc Hexacyanoferrate and Their Electrochemical Behaviour in Presence of Substituted Anilines

The growth of zinc hexacyanoferrate (ZnHCF) hybrid film on the surface of graphite‐epoxy composite (GEC) electrodes was demonstrated by cyclic voltammetry. Surface morphology of the hybrid film was investigated by using scanning electron microscopy. The effect of the type of monovalent cations on the redox behaviour of hybrid film was also studied. This effect indicated that the radius of the hydrated cation mainly determines the ion permeability of the film.     

环氧化蓖麻油的合成及表征

采用酸性氧化铝做催化剂对蓖麻油(CO)进行环氧化,探索环氧化反应时间、反应温度和催化剂等不同条件对蓖麻油环氧化的影响,从而优化出合适的反应条件,采用傅立叶变换红外光谱法(FTIR)、热重分析法(TG)对制备的环氧化蓖麻油(ECO)的结构和性质等进行了研究。利用盐酸-丙酮法对环氧化产物进行环氧值的测定,结果表明,在优化条件下,即采用酸性氧化铝做催化剂,H₂O₂的滴加温度保持在50～55 ℃,反应温度65 ℃,反应时间控制在11.5 h,同时同时加入尿素做稳定剂,可以提高H₂O₂的利用率,使环氧化蓖麻油的环氧值达到2.094×10_-3 mol/g。 对ECO的性能表征结果表明,ECO粘度随着环氧值的增大而增大,随着温度的升高而降低。 ECO在250 ℃前能够基本保持稳定,而后开始分解,有3个明显的热分解阶段：250~390 ℃、390~470 ℃、470~580 ℃,ECO的热稳定性较好。     

反气相色谱法测定环氧树脂的表面张力和溶解度参数

采用反气相色谱(IGC)测定了环氧E51树脂在30、40、50和60 ℃下的表面张力和溶解度参数。采用Schultz法,以正癸烷、正壬烷、正辛烷和正庚烷为非极性溶剂探针,计算了不同温度下环氧E51树脂的色散表面张力。根据Good-van Oss方程,以甲苯为碱性探针,二氯甲烷为酸性探针,计算得到环氧E51树脂的极性表面张力。结果表明,环氧E51树脂的色散表面张力和极性表面张力均随着温度的升高而线性降低。根据不同溶剂探针与树脂间的Flory-Huggins相互作用参数,采用DiPaola-Baranyi和Guillet方法计算得到环氧E51树脂在不同温度下的溶解度参数,其在30、40、50和60 ℃下分别为11.78、11.57、11.48和11.14 MPa1/2。根据表面张力、内聚能和溶解度参数的相互关系,计算得到不同温度下溶解度参数的色散和极性分量。结果发现,环氧E51树脂的溶解度参数的色散分量大于极性分量,且均随着温度的升高而降低。     

缩水甘油胺型聚氨酯胶粘剂的性能研究北大核心CSCD

采用商品化SKE-1型环氧树脂对自制聚氨酯预聚体(NCOPU)进行封端,制备了缩水甘油胺型聚氨酯(GAPU),并用傅里叶-红外光谱(FT-IR)对其结构进行表征,用在线FT-IR监控间苯二甲胺固化GAPU过程,用差示量热扫描(DSC)研究其相分离,用扫描电镜(SEM)观察固化物的表面微观形貌,用热重(TG)分析固化物的热力学稳定性。探讨了聚丙二醇(PPG)分子量的大小、不同质量分数的SKE-1对NCOPU封端及不同种类的固化剂对GAPU固化物力学性能的影响。研究表明:在60℃时用间苯二甲胺固化GAPU,2h即可固化完全,固化物热稳定性能良好,其外推起始分解温度为248.3℃,5%的分解温度为282.6℃。GAPU固化物的力学性能随着GAPU的环氧值减小而减小,在室温以上力学性能下降,在-196℃力学性能增加,其环氧值为0.153,在-196℃的拉伸剪切强度最佳,为16.11MPa。     

Thioxanthone–carbazole as a visible light photoinitiator for free radical polymerization

A thioxanthone (TX) derivative with the additional carbazole chromophore, namely thioxanthone‐carbazole (TX‐C) was synthesized and characterized. The photophysical properties and its efficiency to polymerize methyl methacrylate both in the presence and absence of N,N‐dimethylaniline (DMA) as coinitiator was investigated and compared with that of the commercially available TX. TX‐C was found to display better photophysical properties and in both cases initiate polymerization more efficiently. Detailed real‐time Fourier transform infrared studies revealed that high polymerization rates can be obtained when TX‐C in conjunction with DMA was used. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Analysis of benzophenone and 4-methylbenzophenone in breakfast cereals using ultrasonic extraction in combination with gas chromatography-tandem mass spectrometry (GC-MS)

Benzophenone (BP) and 4-methylbenzophenone (4MBP) are photo-initiators that are generally used to cure ink on carton boards.In this contribution, a fast and reliable method for the determination of BP and 4MBP in breakfast cereals is described. The sample was extracted ultrasonically using a mixture of dichloromethane and acetonitrile (1:1), followed by a clean-up of the extract using solid phase extraction with a silica cartridge. Finally, the extract was analysed by GC-MSⁿ. Benzophenone-d₁₀ was used as internal standard. The presented method is validated in terms of linearity, recovery, repeatability and intra-laboratory reproducibility, specificity, limit of detection and limit of quantification. In conclusion, this method is able to detect both BP and 4MBP at very low concentrations (LOD = 2 μg kg⁻¹) in breakfast cereals.     

Low Dielectric Thermoset from Redistributed Poly(phenylene oxide)

A curable low-molecular-weight poly(phenylene oxide) (PPO) was prepared by the redistribution of regular PPO with bisphenol-A (BPA) followed by etherification of the redistributed-PPO (BPA-PPO) with N,N-diallyl-2-chloroacetamide. The redistributed-PPO with allyl group (AL-PPO) was characterized by proton nuclear magnetic resonance, and Fourier transform infrared spectroscopy. The AL-PPO oligomers with reactive double bounds were cured with triallylisocyanurate (TAIC) and/or phosphorus-containing allyl-functionalized monomer (allyl-DOPO). The glass transition temperatures were measured by dynamic mechanical analysis (DMA). Electrical properties of cured resins were studied using dielectric analyzer (DEA). The flame retardancy was determined by a UL-94 vertical test. The effects of curing accelerator, amount of TAIC and allyl-DOPO incorporated into the network on the glass transition temperatures, dielectric properties, and flame retardancy of the resulting systems were investigated. The results indicated that AL-PPO cured with TAIC exhibited high glass-transition temperature (162–198°C), low dielectric constants (2.36–2.57 at 1 GHz) and dissipation factors (0.0039–0.0043 at 1 GHz). The AL-PPO/TAIC copolymerized with allyl-DOPO could achieve a flame retardancy rating of UL-94 V-0 at about 1.35% phosphorus content. The AL-PPO/TAIC resins have potential applications in the fabrication of printed circuit board.