壬基酚聚氧乙烯(10)醚衣康酸单酯磺酸二钠盐的合成

以壬基酚聚氧乙烯醚(OP-10)、衣康酸(IA)和亚硫酸钠为原料,通过酯化反应和磺化反应成功合成了壬基酚聚氧乙烯醚衣康酸单酯磺酸二钠盐。考察了反应温度、反应时间和物料物质的量比对反应体系的影响,得到的最佳工艺条件为:OP-10与IA的物质的量比为1∶1.05,酯化温度120℃,酯化时间4 h;酯化产物与亚硫酸钠物质的量比为1∶1.05,磺化温度90℃,磺化时间4 h。并通过红外光谱(IR)对产品结构进行对比分析,确定产物结构。     

塑料水杯中邻苯二甲酸酯的迁移污染评价

为了考察塑料水杯在使用条件下的邻苯二甲酸酯(phthalic acid erters,PAEs)污染水平,选取不同材质的塑料水杯为研究对象,采用固相萃取-高效液相色谱法测定塑料水杯中的PAEs,利用非参数检验等统计方法对塑料水杯中饮用水的PAEs进行统计分析.结果表明,仅有1个水杯的饮用水中未检出PAEs,73.1%的水杯饮用水中检出2种或2种以上的PAEs,其中邻苯二甲酸二乙酯的检出率最高.塑料水杯的材质对PAEs总质量浓度没有显著影响,而对邻苯二甲酸丁基苄基酯和邻苯二甲酸二丁酯的质量浓度有一定影响.塑料水杯的颜色对饮用水中PAEs总质量浓度也没有显著影响.虽然使用塑料水杯饮水摄入的PAEs的量要比玻璃水杯高,但与美国EPA所规定的参考剂量相比较,所占比例都不足1%.使用质量合格的塑料水杯饮水带来的PAEs污染很小,不会成为PAEs污染的主要来源.     

Control of shrinkage and final conversion of vinyl ester resins cured in low‐temperature molding processes

Vinyl ester resin is a major thermoset polymer used in low‐temperature composite manufacturing processes such as the Seemann composite resin infusion‐molding process (SCRIMP). Volume shrinkage and residual styrene are important concerns for composites produced in such processes. A low‐shrinkage additive (LSA) is a typical agent added to control the volume shrinkage of vinyl ester resins during molding. In this study, the effects of LSA content and the temperature profile (the temperature gradient and peak temperature) on the volume shrinkage control of a vinyl ester resin were investigated. The reaction kinetics of the resin system were also studied. We achieved good volume shrinkage control if we raised the curing temperature slowly to allow sufficient time for phase separation and if the curing temperature reached a high value after phase separation to allow microvoid formation. On the basis of experimental results, we designed an improved SCRIMP to increase resin conversion, reduce resin shrinkage, and produce composites with better properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1486–1496, 2003     

Well-defined polymer precursors synthesized by RAFT polymerization of N,N-dimethylacrylamide/N-acryloxysuccinimide: random and block copolymers

N,N-dimethylacrylamide (DMA) and N-acryloxysuccinimide (NAS) were copolymerized by the reversible addition–fragmentation chain transfer (RAFT) polymerization technique, to obtain random and block copolymer precursors onto which different side-groups may be statistically grafted via the reactive NAS units. These reactive copolymers have interesting applications in various fields such as coatings and paints, water purification and biology. Random poly(DMA-co-NAS) copolymer chains were synthesized with a 75/25 molar ratio, high conversion, an excellent molecular weight (MW) control from 5000 to 130 000 g mol⁻¹, and low polydispersity index (M_w/M_n<1.1). Poly(DMA-b-NAS) block copolymers were synthesized by a two step method, in which a poly(DMA) homopolymer was prepared first and then used as macro-chain transfer agent to polymerize NAS. For example, a poly(DMA-b-NAS) sample was obtained with an average molecular weight of 44 300/7400 g mol⁻¹ corresponding to 447 DMA and 44 NAS units. Such block copolymers had not yet been synthesized by any controlled polymerization technique. They can be used to prepare polymers with exactly the same backbone and an increasing number of different side groups (e.g. hydrophobic, ionic or fluorescent).     

植物油制备生物柴油的研究

分别以菜籽油、大豆油以及芸香籽油为原料，采用碱催化酯交换法制备了脂肪酸甲酯即生物柴油。结果表明，用碱催化酯交换法制备脂肪酸甲酯，原料的酸价低于1．5mgKOH／g时能够保证较高的脂肪酸甲酯收率，采用酸催化预酯化法对高酸价的油脂原料进行脱酸效果比较显著。浓硫酸不仅是油脂预酯化脱酸反应的催化剂，也是油脂与甲醇进行酯交换反应的催化剂，但与甲醇钠等碱性催化剂相比，相同条件下的酯交换反应转化率低。采用减压蒸馏的方法提纯生物柴油，在0．098MPa的真空度下应控制其馏出温度不超过240℃。     

对映选择性氢化法合成苯甘氨酸甲酯

以α 肟基苯乙酸甲酯为原料,硫酸奎宁为修饰剂,通过Pd/C催化氢化合成苯甘氨酸甲酯。考察了反应温度、溶剂、修饰剂的量对对映选择性的影响。最佳反应条件:25～28℃、乙醇为溶剂、氢气压力101 325kPa、n(修饰剂)∶n(底物)=1∶10,苯甘氨酸甲酯的光学产率达51 3%。     

Larval osmeterial secretions of the swallowtails (Papilio)

The larval osmeterial secretions of sixPapilio species examined displayed a remarkable qualitative change at the fourth larval ecdysis. The secretions of 4th (penultimate) instar larvae ofP. machaon, P. memnon, P. helenus, P. bianor, andP. maackii principally comprised mono- and/or sesquiterpenoids. The compounds identified from these species included -pinene, sabinene, -myrcene, limonene, -phellandrene, (Z)--ocimene, (E)--ocimene, -elemene, -caryophyllene, (E)--farnesene, -selinene, (E,E)--farnesene, germacrene-A, germacrene-B, caryophyllene oxide, methyl 3-hydroxy-n-butyrate, and acetic acid. In contrast, the secretion of 4th larval instar ofP. xuthus, although containing similar terpenic compounds, was accompanied by large amounts of aliphatic acids and their esters: isobutyric acid, 2-methylbutyric acid, methyl isobutyrate and methyl 2-methylbutyrate. On the other hand, the osmeterial secretions of 5th (last) instar larvae varied little in quality among the six species, and the identified compounds consisted of isobutyric acid, 2-methylbutyric acid, methyl isobutyrate, ethyl isobutyrate, methyl 2-methylbutyrate, ethyl 2-methylbutyrate, and isovaleric acid, the last of which was specific toP. bianor andP. maackii. The chemical alteration of osmeterial exudate synchronized at the final larval ecdysis with the larval morphological change (particularly in body coloration) that appears to be of defensive significance against predators.     

Mechanical characterization and chemical resistances of cured unsaturated polyester resins modified with vinyl ester resins based on recycled poly(ethylene terephthalate)

Unsaturated polyester resin (UP) was prepared from glycolyzed oligomer of poly(ethylene terephthalate) (PET) waste based on diethylene glycol (DEG). New diacrylate and dimethacrylate vinyl ester resins prepared from glycolysis of PET with tetraethylene glycol were blended with UP to study the mechanical characteristics of the cured UP. The vinyl ester resins were used as crosslinking agents for unsaturated polyester resin diluted with styrene, using free‐radical initiator and accelerator. The mechanical properties of the cured UP resins were evaluated. The compressive properties of the cured UP/styrene resins in the presence of different vinyl ester concentrations were evaluated. Increasing the vinyl ester content led to a pronounced improvement in the compression strength. The chemical resistances of the cured resins were evaluated through hot water, solvents, acid, and alkali resistance measurements. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3175–3182, 2007     

Moisture absorption by cyanate ester modified epoxy resin matrices. Part I. Effect of spiking parameters

The moisture absorption of cyanate ester modified epoxy resin matrices has been studied under thermal spiking conditions. Enhanced moisture absorption has been observed at spike-temperatures above 120 °C. The results of the desorption studies on both control specimens and the spiked specimens showed that some of the water molecules remained entrained in the polymer. It is postulated that this water could be associated with that which is hydrogen bonded or from the hydrolysis of isolated residual cyanate ester groups because the concentration of entrained water remains constant at spike-temperatures below 180 °C. Above 180 °C a thermally activated process, leading to chain scission as indicated by a reduced recoverability of the glass transition temperature (T_g) on drying.On isothermal resorption, the moisture concentration was found to be similar to that achieved through thermal spiking, showing that the entrained water at the lower spike-temperatures can also be achieved under mild conditions. The T_g is reversibly recovered to within 5 °C, which indicates a degree of relaxation rather than degradation. The moisture diffusion coefficient estimated from the resorption curves is lower than those estimated from the absorption and desorption curves. The isothermal resorption diffusion coefficient also decreased with increasing spike temperature. It is proposed that thermal spiking induced a relaxation of the network but as the spike-temperature approaches the transition region of the wet polymer, further hydrolytically induced relaxation events become feasible.     

阳离子交换树脂催化合成十三碳二元酸二乙酯

以强酸性阳离子交换树脂为催化剂,十三碳二元酸与乙醇为原料合成十三碳二元酸二乙酯,考察了影响反应的因素。结果表明:醇酸摩尔比为4∶1,催化剂用量为酸质量的2%,在3分子筛脱水的情况下反应7 h,酯化率达98.4%,并且催化剂可重复使用3次。