Synthesis and properties of novel amphiphilic sulfated ionomers by the ring‐opening reaction of an epoxidized styrene–butadiene–styrene triblock copolymer

A method for the synthesis of novel sulfated ionomer of styrene–butadiene–styrene triblock copolymer (SBS) was developed. SBS was first epoxidized by performic acid in the presence of a phase‐transfer catalyst; this was followed by a ring‐opening reaction with an aqueous solution of alkali salt of bisulfate. The optimum conditions for the ring‐opening reaction of the epoxidized SBS with an aqueous solution of KHSO₄ were studied. During the ring‐opening reaction, both phase‐transfer catalyst and ring‐opening catalyst were necessary to enhance the conversion of epoxy groups to ionic groups. The products were characterized with Fourier transform infrared spectrophotometry and transmission electron microscopy (TEM). After the potassium ions of the ionomer were substituted with lead ions, the lead sulfated ionomer exhibited dark spots under TEM. Some properties of the sulfated ionomer were studied. With increasing ionic groups or ionic potential of the cations, the water absorbency and emulsifying volume of the ionomer and the intrinsic viscosity of the ionomer solution increased, whereas the oil absorbency decreased. The sulfated ionomer possessed excellent emulsifying properties compared with the sulfonated SBS ionomer. The sodium sulfated ionomers in the presence of 10% zinc stearate showed better mechanical properties than the original SBS. When the ionomer was blended with crystalline polypropylene, a synergistic effect occurred with respect to the tensile strength. The ionomer behaved as a compatibilizer for blending equal amounts of SBS and oil‐resistant chlorohydrin rubber. In the presence of 3% ionomer, the blend exhibited much better mechanical properties and solvent resistance than the blend without the ionomer. SEM photographs indicated improved compatibility between the two components of the blend in the presence of the ionomer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Survey of nitrate and nitrite contents of vegetables grown in Korea.

A scientific basis for the evaluation of the risk to public health arising from excessive dietary intake of nitrate in Korea is provided. The nitrate () and nitrite () contents of various vegetables (Chinese cabbage, radish, lettuce, spinach, soybean sprouts, onion, pumpkin, green onion, cucumber, potato, carrot, garlic, green pepper, cabbage and Allium tuberosum Roth known as Crown daisy) are reported. Six hundred samples of 15 vegetables cultivated during different seasons were analysed for nitrate and nitrite by ion chromatography and ultraviolet spectrophotometry, respectively. No significant variance in nitrate levels was found for most vegetables cultivated during the summer and winter harvests. The mean nitrates level was higher in A. tuberosum Roth (5150 mg kg(-1)) and spinach (4259 mg kg(-1)), intermediate in radish (1878 mg kg(-1)) and Chinese cabbage (1740 mg kg(-1)), and lower in onion (23 mg kg(-1)), soybean sprouts (56 mg kg(-1)) and green pepper (76 mg kg(-1)) compared with those in other vegetables. The average nitrite contents in various vegetables were about 0.6 mg kg(-1), and the values were not significantly different among most vegetables. It was observed that nitrate contents in vegetables varied depending on the type of vegetables and were similar to those in vegetables grown in other countries. From the results of our studies and other information from foreign sources, it can be concluded that it is not necessary to establish limits of nitrates contents of vegetables cultivated in Korea due to the co-presence of beneficial elements such as ascorbic acid and alpha-tocopherol which are known to inhibit the formation of nitrosamine.     

带肋钢筋套筒挤压连接的质量控制

针对太原可口可乐综合厂房主筋采用φ28、φ32三级钢存在的可焊性差的问题，提出了在施工中采用套筒挤压连接的方式，并对该方法的操作要点及质量控制措施进行了总结。     

Synthesis and aggregate formation of poly(styrenesulfonate)-b-poly(ethylene glycol)-b-poly(styrenesulfonate) triblock copolymers in aqueous solution induced by binding with aluminum ions

Summary  Well-defined water-soluble poly(styrenesulfonate)-b-poly(ethylene glycol)-b- poly(styrenesulfonate) (PSS-b-PEG-b-PSS) triblock copolymers with narrow molecular weight distribution (1.29 < M_w/M_n < 1.36) were synthesized in aqueous solution at 70 ^oC via reversible addition-fragmentation chain transfer (RAFT) polymerization. The complex formed by the PSS-b-PEG-b-PSS triblock copolymer coordinated with aluminum ion was investigated with turbidimetry, dynamic light scattering (DSL), zeta-potential, and transmission electron microscopy (TEM). The aggregation formation was based on the neutralization of the SO₃^- groups in the PSS blocks with Al³⁺ ions. The appearance, size and stability of the PSS-b-PEG-b-PSS/Al³⁺ aggregates were controlled by varying the PSS block length and degree of neutralization (DN). At DN = 0.33, where the PSS-b-PEG-b-PSS copolymer was completely neutralized with Al³⁺, the aggregate size increased with increasing PSS block length. The transition from the shrinking coil of small size to the interchain aggregates of large size was found at DN of about 0.33.     

基于资源流分析的企业生态补偿机制研究

循环经济作为一种新型的经济范式,成为理论界和实业界共同关注的焦点问题.在循环经济模式下引入了投入产出的资源流管理模型,该模型反映各个过程中资源流的流向和流量,为建立生态补偿机制提供了详细的基础数据,并利用外部环境的完善,推动生态补偿机制在微观领域的实施,从而达到改善企业环境绩效,减少环境污染的目的.     

固体超强酸S_2O_8~(2-)/SnO_2-SiO_2催化合成环己酮1,2-丙二醇缩酮

采用沉淀-浸渍法制备了固体超强酸S2O28-/SnO2-SiO2,以它为催化剂催化环己酮和1,2-丙二醇合成了环己酮1,2-丙二醇缩酮;考察了带水剂种类及用量、酮醇摩尔比、催化剂用量、反应时间对产品收率的影响,并用正交实验对反应条件进行了优化。实验结果表明,适宜的反应条件为:n(环己酮)∶n(1,2-丙二醇)=1∶1.6、催化剂用量为反应物料总质量的2.0%、带水剂环己烷用量5.0mL、反应时间50min。在此条件下,环己酮1,2-丙二醇缩酮收率达到91.47%;催化剂的稳定性良好,在重复使用5次后环己酮1,2-丙二醇缩酮收率为82.20%,活性下降的主要原因为催化剂表面积碳和吸附了有机物;经傅里叶变换红外光谱和气相色谱质谱分析表明,产物为环己酮1,2-丙二醇缩酮,纯度为100%。     

北京谱仪Ⅱ（BESⅡ）顶点探测器数据获取系统

北京谱仪（ＢＥＳⅡ）顶点探测器数据获取系统是北京谱仪数据获取系统的一部分，该子系统电子学采用快总线标准，本文描述了该系统的硬件结构和软件系统，软件包括快总线系统的微码软件和上层控制软件，该系统的死时间为１．５ｎｓ，对ＢＥＳⅡ系统总死时间的贡献小于０．５ｍｓ。     

Electron microscopic observations and DNA chain fragmentation studies on apoptosis in bone tumor cells induced by ~(153)Sm-EDTMP

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