Domain structure and miscibility studies of blends of styrene–butadiene–styrene block copolymers (SBS) and styrene–glycidyl methacrylate statistical copolymers (PS‐GMA) using SAXS and DMTA

The domain structure and miscibility in the solid state of a series of blends of styrene‐butadiene‐styrene (SBS) block copolymers and styrene‐glycidyl methacrylate (PS‐GMA) statistical copolymers with varying molecular weights and compositions were studied using small angle X‐ray scattering and dynamic mechanical thermal analysis. Depending on the molecular characteristics of each component, different types and degrees of solubilization of PS‐GMA in SBS were found which, in addition to the initially SBS phase morphology, lead to materials with multiphase domain morphologies with differences in size and structure. The degree of solubilization of PS‐GMA into the PS domains of SBS was found to be higher for blends containing PS‐GMA with lower molecular weight (M_w = 18 100 g mol^?1) and lower GMA content (1 wt%) and/or for SBS with higher PS content (39 wt%) and longer PS blocks (M_w = 19 600 g mol^?1). Localized solubilization of PS‐GMA in the middle of PS domains of SBS was found to be the most probable to occur for the systems under study, causing swelling of PS domains. However, uniform solubilization was also observed for SBS/PS‐GMA blends containing SBS with composition in the range of a morphological transition (PS block M_w = 19 600 g mol^?1 and 39 wt% of PS) causing a morphological transition in the SBS copolymer (cylinder to lamella). Copyright © 2006 Crown in the right of Canada. Published by John Wiley & Sons, Ltd     

Effect of glycidyl methacrylate (GMA) content on thermal and mechanical properties of ternary blend systems based on cardanol-based vinyl ester resin,styrene and glycidyl methacrylate

Cardanol-based vinyl ester resin (CVER) was prepared by reacting indigenously synthesized cardanol-based epoxidized novolac resin (CENR) with methacrylic acid (MA) in the presence of triphenylphosphine as catalyst. Five samples of cardanol-based vinyl ester resin containing styrene and glycidyl methacrylate (GMA), as diluents, in the weight ratios 40:0, 30:10, 20:20, 10:30 and 0:40 were prepared at room temperature. Sharp exotherms were observed in DSC scans in the temperature range of 60–170 °C. The onset temperature (T_onset), peak exothermic temperature (T_p) and completion temperature (T_stop) decreased with increase in GMA content in the ternary blend systems of CVER/styrene/GMA. A broad exotherm was observed after the initial sharp exotherm that was attributed to the etherification reaction. Cured samples were found to be stable up to 205–235 °C and started loosing weight above this temperature. Rapid decomposition was observed in the temperature range of 400–550 °C as evidenced by TGA analysis. Increase of GMA content in ternary blend systems of CVER/styrene/GMA lowered the tensile strength progressively and enhanced the impact strength and elongation-at-break. The cured films of VER containing mixture of styrene and GMA exhibited good gloss and impact resistance. The chemical resistance of cured films of VER containing mixture of styrene and GMA showed good resistance to acids, deionized water, synthetic sea water and mineral turpentine oil.     

E-MA-GMA对聚乙烯/水镁石粉高填充体系增容作用的研究

采用含甲基丙烯酸缩水甘油酯的三元共聚物(E-MA-GMA),对聚乙烯/水镁石(PE/MGH)高填充体系(质量比40/60)进行增容改性研究。通过对复合体系进行力学性能测试、DSC分析、环境扫描电镜(ESEM)对材料的冲击断面的微观形貌分析等方面的研究。结果表明:增容剂能够影响材料结构,有效地提高PE/MGH高填充复合材料的力学性能。     

网格监控技术的研究

为网格提供一种可扩展的机制去监控网格中的资源信息是至关重要的，文章介绍了网格的监控对象、监控事件及数据的产生，分析讨论了GMA和MDS这两种常用的网格监控体系结构，前者是一个理论上的模型，后者则是已获得广泛应用的Globus工具集中的一个重要的信息服务监控组件。     

PolyHIPEs: Recent advances in emulsion-templated porous polymers

Porous polymers with well-defined porosities and high specific surface areas in the form of monoliths, films, and beads are being used in a wide range of applications (reaction supports, separation membranes, tissue engineering scaffolds, controlled release matrices, responsive and smart materials) and are being used as templates for porous ceramics and porous carbons. The surge in the research and development of porous polymer systems is a rather recent phenomenon. PolyHIPEs are porous emulsion-templated polymers synthesized within high internal phase emulsions (HIPEs). HIPEs are highly viscous, paste-like emulsions in which the major, “internal” phase, usually defined as constituting more than 74% of the volume, is dispersed within the continuous, minor, “external” phase. This review focuses upon the recent advances in polyHIPEs involving innovations in polymer chemistry, macromolecular structure, multiphase architecture, surface functionalization, and nanoparticle stabilization. The effects of these innovations upon the natures of the resulting polyHIPE-based materials (including bicontinuous polymers, nanocomposites, hybrids, porous ceramics, and porous carbons) and upon the applications involving polyHIPEs are discussed. The advances in polyHIPEs described in this review are now being used to generate new families of porous materials with novel porous architectures and unique properties.     

改性吸水树脂合成及其吸水膨胀橡胶的性能

本文以聚丙烯酸钠为主要原料,用抗坏血酸/过氧化氢为引发体系合成了聚丙烯酸钠系吸水树脂,并将所制备的吸水树脂与天然橡胶制备成吸水膨胀橡胶,考察了甲基丙烯酸缩水甘油酯（GMA）与丙烯酸钠的比例对吸水树脂性能及其吸水膨胀橡胶性能的影响。实验结果表明, GMA改性吸水树脂对吸水树脂及其吸水膨胀橡胶性能的吸水性能有较大的影响,同时GMA改性吸水树脂可与橡胶共硫化。当GMA的物质量比为2%时,制备的吸水橡胶各项性能最佳,力学性能较佳,橡胶吸水膨胀过程中,吸水树脂析出现象显著降低。     

Reactive blends of gelatinized starch and polycaprolactone‐g‐glycidyl methacrylate

Blends of the modified polycaprolactone (PCL) and the gelatinized starch with glycerin were prepared. The modified PCL, PCL‐g‐glycidyl methacrylate (GPCL), was synthesized by melt reaction of PCL and glycidyl methacrylate (GMA) in the presence of benzoyl peroxide (BPO) in a Brabender mixer. The size of the dispersed starch in the GPCL matrix was found to be smaller than that in the PCL matrix. As the relative content of the GMA groups in the GPCL increases, the elongation at break of the blend showed the highest value at a grafted GMA content of 4.2 wt %. With the increase of the glycerin content in the starch, an abrupt change of the mechanical properties of the blend were observed between 40 and 50 wt % glycerin content based on the starch weight. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1507–1516, 2001     

基于关系模型的网格监测系统实例研究

网格自20世纪90年代中期被提出以来,得到迅猛发展,被称作因特网的第三次革命。而网格资源监测是网格系统中非常关键的一环,成为重要的研究方向。分析了网格监测系统的要求,以及现有基于层次数据模型的监测系统的不足,然后着重从技术角度研究了基于关系数据模型的网格监测系统———R-GMA的具体实现。指出了R-GMA未来的研究方向以及网格监测技术的发展趋势。     

Gobal optimization of hybrid kinetic/FBA models via outer-approximation

Flux balance analysis (FBA) is a linear programming-based framework widely used to predict the behavior, in terms of the resulting flux distribution, of cellular organisms in different media. FBA models are constructed using only stoichiometric information, and for this reason they sometimes fail in predicting fluxes precisely. In this work, we formally define the concept of hybrid FBA/kinetic models, in which kinetic information of key processes is used to tighten the search space of standalone FBA formulations, thereby enhancing their predictive capabilities. This approach leads to non-linear non-convex models that may exhibit multiple local optima. To solve them to global optimality, we use a customized outer-approximation algorithm that exploits the structure of the kinetic equations. Numerical results show that our method enhances the quality of standalone FBA models, providing more accurate predictions.     

Guaranteed fillet weld geometry from heat transfer model and multivariable optimization

Numerical heat transfer models of gas metal arc (GMA) fillet welding do not always predict correct temperature fields and fusion zone geometry. The inaccuracy results, to a large extent, due to the difficulty in correctly specifying several input parameters such as arc efficiency from scientific principles. In order to address this problem, a heat transfer model is combined with an optimization algorithm to determine several uncertain welding parameters from a limited volume of experimental data. The resulting smart model guarantees optimized prediction of weld pool penetration, throat and leg-length within the framework of phenomenological laws. A boundary fitted coordinate system was used to account for the complex fusion zone shape. The weld pool surface profile was calculated by minimizing the total surface energy. Apart from the direct transport of heat from the welding arc, heat transfer from the metal droplets was modeled considering a volumetric heat source. The Levenberg–Marquardt and two versions of conjugate gradient method were used to calculate the optimized values of unknown parameters. An appropriate objective function that represented the difference between the calculated and experimental values of the penetration, throat and leg-length was minimized. The calculated shape and size of the fusion zone, finger penetration characteristic of the GMA welds and the solidified free surface profile were in fair agreement with the experimental results for various welding conditions.