乳清蛋白凝胶及其影响因素的机理研究

本文概述了乳清蛋白凝胶的一般机理 ,说明了凝胶形成的大概过程 ,即乳清蛋白分子变性展开、发生分子凝聚、形成凝胶胶束最后形成乳清蛋白凝胶 ;并论述了一些因素如金属盐、pH值和温度等影响乳清蛋白胶特性的可能机理 ,这些因素对乳清蛋白凝胶的形成有较大影响 ,在凝胶过程中需要进行良好的控制以获得所须的产品     

不同氧化酶体系对阿拉伯木聚糖溶液流变学性质影响的研究

本文采用小振幅振荡流变学测量法研究了三种不同氧化酶-过氧化物酶（POX）、葡萄糖氧化酶（GOX）、脂肪氧合酶（LOX）对小麦面粉中水可提取阿拉伯木聚糖（WEAX）流变学性质的影响.结果显示：1）在POX/H2O2反应体系中,一定酶用量范围内（2.4～4.8U/g）,增加POX的用量可提高WEAX发生氧化胶凝的速率及增强凝胶的弹性,进一步增加酶用量则仅可缩短凝胶形成时间;2）在GOX/葡萄糖（Glc）/POX反应体系中,GOX用量对WEAX溶液流变性质的影响与POX的相似,但与POX相比,由GOX催化的氧化胶凝反应有一迟滞期;3）在LOX/亚油酸（LA）反应体系中,LOX对于WEAX的氧化胶凝反应有一最适用量,酶用量过低或过高均不利于凝胶的形成,且LOX的作用要弱于前两种氧化酶.     

Effect of heating temperature and sodium chloride concentration on ultrastructure and texture of gels made from giant squid (Dosidicus gigas) with addition of starch,l-carrageenan and egg white

This paper seeks to compare the ultrastructure of gels made from frozen muscle of giant squid (Dosidicus gigas) at various temperatures with a number of different rheological parameters, with reference to a variety of added ingredients (non-muscle proteins and hydrocolloids) and to NaCl concentration. Interesting data on gel rheological properties were found where formulae containedl-carrageenan, starch and egg white, with a low salt concentration (1.5%). This seems to be because carrageenan forms an independent network which supports the principal structure formed by the fish protein; starch is incorporated into the network and retains water; and egg white forms a supplementary network which helps to improve rheological properties.     

Rheological changes for urethane polymerizations in bulk and in solution

Viscosity rise and extent of reaction were followed during the step growth polymerization of linear and branched urethanes in bulk and in solution. Results indicate that intra-molecular reaction may exist in both linear and branched systems. Adding solvent increases the extent of intra-molecular reaction. The system viscosity was found to correlate with CgM_w, where C is polymer concentration, g is the ratio of branched to linear polymer radii of gyration, and M_w is the weight-average molecular weight.     

Curing of epoxy systems at sub‐glass transition temperature

Three epoxy‐amine thermoset systems were cured at a low ambient temperature. Evolution of the reaction kinetics and molecular structure during cure at the sub‐glass transition temperature was followed by DSC and chemorheology experiments. The effect of vitrification and the reaction exotherm on curing and final mechanical properties of the epoxy thermosets was determined. Thermomechanical properties of the low‐temperature cured systems depend on the reaction kinetics and volume of the reaction mixture. Curing of the fast‐reacting system in a large volume (12‐mm thick layer) resulted in the material with T_g exceeding the cure temperature by 70–80°C because of an exothermal temperature rise. However, the reaction in a too large volume (50‐mm layer) led to thermal degradation of the network. In contrast, thin layers (1.5 mm) were severely undercured. Well‐cured epoxy thermosets could be prepared at sub‐T_g temperatures by optimizing reaction conditions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3669–3676, 2006     

包裹金属离子延迟交联凝胶堵水材料的制备与性能

采用聚合物网络束缚高价金属离子,再采用反相悬浮聚合包裹法制备高价金属离子包裹颗粒,双重作用达到缓慢释放高价金属离子的目的,再与堵水主剂HPAM延缓成胶得到一种凝胶堵水材料。使用旋转粘度仪测定包裹颗粒/HPAM交联体系的成胶性能。结果显示包裹颗粒/HPAM交联体系的表观粘度与微胶囊用量有关,随微胶囊用量增加而增加;包裹颗粒/HPAM交联体系的成胶时间与温度和壁材含量有关,随温度的降低和壁材含量的增加而延长。交联体系成胶时间可以由包裹前的20h延缓到50h,表明包裹颗粒缓释性能良好,达到了延缓成胶的目的。     

锦16块深部液流转向驱油技术

辽河锦16块油井综合含水超过90%,近井地带调剖的效果已很差.研发了一种聚合物/酚醛成胶体系,该体系在30～110℃下可在数小时到教天内形成储能模量G'在0.2～2.0 Pa的可流动弱凝胶,与油基预交联聚合物J5(60～120目)一起,用作深部液流转向剂.讨论了该弱凝胶的组成与配方.试验区有4口水井,15口油井.其中两口水井处理半径15 m,分3个段塞注入J5颗粒量递增(5.0～8.0g/L)的1.5g/L HPAM溶液;另两口水井处理半径18 m,第一段塞为HPAM溶液携带J5颗粒,第二、第三段塞分别为低、高交联的3.0g/L聚合物弱凝胶.注入后注水压力上升,10口可对比油井中3口井无效果,7口井见效,产液量减少,含水下降,产油量增大.     

N,N,N-trimethyl chitosan nanoparticles as a vitamin carrier system

There is considerable interest in incorporating stabilized vitamins into biopolymeric nanoparticles, especially in the development of carriers and active systems for pharmaceutical and food applications. Amongst biopolymer, chitosan is highly desirable owing to its good biocompatibility, biodegradability and ability to be chemically modified. In this paper, nanoparticles from three kinds of water-soluble derivative chitosan (N,N,N-trimethyl chitosan, TMC) have successfully been synthesized by ionic gelation with tripolyphosphate (TPP) anions. Combinations of concentrations of TMC and TPP have resulted in nanoparticles with varying sizes for which the capability for loading with vitamins was investigated. Zeta potential measurement and particle size analysis demonstrated that the size of the nanoparticles was optimized (196 ± 8 nm) when the lowest TMC and TPP amounts were used, i.e., 0.86 mg mL⁻¹ and 0.114 mg mL⁻¹ respectively. As the TMC and/or the TPP concentrations increase, the resulting size of the nanoparticles increases considerably. Three different vitamins (B9, B12 and C) were tested as additives and the final system characterized in relation to size, morphology, spectroscopic and zeta potential properties. In general, the incorporation of vitamins increased all the TMC–TPP original nanoparticle sizes, reaching a maximum diameter of 534 ± 20 nm when loaded with vitamin C. The presence of vitamins also decreases the zeta potential, with one exception observed when using vitamin C. The preliminary results of this study suggested that all TMC/TPP nanoparticles can be successfully used as a stable medium to incorporate and transport vitamins, with potential applications in foodstuffs.     

Experimental Design in the Preparation of Modified HEMA-Based Superporous Hydrogels in an Aqueous Medium

Due to a relatively large number of excipients and their concentrations, which can be used effectively in the preparation of superporous hydrogels, an experimental design based on the Taguchi matrix has proven to be a very valuable tool in screening and narrowing down the final formulation. In this study, the effect of starting materials, their concentrations as well as the starting reaction temperature, were examined in the preparation of superporous hydrogels based on hydroxyethyl methacrylate. A large number of possible formulations and conditions might lead to the production of a reasonable hydrogel network, but some formulations produce stronger or faster swelling superporous hydrogels than others. The final properties of the superporous hydrogels depend upon the events that occur during formation of the gel, including the presence of atmospheric oxygen, which is responsible for the inhibition period seen at the start of the reaction, and also including the change in temperature at which the reaction starts. These events can be largely affected by the choice of ingredients used in the reaction. For this study, eight variables were chosen, and their effects were examined using a Taguchi matrix. The parameters examined were the maximum temperature during the reaction, the time corresponding to the maximum temperature, and the reaction yield which is represented by the weight of the dry final SPH.