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乳状液按其颗粒大小可分为普通乳状液(约IN10pm,微小乳状液(01~0·4Pm),微乳状液(001卜0.lPm).其中微小乳状液比普通乳状液颗粒小,分散均匀,稳定性好,比微乳状液所需乳化剂的用量要低得多,在实际应用中很有前景.但有关微小乳状液的研究工作做得很少[’-‘].在乳化过程中,若不需外界做功,靠乳化剂的自身作用,使两种不相混溶的液体自动混合,生成乳状液称为自发乳化,无需专门的乳化设备即可方便地制备出乳状液.目前自发乳化所得的乳状液颗粒都较大,稳定性较差卜一\若将微JJ、乳状液的制备与其自发形成的条件结合… 相似文献
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通过表面张力、Zeta电位和流变学参数的测定, 研究了聚氧乙烯烷基醚类非离子型表面活性剂(Brij 30和Brij 35)在合成锂皂石(Laponite)纳米颗粒表面的吸附及对Laponite水分散体系中颗粒间相互作用和体系粘度的影响. 结果表明, 这类表面活性剂能显著地吸附在Laponite颗粒表面上, 且吸附量随其分子中POE链长短而不同. 这种吸附没有改变Laponite粒子的带电性质, 但一定程度地降低了Laponite颗粒Zeta电位; 吸附也会减弱颗粒间的相互作用, 降低体系的粘度. 实验以Laponite和Brij为乳化剂, 制备了O/W型乳状液. 乳液稳定性变化和乳液粒径分布结果表明, 体系中Brij的浓度较低时, 乳液的性质主要是由Laponite颗粒决定的; 而Brij浓度较高时, 则主要取决于Brij表面活性剂. 高速剪切含Brij的Laponite水分散体系, 剪切后表面张力随时间的变化表明, 剪切作用会使得吸附在Laponite颗粒表面的Brij分子不同程度地解吸下来. 这也意味着乳液制备时, 高速剪切作用也会造成Brij分子自Laponite颗粒表面的脱附, 这可能是非离子表面活性剂与阳离子表面活性剂对负电固体颗粒稳定乳液影响不同的原因. 相似文献
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乳状液的微观特征影响着油包水乳状液的稳定性,从而影响油基钻井液的稳定性能。室内选用3#白油、26%CaCl2水溶液、JH主辅乳化剂,采用超声分散乳化方法,配制得到油包水型白油乳状液。采用显微图像技术,研究了JH主辅乳化剂加量、油水比、有机土对白油乳状液微观特性的影响;以油水界面张力、动态界面张力以及界面扩张粘弹性等为参数分析了乳状液稳定性的机理。结果表明:JH主辅乳化剂配比为4∶1,加量为4%,油水比为80∶20时,白油乳状液中的分散相呈球形液珠,直径为3.31~12.93μm;油水界面张力为0.559 mN·m-1;JH主辅乳化剂形成的油水界面膜强度大,白油乳状液稳定性好;有机土与JH主辅乳化剂的协同作用使白油乳状液和油基钻井液的稳定性能显著提高。 相似文献
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C12-s-C12·2Br和C12En混合水溶液的胶团化行为 总被引:1,自引:0,他引:1
季铵盐二聚表面活性剂C12-s-C12@2Br(s=2、3、4、6)和非离子表面活性剂C12E10或C12E23在水溶液中生成混合胶团.其临界胶团总浓度cmcT值介于二元复配体系中各组分的临界胶团浓度和之间.当添加少量非离子型表面活性剂(在水溶液中的摩尔分数α2=0.1)时,混合胶团中C12E10或C12E23的摩尔分数均已超过0.35;随着溶液中非离子型表面活性剂含量的增大,混合胶团中逐渐以C12E10或C12E23成分为主. 相似文献
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季铵盐二聚表面活性剂C12-s-C12·2Br(s=2、3、4、6)和非离子表面活性剂C12E10或C12E23在水溶液中生成混合胶团.其临界胶团总浓度cmcT值介于二元复配体系中各组分的临界胶团浓度cmc01和cmc02之间.当添加少量非离子型表面活性剂(在水溶液中的摩尔分数α2=0.1)时,混合胶团中C12E10或C12E23的摩尔分数均已超过0.35;随着溶液中非离子型表面活性剂含量的增大,混合胶团中逐渐以C12E10或C12E23成分为主. 相似文献
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利用微通道法乳化技术原理,研制了一个可拆卸T型玻璃微通道装置,以聚乙烯醇水溶液为连续相,聚(乳酸-co-羟基乙酸)(PLGA)的二氯甲烷溶液为分散相,制备了单分散的PLGA微球.考察了乳化剂用量、连续相和分散相流速以及PLGA浓度对形成的液滴平均粒径和变异系数(CV值)的影响.结果表明,增大乳化剂用量,提高连续相流速或降低分散相流速,制备得到的PLGA微球直径减小;分散相浓度在5~20 g/L之间变化时,其对微球直径的影响有限.PLGA微球表面光滑无孔,且内部是实心的.用本装置制备得到的PLGA微球,其粒径范围在30~200μm之间,CV值在15%以下,最低可至3%.该方法可使用挥发性有机溶剂作为分散相而且能避免微球制备时易堵塞等问题,可应用于药物缓控释领域中微米级单分散微球的制备. 相似文献
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血浆中极长链脂肪酸的毛细管气相色谱分析 总被引:3,自引:0,他引:3
建立了血浆中极长链脂肪酸毛细管气相色谱法,并用于测定了10例正常人和4例临床拟诊为肾上腺白质营养不良(ALD)病人血浆中极长链脂肪酸,其中一例肯定了ALD的临床诊断。 相似文献
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环境因素对正负表面活性剂体系相行为的影响 总被引:3,自引:0,他引:3
在1:1正负离子表面活性剂混合体系(十二烷基硫酸钠/辛基三甲基溴化铵 SDS-C8NM3Br; 十二烷基硫酸钠/十二烷基三甲基溴化铵,SDS-C12NM3Br)中加入短链脂肪醇 (乙醇,正丙醇,正丁醇),正负离子表面活性剂沉淀溶解,出现表面活性剂双水相.上相有液晶存在,下相有囊泡自发形成.折光率数据和电镜结果表明:上相为表面活性剂富集相,下相表面活性剂浓度较低.混合体系中,出现表面活性剂双水相所需短链脂肪醇的体积百分数,随短链脂肪醇的链长增加而降低.温度升高,出现表面活性剂双水相所需短链脂肪醇的体积百分数降低.对SDS/C8NM3Br/H2O体系的研究结果表明:超声处理,可使混合体系中沉淀向囊泡转化,与短链脂肪醇的加入后的作用类似. 相似文献
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The molar execess enthalpies of C_1 to C_5 normal alcohols with 1,4-dioxane have been measured with a Picker flow microcalorimeter. From our measurements we can come to the following results. Mixing n-alcohols with 1,4-dioxane are all endothermic processes. The maximum values of H~E are situated near 0.49 mole fraction of n-alcohols. H~E of these systems increase with increasing chain length of the alcohols, whereas the increments for two neighbour-alcohols decrease with increasing the number of carbon. 相似文献
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D. A. Stepanov A. Ermakova V. I. Anikeev 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(1):21-25
The objects of study were mixtures containing triglycerides and lower alcohols and also the products of the transesterification
of triglycerides, glycerol and fatty acid esters. The Redlich-Kwong-Soave equation of state was used as a thermodynamic model
for the phase state of the selected mixtures over wide temperature, pressure, and composition ranges. Group methods were applied
to determine the critical parameters of pure substances and their acentric factors. The parameters obtained were used to calculate
the phase diagrams and critical parameters of mixtures containing triglycerides and lower alcohols and the products of the
transesterification of triglycerides, glycerol and fatty acid esters, at various alcohol/oil ratios. The conditions of triglyceride
transesterification in various lower alcohols providing the supercritical state of reaction mixtures were selected. 相似文献
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在固定床反应器中,以大豆油为模型原料,研究了反应温度、压力、氢油比和空速等条件对Pt/SAPO-11催化油脂一步加氢制异构烷烃反应的影响,并分析了反应中间产物、气体产物(CO,CO2)及烷烃终产物的变化趋势. 结果表明,高温、低压或低氢油比可抑制酯、羧酸和醛的氢解以及醇的生成,促进油脂脱氧选择性地向脱羧和脱羰方向进行;异构烷烃收率随温度升高或空速减小而先增加后下降,但反应压力和氢油比的影响不大. 另外,对油脂一步加氢过程可能的反应历程进行了讨论. 相似文献
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麻疯油转酯化产物的高效液相色谱分析 总被引:2,自引:0,他引:2
建立了高效液相色谱法同时测定麻疯油转酯化产物中4种主要脂肪酸甲酯的分析方法。样品经膜处理后用丙酮溶解,采用Hypersil ODS(C18)色谱柱进行分离。以乙腈为流动相进行等度洗脱,内标法定量,同时对色谱条件进行优化。结果表明,在优化的色谱条件下4种脂肪酸甲酯在10 min内得到良好的分离,标准曲线的线性相关系数均达到0.999以上,平均回收率为96%~98%,重现性相对标准偏差为7.2%~10.2%,重复性相对标准偏差为0.31%~2.02%。与气相色谱法相比,该方法具有较高的灵敏度,可用于麻疯油转酯化产物中脂肪酸甲酯含量的测定,为麻疯油转酯化反应制备生物柴油的定性定量分析提供了参考依据。 相似文献
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《Colloids and surfaces. B, Biointerfaces》2010,75(2):492-497
Fats are widely present in a large variety of food and represent the main source of energy for the body. In the current study we investigate the behaviour of fatty acids at liquid–liquid interfaces, mimicking some steps of the very complex digestion process. Octanoic acid is used as an example of middle chain fatty acids. For the oil phase we choose sunflower oil as an industrial product and hexane as pure oil.The influence of the fatty acid concentration and the pH of the aqueous phase on the interfacial tension is determined by profile analyse tensiometry (PAT), which allows to examine the way of adsorption and transition of the fatty acids from one phase to the other. Predominantly, the pH affects the dissociation and thereby the strength of the hydrophilic character of the fatty acid. The adsorption behaviour indicates the different interfacial activity of the studied octanoic acid. 相似文献
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Monolayers of aliphatic long chain alcohols (CnH2n+1OH) were found to induce nucleation of ice at temperatures approaching O°C in contrast to water-soluble alcohols which are efficient antifreeze agents. The corresponding fatty acids and alcohols with bulky hydrophobic groups, induce ice nucleation at temperatures lower by as much as 12°C. The freezing point induced by the amphiphilic alcohols was found to be sensitive not only to area per molecule but also to chain length and parity, reaching higher temperatures for monolayers with n odd. Grazing incidence X-ray diffraction studies performed on some of these alcohols at the air/water interface (at 5°C and at zero pressure), demonstrated the formation of crystalline two-dimensional clusters with a distorted hexagonal cell whose dimensions resemble those of hexagonal ice. The catalysis of ice nucleation by these alcohol monolayers may be rationalized in terms of the structural match between the monolayer domains and the ab layer of hexagonal ice. 相似文献