辛硫磷微乳剂浊点的影响因素分析

配制了10％辛硫磷微乳剂,研究了体系中复配表面活性剂、助表面活性剂及电解质对微乳剂浊点的影响.结果表明:可用浊点法筛选出HLB值较高的表面活性剂,再结合微乳剂性能指标确定出适合体系的复配表面活性剂.微乳剂的浊点随复配表面活性剂中非离子表面活性剂含量的增多而升高,但制剂冷贮稳定性能下降.助表面活性剂的种类和含量对微乳剂浊...     

不同影响因子对微乳剂浊点的影响

采用升温法测定微乳剂的浊点,研究各因子对微乳剂浊点的影响,结果表明：表面活性剂的HLB（亲水亲油平衡）值增大,其亲水性增强,微乳剂的浊点升高.水中Ca^＋、Mg^＋浓度增加,微乳剂的浊点降低.pH对微乳剂的浊点无明显影响.助表面活性剂的碳链越长,对微乳剂浊点影响越大,浊点下降越多.     

砂生槐总碱水乳剂及微乳剂农药的研制

为了制备砂生槐生物碱乳剂和微乳剂农药，筛选了不同溶剂和助溶剂系统，考察了亲脂性总碱在不同溶剂系统下的增溶作用。在乳剂配置的基础上，通过绘制生物碱原油-混合表面活性剂-水的拟三元相图，筛选出助表面活性剂乙醇，当Km值（助乳化剂和乳化剂的质量比值）为1：1时有较大微乳区形成。所形成的微乳经过测定是O／W型微乳性质稳定，浊点在57℃。通过论文数据可以指导配置不同质量浓度的砂生槐生物碱乳剂和微乳剂农药。     

聚醚型非离子表面活性剂的浊点及其影响因素

总结了非离子表面活性剂浓度、外加聚合物、离子表面活性剂、无机电解质、助表面活性剂等对聚醚型非离子表面活性剂水溶液浊点的影响规律 ,发现聚合物由于其结构和分子量不同对浊点的影响也不同 ,一般可使浊点降低 ;加入离子表面活性剂可以和非离子表面活性剂形成混合胶束 ,从而使浊点升高 ;无机盐由于存在盐析和盐溶两种不同效应而对浊点的影响比较复杂 ;醇和有机酸等助表面活性剂根据其碳链的长短不同而影响浊点。这些规律对非离子表面活性剂的研究和应用有一定的指导意义。     

正交试验法在辛硫磷微乳剂配方选择中的应用研究

采用单因素试验法初选出10%辛硫磷微乳剂的适宜表面活性剂组份,再通过正交试验法以浊点为主要考察指标对复配表面活性剂的用量、配比、助表面活性剂用量进行了筛选和优化,确定了该微乳体系中最佳表面活性剂组分及其含量:农乳1602#+宁乳33#为9%,农乳500#为5%、乙醇5%及消泡剂0.2%。研究结果表明:应用正交试验法可快速筛选出适量的表面活性剂及助表面活性剂,获得性能优异的微乳剂配方,并可降低配方成本。     

不同影响因子对苯醚甲环唑微乳剂理化性质的影响

从助溶剂、表面活性剂、水质等不同影响因子对苯醚甲环唑微乳剂理化性质的影响进行了研究，测定了其低温和热贮稳定性等理化性状。结果表明，表面活性剂的HLB值〉11．5、助溶剂为甲醇时配制的微乳剂较好，不同水质均可配出外观均相透明的微乳剂，采用适当的离子/非离子表面活性剂搭配可以在表面活性剂用量较低时获得稳定的微乳剂。     

农药微乳剂及其浊点问题的探讨和初步研究

浊点是以非离子表面活性剂为主要组分的微孔剂剂型的特性与质量技术指标之一。其浊点高低主要解决于原药性质及所含表面活性剂的种类和用量,配制微乳剂通常应该选择浊点高的非离子表面活性剂,对一般微乳剂的浊点指标建议定为≥５４℃。     

不同影响因子对虫螨腈微乳剂理化性质的影响

研究了助溶剂、表面活性剂等不同影响因子对虫螨腈微乳剂理化性质的影响,测定了其低温和热贮稳定性等理化性状。结果表明,表面活性剂的HLB值大于12.6、助溶剂为环己酮时配制的微乳剂较好;采用适当的离子/非离子表面活性剂搭配可以在表面活性剂用量较低时即获得理化性质稳定的微乳液。在近中性条件下,不同因子对10%虫螨腈微乳剂热贮分解率基本没有影响。     

n-CnH2n＋1 OH对毒死蜱微乳剂透明温度范围的影响

研究了n-CnH2n 1OH(5≤n≤8)对微乳剂透明温度范围的影响.研究结果表明:n值增大,混合表面活性剂含量增加,体系易于形成微乳;当醇及其含量一定时,混合表面活性剂配比对微乳剂的透明温度范围有较大影响;随醇含量增加,微乳剂的透明温度上限降低,下限略有增加;随n值增大,透明温度范围上限温度基本升高,下限温度变化不规律.     

高效氟氯氰菊酯微乳剂形成规律探索

通过研究高效氟氯氰菊酯微乳剂形成过程中表面活性剂混剂、助表面活性剂与高效氟氯氰菊酯最大加入量的关系，利用多元回归处理方法，建立了表面活性剂混剂、助表面活性剂与高效氟氯氰菊酯最大加入量三者之间的数学模型；通过测定不同温度下高效氟氯氰菊酯的最大加入量，得出高效氟氯氰菊酯最大加入量随温度升高而增大的规律。     

添加剂对非离子表面活性剂浊点的影响

研究了十二烷苯磺酸钠（LAS）、正丁醇、仲丁威对非离子表面活性剂TX－10浊点的影响。LAS与TX－10形成混合胶束，使TX－10增溶能力提高，浊点也提高；正丁醇对其影响比较复杂，少量正丁醇对浊点没有影响，当正丁醇量较大时，使单独TX－10体系浊点降低，使混合体系浊点略有升高；仲丁威使其浊点下降。正丁醇、仲丁威对TX－10浊点的影响与它们在胶束中的增溶位置有关。     

Effect of different additives on the cloud point of a polyethylene oxide-polypropylene oxide-polyethylene oxide block copolymer in aqueous solution

Cloud point studies on aqueous solutions of a polyethylene oxide (PEO)-polypropylene oxide-PEO triblock copolymer (Pluronic^® L64: EO₁₃PO₃₀EO₁₃, total m.w.=2900, PEO=40%; EO=ethylene oxide; PO=propylene oxide) in the presence of different additives show some interesting features. The effect of various inorganic salts was an increase or decrease in cloud point based on their salting in and salting out action and followed the Hofmeister lyotropic series. Nonelectrolytes and hydrotropes increased the cloud point by influencing water structure. Hydrotropes altered the cloud point of the copolymer at much lower concentrations than inorganic salts. Ionic surfactants produced a marked increase in the cloud point of copolymer solutions. The effect was greater for surfactants with greater hydrophobicity. Alcohols and other organic liquid additives that are infinitely miscible with water increase the cloud point of the copolymer, whereas additives that are partially miscible in water decrease the cloud point.     

The influence of trace components on the melting point of methyl soyate

The objective of this study was to determine the effect of various amounts of unsaponifiables and bound glycerol on the crystallization temperatures of methyl soyate used as biodiesel. The preparation of methyl esters did not affect the amount of unsaponifiable matter in biodiesel. A synthetic unsaponifiable mixture added to distilled methyl soyate and blends of methyl soyate and No. 1 diesel fuel (20:80, vol/vol) did not affect the crystallization onset temperature, cloud point, or pour point at concentrations up to 3% by weight. The amounts of monoglycerides and diglycerides in methyl soyate decreased from 2.60 and 9.87%, respectively, to 0% as the methanol/soybean oil ratio increased from 90 to 200% of the theoretical requirement. Transesterification reactions conducted with less than 130% of the theoretical amount of methanol resulted in methyl soyate with a higher cloud point because of the presence of saturated mono- and diglycerides. Pure mono- and diglycerides added to distilled methyl soyate at 0 to 1.0% did not change the pour point of the esters, but the cloud point of esters increased with increasing amount of saturated mono- or diglyceride. Pure saturated mono- or diglyceride presented in concentrations as low as 0.1% increased the cloud point of methyl soyate. Similar results were obtained with mono- and diglyceride mixtures present in incompletely converted methyl soyate.     

A Novel Thermosensitive Poly(methyl 2-acetamidoacrylate)

The thermosensitive properties of aqueous poly(methyl 2-acetamidoacrylate) (PMAA) solutions were investigated in the absence or presence of sodium sulfate. Poly(methyl 2-acetamidoacrylate) with a molecular weight of 23,000 (PMAA-1) exhibited the cloud point. On heating the PMAA-1 solution, the transmittance began to decrease from near 34°C and increased again after the minimum value was shown at 36.0°C. The minimum transmittance increased linearly with an increasing concentration of the polymer although the minimum-transmittance temperature did not depend on polymer concentration. The minimum transmittance was affected by the pH and the 1-butanol added. This finding suggests that the cloudiness is controlled by a delicate balance of hydrophilicity and hydrophobicity and by intra- and/or inter-molecular hydrogen bonding. Poly(methyl 2-acetamidoacrylate) with a molecular weight of 15,000 (PMAA-2) did not exhibit cloudiness in distilled water. However, the addition of sodium sulfate caused cloudiness to appear. The cloud point of a PMAA-2 solution depended on concentrations of polymer and salt added. It decreased with an increase in polymer and salt concentrations. The salting-out constants were determined from the relationship between the cloud point and concentrations of polymer and salt.     

Phase equilibria of poly(methyl methacrylate) in supercritical mixtures of carbon dioxide and chlorodifluoromethane

Phase behavior data are presented for poly(methyl methacrylate) (PMMA: M_w= 15,000, 120,000) in supercritical solvent mixtures of carbon dioxide (CO₂) and chlorodifluoromethane (HCFC-22). Experimental cloud point curves, which were the phase boundaries between single and liquid-liquid phases, were measured by using a high-pressure equilibrium apparatus equipped with a variable-volume view cell at various CO₂ compositions up to about 63 wt% (on a polymer-free basis) and at temperatures up to about 100 °C. The cloud point curves exhibited the characteristics of a lower critical solution temperature phase behavior. As the CO₂ content in the solvent mixture increased, the cloud point pressure at a fixed temperature increased significantly. Addition of CO₂ to HCFC-22 caused a lowering of the dissolving power of the mixed solvent due to the decrease of the solvent polarity. The cloud point pressure increased with increasing the molecular weight of PMMA.     

Effect of electrolytes on foaming of nonionic surfactant solutions

The effect of electrolytes and other additives on the foaming of solutions of the nonionic surfactant octoxynol 9 (Triton X-100) was investigated and correlated with their effect on the cloud point. Foams were generated by pouring solutions as a thin stream into a vertical tube. The height of the generally fast-draining foam columns was measured as a function of time, and their stability was rated according to the damage sustained within 13 min. The surfactant concentrations used, 0.050, 0.100 and 2.00%, were above the critical micelle concentration. Increasing concentrations increased foam height but not foam stability. The electrolytes NaCl and Na₂SO₄ salted the surfactant out. They reduced its cloud point in proportion to their concentration. They also reduced the foam height, albeit to a lesser extent than the cloud point, but hardly reduced the foam stability below the cloud point.     

Effect of Organic Additives on the Phase Separation Phenomenon of Amphiphilic Drug Solutions

The effect of various organic additives, viz. sugars, ureas, alcohols, hydrotropes and bile salts on the clouding (phase separation) phenomenon of the amphiphilic antidepressant drug amitriptyline hydrochloride was investigated in the present study. All sugars lowered the cloud point (CP) due to their water structure-making property. Urea and alkylureas were found to lower the CP. In contrast, thioureas increased the CP slightly, but the presence of methyl group(s) had a similar effect in alkylureas. Short chain alcohols affected the CP insignificantly while higher ones decreased it, and medium chain alcohols showed peak behavior. Addition of hydrotropes and bile salts increased the CP at lower concentrations, while a decrease was observed at higher concentrations (like the medium chain alcohols). In addition, thermodynamic parameters were also evaluated but only for those additives which formed mixed micelles with the drug.     

Phase separation behavior and morphologies of PMMA/poly(styrene‐co‐acrylonitrile)/clay nanocomposites prepared by solution mixing

Nanocomposites of blends of PMMA and poly(styrene‐co‐acrylonitrile) (SAN) with natural (PM) or organically modified montmorillonite clays (Cloisite 30B, 25A, and 15A) were prepared by solution mixing and the effect of clay on the phase separation behavior along with morphologies of nanocomposites was investigated. Nanocomposites containing clay C30B prepared from methyl ethyl ketone showed the noticeable decrease in the cloud points. None of the other nanocomposites showed the increase in the cloud point. Location of clay particles in the phase separated matrix is observed to be different depending on the type of clays and solvents. The lowest cloud point of nanocomposites containing C30B may arise from the good dispersion of C30B where Clay C30B may act as the nucleating agent inducing phase separation. Dynamic mechanical and thermal analyses support above observations. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010