两亲性海藻多糖在乳化和分散中应用的研究进展

海藻多糖是一种天然的凝胶多糖，其分子链上原生的亲水、疏水基团赋予其天然的两亲性，能够在一定程度上改善非均相之间的界面相容性，具有天然凝胶网络结构的海藻多糖还可在溶胶体系中有效阻止分散相之间的再聚集，因而海藻多糖在乳化及分散中具有极佳的应用潜能。本文介绍了海藻酸盐、岩藻多糖、卡拉胶、琼脂、石莼多糖等常见海藻多糖的化学组成、结构与性质, 并从其糖基单元上的羧基、硫酸酯基等亲水基团与甲氧基、乙酰基、蛋白质等疏水基团构成的两亲性结构出发，总结了两亲性结构对海藻多糖分子构型、表面活性及流变性质的影响，进而综述海藻多糖两亲性结构在乳化和分散中的应用。同时，还总结了通过物理或化学手段增强海藻多糖两亲性能的相关研究，例如带电疏水粒子的静电耦合、长碳链疏水化合物的化学接枝等，介绍了衍生化海藻多糖在乳化和分散中应用的研究进展，并对海藻多糖界面吸附活性增强的方向进行了展望。     

Gemini型表面活性剂在油田的应用与研究进展

双子表面活性剂因其独特的结构与优异的性质,近年来在油田领域得到了广泛的应用。从驱油用表面活性剂性质入手,主要介绍了双子表面活性剂的性能(表面活性、增溶作用、降低油水界面张力和乳化能力)和影响因素以及国内运用双子表面活性剂在提高采收率和降压增注方面取得的成果,并对未来的发展趋势进行了展望。     

改性食用微晶纤维素的研制与应用

用天然多糖高分子聚合物对微晶纤维素进行形态结构改性，使其成为稳定的水分散体系用作冷冻食品乳化稳定剂和保形剂     

新型水溶性复合肥防结块剂的制备及其防结块效果研究

由改性天然多糖和表面活性剂复配制备一种水溶性防结块剂。研究改性天然多糖与表面活性剂的质量配比、改性天然多糖和表面活性剂的总质量分数及防结块剂的用量对防结块效果的影响,并将其防结块效果与高聚物/表面活性剂型防结块剂比较。结果表明:当改性天然多糖与表面活性剂质量比为0.50、w(改性天然多糖+表面活性剂)为20%、防结块剂质量分数为0.3%时,通过加速结块法处理复合肥,可使其防结块率达到87%以上,与高聚物/表面活性剂型防结块剂相差不大,防结块效果较好。     

改性食用微晶纤维素的研制与应用

用天然多糖高分子聚合物对微晶纤维素埋形态结构改性，使其成为稳定的水分散体系用作冷冻食品乳化稳定剂和保形剂。     

非离子型表面活性剂对氯乙烯-水界面张力和保胶能力的影响

以聚乙烯醇/羟丙基甲基纤维素(KH20/60SH50)为主分散剂.非离子表面活性剂Span 60为助分散剂,考察氯乙烯悬浮聚合中油-水界面张力和保胶能力随非离子表面活性剂浓度的变化,发现非离子表面活性剂降低界面张力的能力和效率都强于主分散剂,但界面保胶能力不如后者;从Gibbs界面吸附公式和R值理论出发建立非离子表面活性剂、主分散剂在油-水界面上的竞争吸附模型,认为主分散剂/助分散剂混合使用时,助分散剂优先吸附于界面,在降低界面张力的同时也使分散体系保胶能力下降.     

表面活性剂在油砂表面的吸附滞留性研究进展

为了弄清在化学驱尤其是三元复合驱过程中表面活性剂在地层岩石表面吸附损失的原因,本文在大量的文献阅读基础上综述了不同体系中表面活性剂在固-液界面的吸附机理,国内外在降低表面活性剂在油砂表面吸附的新进展,根据国内驱油用表面活性剂的性质特点,对降低表面活性剂在大庆油砂表面的吸附滞留方法提出一些新的见解。     

PC-40超分子表面活性剂 制备与室内评价

为改善表面活性剂驱油过程中的表面活性损失及聚驱后储层残余聚合物的再利用,本文利用分子间的共价键作用,进行分子自组装,研制出一种具有高表面活性低损耗的新型表面活性剂PC-40。并对这种新型超分子表面活性剂在界面张力、润湿角、动态吸附量及乳化性等方面进行了室内评价试验。当PC-40浓度达到较高浓度时,油水界面张力达到10~(-2)mN·m~(-1),同时表观粘度有所增大,可通过增稠作用携带注聚后孔道中残余的聚合物增强驱油效率。PC-40溶液具有一定的乳化作用,可使原油充分乳化形成稳定的乳状液;当动态吸附达到平衡,吸附量趋于稳定状态,表面活性损失量相对较低;随着浓度上升,润湿性逐渐向亲油转变,界面张力随之降低,适用于聚驱后进一步提高采收率。     

低聚表面活性剂的研究进展和应用

表面活性剂是分子中带有性质不同的亲水基和疏水基的两亲结构化合物,是与乳化、增溶、分散、润湿、起泡等界面现象有关的重要化学物质,是一种功能性精细化工产品。低聚表面活性剂是由联接基团通过化学键将两个或多个单体表面活性剂连接在一起,由此产生优异的表面活性等一系列的性质,从而得到了广泛的应用。本文介绍了其发展简史、研究进展及应用。     

双子表面活性剂结构对性能的影响

综述了双子表面活性剂亲水头基的性质、疏水尾基的性质及长度、连接基的性质及长度、反离子等结构参数对其溶解性、表面活性、胶束形状、起泡性及钙皂分散能力等的影响。双子表面活性剂是一类新型表面活性剂,具有临界胶束浓度低、表面活性高、增黏能力强等一系列优异性能,这些优良性能使其具有良好的应用潜力。指出了结构参数对于双子表面活性剂有针对性的应用的重要意义,并展望了这类表面活性剂的应用前景。     

Enzymatic Transformations Involved in the Biosynthesis of Microbial Exo‐polysaccharides Based on the Assembly of Repeat Units

Microbial exo‐polysaccharides can serve as valuable biopolymers in medicine, food and the feed industry as well as in various technical applications as substitutes of petro‐based polymers or with unusual performance. Due to their different natural functions, they have vastly diverse structures, which lead to a very different properties. This structural diversity is brought about by complex biosyntheses based on enzymes whose genes are mostly encoded in clusters within the genomes of the different microbial species. The organisation of the genes and the chemical structures of the corresponding polysaccharides are closely related. Here, we will mainly focus on the genetics and biosynthesis of some major bacterial hetero‐polysaccharides that are based on repeat unit assembly and will present specific examples of enzymatic transformation steps. Finally, a short outlook will be given on how in vivo modifications based on enzymatic transformations could be used to engineer these polymers.     

Advancements in non-starch polysaccharides research for frozen foods and microencapsulation of probiotics

Conventionally used in the food industry as stabilizing, thickening, gelling, and suspending or dispersing agents, non-starch polysaccharides such as xanthan gum are known to improve the texture of certain frozen products. Another polysaccharide that has received significant attention in recent years is chitosan, a natural biopolymer derived from chitin. In the wake of growing interest in finding ideal encapsulating agents for probiotics, non-starch polysaccharides have been investigated. Scattered research can be found on the effect of each individual polysaccharide, but there remains a void in the literature in terms of closely comparing the characteristics of non-starch polysaccharides for these applications, especially when more than one biopolymer is employed. A good understanding of the tools capable of elucidating the underlying mechanisms involved is essential in ushering further development of their applications. Therefore, it is this review’s intention to focus on the selection criteria of non-starch polysaccharides based on their rheological properties, resistance to harsh conditions, and ability to improve sensory quality. A variety of critical tools is also carefully examined with respect to the attainable information crucial to frozen food and microencapsulation applications.     

Advancements in non-starch polysaccharides research for frozen foods and microencapsulation of probiotics

Conventionally used in the food industry as stabilizing, thickening, gelling, and suspending or dispersing agents, non-starch polysaccharides such as xanthan gum are known to improve the texture of certain frozen products. Another polysaccharide that has received significant attention in recent years is chitosan, a natural biopolymer derived from chitin. In the wake of growing interest in finding ideal encapsulating agents for probiotics, non-starch polysaccharides have been investigated. Scattered research can be found on the effect of each individual polysaccharide, but there remains a void in the literature in terms of closely comparing the characteristics of non-starch polysaccharides for these applications, especially when more than one biopolymer is employed. A good understanding of the tools capable of elucidating the underlying mechanisms involved is essential in ushering further development of their applications. Therefore, it is this review’s intention to focus on the selection criteria of non-starch polysaccharides based on their rheological properties, resistance to harsh conditions, and ability to improve sensory quality. A variety of critical tools is also carefully examined with respect to the attainable information crucial to frozen food and microencapsulation applications.     

Physicochemical Properties of Dry-Heated Peanut Protein Isolate Conjugated with Dextran or Gum Arabic

Peanut protein isolate (PPI) were conjugated with dextran or gum arabic through glycation to study the physiochemical properties of PPI–polysaccharides conjugates. Structural features, solubility as well as emulsifying properties of the two conjugates were compared. The degree of graft value of the two conjugates suggested that glycation of PPI with gum arabic took place more easily than with dextran. Glycated conjugates had better solubility and emulsifying ability than native PPI. Analysis of structural features of the conjugates suggested that their improved functional properties could be the result of less α-helix secondary structure, lower surface hydrophobicity and less compact tertiary structure. The solubility of PPI–dextran conjugates was improved for the pH range 3–9, while that of PPI–gum arabic conjugates was improved above neutral pH range. Moreover, better emulsifying ability was observed in PPI–gum arabic conjugates than PPI–dextran conjugates.     

Synthesis of EDTA-monoalkyl ester chelates and evaluation of the surface active properties

Some new chelating agents were synthesized from ethylenediamine-tetraacetic acid dianhydride and long chain alcohols. The equivalent reactions between the chelating agents and several metal ions gave the corresponding chelates in good yields. Surface-and interfacial tensions, dispersing power and emulsifying power of these chelates were determined. These chelates showed excellent surface activities, especially the dispersing and emulsifying powers.     

非离子表面活性剂十二烷基聚甘油醚的合成与性能研究

在碱催化作用下以十二烷基缩水甘油醚(AGE)与聚甘油反应合成了一种非离子表面活性剂十二烷基聚甘油醚,并研究了不同甘油聚合度(n)对产物表面化学性能的影响。结果显示,当n=2时,γcmc和cmc最低;n=10时,泡沫性能、钙皂分散性能和增溶性能最好;n=4时,乳化性能最好。     

Recent developments in chemical modification and characterization of natural fiber‐reinforced composites

A critical review of the literature on the various aspects of natural fibers and biocomposites with a particular reference to chemical modifications is presented in this paper. A notable disadvantage of natural fibers is their polarity which makes it incompatible with hydrophobic matrix. This incompatibility results in poor interfacial bonding between the fibers and the matrix. This in turn leads to impaired mechanical properties of the composites. This defect can be remedied by chemical modification of fibers so as to make it less hydrophilic. This paper reviews the latest trends in chemical modifications and characterizations of natural fibers. The structure and properties of natural fibers have been discussed. Common chemical modifications and their mechanisms have also been elaborated. The importance of chemical modifications and the resultant enhancement in the properties of the composites have also been reviewed. Recent investigations dealing with chemical modifications of natural fiber‐reinforced composites have also been cited. POLYM. COMPOS., 2008. © 2007 Society of Plastics Engineers     

Lecithin production and properties

Soy lecithins are important emulsifiers used in the food, feed, pharmaceutical, and technical industries. Native lecithin is derived from soybean oil in four steps: hydration of phosphatides, separation of the sludge, drying, and cooling. Such lecithin has both W/O and O/W emulsifying properties. Products with improved emulsifying properties can be obtained by modifications, involving mainly fractionation in alcohol, hydrolysis (enzymatic, acid, or alkali), acetylation, or hydroxylation. Careful processing is required to produce lecithins of a high chemical, physical, and bacteriological quality.     

十二烷基甘油醚羧酸盐的性能研究

文章测定了十二烷基甘油醚羧酸盐阴离子表面活性剂的一系列性能,结果显示同AEO7、LAS相比,它的γcmc较低,为24.07 mN/m,具有良好的降低表面张力性能,泡沫高度5 min后仍维持58 mm,稳泡性较好,对苯的增溶能力为130 ml/mol,润湿、乳化、钙皂分散性能均较好。