Effect of amount of emulsifier added in the second stage on morphology of composite latex particles

In this article, PBA/P(MMA–crosslinking agent)-composite particle latexes were prepared by semicontinuous seeded emulsion polymerization. To determine the seed emulsion's saturating capacity of an emulsifier, a mathematical model was built to simulate the changes of the seed PBA emulsion's surface tension with the amount of emulsifier added dropwise. The effects of the emulsifier amount added in the second stage and the addition method on the morphology of the composite particles were studied. The results were shown as follows: If the amount of emulsifier added in one batch to the seed emulsion in the second stage was less than or equal to the saturating capacity of emulsifier of the seed emulsion (Cs), the morphology of the particles was “core–shell”; otherwise, a few particles were of a core–shell structure. However, if shell materials were preemulsified and added dropwise at an appropriate rate, the latex particles were still of a core–shell structure, even when the amount of emulsifier added to the seed emulsion was greater than the Cs. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 969–975, 1998     

Lipide als Backmittel

Lipids as Baking Aids Vegetable raw materials for subsequent treatment to food generally show no optimal processing properties. This is also valid for bread grain. The ingredients of the corn which establish the processing quality have to be modified by technological measures in such a way that bread of optimal nutrient, eating and consumer quality is produced. The consumer is aware above all of eating and consumer qualities, according to the kind of bread high specific volume and different crumb softness and elasticity are characteristics which can easily be recognized. It is an important target of the baking technology to improve these properties. Especially since manual work has been replaced in the bakery by machines, it has become necessary to improve bread quality by influencing the ingredients. The example of using lipids (lecithine, diacetyltartaricacidmonoglycerides, monoglycerides) shows in which way volume and crumb texture of bread can be influenced.     

HEAT AND MOISTURE TRANSFER IN BAKING OF POTATO SLABS

ABSTRACT

Heal and moss transfer in a slab of potato potato during baking were explained using a multiphase porous media model that includes internal evaporation and capillary, diffusive, and pressure driven transport of water and vapor. The model also includes the effect of the formation of a surface “skin” during baking. Model predictions were validated using experimental data. Most of the temperature drop in the material occurs in a relatively thin and dry surface region, while much of the interior stays at somewhat uniform temperature. Moisture content inside the material stays uniform except near the surface region where it drops to very low values. Evaporation occurs over a significant region, as opposed to at a sharp front. Baking time reduces significantly with thickness, however at d slower rate compared to conduction-only heating (no moisture transport). In addition, the surface temperature also reaches a higher value for a thinner material, which may help develop the often     

Simulation model for the emulsion copolymerization of acrylonitrile and styrene in azeotropic composition

A simulation model based on the “unit segment” concept which provides prediction of conversion and molecular weight of product, is proposed for the emulsion polymerization of AN and St in azeotropic composition. Effects of initiator concentration and emulsifier concentration on conversion and molecular weight were studied experimentally and theoretically. It is found that the desorption of AN radicals should be taken into account, and the number of radicals per particle is always less than 0.5. The concentration of polymer particles is proportional to the 0.58 power in respect of the emulsifier concentration and to the 0.35 power in respect of the initiator concentration. The auto-acceleration effect becomes significant when both initial emulsifier concentration and initiator concentration decrease, which influences the average molecular weight of the products. The azeotropic composition of AN–St is 28.5:71.5 by weight for this system at 60°C reaction temperature.     

Effects of microwave and conventional baking on the oxidative stability and fatty acid composition of puff pastry

The effects of microwave and conventional baking on the fatty acid and trans fatty acid compositions of puff pastries, which contain high amounts of hydrogenated fat, were investigated. In addition, free fatty acids, peroxide value, and induction time for oxidative stability by the Rancimat method have been compared for microwave- and conventionally baked puff pastries. The data indicate there were considerable changes in acidity, peroxide value, and Rancimat induction time in both microwave- and conventionally baked samples. Although the content of saturated fatty acid such as palmitic and stearic and the ratio of saturated to unsaturated fatty acids did not change significantly, an apparent increase was determined in trans oleic acid levels by both baking methods. In addition, a significant decrease in linoleic acid content of the samples was found by microwave baking.     

Über physiologische Wirkungen „oxidierter Fettsäuren”︁ aus geblasenen Ölen

Physiological Actions of “Oxidized Fatty Acids” from Blown Oils Feeding experiments were carried out on 60 rats for 189 days using “oxidized fatty acids” which were isolated by the DGF-method C-III 3 (53). The “oxidized fatty acids” corresponded to oxy-dimeric linoleic acid with respect to molecular weight and elemental formula. The investigations included weight gain of the experimental animals, histological examination of the internal organs, and composition of depot and cellular fats. The results of these studies are reported. Growth retardations were observed as a clear indication of harmful action of “oxidized fatty acids”.     

Hybrid thermosets from polyisocyanate/water glass/emulsifier systems: Effects of melamine‐formaldehyde resin

Melamine‐formaldehyde resin (MF) was selected as potential reactive emulsifier for polyurea‐based thermoset resins produced from polyisocyanate/water glass (WG)/emulsifier systems. As emulsifier tricresylphosphate and/or MF served for the initial water‐in‐oil type (“water” = WG; “oil” = polyisocyanate + emulsifier) emulsions. The MF content of the systems has been varied (≤15 wt %) and its effect on the structure, mechanical, thermal and flammability properties of the final polyurea‐based thermosets studied. It was found that MF is a suitable emulsifier, which can fully replace the phosphate without negatively affecting the properties of the resulting hybrid thermosets. Moreover, hybridization with MF was often accompanied with pronounced improvements in fracture mechanical and static flexural properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of inorganic fillers in binary processing aids on the rheology of a metallocene linear low‐density polyethylene

Inorganic fillers including porous diatomite, flaky talc, and spherical calcium carbonate were blended with polyethylene glycol (PEG) to prepare binary processing aids, and the effect of varied binary processing aids on the melt flow properties and extrudates distortion of a metallocene linear low‐density polyethylene (mLLDPE) was studied. It was found that the binary processing aids exhibit better effect on viscosity reduction of mLLDPE than that obtained when PEG was added alone. The morphology of inorganic fillers influences the effect of binary processing aids. The diatomite/PEG binary processing aid shows the most noticeable effect, followed by the talc/PEG binary processing aid, and then the calcium carbonate/PEG binary processing aid. The influence of particle size of the diatomite on the effectiveness of the diatomite/PEG binary processing aid was also studied. The mechanism for the improved effect of binary processing aids on reducing viscosity of mLLDPE was proposed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1824–1829;2005     

Role of glycolipids in breadmaking

In wheat flour used for breadmaking, glycolipids are essential “endogenous surfactants” (1). Bread volume and crumb structure of wheat flour‐based bakery products are influenced by glycolipids, without the decisive mode of action being conclusively known. Little information on how glycolipids from other plant sources perform as wheat flour improvers is available. In this paper we review our work done on revealing the baking performance of the four major glycolipid classes present in commercial lecithins (sterol glucosides (SG), acylated sterol glucosides (ASG), cerebrosides and digalactosyl diacylglycerides (DGDG). Our purpose is to better understand the role of these substances in the baking process. Our results suggest that there are two groups of glycolipids with excellent baking performance. Both groups were found to have an impact on the dough liquor rather than on the gluten‐starch matrix. The cerebrosides and DGDG most likely influenced the overall baking result by directly stabilizing the dough liquor/gas cell interface, while ASG and SG did this indirectly through a synergistic effect with a dough liquor constituent, most probably the endogenous flour lipids.     

Optimization of formulations for dietetic pastry products

Optimized formulations of dietetic pastry products such as cake and sponge cake premixes were formulated using the surface response methodology. % Emulsifier agent and baking time were the selected independent variables for cake, as well as % emulsifier agent % chlorinated flour the variables selected for sponge cake. Three different level of each variable summing up thirteen experimental formulae of each product were assessed to optimize the variables that could have some influence in the sensory characteristics of these dietetic products. The total sensory quality was determined for both dietetic products using the composite scoring test and a panel of 18 trained judges. Looking at the contour graphic and considering economic aspects the best combination of variables for cake formulation was 2% emulsifier agent and 48 minutes for baking time, With respect to sponge cake, the best combination was 6% emulsifier agent and 48% chlorinated flour. Shelf life studies showed that both dietetic formulations remained stable during storage conditions of 75 days at 30 degrees C. During this period, significant differences in sensory characteristics were not found (p < 0.05). Data of peroxide values were kept under the critical value reported for detection of organoleptic rancidity. Reported values of hedonic test showed that these dietetics pastry products had good acceptability, and open up marketing opportunities for new products with potential health benefits to consumers.     

三乙醇胺系矿渣复合助磨剂的研究

采用了数种三乙醇胺系复合助磨剂,在相同的粉磨条件下与矿渣共磨,每隔0.5h测定其比表面积并与空白样品对比;然后对所得矿粉用图像分析仪和扫描电镜进行了形貌分析;同时研究了三乙醇胺系复合助磨剂对矿渣-水泥体系标准稠度用水量、凝结时间和胶砂强度等各项性能的影响。结果表明三乙醇胺系复合助磨剂对矿渣的助磨效果好于单一助磨剂,且对矿渣-水泥体系各项性能无不良影响。     

Untersuchung über die agglomeration von polymerisatlatices

Different polymer latices are often incompatible, even when the emulsifying agent is the same in each. If one polymer has a proportion of hydrophilic groups (type ?A”? latex) and the other does not (type ?S”? latex), a mixture of the two latices may coagulate within seconds of mixing. Quite small proportions of type ?A”? will cause agglomeration of the particles of a type ?S”? latex. If 1% of a latex prepared from ethyl acrylate and acrylic acid (95:5) is added to a poly(butylacrylate) latex, D?_w, = 800 Å, and the pH is adjusted to 8–9, the resulting latex is characterized by D?_n, = 6300 Å, D?_w, = 7300 Å; addition of any given type ?S”? latex increases the average particle size still more. The mechanisms involved were studied by observing changes in particle size distribution, by the use of polymerizable dyes as markers, and by electron microscopy. The results of these investigations are : The latices are protected only in some respect by the emulsifier. The protective ionic doublelayer formed by the emulsifier around a type ?S”? particle repels other particles, but not type ?A”? particles. If a collision occours between particles of type ?A”? und type ?S”? they stick together; this process is repeated as often as a type ?S”? particle hits the surface of ?A”?. All the type ?S”? particles of the associate combine to one big particle in such a way that the ?A”? particle stays at the surface and remains active for further agglomeration.     

低温、低浊、低碱度水助凝效能试验研究

针对低温、低浊、低碱度水,以聚合氯化铝为絮凝剂,通过烧杯试验,确定了生石灰(CaO)、阴离子型聚丙烯酰胺(APAM)、活化硅酸(AS)单独助凝的最优条件,进一步考察了APAM、AS分别与CaO联用的助凝效果。研究结果表明:5种助凝剂均能起到一定的助凝作用,但APAM、AS分别与CaO联用的助凝效果不理想。滞后聚合氯化铝30 s投加0.3 mg/L APAM,浊度去除率可达88.1%;AS投加时间对有机物去除效果影响显著,延迟聚合氯化铝30~60 s投加时,对CODMn和TOC去除效果最好。兼顾除浊和除有机物,AS助凝效果最佳,是提高混凝沉淀工艺污染物去除率的有效途径之一。     

Evaluation of secondary lubricants for rigid PVC extrusion

A common system of primary lubricants in rigid PVC extrusion compounds is calcium stearate plus paraffin wax. Secondary lubricants are frequently added to this system at low concentrations with the intention of improving such properties as metal release, thermal stability, plateout, extrudate surface appearance, etc. This paper discusses the results of laboratory studies designed to evaluate the contribution to these properties of two commonly used secondary lubricants: AC629A, an oxidized low molecular weight polyethylene, and K175, an acrylic “lubricating processing aid.” Surprisingly, the testing showed little improvement in performance when these auxiliary lubricants were added.     

Product sampling during transient continuous countercurrent hydrolysis of canola oil and development of a kinetic model

A chemical kinetic model has been developed for the transient stage of the continuous countercurrent hydrolysis of triglycerides to free fatty acids and glycerol. Departure functions and group contribution methods were applied to determine the equilibrium constants of the four reversible reactions in the kinetic model. Continuous countercurrent hydrolysis of canola oil in subcritical water was conducted experimentally in a lab-scale reactor over a range of temperatures and the concentrations of all neutral components were quantified. Several of the rate constants in the model were obtained by modeling this experimental data, with the remaining determined from calculated equilibrium constants. Some reactions not included in the present, or previous, hydrolysis modeling efforts were identified from glycerolysis kinetic studies and may explain the slight discrepancy between model and experiment. The rate constants determined in this paper indicate that diglycerides in the feedstock accelerate the transition from “emulsive hydrolysis” to “rapid hydrolysis”.     

Influence of Yb and Si content on the sintering and phase changes of Yb:YAG laser ceramics

Yb-doped yttrium aluminum garnet (Yb:YAG) ceramics were prepared via solid state reaction of oxide powders. The Yb concentration ranged from 0 to 10 at.%. Silicon in the form of tetraethyl orthosilicate (TEOS) was added as a sintering aid in amounts of 0.3 and 0.5 wt.% with respect to the weight of solid. Thermal analyses (high temperature XRD, TG-DSC, dilatometric analyses) were performed on various compositions. Sintering was conducted under high vacuum and clean atmosphere. The influence of TEOS addition and Yb content was observed both in connection with phase transformations in function of temperature, and with microstructure and properties of sintered materials.     

Determination of monoglycerides,diglycerides, triglycerides and glycerol in fats by means of gel permeation chromatography [C‐VI 5b(02)]

The “Joint Committee for the Analysis of Fats, Oils, Fatty Products, Related Products and Raw Materials (GAFett)” has developed the following method for the determination of the content of monoglycerides, diglycerides, triglycerides and glycerol in fats and fat derivatives. It is intended to include this method in Section C, Chapter VI of the German Standard Methods.     

无皂乳液聚合的理论研究、制备方法及应用

无皂乳液聚合法可以制备表面洁净的单分散性微球和功能微球 ,并可消除乳化剂对环境的污染。综述了无皂乳液聚合中的反应机理及体系稳定性方面的研究 ,对无皂乳液聚合的制备方法及应用前景作了详尽的介绍。     

Use of SDA soybean oil in bakery applications

Stearidonic acid (SDA) soybean oil is a sustainable, land‐based source of omega‐3 fatty acids. SDA soybean oil can be formulated directly into baked products or incorporated into shortening blends for use in a variety of baking applications. Little has been published in the scientific and other literature concerning the functional and sensory performance of baking applications comprising SDA soybean oil. In this article, we review work that has been done to evaluate the performance of SDA soybean oil in an array of bakery applications. Consumer acceptance data showed that incorporation of SDA soybean oil in application models such as bagels, breakfast bars, pastries, cookies, icings and chocolate coatings resulted in acceptable product functionality and flavor. The results also indicated that SDA soybean oil imparted functional and sensory attributes in baked products that were similar to commercial soybean oil.