Emulsions storage

The octenylsuccinic acid anhydride treated starches give on the average smaller oil droplet particle sizes and better emulsion storage stability than both gum arabic and a starch dextrin. 

Understanding the relationship between the composition of a mixture and its properties is fundamental to the development of formulated products. In the pesticide industry, formulation chemists seek to translate such an understanding into products that meet criteria established for properties such as suspensibility, emulsibility, storage stability, compatibility, and most importantly, biological activity. The preferable way to acquire the necessary knowledge is to deduce the properties of mixtures in terms of mechanisms that are operative at the microscopic level. However, mixtures are extremely complex systems and the available theory is usually insufficient for developing useful theoretical models. For example, we are unable quantitatively to predict, on the basis of molecular theory, the suspensibility of a wettable powder from a knowledge of its composition. 

Emulsion storage stability is quickly determined by the 24 h settlement test (see Section 4.20.13). The size of bitumen globules, as well as their size distribution, can be determined using electronic microscopes or electronic apparatuses for sieve analysis. A quick and far less costly method to determine the suitability of the bitumen emulsion in road... 

It must be emphasised that an anionic emulsion should never be mixed with a cationic emulsion, since as a result of their opposite electrostatic charge, instant breaking occurs. Barrels or tanks that were used in the past for the opposite emulsion type should be cleaned thoroughly with plenty of water or solution in case they are to be used again. It should be ensured that no trace of emulsion of opposite type exists. Tanks that were used for bitumen storage in the past can be used for emulsion storage, once they are checked for foreign bodies or detached parts of old bitumen. 

Neat emulsion polymer must be protected from water contamination, which causes gelling of the product and can make pumping difficult or impossible. In areas of high humidity, tank vents should be outfitted with a desiccant in order to prevent water condensation within the emulsion storage tank. Even small amounts of condensation can cause significant amounts of product gelling. As with liquid... 

Fortified rosin can also be converted to high free-rosin emulsions by using various stabilizers. Typically, these are 35% soHds emulsions, which exhibit exceUent stabiHty in relation to storage and mechanical action, such as is found in transfer pumps. Generally, fortified rosin emulsions are more efficient sizes than their soap-based Hquid or paste counterparts. 

EmulsffiedAsphalts (ASTMD244). This standard covers a variety of tests for the composition, handling, nature and classification, storage, use, and specifying of asphalt emulsions used primarily for paving purposes. 

Product Stability and Emulsion Stability. These properties are not necessarily related, but are both highly prized in the selection of a carrier. The first refers to the storage or shelf stabiUty of the product. Many carrier preparations are not properly balanced, or unsuitable emulsifiers have been used. Upon storing, these products separate in layers, particularly when exposed to temperature changes. 

Because nitrile rubber is an unsaturated copolymer it is sensitive to oxidative attack and addition of an antioxidant is necessary. The most common practice is to add an emulsion or dispersion of antioxidant or stabilizer to the latex before coagulation. This is sometimes done batchwise to the latex in the blend tank, and sometimes is added continuously to the latex as it is pumped toward further processing. PhenoHc, amine, and organic phosphite materials are used. Examples are di-Z fZ-butylcatechol, octylated diphenylamine, and tris(nonylphenyl) phosphite [26523-78-4]. All are meant to protect the product from oxidation during drying at elevated temperature and during storage until final use. Most mbber processors add additional antioxidant to their compounds when the NBR is mixed with fillers and curatives in order to extend the life of the final mbber part. 

The emulsion polymerization of acrylamide yields a high-molecular polymer (with the molecular weight reaching 2.5-10 ), which can be easily dispersed in water to obtain water-in-oil type latex (containing 30-60% polymer). On prolonged storage, the emulsion exhibits lamination, but subsequent stirring allows easy redispersal of the product. 

Bactericides are substances that destroy bacteria, and they can be used in various ways. They may be incorporated into the soluble-oil concentrate, either at concentrations suitable to protect the oil in storage, or at levels sufficient to provide a persistent bactericidal effect on the emulsion in service. The cost of providing sufficient bactericide to cover the use of the soluble oil at a high dilution might prove prohibitive. Continued use of the same bactericide may produce resistant strains of bacteria. 

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