Liquid grades

Liquids represent a simple and convenient physical form and various thickening agents based on acrylic polymer chemistry are available in this form. Two main routes for producing such liquids are known. Firstly, a water-in-oil polymerisation process can be used for the preparation of polymers that are directly soluble in water. Alternatively, an oil-in-water emulsion process is used where the polymer composition is chosen to be water insoluble during the preparation stage, but which can be made water soluble by a neutralisation reaction after polymerisation has been completed. More specific information on these two key processes is given in the following sections. 

As described earlier in the section on bead or suspension polymers (Section 3.3.1.2), a solution of monomer(s) is prepared in water and then mixed into a low to medium viscosity non-volatile oil phase. In this process, which is often referred to as an inverse emulsion polymerisation technique, surfactants which promote the formation of water-in-oil emulsions are commonly used. These would usually be materials with an HLB (hydrophihc-lipophilic balance) value in the range 4—7, an example of which is sorbitan mono-oleate. In order to achieve the desired droplet particle size of a maximum around 1 pim prior to polymerisation, high shear homogenisers are used to assist the formation of such very small 

This is a very versatile process for the polymer chemist, as the polymer can be any one of the three chemical types of anionic, non-ionic or cationic. The polymer molecular weight can vary from low-, through medium-, to high- and cross-Hnking agents can be included in the initial monomer solution, all without changing the nature of the product in the as-sold form. However, the intentional variation of any or aU of these factors will have a substantial effect on the viscosity behaviour of the system when the polymer is eventually used in an aqueous system. 

A further component that can be varied, to take into account the requirement or specific needs of the end-use environment, is that of the continuous phase oil. For products to be used as thickeners in general industrial operations, such as Improved Oil Recovery or Print Paste formulations for textiles, this phase is usually based on a mineral oil hydrocarbon. In products developed for more specialised or demanding end uses, such as cosmetic and toiletry formulations, special grades are available where the continuous phase is a medicinal-grade high-purity white oil. Hydrophobic esters and even silicone-based fluids have also been used as the continuous oil phase. 

Thickening agents based on aqueous emulsion polymer chemistry were first developed [9] in the late 1950s and represent another important class of thickening agents. In this physical form, a monomer composition is chosen that provides a balance between the hydrophilic nature of a carboxylic acid monomer (such as acrylic, or more usually methacrylic acid) and a hydrophobic alkyl (meth)acrylate monomer (such as methyl methacrylate, ethyl acrylate, butyl acrylate or mixtures of such species). Whilst the carboxylic acid is in the free-acid form the overall composition is balanced to sufficiently hydrophobic to be water immiscible. This allows the monomer mixture to be reacted using a conventional oil-in-water emulsion polymerisation technique. 

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The n-hexane (Fluka), n-heptane (Prolabo) and n-octane (Fluka) were all used as received with purities of >99.5%, >99.5% and >99.0%, respectively. The major organic impurities were subtracted from the exit gas analysis before calculating the product distribution. The hydrogen was obtained from Air Liquide (Grade U). 

Exact data on world output or world consumption of sulfur dyes are not available. The quantities cited in statistics refer to commercial dyes with no account taken of their concentration. Thus, highly concentrated powdered types are lumped together with relatively weak liquid grades. 

Completeness and Color of Solution A solution of 5 g of sample in 50 mL of water is colorless. It is clear for liquid grades and not more than slightly hazy for solid grades. Ethylene Glycol and Diethylene Glycol... 

The USPNF 23 describes polyethylene glycol as being an addition polymer of ethylene oxide and water. Polyethylene glycol grades 200-600 are liquids grades 1000 and above are solids at ambient temperatures. 

Liquid grades (PEG 200-600) occur as clear, colorless or slightly yellow-colored, viscous liquids. They have a slight but characteristic odor and a bitter, slightly burning taste. PEG 600 can occur as a solid at ambient temperatures. 

Polyethylene glycols should be stored in well-closed containers in a cool, dry place. Stainless steel, aluminum, glass, or lined steel containers are preferred for the storage of liquid grades. 

Properties Colorless to oily yellow liquid. Grade Technical (88% min), purified (98% min). Use Pharmaceutical intermediate. 

Acyclic isoprenoidal alkanes may be important constituents, particularly pristane (2,6,10,14-tetra-methylpentadecane) and phytane (2,6,10,14-tetra-methylhexadecane) (Fig. 4.23a). Unfortunately, the term isoalkane is sometimes used to describe all the branched alkanes and not just the 2-methylalkanes. Acyclic alkanes normal surface conditions, while those up to C15 are liquids. The n-alkanes with >15 C atoms tend to be viscous liquids grading into solid waxes (the transition depending upon the ambient temperature). 

CHLOROWAX is miscible with many organic solvents, including aliphatic, aromatic and terpene hydrocarbons chlorinated aliphatic and aromatic hydrocarbons hydrogenated naphthas ketones, esters and drying oils. They are insoluble in water, glycerine and glycols. With a few exceptions, the liquid grades are insoluble in the lower alcohols. 

Depending on molecular weight, polyisobutylene, PIB, can be liquid or solid. Liquid grades of PIB are frequently used as plasticizers. Solid grades are chemically inert elastomers which have resistance to the oxidative and thermal degradation and a low gas permeability. Because of these properties they find many applications. Some of these applications require plasticizers. 

Liquid fertilizers commonly used are UAN (urea and ammonium nitrate mixture) containing 28, 30, and 32 mass% N anhydrous ammonia, which contains 82 mass% N superphosphoric acid, which is a concentrated form of phosphoric acid with a grade of 0-70-0 and ammonia reacted with superphosphoric acid to produce a liquid fertilizer of 10-34-0 or 11-37-0 grade. Different liquid grades of fertilizer can be produced using a variety of chemicals for grades similar to the dry fertilizer grades. 

Most of the ammonium polyphosphate liquids (10-34-0 or 11-37-0) are used in small mix plants to produce NPK mixtures. A typical plant is shown in Figure 10.9. Ammonium polyphosphate solution is mixed nitrogen solutions (UAN solution) and potash to produce various clear liquid grades such as 7-21-7, 8-8-8, and 21-7-0. 

The vacuum filtration of the solutions at the end of the experiments was carried out using cellulose filter papers with a 2.5- xm particle retention in liquid (Grade 42, Whatman, Maidstone, England). 

Notes At SO C liquid grade, (lenerally approved (in Europe) for food-contact applications ... 

A significant proportion of water soluble polyelectrolytes are produced as liquid grade products that are predominantly inverse, that is water-in-oil emulsions. In this process the aqueous monomer is dispersed in a non-aqueous continuous phase through a combination of high-shear mechanical mixing and the use of low hydrophile-Hpophile balance (HLB) surfactants such as sorbitan mono oleate or similar. The resultant dispersion contains droplets having an average particle diameter of only about 1 pm. 

The use of PEGs in the lubricant sector is basically restricted to the liquid grades PEG 200, PEG 300, and PEG 400. They are used in those cases where solubility in water, absolute physiological safety, and skin compatibility are essential. 

Under the German Food Law, PEGs are approved as humectants for papers, cardboard, and boards for food packaging. As well as liquid grades, mixtures of liquid and solid PEGs (e.g., PEG 400 and PEG 1500 in a 1 1 ratio) are often used and can be applied to a 1 to 5% aqueous solution. The amount applied is governed by the weight per m , and the stuff composition. The solution can be applied by brush dampers, size presses, jet dampers, or similar units. 

Polyethylene glycols, chiefly the liquid grades, are used as humectants and plasticizers for dextrin-based adhesives. The addition of PEG prevents embrittlement and reduces the tendency of the bonded papers to curl up. 

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