Water-absorbing polymer

Manufacture of highly water-absorbent polymers with uniform particle size and good flowability can be carried out by reverse phase suspension polymerization of (meth)acrylic acid monomers in a hydrocarbon solvent containing crosslinker and radical initiator. Phosphoric acid monoester or diester of alka-nole or ethoxylated alkanole is used as surfactant. A polymer with water-absorbent capacity of 78 g/g polymer can be obtained [240]. 

O Water absorbing polymer Figure 8.26 Asymmetric reduction of ketones in CO2 by Geotrichum candidum immobilized whole cell [20], (a) Time course for the reduction of o-fluoroacetophenone (b) substrate specificity (c) apparatus for C. candidum-cata yzed reduction with semiflow process using scC02. 

Matsuda recently reported an elegant solution for using a delicate enzyme system in an IL solvent system (Fig. 20). The authors prepared Geotrichum candidum IF05767 dried cell on water-absorbing polymer BL-100 and used... 

C. O. Walker. Method for controlling lost circulation of drilling fluids with water absorbent polymers. Patent US 4635726,1987. 

DC Harsh, SH Gehrke. Characterization of ionic water absorbent polymers Determination of ionic content and effective crosslink density. In L Brannon-Peppas, RS Harland, eds. Absorbent Polymer Technology. Amsterdam Elsevier, 1990, pp 103-124. 

The class of hydrophilic and water-absorbent polymers are superabsorbent polymers (SAP). Super absorbent polymers are polymers that can absorb and retain extremely large amounts of a liquid relative to its own mass. 

Water absorbing polymers, sometimes referred to as hydrogels, absorb aqueous solutions through hydrogen bonding with the water. An SAP s ability to absorb water is a factor of the ionic concentration of an aqueous solution. In deionized and distilled water, SAP may absorb 500 times its weight (from 30 to 60 times its own volume), but when put into a 0.9% saline solution, the absorbency drops to maybe 50 times its weight. The presence of valent cations in the solution will impede the polymer s ability to bond with the water molecule. 

Enantioselectivities were high, 97% and above, with the S isomer being the major product. The catalyst was the whole resting cell of the fungus Geo-trechum candidum immobilized on a water-absorbing polymer. 

The asymmetric reduction of ketones is carried out with a flow reactor using an alcohol dehydrogenase inunobilized on a water-absorbing polymer. Although the... 

In another Q A in the same guidance, the EPA said that if a polymer is deliberately converted to a water-absorbing polymer by neutralization, that conversion constitutes manufacture for commercial purposes as a chemical substance, rather than processing.. .. The resulting neutralized substances would also not be excluded from reporting under 720.30(h)(7). This is consistent with the requirement that the excluded substance cannot provide a primary property that determines the use of the resulting product. 

Farrar D, Elesher P, Skinner M et al (1995) Water absorbing polymers. US Patent 5,384,343 Crawford RL (1981) Lignin biodegradation and transformation. Wiley, New York Updegraff DM (1969) Semimicro determination of cellulose in biological materials. Anal Biochem 32 420-424... 

Construction Materials. Superabsorbent polsrmers are used to control liquid water in a variety of construction-related products. Joint-sealing composites are made by blending superabsorbents into chloroprene rubber (54) or into poly(ethylene-co-vinyl acetate) (55). These composites are used like mortar in the concrete block walls of the structure. Gaps left during construction are subsequently filled as the superabsorbent swells in any water, and subsequent leaks are prevented. A water-blocking construction backfill has also been developed from cement, water absorbing polymer, and an asphalt emulsion (56). 

In part 2 (chemical concepts) students seareh for explanations in their textbook chapter about organic chemistry its nomenclature and flie strueture-property relations of water-absorbing polymers. The instruetional funetion of studying these chemical concepts is to satisfy students euriosity and to fulfil their need. 

Figure 9 SEM of starch-clay hydrogel (left x500 magnification 80 pm piece). Right part shows the polarised microscope picture of a 0.3 mm piece of a clay-hybrid water absorbent polymer with the birefringence as a result of the clay.

The asterisk indicates those materials related to water-absorbing polymers... 

As the water-absorbing polymer for the absorption sheet, poly-(aerylie acid) is often used. In order to keep the total cost of foodpackaging material low, a mass-produced expensive polymer is preferred. 

Water-absorbing polymer film (prepared by irradiating... 

Water absorbing polymer layer (sodium poly(acrylic acid))... 

Contact water absorbing sheet (include highly permeable material and water absorbing polymer as shown in Fig. 1)... 

This method makes snow by freezing water-absorbed polymer gel on cooling pipes. The polymer used in this method is a poly(acrylic acid) type. To this polymer 100-120 times the water is absorbed and then sprayed and frozen on the cooling pipes installed on the slopes. 

The synthesis of the first water-absorbent polymer goes back to 1938, when AA and divinylbenzene were thermally polymerized in an aqueous medium. In the late 1950s the first generation of hydrogels appeared, mainly based on hydroxyalkyl methacrylate and related monomers, and with swelling capacity up to 40-50%. These hydrogels were used in the development of contact lenses that revolutionized ophthalmology. 

Sample drying can be accomplished in several ways such as air drying and oven drying before extraction. Flowever, these approaches are not suited when analysing volatile or seml-volatlle components as they would be removed from the sample before extraction or analysis. The In-cell method can remove moisture when the wet sample Is mixed with a water absorbing polymer (Ullah et al 2012). 

Typically, a water-absorbent polymer is applied comprising a copolymer of a basic monomer with an acidic monomer. This combination is suitable for moisture removal under high ionic strength conditions. Results also demonstrate that when the polymer is mixed with diatomaceous earth (DE), absorbent the water-removal efficiency increases significantly. Water-removal efficiency increases significantly due to improved flow characteristics. 

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