Vinyl swelling properties

The first conversion on a polymer to introduce a ethyl methyl ketone moiety was performed, without dilution, in the liquid reactants vinyl methyl ketone and condensed hydrogen fluoride, which scarcely solvate the polystyrene support. Recently, Tesser and co-workers [78] reported an unsuccessful attempt to verify this type of transformation on polystyrene, supposing that their failure depended upon the particular batch of polymer used. Obviously the swelling properties of the cross-linked supports in the poorly solvating reaction liquid — condensed hydrogen fluoride - differed in these independent experiments. Therefore, to describe completely a procedure to modify an insoluble, but swelling, polymer, it is essential to specify the solvation power of the hquid mixture of reactants. 

Cationic HGs swell and release a drug in the low pH environment of the stomach (Fig. 3.6). Risbud et al. (2000) prepared a pH-sensitive, chitosan/ poly(vinyl pyrrolidone) (CS/PVP)-based, controlled drug release HG using air-dried and freeze-dried amoxiciUm. Porous freeze-dried hydrogel exhibited superior pH-dependent swelling properties over non-porous air-dried HGs. Freeze-dried membranes released around 73% of the amoxicillin (33% by air-dried) in 3 h at pH 1.0, and thus had the better drug release properties. 

Deen GR, Lim EK, Mah CH, Heng KM (2012) New cationic linear copolymers and hydrogels of N-vinyl caprolactam and N-acryloyl-N -ethyl piperazine Synthesis, reactivity, influence of external stimuli on the LCST and swelling properties. Ind Eng Chem Res 51 13354 Di Meo C, Capitani D, Mannina L, Brancaleoni E, Galesso D, De Luca G, Crescenzi V (2006) Synthesis and NMR characterization ofnewhyaluronan-basedNO donors. Biomacromolecules 7 1253... 

Jansson A, Jamstrom L, Ratto P, Thuvander F. 2006. Physical and Swelling Properties of Spray-Dried Powders made from Starch and Poly(vinyl alcohol). Stttfch/Starke 58(12) 632-641. 

In attempts to further improve the stability of fluorine-containing elastomers Du Pont developed a polymer with no C—H groups. This material is a terpolymer of tetrafluoroethylene, perfluoro(methyl vinyl ether) and, in small amounts, a cure site monomer of undisclosed composition. Marketed as Kalrez in 1975 the polymer withstands air oxidation up to 290-315°C and has an extremely low volume swell in a wide range of solvents, properties unmatched by any other commercial fluoroelastomer. This rubber is, however, very expensive, about 20 times the cost of the FKM rubbers and quoted at 1500/kg in 1990, and production is only of the order of 1 t.p.a. In 1992 Du Pont offered a material costing about 75% as much as Kalrez and marketed as Zalak. Structurally, it differs mainly from Kalrez in the choice of cure-site monomer. 

Other material properties that are of general interest to the polymer chemist are shown in Table 3. Linear toluene swell is indicative of cross-link density in the material. The vinyl-phenyl modified rubber showed the lowest degree of swell. This is due to additional cross-links introduced by the vinyl groups during synthesis. The unmodified rubber was found to swell considerably in toluene and was found to dissolve partially in the solvent. 

Uses Dielectric liquids in fixed paper capacitors heat-transfer liquid widely used in transformers and utility transmission lines swelling agents for transmission seals ingredient in lubricants, oils, and greases plasticizers for cellulose products, vinyl, and chlorinated rubbers in polyvinyl acetate to improve fiber-tear properties. In fluorescent and high-intensity discharge ballasts manufactured prior to 1979 (U.S. EPA, 1998) and in electric motors (Monsanto, 1960). 

Landells, G., and C. S. Whewell Preparation and properties of regenerated cellulose containing vinyl polymers. I. Internal deposition of polymers. J. Soc. Dyers Colourists 67, 338 (1951). II. Staining, swelling, and stiffness characteristics. J. Soc. Dyers Colorists 71, 171 (195S). III. Moisture relations. J. Soc. Dyers Colorists 73, 496 (1957). 

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