Swelling 978 INDEX

Swelling Index Swelling is defined as the increase in volume of a gel or solid associated with the uptake of a liquid or gas [7]. In fact, swelling represents the first stage in every polymer solution process, in which the solvent molecules diffuse through the polymer matrix to form a swollen, solvated mass, known as polymer gel. However, the gel formed after swelling polymer networks does not break up and the polymer molecules do not diffuse out of the swollen mass, and therefore, no real solution can be formed. 

In Project 4, the consolidation of fine soils is studied. As the oedometer tests are long and the number of test rigs available is limited, typically students use results from previously performed tests, without carrying them on their own. With those results a series of parameters has to be determined (compression index, swelling index, consolidation coefficient, overconsolidation ratio, etc.). The preparation of the spreadsheets includes the analytical and graphical determination, within the spreadsheet, of the mentioned quantities. Later, this information is used to study the consolidation process in a realistic (field) problem, by... 

Viscosity Index Improvers. VI improvers are long-chain, high molecular weight polymers that increase the relative viscosity of an oil at high temperatures more than at low temperatures. In cold oil the molecules of the polymer adopt a compressed coiled form so that the affect on viscosity is minimized. In hot oil the molecules swell, and interaction with the oil produces a proportionally greater thickening effect. Although the viscosity of the oil—polymer mixture decreases as the temperature increases, viscosity does not decrease as much as the oil alone would decrease. 

Free-swelling tests are commonly used to measure a coal s caking characteristics. A sample of coal is packed in a cmcible or tube, without compaction, and heated at a fixed rate to about 800°C. Infusible coals distill without changing appearance or state of agglomeration. The fusible coals soften, fuse, and usually sweU. The profile of the resultant coke is compared to a series of reference profiles so that a swelling index can be assigned. The profiles represent indexes between 0 and 9. The best cokes come from coals having indexes between 4 and 9. 

Eor the free swelling index which is also known as the cmcible swelling number (ASTM D720), a coal sample is rapidly heated to 820°C in a covered cmcible. Then the profile of the resulting char is compared to a series of standard numbered profiles (18). Eor the Roga index weighed amounts of coal and standard anthracite are mixed and carbonized, and the product coke is tested in a Roga dmm for its resistance to abrasion (89). 

Physical Properties The free-swelling index (FSl) measures the tendency of a coal to swell when burned or gasified in fixed or fluidized beds. Coals with a high FSl (greater than 4) can usually be expected to cause difficulties in such beds. Detads of the test are given by the ASTM D 720 (American Society for Testing and Materials, op. cit.) and U.S. Bureau of Mines Report of Investigations 3989. 

The gel content (toluene insoluble per cent) of the rubber and the swelling index of the gel (the ratio of the volume of a swollen gel to its unswollen volume). The former is a measure of the amount of cross-linked material and the second a measure of the intensity of cross-linking. It has been found that a sample of medium gel content (5-20%) and a medium swelling index (10-20) gives the best impact strength in the blend. 

Materials Melt Index Die Swell, % Density, qm/cc Intrinsic Viscosity Haze, % Gloss Tear Strength, ms An 4.52 Anmr 4.5 5.05... 

Chatteijee, A. 2005. Application of localized reactivity index in combination with periodic DFT calculation to rationalize the swelling mechanism of clay type inorganic material. J. Chem. Sci. 117 533-539. 

PVA has also been extensively used for immobilization of biocatalysts in a membranous form. As compared to PAAm, PVA is more hydrophilic and having adhesive property with better tensile strength in dry conditions. But it has high swelling index and dissolves readily in water when not cross-linked. PVA can be cross-linked using a variety of reagents including... 

Indirect evidence for solvent exchange can also be gained by in-situ ellipsometry. This technique can provide information of film thickness and optical properties as a function of the electrode potential. Figure 2.19 shows that the film swells during oxidation and shrinks during reduction, in agreement with EQCM measurements. A decrease in the refractive index from 1.42 to 1.38 during oxidation also supports the uptake of water, which has a refractive index of 1.33. 

Emulsion Polvmer Additive/ Cataivst XN Added Cured Polymer X N Swell Observed Theoretical Index ... 

Swell Index and Percent Solubles Measurements. Polymer films were cast on polyester film at 25X solids with various post additives. The films were air dried (16-48 h) then cured for 3 and 10 min at 150 C In a converted oven. Small samples (50-100 mg) of film were weighed, soaked In dimethylformamide (DHF) for 1 h, briefly pat-dried and reweighed In an A1 weighing pan. The samples were then redried at 150 C (20 torr) or 170 C, 1 atm for 30 min. 

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