Immersion test reagents

The change in volume as well as weight of the test piece after immersion, with respect to time, is recorded. The test chemicals and reagents used in immersion test and the nature of attacks are as given in the table below ... 

Table 12.18 provides a list of standard test methods for the evaluation of solvent and chemical susceptibilities of polymers and their blends. These tests are to help in (1) designing of fabricated parts, (2) comparison of different materials and (3) characterization of materials for long term performance, etc. The materials performance, summarized after the immersion in reagents for 7 days at elevated temperatures according to ASTM D 543, based on changes in weight, dimensions, appearance and mechanical properties, is shown in Table 12.19. 

Immersion into a reagent ASTMG31 Standard practice for laboratory immersion corrosion testing of metals Conditions of immersion testing in a reagent... 

The chromatogram is freed from mobile phase, immersed in the dipping solution for 3 s or homogeneously sprayed with the spray solution and then dried in a stream of cold air. Triazines must be converted to chlorinated derivatives by exposing the chromatogram to chlorine gas (see Procedure Tested ) before application of the reagent. 

The ninhydrin test will not interfere with the Ehrlich reagent. Therefore, a plate can be examined under UV light, immersed in iodine vapors, treated with ninhydrin, and the Pauly or Ehrlich reagents successively. 

Test Preparation Transfer about 50 mg of sample, accurately weighed, into a glass-stoppered, 25-mL conical flask add 5 mL of Internal Standard Solution by pipet and mix to dissolve. Immerse the flask in a water bath maintained at a temperature between 45° and 50°, and volatilize the chloroform with the aid of a stream of nitrogen. Add 3 mL of Propionating Reagent, and heat at 75° for 30 min. Volatilize the reagents with the aid of a stream of nitrogen at room temperature, add about 5 mL of chloroform, and mix. 

Place a drop of the neutral or alkaline test solution in a micro test-tube, and add 1 drop of m sodium chloride solution and 2 drops of the iron(III) periodate reagent. Carry out a blank test with a drop of distilled water simultaneously. Immerse both tubes for 15-20 seconds in water at 40-50°C. A white (or yellowish-white) precipitate indicates the presence of lithium the blank remains clear. 

G-H. Dependence of the Rate on Temperature. In order to determine the temperature dependence of the enzyme-catalyzed rate, the reaction is carried out at several different temperatures, which are held constant to within 0.3°C or better. Choose from mns E a set of initial concentrations that gives an absorbance of —0.5 at room temperature after the standard assay. Convenient temperatures for these runs, denoted as runs G, are 0°C (ice bath), 12, 25, 35, and 45°C. In each case, prepare the enzyme-water-buffer mixture in the assay tube, put about 2 mL of the sucrose stock solution in another test tube, and immerse both tubes in the thermostat bath for a few minutes to achieve temperature equilibrium. Next, pipette 1.0 mL of the equilibrated sucrose solution into the assay tube and read the bath temperature. Leave the assay tube in the constant-temperature bath until, 5.0 min after the addition of the sucrose solution, the reaction is terminated by the addition of 2.0 mL of the dinitrosalicylate reagent. Then complete the assay as usual. 

In the Krais-Viertel reagent test the wool is immersed in a solution of ammonia in caustic soda [23]. The test entails timing of the appearance of the characteristic swellings in this reagent. When the fibre has been damaged with acid, the time for appearance is decreased. 

The stability of the membranes obtained against various solvents was investigated by Immersing the membranes in the solvent concerned at 40°C for about three weeks. After that their mechanical and osmotic properties were tested again and compared with their properties before the treatment. The results of the experiments are shown in table I. The stability of the membranes subjected to cross-linking by an organic reagent is very satisfactory. Additional treatment with Cr(III) solutions... 

Three samples of RubCon were made for each term of exposure. Before immersing in the medium, samples were measured and weighed. After reaction of the corrosion reagents with RubCon, the samples were taken out of the exicators, dried with filtering paper, and put on a compression test with a speed of 60 MPa/min. 

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