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1、International Standard (! 4655 0 N 4 4!Y m2 is the mass, in milligrams, of water produced by the test portion. If the results of duplicate determinations do not agree within 0,5 unit, carry out two further determinations. 5 Nitration method 5.1 Reagents All recognized health and safety precautions s
2、hall be taken when carrying out the procedure specified in this international Standard. During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity. 5.1.1 5.1.2 5.1.3 5.1.4 5.1.5 5.1.6 Nitric acid, 70 % (m/m).
3、Sodium hydroxide, solution, c(NaOH) = 5 mol/dm3. Diethyl ether, free from peroxides. Sodium chloride, saturated solution. Sodium sulfate, anhydrous. Sodium hydroxide, solution, c(NaOH) = 0,l mol/dmJ, 5.1.7 Standard SBR, of accurately known bound styrene content (approximately 23,5 %I, determined in
4、accordance with IS0 2453. 5.2 Apparatus Ordinary laboraty apparatus, and 5.2.1 Boiling flask, 100 ml, with standard conical joint to fit the condenser (5.2.2). 3 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/997254
5、5001 Not for Resale, 04/23/2007 22:46:53 MDTNo reproduction or networking permitted without license from IHS -,-,- 5.2.2 Reflux condenser, water-cooled, of adequate length and configuration to prevent loss of nitric acid vapour, having standard conical joint to fit the flask (5.2.1). 5.2.3 Ultraviol
6、et spectrometer, with 10 mm silica cells, capable of measuring absorbance (optical density) within the range 260 to 290 nm. 5.3 Sampling Sampling shall be carried out in accordance with one of the methods specified in IS0 123. 5.4 Preparation of test sample Prepare the test sample as specified in 4.
7、4. 5.6 Procedure Cut the test sample finely and weigh, to the nearest 0,l mg, a portion having a mass in grams equal to 4,5 divided by the estimated percentage total bound styrene content. Place the test portion in the flask (5.2.1). Add 20 cmaof nitric.acid (5.1.1) and a few Carborundum boiling chi
8、ps to the flask. Place the flask on a cold hot-plate, heat and reflux vigorously for 16 to 18 h under the reflux condenser (5.2.2). Turn off the heat, pour IO to 20 cm3 of water into the top of the condenser, and allow the water to be drawn into the flask as it cools. NOTE - Carry out the following
9、transfer operations and subsequent extractions carefully, since the skill with which they are performed determines the accuracy of the determination. Transfer the reaction mixture to a 400 cm3 beaker, using water from a wash-bottle to rinse the flask and standard conical joint into the beaker. Cool
10、the beaker to room temperature. Add 50 cm30f the sodium hydroxide solution (5.1.2) to the flask and again rinse into the beaker with water. If the solution in the beaker is not strongly acid, as indicated by pH paper, add nitric acid to make it so. Cool to room temperature. Transfer the solution to
11、a 500 cm3 separating funnel and rinse the beaker with water into the funnel. Shake the solution in the separating funnel with 50 cm3 of the diethyl ether (5.1.3) and allow the layers to separate. Drain the lower aqueous layer into the beaker. Add 25 cm3 of the sodium chloride solution (5.1.4) to the
12、 ether layer. Drain a few cubic centimetres into the beaker to wash the stem of the separating funnel. Shake and allow layers to separate. Drain the aqueous layer into the beaker. Drain the ether layer into a 250 cm3 beaker containing 4 to 5 g of the sodium sulfate (5.1.5). Add a further E-0 cm3 of
13、ether to the separating funnel and drain a few cubic centimetres into the 250 cm3 beaker, to wash the stem of the funnel. Carefully swirl the 250 cm3 beaker and transfer the ether extract to a second separating funnel. Extract the aqueous layer in the same manner twice more, dry- ing each ether extr
14、act over the same sodium sulfate and collec- ting it in the second separating funnel. Extract the combined ether extracts four times with 50 cmspor- tions of the sodium hydroxide solution (5.1.6). Collect the aqueous extracts in a 250 cm3 volumetric flask. After each ex- traction, drain a few cubic
15、centimetres of the next portion of sodium hydroxide solution, before shaking, to rinse the stem of the separating funnel, adding the drainings to the volumetric flask. Dilute to the mark with the sodium hydroxide solution (51.6) and mix well. Pipette 25 cm3 into a second 250 cm3 volumetric flask, di
16、lute to the mark with the sodium hydroxide solution (5.1.6) and mix well. With the sodium hydroxide solution (5.1.6) in the reference cell of the ultraviolet spectrometer (5.2.31, measure the absorbance of the solution from the second volumetric flask at 265,274 and 265 nm. 5.6 Determination of cali
17、bration constants (K, K2 and K3) Cut finely a sample of the standars SBR (5.1.7) and weigh, to the nearest 0,l mg, at least three portions of approximately 190 mg. Carry out on each portion the nitration procedure specified in 5.5. For each portion calculate the absorptivity (specific extinction coe
18、fficient) of nitrated styrene at each wavelength from the formula A/Co - K (1 - xl X where A is the absorbance of the solution; Cs is the concentration, in grams per cubic decimetre, of standard SBR in the solution; K is the absorptivity of nitrated butadiene = 0,373 et 265 nm, 0,310 at 274 nm and.0
19、,265 at 285 nm; X is the fraction of bound styrene in the standard SBR. Calculate the average absorptivity K at each wavelength from the results on the three separate portions. 5.7 Expression of results Calculate the total bound styrene S as a percentage by mass of the dry polymer content of the lat
20、ex, from the equation where St = (fOOA1lC - 37,3)/(K, - 0,373) s, = (lOOA2/C - 31,O)/(K2 - 0,310) s3 = M10A3/C - 26,5)/(K3 - 0,265) 4 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2
21、007 22:46:53 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 4655-1985 (El where 6 Test report A, A2 and A3 are the absorbances of the solution at wavelengths of 265, 274 and 265 nm respectively; C is the concentration of test portion calculated from C = 0,4 m m being t
22、he mass, in grams, of the original test por- tion, in 250 cm3; K, K2 and K3 are the absorptivities of nitrated styrene at wavelengths of 265, 274 and 265 nm respectively, determined as in 5.6. If the results of duplicate determinations do not agree within 0,6 unit, carry out two further determinatio
23、ns. Time I Heaters switched on min for benzoio acid for naphthalene 1 1 to3 1 to 5 2 3 to 5 2 to 7 3 5 to 7 3 to 9 4 7 to 9 5to 10 5 9to 11 6to 11 for test portion 1 to 4 3 to 6 5 to 8 7to 10 9 to 12 8 10 to 12 7to 12 10 to 13 7 10 to 13 8to 13 10 to-14 8 11 to 14 9 to 14 10 to 15 9 12 to 15 10 to 1
24、5 10, 12to 18 10 12 to 16 10 to 15 11, 13 to 17 11 13 to 18 10, 12 to 18 11, 14 to 18 12 13 to 18 10, 12 to 18 12, 14 to 18 13 14 to 17 10, 12 to 18 12, 14 to 18 14 14 to 17 11, 13 to 17 12, 14 to 18 15 15 to 18 11, 13 to 17 13, 15 to 18 16 16 to 19 11, 13 to 17 13, 15 to 19 17 16 to 19 12, 14 to 18
25、 14, 16 to 19 18 17 to 20 12, 14 to 18 14, 18 to 20 19 18 to 21 13, 15 to 19 15, 17 to 21 20 19 to22 14, 18 to 20 15, 17 to 21 21 22 23 24 25 20 to 23 21 to 24 17, 18, 23 to 25 18, 19, 24 to 28 19, 20, 25 to 27 20. 21. 25 to 28 15, 17 to 21 14, 15, 18, 20 to 22 18, 18 to 22 15, 16, 19, 21 to 23 17,
26、19 to 23 18, 17, 20, 22 to 24 18, 20 to 24 17, 18,21,23to25 19, 21 to 25 18, 19,22, 24 to 28 28 27 28 29 30 2i, ti, 27, 28 23. 24.28. 29 24, .25, 28 io 30 25, 28, 28 to 30 20, 22 to 28 19, 20,23, 25 to 27 21,23to27 20, 21, 24, 28 to 28 23, 25 to 29 21, 22, 27 to 30 24,28 to 30 22, 23, 27 to 30 24,28
27、 to 30 24, 25, 27 to 30 The test report shall include the following particulars : a) the type and identification of the product tested; b) reference to this International Standard; c) the method used (carbon/hydrogen or nitration); d) the results and the method of expression used; + e) any unusual f
28、eatures noted during the determination; f) any operation not included in this International Stan- dard or in the International Standards to which reference is made, or regarded as optional. Table - Heating schedules for carbon/hydrogen method 5 Copyright International Organization for Standardizatio
29、n Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:46:53 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 4855-1985 (El Oxygen Air i k L B- -B I E - . - F -_- _. . - - J H H A Pressure-release vessels B G
30、uard tubes C Needle valves D Rotameters E Purification tube F Furnace G Combustion tube H Absorption tubes Figure 1 - Arrangement of combustion apparatus for carbon/hydrogen method Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical
31、 Standards 1/9972545001 Not for Resale, 04/23/2007 22:46:53 MDTNo reproduction or networking permitted without license from IHS -,-,- 1 Side arm t+3 3 x 15 long Dimensions in millimetres Silica wool- I %10,- Copper(H) oxide 00% in wire form (4.1.4) bl for carbon dioxide 9 Copyright International Org
32、anization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:46:53 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 4955-1985 (EI Dimensions in millimetres Purification tube- . c. l-l L-
33、 Combustion tube I #f-j - . II I Ill II I Ill -Heat-resistant insulating board -Exfoliated mica YThermocouples Silica tubes (wound with 7zniJ-chromium Figure 5 - Furnace for carbon/hydrogen method - Sectional view through axes of tubes 10 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:46:53 MDTNo reproduction or networking permitted without license from IHS -,-,-