ISO-182-3-1993.pdf
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1、INTERNATIONAL STANDARD IS0 182-3 First edition 1993-04-01 Plastics - Determination of the tendency of compounds and products based on vinyl chloride homopolymers and copolymers to evolve hydrogen chloride and any other acidic products at elevated temperatures - Part 3: Conductometric method Plastiqu
2、es - D 200 “C for compounds and products for cable in- sulation and sheathing; 180 “C to 200 “C for plasticized compounds and products, depending on their stabilization. 10 Test procedure 10.1 Preparation of test portion Weigh, to the nearest 0,Ol g, 2 g of the test sample, prepared in accordance wi
3、th the appropriate part of clause 7. Introduce this test portion into the chosen dehydrochlorination cell (6.1) and connect the cell to the remainder of the apparatus (6.3 or 6.41, taking particular care to ensure that all joints are tightly closed and, where appropriate, that all ground glass joint
4、s are sealed with a suitable stopcock grease. 7 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 07:19:56 MDTNo reproduction or networking permitted without license from IHS -,-,-
5、 IS0 1823:1993(E) 10.2 Preliminary operations 12 Precision Heat the oil bath (6.5) to the agreed test temperature. Start the flow of nitrogen through the dehydrochlorination cell, adjust to a flow-rate of 120 cm3/min f 4 cm3/min and flush the cell for about 5 min to eliminate air. During this period
6、, the dehydrochlorination cell shall not be heated. The ni- trogen flowing through the cell shall be allowed to escape to the atmosphere without passing through the absorbing liquid contained in the measurement cell (6.8). 10.3 Speclal precautions when using dehydrochlorination cell A In a two-year
7、period (1989 and 19901, international round-robin tests were carried out to evaluate the precision of the method described in this part of IS0 182, in comparison with the pH-meter method (IS0 182-2 tl). Three different PVC compounds were tested: 1 Unplasticized compound for pipes; PVC 2 Plasticized
8、compound for cable sheathing; 3 A Italy I (1990); F Italy II (I 989); Belgium D France I; ;I; Introduce 180 ml of demineralized water as specified in 5.3 into the measurement cell and start the stirrer. Allow the measurement cell to reach thermal equilib- rium in the range 23 “C f 2 “C and maintain
9、it at that temperature. All samples were supplied by laboratory A (Italy I). All tests were conducted with dehydrochlorination cell A at 200 “C. The data shown in table 1 were obtained. 12.1 Repeatability Insert the conductivity probe into the demineralized water to the depth recommended by its manu
10、fac- turer. By application of the statistical method according to IS0 572521 to the data obtained for sample 1, the following value of the repeatability f was obtained (see annex B): NOTE 4 It may be necessan/ to conduct the test in a temperature-controlled room. Alternatively, it may be necessary t
11、o surround the measuring cell with a water bath in order to maintain the temperature at 23 “C f 2 “C, or a narrower interval if required by the supplier of the conductance meter. r = 6,64 The calculation was not made for samples 2 and 3, owing to insufficient data. However, by comparison of the stan
12、dard deviations, the repeatability appears to be of the same order of magnitude. 10.5 Decomposition of the test portion 12.2 Reproducibility Immerse the dehydrochlorination cell rapidly in the oil bath and immediately place the end of the connecting tube into the demineralized water contained in the
13、 measurement cell. From the same table of results, by the appropriate calculation, the following values for the reproducibility R and the overall mean stability time m were obtained (see annex B): Start the stopclock and/or the recorder at the moment when the tube .is immersed in the demineralized w
14、a- ter and continue the test at least until a change of 50 pS/cm is observed in the conductivity of the water. R=r=6,64 m = 78,12 min 12.3 Comparison with the pH-meter method (IS0 182-2) 11 Expression of results From the data shown in the right-hand columns of table 1, the results of the statistical
15、 calculation are: m = 78,46 min Record the stability time rs, in minutes, as the time r = 3,77 taken to achieve a 50 pS/cm change in conductivity. R = 4,15 8 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001
16、 Not for Resale, 04/20/2007 07:19:56 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 182-3:1993(E) which is comparable to those values obtained by the conductometric method. 12.4.1 The size of the cut or ground particles of the test portion, as pointed out in 7.2. On te
17、st portions of the same sample of unplasticized PVC having different particle sizes, the values shown in table2 were obtained. 12.4 Factors affecting the stability time 12.4.2 The decomposition temperature. From tests conducted by laborator/ C (Belgium), the On two samples each of two different comp
18、ounds of principal factors affecting the stability time tS appear unplasticized PVC, values shown in table3 were ob- to be those described in 12.4.1 and 12.4.2. tained. Table 1 - ReDeat determinations of stabilitv time for three PVC Droducts over a two-vear Deriod Stability time, t, min I . Test ter
19、n- Conductometric method (IS0 1823) pH-meter mathod (IS0 182-21 Year Sample Type11 Lab- P.M. oratory ture Standard Numbor Range Mean deviation, Overall mean of s teata “C -r min min min min min WC-U 2 76 to 77 78to81 WC-U 2 76 to 82 77to77 PVC-U 2 79to81 PVGU 2 76to78 PVC-U - - 1989 1989 1989 1990 1
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