1、DEUTSCHE NORM August 2000 Rubber Pol yc h loro prene latex Determination of alkalinity (IS0 13773 : 1997) I - I I IS013773 I ICs 83.040.1 O Kautschuk und Elastomere - Polychloropren-Latex - Bestimmung der Alkalitt (IS0 13773 : 1997) This standard incorporates International Standard IS0 13773 Rubber
2、- Polychloroprene latex - Determination of alkalinity. A comma is used as the decimal marker. National foreword This standard has been prepared by ISO/TC 45. The responsible German body involved in its preparation was the Normenausschuss Materialprfung (Materials Testing Standards Committee), Techni
3、cal Committee Prfung von Latex. The DIN Standards corresponding to the International Standards referred to in clause 2 of the IS0 Standard are as follows: IS0 123 DIN 53562 IS0 976 DIN IS0 976 IS0 3696 DIN IS0 3696 National Annex NA Standards referred to (and not included in Normative references) DI
4、N 53562 DIN IS0 976 Sampling of rubber latex Rubber and plastics - Polymer dispersions and rubber latices - Determination of pH (IS0 976 : 1996) IS0 Standard comprises 8 pages. Q No pari of this standard may be reproduced without the prior permission of Ref. No. DIN IS0 13773 : 2000-0; DIN Deutsches
5、 Institut fr Nonnung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany, has the exclusive right of sale for German Standards (DIN-Nonen). English price group 07 Sales No. 040 o1 .o Page 1 IS0 13773 : 1997 Rubber Pol yc h loro pre ne latex Determination of alkalinity Foreword IS0 (the Internati
6、onal Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of preparing International Standards is normally carried out through IS0 technical committees. Each member body interested in a subject for which a technical committee has been
7、 established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. IS0 collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standa
8、rdization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 YO of the member bodies casting a vote. International Standard IS0 13773 was prepared by Technical Co
9、mmittee ISO/TC 45, Rubber and rubber products, Subcommittee SC 3, Raw materials (including latex) for use in the rubber industry. Annexes A and B of this International Standard are for information only. Page 2 IS0 13773 : 1997 WARNING - Persons using this International Standard should be familiar wi
10、th normal laboratory practice. This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions. 1 Scope Th
11、is International Standard specifies a method for the determination of the alkalinity of polychloroprene latex prepared by the polymerization of chloroprene in an alkaline emulsion. It is not suitable for polychloroprene latex prepared in a non-ionic emulsion, for natural rubber latex concentrate nor
12、 necessarily for synthetic rubber latices other than polychloroprene. 2 Normative references The foliowing standards contain provisions which, through reference in this text, constitute provisions of this International Standard. All standards are subject to revision, and parties to agreements based
13、on this Intemational Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and IS0 maintain registers of currently valid International Standards. IS0 123:1985, Rubber latex - Sampling. IS0 976:1996, Rubber and pla
14、stics - Polymer dispersions and rubber latices - Determination of pH. IS0 3696:1987, Water for analytical laboratory use - Specification and test methods. 3 Principle A test portion of the latex is titrated electrometrically against hydrochloric acid to the second point of inflexion of the titration
15、 curve (pH in the range 4 to 5). The alkalinity is calculated from the amount of acid required. The alkalinity is commonly expressed as its two component parts in practice, .e. the amount of acid required to the first point of inflexion (pH in the range 1 O to 11) which measures the amount of free a
16、lkali (the alkaline reserve) and the amount of additional acid required to the second point of inflexion which is a measure of the amount of saponified anionic organic surfactants in the latex, usually refered to as the “delta titre“. NOTE -When using a pH-meter to control the titration, it was form
17、erly the practice to define the points of inflexion as pH 103 and 43. However since these do not always correspond to the points of inflexion the results obtained would be approximate. The results are expressed in millimoles of hydrochloric acid per 100 g of latex. 4 Reagents For the analysis, use o
18、nly reagents of recognized analytical grade and only distilled water free of dissolved carbon dioxide, or water of equivalent purity (grade 3 as defined in IS0 3696). Page 3 IS0 13773 : 1997 4.1 Stabilizer solution: a 10 YO (dm) solution of a non-ionic stabilizer of the alkyl phenol polyethylene oxi
19、de condensate type. NOTE - The precise nature of the stabilizer is not critical provided that it imparts acid stability to the latex and does not interfere with the titration. 4.2 Hydrochloric acid, standard volumetric solution, c(HCI) = 0,l mo1/dm3. 5 Apparatus Standard laboratory apparatus, plus t
20、he following: 5.1 Automatic potentiometric titrator, fitted with an automatic burette and capable of delivering a volume of up to 50 cm3. NOTE - It is permissible to use a manually operated 50 crn burette. In this case, it is desirable to make a preliminary assessment of the approximate end-points.
21、5.2 Combined pH-electrode, with built-in glass electrode, suitable for use with solutions up to pH 14,O. 5.3 Magnetic or mechanical stirrer, with variable speed and non-metallic paddle or magnetic bar. The motor shall be properly grounded to avoid interference. 6 Sampling Carry out sampling in accor
22、dance with one of the methods specified in IS0 123. NOTE - Unsealed samples of alkaline polychloroprene latex rapidly absorb carbon dioxide from the air. 7 Procedure Adjust the temperature of the reagents and test sample to 23 “C k 1 OC and calibrate the titrator in accordance with the manufacturers
23、 instructions or as described for pH-meters in IS0 976. Weigh, to the nearest 0,Ol g, an approximately 35 g test portion of the latex into a clean glass or plastic beaker of about 150 cm3 capacity. Insert and start the stirrer (5.3). Adjust the speed of the stirrer to obtain a small vortex at the su
24、rface of the liquid and slowly add 10 cm3 of the stabilizer solution (4.1) from a pipette. Insert the electrode (5.2) and the reagent discharge tip of the titrator. If there are signs of shock or coagulation on adding the stabilizer, dilute it with an equal volume of water before addition. Start the
25、 titration for an automatic controlled addition of up to 50 cm3 of hydrochloric acid (4.2) where the volume increment and addition speed are based on the pH change. Record the volumes of acid V, and V, measured at the first and second inflexion points of the titration curve (approximately pH 10,5 an
26、d 45, respectively). Record the precise pH at the points of inflexion. If a manually operated burette is used (see note to 5.1), it is desirable to carry out a preliminary titration to give an approximate indication of the end-points. In subsequent titrations, add the hydrochloric acid in small incr
27、ements through the range of the point of inflection. If there are indications of coagulation during the determination, repeat the procedure but using 20 cm3 of stabilizer solution. Page 4 IS0 13773 : 1997 Repeat the determination using a fresh test portion of latex. If the calculated figures for the
28、 alkalinity differ by more than 0,02 mmol, carry out the determination again using two fresh test portions. 8 Expression of results 8.1 Set the calculation parameters of the automatic titrator so as to obtain the alkaline reserve AR of the latex, expressed in millimoles of hydrochloric acid per 100
29、g of latex, using the equation: cv, AR = - x IO0 rn where c is the actual concentration of the hydrochloric acid, expressed in moles of HCI per cubic decimetre; V, is the volume, in cubic centimetres, of hydrochloric acid required to reach the first end-point; rn is the mass, in grams, of the test p
30、ortion. 8.2 Calculate the delta titre AT of the latex, expressed in millimoles of hydrochloric acid per 100 g of latex, as follows: rn where V2 is the volume, in cubic centimetres, of hydrochloric acid required to reach the second end-point; c, V, and rn are as defined in 8.1. 8.3 Calculate the alka
31、linity A, of the latex, expressed in millimoles of hydrochloric acid per 100 g of latex, as follows: A=AR+AT where AR and AT are as defined in 8.1 and 8.2. 9 Testreport The test report shall include the following particulars: a) a reference to this International Standard; b) all details necessary fo
32、r identification of the sample; c) the alkalinity of the latex, expressed to the nearest 0,l mmol; d) the alkaline reserve and the delta titre of the latex, expressed to the nearest 0,l mmol of hydrochloric acid per 100 g of latex; e) the pH recorded at the first and second points of inflexion; f) t
33、he amount of stabilizer solution used; Page 5 IS0 13773 : 1997 g) h) details of any unusual features noted during the determination; details of any operation not included in this International Standard or in the International Standards to which reference is made, as well as any operation regarded as
34、 optional; i) the date and place of the test. Page 6 IS0 13773 : 1997 Annex A (informative) Precision of the test method With accurate operation and control, it is possible to attain the following precision: A.l Repeatability Within the range +I 0,02 mmol. A.2 Reproducibility Not established. NOTE -
35、 The work carried out to generate the precision data was initiated before the publication of ICOiTR 9272:1986, Rubber and rubber products - Detennination of precision for test method standards. Consequently, the data are not expressed in the format recommended by this Technical Report. Page 7 IS0 13
36、773 : 1997 Volume cm3 0,oo 1,71 2,57 3,OO 3,86 4,86 5,86 6,86 7,86 8,83 934 10,09 1033 10,86 11,14 11,37 11,58 11,79 12,02 12,27 12,58 12,95 13,40 13,97 14,69 15,59 16,59 17,59 18,59 19,59 20,59 21,59 22,59 23,59 24,59 25,59 26,59 27,59 28,29 29,59 30,59 31,59 32,59 33,59 34,59 3559 36,49 37,29 37,9
37、4 38,55 Annex B (informative) Example of the variation in pH during a titration Increment cm3 0,oo 1,71 0,86 0,43 0,86 1 ,o0 1 ,o0 1 ,o0 1 ,o0 0,97 0,71 0,55 0,44 0,33 0,28 0,23 0,21 0,21 0,23 0,25 0,31 0,37 0,45 0,57 0,72 090 1 ,o0 1 ,o0 1 ,o0 1 ,o0 1 ,o0 1 ,o0 1 ,o0 1 ,o0 1 ,o0 1 ,o0 1 ,o0 1 ,o0 0
38、,70 1,30 1 ,o0 1 ,o0 1 ,o0 1 ,o0 1 ,o0 1 ,o0 0,90 0,80 0,65 0,61 Signal PH 12,603 12,511 12,458 12,429 12,369 12,293 12,208 12,108 1 1,988 11,842 11,703 11,564 11,421 11,286 11,148 11,018 10,891 10,766 10,634 10,507 10,372 10,236 10,099 9,960 9,819 9,681 9,558 9,456 9,368 9,290 9,217 9,150 9,087 9,0
39、23 8,961 8,899 8,836 8,770 8,702 8,630 8,556 8,473 8,381 8,281 8,168 8,035 7,899 7,758 7,626 7,492 Signal change APH 0,000 0,092 0,053 0,029 0,060 0,076 0,085 0,100 0,120 O, 146 0,139 0,139 O, 143 0,135 0,138 0,130 0,127 O, 125 0,132 0,127 0,135 0,136 0,137 0,139 0,141 0,138 0,123 o, 102 0,088 0,078
40、 0,073 0,067 0,063 0,064 0,062 0,062 0,063 0,066 0,068 0,072 0,074 0,083 0,092 0,100 0,113 0,133 O, 136 0,141 0,132 0,134 Difference ApH/cm3 0,000 0,054 0,062 0,067 0,070 0,076 0,085 0,100 0,120 0,151 O, 196 0,253 0,325 0,409 0,493 0,565 0,605 0,595 0,574 0,508 0,435 0,368 0,304 0,244 0,196 0,153 0,
41、123 0,102 0,088 0,078 0,073 0,067 0,063 0,064 0,062 0,062 0,063 0,066 0,097 0,055 0,074 0,083 0,092 o, 1 O0 0,113 0,133 0,151 0,176 0,203 0,220 Page 8 IS0 13773 : 1997 7,351 7,219 7,073 6,956 6,775 6,626 6,469 6,303 6,130 5,934 5,700 5,402 4,987 4,504 4,076 3,739 3,454 3,216 3,017 2,860 2,735 2,591
42、2,450 2,411 39,lO 3957 40,Ol 40,41 40,96 41,37 41,78 42,20 42,62 43,05 43,48 43,91 44,35 44,79 45,24 45,69 46,15 46,61 47,08 47,55 48,03 48,75 49,68 50,OO 0,141 0,256 0,132 0,281 0,146 0,332 0,117 0,293 0,181 0,329 O, 149 0,363 0,157 0,383 O, 166 0,395 0,173 0,412 0,196 0,456 0,234 0,544 0,298 0,693
43、 0,415 0,943 0,483 1,098 0,428 0,951 0,337 0,749 0,285 0,620 0,238 0,517 o, 199 0,423 0,157 0,334 0,125 0,260 0,144 0,200 0,141 0,152 0,039 0,122 0,55 0,47 0,44 0,40 0,55 0,41 0,41 0,42 0,42 0,43 0,43 0,43 0,44 0,44 0,45 0,45 0,46 0,46 0,47 0,47 0,48 0,72 0,93 0,32 Figure B.1 - Example of titration and derivative curves
