Carbon Black—Total and External Surface Area by Nitrogen
Contents
1. N1214 Raw Data Calculation Vol Ads Rel Press Correlation NSA P Po cm g Range Coefficient m g 0 0500 26 716 0 1000 29 753 Sa TF nen 0 1500 32 313 0 05 0 15 0 999981 123 9 0 2000 34 692 0 05 0 20 0 999992 124 0 0 2500 37 110 0 05 0 25 0 999990 123 6 0 3000 39 641 0 05 0 30 0 999935 122 8 N3268 Raw Data Calculation Vol Ads Rel Press Correlation NSA P Po cm g Range Coefficient m g 0 0500 16 675 0 1000 18 318 see wats TOR 0 1500 19 859 0 05 0 15 0 999960 75 6 0 2000 21 426 0 05 0 20 0 999948 76 3 0 2500 23 035 0 05 0 25 0 999964 76 6 0 3000 24 751 0 05 0 30 0 999979 76 6 N6838 Raw Data Calculation Vol Ads Rel Press Correlation NSA P Po cm g Range Coefficient m g 0 0500 8 194 0 1000 9 113 weiss ee nae 0 1500 9 945 0 05 0 15 0 999939 38 2 0 2000 10 739 0 05 0 20 0 999950 38 5 0 2500 11 543 0 05 0 25 0 999972 38 6 0 3000 12 364 0 05 0 30 0 999973 38 4 A The most accurate NSA is measured between 0 05 and 0 20 relative pressure B The most accurate NSA is measured between 0 05 and 0 30 relative pressure Alison Lennie The Prasino Group pursuant to License Agreement No further reproductions authorized AO pess6 10 ui Surface area m7 g Vm X 4 35 5 where Vm 1 B M B Y axis intercept 107 M slope of the straight line 107 and 4 35 area occupied by 1 cm of nitrogen 6 02 x 1077 16 2 x 10 22400 6 02 X 10 Avogadro s number 16 2 X 107 area of nitro2. Copyright by ASTM Int l all rights reserved Tue Jan 31 16 43 23 EST 2012 Downloaded printed by Alison Lennie The Prasino Group pursuant to License Agreement No further reproductions authorized AO pesse6 10 tm 7 Sampling 7 1 Samples may be taken in accordance with Practices D1799 and D1900 8 Sample Preparation Procedure 8 1 Dry a portion of carbon black at 125 C for 1 h If the carbon black is known to be substantially free of moisture or subsequent preparation steps are known to be adequate for moisture removal then this step may be omitted 8 2 Condition an empty sample cell for a minimum of 10 min at the same conditions intended for degassing the sample Weigh the empty sample cell to the nearest 0 1 mg and record the mass 8 3 Weigh approximately 0 4 g of the carbon black into the sample cell Note 1 For carbon black powder samples add enough carbon black to give a depth of approximately 2 in in straight wall sample tubes or approximately 0 4 g for bulb type sample cells 8 4 Flow Degassing 8 4 1 Open the gas control valve and insert the delivery tube into the sample tube and allow purging with either helium or nitrogen for a minimum of min 8 4 2 Place a heating mantle or other source of heat around the sample cell and degas the sample at 300 10 C for 1 2 h or longer to ensure that all traces of moisture condensing in the top of the tube are absent The minimum degassing time that gives a
3. 8 5 4 Once the typical degassing times have been deter mined future samples can be degassed on the basis of time alone if desired allowing a reasonable margin of excess time Copyright by ASTM Int l all rights reserved Tue Jan 31 16 43 23 EST 2012 2 Downloaded printed by Some samples will be found to require less than 2 h especially if moisture exposure has been minimal In these cases the minimum time that gives a stable surface area may be used for degassing see Note 2 8 5 5 Go directly to Section 9 and continue the remaining steps of the procedure 9 Measurement Procedure 9 1 Refer to the user s manual or specific instructions for the multipoint gas adsorption analyzer to be used and become thoroughly familiar with the procedures There are numerous instruments available that offer a variety of saturation vapor pressure P measurement options and Dewar sizes 9 2 Fill the Dewar with liquid nitrogen LN2 and allow it to reach temperature equilibrium The Dewar should be refilled approximately once per hour or between each analysis The time required to reach equilibrium is dependent upon Dewar size and quality 9 2 1 Small Dewar lt 1 L Fill and cover the Dewar for a minimum of 2 h prior to use The Dewar should be cleaned and dried at the end of each day 9 2 2 Large Dewar gt I L Fill and cover the Dewar for a minimum of 16 h prior to use unless continuous P measure ments are employed For continuou
4. Keywords 13 1 Brunauer Emmett Teller carbon black B E T nitro gen adsorption nitrogen surface area statistical thickness surface area surface area by multipoint B E T method exter nal surface area ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard Users of this standard are expressly advised that determination of the validity of any such patent rights and the risk of infringement of such rights are entirely their own responsibility This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised either reapproved or withdrawn Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM International Headquarters Your comments will receive careful consideration at a meeting of the responsible technical committee which you may attend If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards at the address shown below This standard is copyrighted by ASTM International 100 Barr Harbor Drive PO Box C700 West Conshohocken PA 19428 2959 United States Individual reprints single or multiple copies of this standard may be obtained by contacting ASTM at the above address or at 610 832 9585 phone 610 832 9555 fax or serv
5. Parameters for Test Method D6556 Carbon Black NSA Type 1 Precision Units 10 m kg m g Number of Mean Material Laboratories Level Sr r SR R SRB D6 N762 19 30 6 0 25 2 33 0 41 3 82 SRB F6 N683 19 35 3 0 47 3 77 0 60 4 83 SRB E6 N660 19 36 0 0 40 3 16 0 48 3 77 SRB C6 N326 18 78 3 0 40 1 44 0 78 2 82 SRB B6 N220 19 110 0 0 53 1 37 0 94 2 42 SRB A6 N134 19 143 9 0 70 1 37 1 30 2 56 Average 72 4 Pooled Values 0 48 1 87 0 81 3 18 Alison Lennie The Prasino Group pursuant to License Agreement No further reproductions authorized AO pesse6 10 tm TABLE 3 Precision Parameters for Test Method D6556 Carbon Black STSA Type 1 Precision Units 10 m kg m g Number of Mean Material laboratories Level Sr r SR R SRB D6 N762 16 29 6 0 45 4 32 0 76 7 29 SRB F6 N683 16 34 1 0 61 5 06 0 72 6 02 SRB E6 N660 16 35 1 0 77 6 24 0 78 6 27 SRB C6 N326 15 79 2 0 69 2 45 1 42 5 09 SRB B6 N220 16 105 4 0 96 2 59 1 86 5 00 SRB A6 N134 16 135 7 1 37 2 87 3 17 6 60 Average 69 8 Pooled Values 0 86 3 49 1 70 6 87 different laboratories on identical test material will exceed the reproducibility on an average of not more than once in 20 cases in the normal and correct operation of the method Two single test results produced in different laboratories that differ by more than the appropriate value from Table 2 must be suspected of being from different populations and some appro priate investigative o
6. sample identification 11 1 2 Number of data points and relative pressures used to obtain both NSA and STSA 11 1 3 The sample mass to the nearest 0 1 mg and 11 1 4 The NSA or STSA or both of the sample reported to the nearest 0 1 m7 g Magee R W Rubber Chemistry and Technology Vol 68 No 4 1995 p 590 Copyright by ASTM Int l all rights reserved Tue Jan 31 16 43 23 EST 2012 4 Downloaded printed by 12 Precision and Bias 12 1 These precision statements have been prepared in accordance with Practice D4483 Refer to this practice for terminology and other statistical details 12 2 The precision results in this precision and bias section give an estimate of the precision of this test method with the materials used in the particular interlaboratory program de scribed below The precision parameters should not be used for acceptance or rejection testing of any group of materials without documentation that they are applicable to those par ticular materials and the specific testing protocols of the test method Any appropriate value may be used from Tables 2 and 3 12 3 Nitrogen Surface Area NSA 12 3 1 A Type 1 interlaboratory precision program was conducted Both repeatability and reproducibility represent short term daily testing conditions The testing was per formed using two operators in each laboratory performing the test once on each material on each of two days total of four tests The number of partici
7. stable surface area that is a surface area that does not increase with additional degassing may be used for degassing Note 2 For carbon blacks at their moisture pickup equilibrium like standard reference blacks longer degassing times may be required in order to achieve stable results For SRB B8 it is recommended to extend the degassing time to at least 60 min 8 4 3 Once the typical degassing times have been deter mined future samples can be degassed on the basis of time alone if desired allowing a reasonable margin of excess time Some samples will be found to require less than 1 2 h especially if moisture exposure has been minimal In these cases the minimum time that gives a stable surface area may be used for degassing 8 4 4 After degassing the sample tube may be moved directly to the analyzer Otherwise remove the sample tube from the heat source and continue the flow of purging gas until it is ready for analysis 8 4 5 Go directly to Section 9 and continue the remaining steps of the procedure 8 5 Vacuum Degassing 8 5 1 With the apparatus at atmospheric pressure place the sample cell containing the carbon black onto the degassing apparatus 8 5 2 Begin the degassing procedure as appropriate for the apparatus 8 5 3 Place a heating mantle or other source of heat around the sample cell and degas the sample at 300 10 C for 1 2 h or longer as required to obtain and hold a pressure less than 1 4 Pa 10 um Hg
8. and it includes the total surface area inclusive of micropores pore diameters less than 2 nm 20 A The external surface area based on the statistical thickness method STSA is defined as the specific surface area that is accessible to rubber 4 2 CTAB Surface Area formerly Test Method D3765 has been withdrawn The CTAB value may be estimated from the STSA value using Eq 1 The equation is based on a linear regression of the STSA and CTAB measured values of the SRB 5 standards CTAB STSA 1 0170 2 6434 1 5 Apparatus 5 1 Multipoint Static Volumetric Gas Adsorption Apparatus with Dewar flasks and all other accessories required for operation 5 2 Sample Cells that when attached to the adsorption apparatus will maintain isolation of the sample from the atmosphere equivalent to a helium leak rate of lt 10 cm min per atmosphere of pressure difference 5 3 Balance Analytical with 0 1 mg sensitivity 5 4 Heating Mantle or Equivalent capable of maintaining a temperature of 300 10 C 5 5 Oven Gravity Convection capable of maintaining a temperature of 125 10 C 6 Reagents 6 1 Liquid Nitrogen 98 or higher purity 6 2 Ultra High Purity Nitrogen Gas cylinder or other source of prepurified nitrogen gas 6 3 Ultra High Purity Helium Gas cylinder or other source of prepurified helium gas Copyright ASTM International 100 Barr Harbor Drive PO Box C700 West Conshohocken PA 19428 2959 United States
9. f the American Chemical Society Vol 60 1938 p 309 Copyright by ASTM Int l all rights reserved Tue Jan 31 16 43 23 EST 2012 Downloaded printed by 3 P 10 4 2 Plot P P on the X axis versus V PP on the Y axis for data sets having P P in the range of 0 05 to 0 30 linear region of B E T equation 10 4 3 The data points three or more that give the best straight line are used to calculate the slope and y intercept The slope and y intercept are used to calculate the surface area For examples of how to select the proper relative pressure range see Table 1 10 4 4 As an alternative the interpretation of the proper relative pressure can generally be simplified by specifying the following pressure ranges for the various carbon black types BET Range N300 and Carcass Grades 0 1 0 3 N100 and N200 0 05 0 2 Carbon Blacks gt 130 m g 0 05 0 1 It is the responsibility of the operator to assure that these guidelines are appropriate for their samples 10 4 5 A B E T plot that yields a negative y intercept could be indicative of the presence of micropores lt 2 nm diameter but other factors can produce a negative y intercept The surface area is calculated from three or more points within the pressure range that yields the highest correlation coefficient and a positive y intercept 10 4 6 Calculate the nitrogen surface area to the nearest 0 1 m g as follows TABLE 1 Example of NSA Data Analysis
10. gen molecule in m7 and 22400 number of cm occupied by one mole of gas at STP 10 5 Statistical Thickness Surface Area 10 5 1 Determine the STSA of the black using a plot of the volume of nitrogen gas adsorbed per gram of sample at STP Va versus the statistical layer thickness t 10 5 2 Prepare the V t plot by plotting nm on the X axis versus V dm kg at STP on the Y axis for data sets having P P equally spaced in the range of 0 2 to 0 5 where t Statistical layer thickness of carbon black 0 088 P P 0 645 P P 0 298 10 5 3 Determine the slope of the V t plot using standard linear regression 10 5 4 Calculate the STSA to the nearest 0 1 m g as follows STSA M X 15 47 6 where M slope of the V t plot and 15 47 a constant for the conversion of nitrogen gas to liquid volume and conversion of units to m7 g 10 5 5 STSA is based on a thickness model developed using an N762 carbon black This carbon black was chosen because of its low surface area and low structure level This universal model does not perfectly apply to all carbon blacks conse quently while it is theoretically impossible for external surface area to be higher than total surface area in practice there are instances where STSA is higher than NSA For analyses that yield STSA values that are higher than NSA the measured STSA value should be reported 11 Report 11 1 Report the following information 11 1 1 Proper
11. ice astm org e mail or through the ASTM website www astm org Permission rights to photocopy the standard may also be secured from the ASTM website www astm org COPYRIGHT Copyright by ASTM Int l all rights reserved Tue Jan 31 16 43 23 EST 2012 5 Downloaded printed by Alison Lennie The Prasino Group pursuant to License Agreement No further reproductions authorized
12. on Black Sampling Bulk Ship ments D3765 Test Method for Carbon Black CTAB Cetyltrim ethylammonium Bromide Surface Area D4483 Practice for Evaluating Precision for Test Method Standards in the Rubber and Carbon Black Manufacturing Industries 3 Summary of Test Method 3 1 The total and external surface areas are measured by evaluating the amount of nitrogen adsorbed at liquid nitrogen 1 This test method is under the jurisdiction of ASTM Committee D24 on Carbon Black and is the direct responsibility of Subcommittee D24 21 on Carbon Black Surface Area and Related Properties Current edition approved Aug 1 2010 Published September 2010 Originally approved in 2000 Last previous edition approved in 2009 as D6556 09 DOI 10 1520 D6556 10 For referenced ASTM standards visit the ASTM website www astm org or contact ASTM Customer Service at service astm org For Annual Book of ASTM Standards volume information refer to the standard s Document Summary page on the ASTM website 3 Withdrawn The last approved version of this historical standard is referenced on www astm org temperature by a carbon black at several partial pressures of nitrogen The adsorption data is used to calculate the NSA and STSA values 4 Significance and Use 4 1 This test method is used to measure the total and external surface area of carbon blacks based on multipoint nitrogen adsorption The NSA measurement is based on the B E T theory
13. pating laboratories is listed in Table 2 12 3 2 The results of the precision calculations for this test are given in Table 2 The materials are arranged in ascending mean level order 12 3 3 Repeatability The pooled relative repeatability r of the NSA test has been established as 1 87 Any other value in Table 2 may be used as an estimate of repeatability as appropriate The difference between two single test results or determinations found on identical test material under the repeatability conditions prescribed for this test will exceed the repeatability on an average of not more than once in 20 cases in the normal and correct operation of the method Two single test results that differ by more than the appropriate value from Table 2 must be suspected of being from different populations and some appropriate action taken Note 4 Appropriate action may be an investigation of the test method procedure or apparatus for faulty operation or the declaration of a significant difference in the two materials samples and so forth which generated the two test results 12 3 4 Reproducibility The pooled relative reproducibil ity R of the NSA test has been established as 3 18 Any other value in Table 2 may be used as an estimate of reproducibility as appropriate The difference between two single and independent test results found by two operators working under the prescribed reproducibility conditions in TABLE 2 Precision
14. ple to the nearest 0 1 mg This may be done before or after measuring nitrogen adsorption Avoid inconsistent use of helium as a buoyancy error of 1 mg cm of cell volume can occur As an alternative the carbon black mass may be determined directly by pouring it from the sample cell into a tared weighing pan taking care to remove all of the carbon black 10 Calculation 10 1 Most automated instruments will perform the follow ing computations at the completion of the analysis The user must verify that the internal computations conform to the following method 10 2 Sample Mass sample mass dried mass of cell sample mass of cell 2 Record masses to nearest 0 1 mg 10 3 Volume of Nitrogen Adsorbed 10 3 1 Calculate total volume of nitrogen adsorbed per gram of sample to the nearest 0 0001 cm g as follows 3 Volume of Nitrogen for each dosing in cm a sample mass in g 10 4 Nitrogen Surface Area 10 4 1 Determine the nitrogen surface area NSA using a B E T plot from the Brunauer Emmett and Teller equation as follows 3 P 1 cC 1_ P V P V C VC P A where P manometer pressure in kPa P Saturation vapor pressure of nitrogen in kPa Vm Volume of nitrogen per gram that covers one mono molecular layer in standard cm g and B E T constant Its numerical value depends on the heat of adsorption of the monomolecular layer io Il Brunuaer Emmett and Teller Journal o
15. propriate value from Table 3 must be suspected of being from different populations and some appropriate action taken Note 5 Appropriate action may be an investigation of the test method procedure or apparatus for faulty operation or the declaration of a significant difference in the two materials samples and so forth which generated the two test results 12 4 4 Reproducibility The pooled relative reproducibil ity R of the STSA test has been established as 6 87 Any other value in Table 1 may be used as an estimate of reproducibility as appropriate The difference between two single and independent test results found by two operators working under the prescribed reproducibility conditions in different laboratories on identical test material will exceed the reproducibility on an average of not more than once in 20 cases in the normal and correct operation of the method Two single test results produced in different laboratories that differ by more than the appropriate value from Table 3 must be suspected of being from different populations and some appro priate investigative or technical commercial action taken 12 5 Bias In test method terminology bias is the differ ence between an average test value and the reference true test property value Reference values do not exist for this test method since the value or level of the test property is exclusively defined by the test method Bias therefore cannot be determined 13
16. r technical commercial action taken 12 3 5 Bias In test method terminology bias is the differ ence between an average test value and the reference true test property value Reference values do not exist for this test method since the value or level of the test property is exclusively defined by the test method Bias therefore cannot be determined 12 4 Statistical Thickness Surface Area STSA 12 4 1 A Type 1 interlaboratory precision program was conducted Both repeatability and reproducibility represent short term daily testing conditions The testing was per formed using two operators in each laboratory performing the test once on each material on each of two days total of four tests The number of participating laboratories is listed in Table 3 12 4 2 The results of the precision calculations for this test are given in Table 3 The materials are arranged in ascending mean level order 12 4 3 Repeatability The pooled relative repeatability r of the STSA test has been established as 3 49 Any other value in Table 3 may be used as an estimate of repeatability as appropriate The difference between two single test results or determinations found on identical test material under the repeatability conditions prescribed for this test will exceed the repeatability on an average of not more than once in 20 cases in the normal and correct operation of the method Two single test results that differ by more than the ap
17. s P use a 2 h Dewar equilibration Once equilibration is reached a large Dewar can maintain this equilibration for several days if kept filled and covered The cleaning frequency is left to the discretion of the operator but is not to exceed once per week 9 3 Following is a list of P measurement options 9 3 1 Continuous P measurement at each relative pressure point This method is considered the best practice however it generally increases analysis time 9 3 2 Single P Per Analysis Although this value can be measured before during or after the run a P value measured at the end of the analysis is preferred since STSA is calculated from the last data points acquired and is significantly influ enced by P values This method requires that a P value be determined prior to initiating any measurements to ensure equilibrium of the Dewar as described in 9 4 Subsequently a new P value is measured for each run which is used for calculating NSA STSA values 9 3 3 Daily P This method is used when evidence of a stable Dewar is present and no changes in atmospheric pressure greater than 0 13 kPa 1 mm Hg occur 9 3 4 Calculated P This method calculates a P value by measuring atmospheric pressure and adding a value between 1 3 and 2 6 kPa 10 and 20 mm Hg The operator is responsible for determining the constant used in their labora tory however 2 0 kPa 15 mm Hg is most commonly used 9 4 With the exception of continuo
18. us P measurements it is recommended that the P value be determined prior to initiat ing NSA STSA analyses A P value of 1 3 to 2 6 kPa 10 to 20 mm Hg above atmospheric pressure and two consecutive P values that differ by no more that 0 13 kPa 1 mm Hg over a 10 min time period are indications of a stable Dewar Experi ence will teach the operator about expected differences in P and atmospheric pressure in their laboratory Alison Lennie The Prasino Group pursuant to License Agreement No further reproductions authorized Al pess6 10 tm Nore 3 A minimum wait time of 10 min is recommended between P measurements as immersing the P cell into the LN2 disrupts the G temperature equilibration P measurements taken at short intervals will result in erroneously high and unstable values 9 5 Determine the free space of the sample cell by measure ment with helium or by calculation using an assumed carbon black density of 1 9 g cm 9 6 Obtain a minimum of five data points evenly spaced in the 0 1 to 0 5 relative pressure P P range For some tread carbon blacks particularly N100 and N200 series it is neces sary to measure two additional data points 0 05 and 0 075 in order to increase the accuracy of the NSA measurement A data point consists of the relative pressure of equilibrium and the total amount of nitrogen gas adsorbed by the sample at that relative pressure 9 7 Determine the mass of the cell with dry sam
19. y Designation D6556 10 ull INTERNATIONAL Standard Test Method for Carbon Black Total and External Surface Area by Nitrogen Adsorption This standard is issued under the fixed designation D6556 the number immediately following the designation indicates the year of original adoption or in the case of revision the year of last revision A number in parentheses indicates the year of last reapproval A superscript epsilon e indicates an editorial change since the last revision or reapproval 1 Scope 1 1 This test method covers the determination of the total surface area by the Brunauer Emmett and Teller B E T NSA theory of multilayer gas adsorption behavior using multipoint determinations and the external surface area based on the statistical thickness surface area method 1 2 The values stated in SI units are to be regarded as the standard The values given in parentheses are for information only 1 3 This standard does not purport to address all of the safety concerns if any associated with its use It is the responsibility of the user of this standard to establish appro priate safety and health practices and determine the applica bility of regulatory limitations prior to use The minimum safety equipment should include protective gloves sturdy eye and face protection 2 Referenced Documents 2 1 ASTM Standards D1799 Practice for Carbon Black Sampling Packaged Shipments D1900 Practice for Carb
Download Pdf Manuals
Related Search