ASTM D6576 – 00

Designation: D 6576 – 00 Standard Specification for Flexible Cellular Rubber Chemically Blown1 This standard is issued under the fixed designation D 6576; 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. This standard has been approved for use by agencies of the Department of Defense. Replaces MIL-R-6130. 1. Scope 1.1 This specification establishes requirements for chemi- cally blown cellular rubber. 1.2 In the case of conflict between the provisions of this specification and those of detailed specifications or test meth- ods for a particular product, the latter shall take precedence. 1.3 Unless specifically stated otherwise, by agreement be- tween the purchaser and the supplier, all test methods shall be performed in accordance with the test methods specified in this specification. 1.4 The values stated in SI units are to be regarded as the standard. The inch-pound units given in parentheses are for information only. 1.5 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. 1.6 This specification and ISO 6916 are not equivalent. NOTE 1—This specification was revised using the updated test methods and specification in Specification D 1056 – 98. 2. Referenced Documents 2.1 ASTM Standards: D 297 Test Methods for Rubber Products—Chemical Analysis2 D 471 Test Method for Rubber Property—Effect of Liq- uids2 D 635 Test Method for Rate of Burning and/or Extent and Time of Burning of Self-Supporting Plastics in a Horizon- tal Position3 D 883 Terminology Relating to Plastics3 D 1055 Specifications for Flexible Cellular Materials— Latex Foam3 D 1056 Specification for Flexible Cellular Materials— Sponge or Expanded Rubber3 D 3575 Test Methods for Flexible Cellular Materials Made from Olefin Polymers4 2.2 SAE Standard:5 SAE J 1351-1993 Hot Odor Test for Insulation Materials 2.3 Military Standards/Specifications:6 MIL STD 105 Sampling Procedures and Tables for Inspec- tion by Attributes MIL STD 129 Marking for Shipment and Storage MIL STD 293 Visual Inspection Guide for Cellular Rubber Items MIL R 6130 C Standard Specification for Flexible Cellular Rubber Chemically Blown 2.4 Federal Standards/Specifications:6 PPP-B576 Box, Wood, Cleated, Veneer, Paper Overlaid PPP-B591 Box, Fiberboard, Wood-Cleated PPP-B601 Box, Wood, Cleated Plywood PPP-B621 Box, Wood, Nailed and Lock-Corner PPP-B636 Box, Shipping, Fiberboard 2.5 ISO Standards: ISO 6916 Flexible Cellular Polymeric Materials7 3. Terminology 3.1 For definitions of technical terms pertaining to cellular flexible rubber used in this specification, refer to Terminology D 883. 3.2 Definitions: 3.2.1 cellular material—a generic term for materials con- taining many cells (either open or closed, or both) dispersed throughout the mass. 3.2.2 closed cell—a product whose cells are totally enclosed by its walls and hence not interconnecting with other cells. 3.2.3 open cell—a product whose cells are not totally enclosed by its walls and open to the surface, either directly or by interconnecting with other cells. 1 This specification is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.22 on Cellular Materials—Plastics and Elastomers. Current edition approved July 10, 2000. Published October 2000. 2 Annual Book of ASTM Standards, Vol 09.01. 3 Annual Book of ASTM Standards, Vol 08.01. 4 Annual Book of ASTM Standards, Vol 08.02. 5 Available from SAE World Headquarters, 400 Commonwealth Dr., Warrendale, PA 15096–0001. 6 Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700 Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS. 7 Available from American National Standards Institute, 11 W. 42nd St., 13th Floor, New York, NY 10036. 1 Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States. 4. Classification 4.1 Types—This specification covers two types of cellular rubber designated as follows: 4.1.1 Type I—Open cell (sponge rubber). 4.1.2 Type II—Closed cell (expanded rubber). 4.2 Grades—Both types are divided into three grades des- ignated by the letters A, B, and C added to the roman numeral prefix. 4.2.1 Grade A—Oil- and flame-resistant. 4.2.2 Grade B—No requirements for oil, flame resistance, or low temperature. 4.2.3 Grade C—Low-temperature resistant (oil and flame resistance not required). 4.3 Conditions—Each type and class has been divided into three different conditions. Each condition is based on a specific range of firmness as expressed by compression deflection as follows: 4.3.4 Condition—Super soft a compression deflec- tion range of > 0 to #14 kPa (>0 to #2 psi) 4.3.2 Condition—Soft a compression deflec- tion range of >14 to #35 kPa (>2 to #5 psi) 4.3.3 Condition—Soft-medium a compression deflec- tion range of >35 to #63 kPa (>5 to #9 psi) 4.3.4 Condition—Medium a compression deflec- tion range of >63 to #91 kPa (> 9 to #13 psi) 4.3.5 Condition—Medium-firm a compression deflec- tion range of >91 to #119 kPa (>13 to #17 psi) 4.3.6 Condition—Firm a compression deflec- tion range of >119 to #175 kPa (>17 to #25 psi) 5. Significance and Use 5.1 This specification is a revision of MIL R 6130C retain- ing most of the MIL R 6130C material designations and property requirements while conforming to ASTM form and style. It is intended to establish requirements for chemically blown cellular rubber used by government and industry, and is intended as a direct replacement for MIL R 6130C. 6. Materials and Manufacture 6.1 Materials—The materials shall be homogeneous. Ex- cept for the following production allowances: 6.1.1 Tears and edge cracks that do not interfere with specified product yield. 6.1.2 Depression and pock marks not exceeding 1 in. 6.1.3 Splices and butt splices. 6.1.4 Laminating sheets to achieve thickness. 6.2 The material shall not include the following: 6.2.1 Cemented, bonded, shredded, or reprocessed cellular rubber. 6.2.2 Grade A cellular rubber shall not contain natural rubber. 6.3 Form—Chemically blown cellular rubber shall be fur- nished as sheets, rolls, or molded shapes as specified, and shall have a uniform cell structure, with thin skin or rind surfaces. Cut or split sheets void of skin or rind surfaces may be furnished only for Type II material when specified. 6.4 Skin or Rind—The surface formed by contact with the mold shall be considered a skin or rind. It shall be of the same compound, and vulcanized integrally with the cellular struc- ture. Type I shall have skin or rind. Type II may or may not have skin or rind. 6.5 Cut or Split Sheets (Type II Only)—When two or more sheets are derived from one thick sheet, the cut or split sheets shall not be required to posses a skin or rind on either major surface. 6.6 Surfacing—Cellular rubber shall be backed or surfaced with fabric, adhesive, or other materials, when and as specified in the contract or order or by applicable drawings. 7. Physical Properties 7.1 The various types and grades of cellular rubber shall conform to the physical properties listed in Table 1 together with any additional requirements indicated by suffix letters in the grade designations as described in Section 4 and Table 2. 8. Tolerances on Dimensions 8.1 Tolerances on dimensions of flexible cellular rubber materials are given in Table 3. 8.2 Molded Shapes—Tolerance requirements for molded shapes shall be as specified in drawings, contracts, or by the procuring activity. 8.3 Sheets and Rolls—Unless otherwise specified, the tol- erance requirements for thickness, lengths and width of sheets shall be as specified in Table 3. 9. Test Methods 9.1 Unless specifically stated otherwise, all test methods shall be in accordance with the test methods specified in Sections 10-18. 9.2 Precision and Bias—The repeatability standard devia- tions for each test method has been determined. The reproduc- ibility of these test methods is being determined and will be available on or before March 2006. NOTE 2—One laboratory tested one closed-cell, flame-resistant, non-oil resistant, 96-kg/m3, 14-35-kPa product as a representative sample. This sample was used for shrinkage, recovery, and oil-resistance testing. 10. Test Conditions 10.1 Standard Conditions—Unless otherwise specified herein, conduct the test method at 23 6 2°C (73.4 6 3.6°F) and a relative humidity of 50 6 5 % 10.2 Specimen Conditioning—Unless otherwise specified, condition all test specimens at standard conditions for at least 22 h prior to testing. 11. Compression Deflection 11.1 Test in accordance with Sections 17 to 22 of Specifi- cation D 1056. 12. Low-Temperature Flex Resistance 12.1 Test in accordance with Sections 56 to 60 of Specifi- cation D 1056. Exposure temperatures shall be in accordance with Table 4. 13. Accelerated Aging 13.1 Test in accordance with Sections 34 to 41 of Specifi- cation D 1056. 14. Recovery 14.1 Measure the thickness of each test specimen to 0.0254 mm (0.001 in.). D 6576 2 14.2 Compress the specimen to 50 % of the original thick- ness for a period of 46 6 0.5 h. 14.3 Remeasure the thickness of each specimen 5 6 1 min after removal from the compression apparatus. 14.4 Calculate the recovery as follows: recovery, % 5 B A 3 100 (1) where: A = original thickness, and B = thickness 5 6 1 min after removal from apparatus. TABLE 1 Physical PropertiesA Property Type I Basic Requirements (Open Cell) Type II Basic Requirements (Closed Cell) Test Method, Section Compression deflection, kPa (psi), 25 % deflection super soft >0 to #14 (>0 to #2) >0 to #14 (>0 to #2) 11 soft >14 to #35 (>2 to #5) >14 to #35 (>2 to #5) soft-medium >35 to #63 (>5 to #9) >35 to #63 (>5 to #9) medium >63 to #91 (>9 to #13) >63 to #91 (>9 to #13) medium-firm > 91 to #119 (>13 to #17) > 91 to #119 (>13 to #17) firm >119 to #175 (>17 to #25) >119 to #175 (>17 to #25) Low-temperature resistance, flex, 180° bend Grade A –40°C (–40°F) pass pass 12 Grade B –40°C (–40°F) pass pass Grade C –55°C (–67°F) pass pass Accelerated aging, % retention of original 25 % deflection after 7 days at 158°F all grades and conditions 620 % 630 % 13 Recovery, min, %, after 50 % deflection all grades and conditions 90 70 14 Flame resistance, max, s Grade A 30 30 15 Grade B not required not required Grade C not required not required Shrinkage, max, %, 7 days at 158°F All grades and conditions not required 10 16 Water Absorption, max, % all grades and conditions not required 10 % max for densities 10 lb/ft3 and under 5 % max for densities over 10 lb/ft3 17 Oil aging, % change in volume, IRM Oil 902 Grade A –15 to +30 –15 to +30 18 Grade B not required not required Grade C not required not required Color all grades and conditions as manufactured unless otherwise specified as manufactured unless otherwise specified visual AUnless otherwise specified, the basic requirements listed are for all types, grades, and conditions. TABLE 2 Optional Requirements Added by Suffix Letters Property Type I Optional Requirements (Open Cell) Type II Optional Requirements (Closed Cell) Test Method Section Suffix H: Flexing, max, % set all grades and conditions 10 10 Appendix X1 Suffix O: Odor in accordance with SAE J-1351 all grades and conditions rating to be determined rating to be determined Appendix X1 Suffix W: Density in accordance with Test Methods D 3575 or Specification D 1056 all grades and conditions density to be determined density to be determined Suffix Y: Sulfur Content, max, % by weight all grades and conditions 0.60 0.60 Appendix X1 D 6576 3 14.5 The repeatability standard deviation has been deter- mined to be 0.0029 %. The reproducibility of this test method is being determined and will be available on or before March 2006. Recovery, % 1 88.80 2 89.70 3 89.50 4 89.60 5 89.40 6 89.30 7 89.80 8 89.70 9 89.70 10 89.60 Average 89.51 % Standard Deviation 0.00292309 % 15. Flame Resistance 15.1 Test in accordance with Test Method D 635 with the following exceptions: 15.2 Test three specimens and record average propagation time. 15.3 Specimen Size: 7.0 6 1 mm (0.275 6 0.04 in.) thick by 12.7 6 1 mm (0.5 6 0.04 in.) wide by 125 6 5 mm (4.92 6 0.2 in.) in length. 15.4 Clamp the specimen on one end with its longitudinal axis horizontal. 15.5 The blue flame shall be 38 mm (1.49 in.) in height. 15.6 Apply the flame for 60 6 1 s. 15.7 Remove the flame after 60 6 1 s and record the average propagation time in seconds. 16. Shrinkage 16.1 Scope—This test method covers the evaluation of shrinkage of flexible cellular elastomeric materials. 16.2 Significance and Use—This test method provides a relatively simple and short-term evaluation of in-use perfor- mance with regard to shrinkage. 16.3 Apparatus—Air-circulating oven equipped with a con- trol to maintain a temperature of 70 6 1°C (158 6 2°F) during the test and having an expanded metal shelf, and a steel rule, graduated in millimetres (inches), capable of measuring to increments of 1.0 mm (0.05 in.). 16.4 Test Specimen—Use three specimens approximately 300 by 75 mm (12 by 3 in.) cut from each of the test samples. 16.5 Procedure—At each of two points, approximately 250 mm (10 in.) apart on the centerline of each specimen, place a benchmark. Condition the specimen 24 h at a temperature of 23 6 2°C (73 6 3.6°F) and measure the distance between the benchmarks to the nearest 1.0 mm (0.05 in.). Place the specimens on an expanded metal shelf in an oven operating at a temperature of 70 6 1°C (158 6 2°F). After 7 days 6 2 hours, remove the specimens from the oven, condition for at least 2 h at 23 6 2°C, and remeasure. 16.6 Calculation—Calculate percent shrinkage as follows: change in length, % 5 L1 – L2 L1 3 100 (2) where: L1 = original length, and L2 = length after oven-aging. 16.7 Report—Report the shrinkage as the change in length between the two benchmarks expressed as a percentage of the length originally measured. TABLE 3 Dimensions and Tolerances of Cellular Rubber Products for General Applications Sponge Rubber Form Thickness Dimension, mm (in.) Thickness Tolerance, mm (in.) Length and Width Dimension, mm (in.) Length and Width Tolerance, mm (in.) Sheet and strip 3.2 (0.125) and under 0.4 (0.016) 152 (6) and under 1.6 (0.063) over 3.2 (0.125) to 12.7 (0.50), incl 0.8 (0.032) over 152 (6) to 457 (18), incl 3.2 (0.125) over 12.7 (0.50) 1.2 (0.047) over 457 (18) 0.5 % Molded or special shapes 6.4 (0.250) and under 0.8 (0.032) 6.4 (0.250) and under 0.8 (0.032) over 6.4 (0.250) to 76.2 (3), incl 1.6 (0.063) over 6.4 (0.250) to 76 (3), incl 1.6 (0.063) over 76 (3) to 457 (18), incl 3.2 (0.125) over 457 (18) 0.5 % Expanded Rubber Sheet and strip 12.7 (0.50) and under 1.6 (0.063) 152 (6) and under 6.4 (0.250) over 12.7 (0.50) 2.4 (0.094) over 152 (6) to 305 (12), incl 9.6 (0.375) over 305 (12) 3 % Molded or special shapes 3.2 (0.125) to 12.7 (0.50), incl 1.6 (0.063) 152 (6) and under 6.4 (0.250) over 12.7 (0.50) to 38.1 (1.50), incl 2.4 (0.094) over 152 (6) to 305 (12), incl 9.6 (0.375) over 38.1 (1.50) to 76.2 (3), incl 3.2 (0.125) over 305 (12) 3 % TABLE 4 Low-Temperature Flex-Resistance Temperatures Type Grade Temperature I A and B –40 6 1°C (–40 6 2°F) I C –55 6 1°C (–676 2°F) II A and B –40 6 1°C (–40 6 2°F) II C –55 6 1°C (–676 2°F) D 6576 4 16.8 The repeatability standard deviation has been deter- mined to be 0.004 %. The reproducibility of this test method is being determined and will be available on or before March 2006. Shrinkage, % 1 6.4 2 6.0 3 6.8 4 6.0 5 5.6 6 5.6 7 5.6 8 6.0 9 5.6 10 5.6 Average 5.9 % Standard Deviation 0.00413 % 17. Water Absorption (Type II Only) 17.1 Test in accordance with Sections 42 to 48 of Specifi- cation D 1056. 18. Oil Aging 18.1 Determine the volume of specimens. Measure the diameter and thickness to the nearest 0.40 mm (0.015 in.). 18.2 Specimen Size—Round specimen approximately 41.3 mm (1.625 in.) in diameter. 18.3 Immerse in petroleum base reference oil IRM 902 of Test Method D 471. 18.4 Immersion for 70 h 6 30 min at 70 6 1°C (158 6 2°F). 18.5 At the end of the immersion period, remove the specimen and immediately blot lightly with a paper towel, and measure in accordance with 18.1. 18.6 Run the test in duplicate. Report the average. 18.7 Calculation—Calculate the percent change in volume as follows: change in volume, % 5 V1 – V2 V1 3 100 (3) where: V1 = original volume, and V2 = volume after immersion in oil. 18.8 The repeatability standard deviation has been deter- mined to be 0.018 %. The reproducibility of this test method is being determined and will be available on or before March 2006. Oil Aging, % 1 10.1 2 14.2 3 13.7 4 12.0 5 9.2 6 11.7 7 11.8 8 15.1 9 11.7 10 11.3 Average 12.1 % Standard Deviation 0.0181 % 19. Keywords 19.1 cellular; closed-cell; elastomeric; flexible; open cell; rubber APPENDIXES (Nonmandatory Information) X1. X1.1 Apparent Density X1.1.1 Test in accordance with Test Methods D 3575 or Specification D 1056. Record on the report which test method was used. X1.2 Free Sulfur Content X1.2.1 Test in accordance with Test Methods D 297. X1.3 Flexing X1.3.1 Test in accordance with Sections 24–26 of Specifi- cations D 1055. X1.3.2 Run the test in triplicate. Record the average. X1.3.3 Specimen Size—Approximately 50 by 50 by 25 mm (2 by 2 by 1 in.) thick. X1.3.4 Each specimen shall undergo 250 000 cycles of flexing. The amplitude of compression and decompression shall be 50 % of the original thickness of each specimen. X1.3.5 Calculate compression set in accordance with Sec- tion 19 of Specifications D 1055. X1.4 Odor X1.4.1 Test in accordance with Test Method SAE J 1351. X1.4.2 When specified, treat material to minimize the odor (see X2.5.2.1 (5)) D 6576 5 X2. MANDATORY GOVERNMENT REQUIREMENTS X2.1 Marking X2.1.1 Identification Marking—Each piece of cellular rub- ber shall be marked, if size permits, in a permanent and legible manner using marking material which will not harm the rubber. The marking shall include the following: X2.1.1.1 ASTM designation D 6576. X2.1.1.2 Type. X2.1.1.3 Grade. X2.1.1.4 Condition. X2.1.1.5 NSN (when applicable). X2.1.1.6 Manufacturer’s part number (when applicable). X2.1.1.7 Contract or order number. X2.1.1.8 Manufacturer’s name or trademark. X2.1.1.9 Quarter and calendar year of cure. X2.1.2 Sheets—Marking on sheet material shall be applied to one side only in rows spaced not more than 12.7 cm (5 in.) apart in constantly recurring characters not less than 9.53 mm (0.375 in.) in height extending either lengthwise or crosswise over the sheet. X2.2 Age Controls X2.2.1 Cellular rubber covered by this specification shall not be delivered to any government activity when it is more than 4 quarters old (see X2.1.1). X2.3 Quality Assurance Provisions X2.3.1 Responsibility for Inspection—Unless otherwise specified in the contract, the contractor is responsible for the performance of all inspection requirements as specified herein. Except as otherwise specified in the contract, the contractor my use his own or any other facilities suitable for the performance of the inspection requirements specified herein, unless disap- proved by the Government. The Government reserves the right to perform any of the inspections set forth in this specification where such inspections are deemed necessary to ensure sup- plies and services conform to the prescribed requirements X2.3.2 Classification of I