MIL-T-68410
4.4 Test conditions
4.4.1 Atmospheric. Unless otherwise specified for the particular test, all tests shall be accomplished under standard atmospheric conditions of 50 +2 percent relative humidity at a temperature of 23 +1°C (73° +2°F) Samples shall be exposed to these conditions for at least 2 hours before testing.
4.4.2 Oven aging. Oven aging specimens shall be given an accelerated aging by subjecting them to dry circulating air for 70 +1 hours at 100° +1°C (212° +2°F).
4.5 Quality conformance. Quality conformance tests for acceptance of individual lots shall consist of tests for all requirements specified in section 3 as listed in table x.
TABLE x. Quality conformance tests.
Characteristic |
Reference |
Requirements applicable to individual units |
Number of determinations per sample unit |
Results reported as-- |
||
Requirement |
Test Method |
Pass or fail 1 |
Numerically nearest 2 |
|||
Thickness Weight Compressibility Recovery Low Temperature resistance Adhesive strength Accelerated crazing |
3.4 & table I 3.5.1 & table I Table IV Table IV Table IV 3.7 3.8 |
4.6.1 4.6.2 4.6.3 4.6.3 4.6.4 4.6.5 4.6.6 |
x x x x x x x |
Average of 5 Average of 3 Average of 2 Average of 2 Average of 3 3 2 |
x x |
0.001 inch 0.05 lb Percent Percent Percent |
1 If failure is indicted, report either description of failure or numerical point of failure, as applicable.
2 All test reports shall include all values on which average or unit results are based.
4.6 Test methods
4.6.1 Thickness. The thickness of samples shall be measured in not less than five areas and the average thickness computed from the results of the individual determinations. The gages employed shall have flat, parallel bearing surfaces 0.250+0.010, -0.000 inch in diameter at both contact areas, and the pressure exerted shall be 1/4 pound. The accuracy of measurement shall be 0.001 inch.
4.6.2 Weight. A specimen approximately 12 inches in length shall be cut from the sample. The width and length of the specimen shall be determined to the nearest 0.01 inch, and the weight determined with a balance to an accuracy of 1 percent. The weight per square yard shall be calculated from the test results.
4.6.3 Compressibility and recovery. Specimens 1 inch in diameter shall be cut and plied up to at least 1/4 inch in thickness. The pieces shall be arranged in a single stack with edges even. The thickness of the combined samples shall be measured under an initial load 1 pound per sq. inch (psi), applied for 15 seconds. The stacked specimens shall be compressed under a load of 78.5 pounds for 5 minutes and the amount of compression recorded. The pressure shall be released for 5 minutes and another measurement made under a 1-pound load per square inch. The percent of compressibility and percent of recovery shall be calculated by the following formulas:
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