Answer :
Final answer:
The correct ASTM standard for testing rubber property - durometer hardness is ASTM D2240. This method measures the material's resistance to indentation, offering a numerical durometer hardness value. Other mentioned standards evaluate different properties like impact resistance and tensile strength. so,the correct option is:(a) ASTM D2240
Explanation:
The test method for rubber property-durometer hardness is ASTM D2240. Durometer hardness tests gauge the hardness of rubber and elastomers among other materials. This standard utilizes a precise indenting force and measures the material's resistance to deformation. Hardness, in this context, is a crucial physical property for materials that need to maintain shape or resist wear under force. ASTM D2240 defines hardness as the resistance of a material to indentation. The durometer scale, which is used in this testing method, provides a numerical value representing the hardness, with higher values indicating harder materials.
Other ASTM tests mentioned, such as ASTM D256, ASTM D412, and ASTM D638, assess different properties. For example, ASTM D256 measures impact resistance, ASTM D412 tests tensile properties, and ASTM D638 for tensile strength.