Значение и использование

This test method may be used for routine inspection purposes by subjecting a required number of specimens to the test conditions for a specified time and noting the number that fail. The cracking obtained with the test reagent is indicative of what may be expected from a wide variety of surface-active agents, soaps, and organic substances that are not absorbed appreciably by the polymer.

Environmental stress-cracking is a property that is highly dependent upon the nature and level of the stresses applied and on the thermal history of the specimen (1). Under the conditions of the test method, high local multiaxial stresses are developed through the introduction of a controlled imperfection (2,3). Environmental stress-cracking has been found to occur most readily under such conditions.

Note 2—Different types of polyethylene plastics as defined in Specification D 1248 are generally tested under different levels of strain and stress. When it is expressly desired to compare the types at equal levels of strain, the specimens for all types should be tested under Condition B, Table 1 (4).

Information from this test method is not intended to be used for direct application to engineering problems.

Note 3—Caution should be used in comparing and ranking various ethylene plastics into distinct and separate groups by this test method (see Section 13 and Note 12).
As thermal history is recognized as an important variable, test results by this test method employing laboratory molded samples cannot necessarily be expected to show agreement with test results from samples obtained by other means. The true performance potential of a given ethylene plastic may, however, best be determined with specimens obtained from commercially prepared items (5).

TABLE 1 Standard Test Conditions

ConditionSpecimen ThicknessNotch DepthBath Temperature, °C mm^Ain.mm^Ain. A^Bmin3.000.1200.500.02050 max3.300.1300.650.025 B^Bmin1.840.07250.300.01250 max1.970.07750.400.015 C^Cmin1.840.07250.300.012100^C max1.970.07750.400.015

^A Dimensional values are not exactly equivalent. However, for referee purposes the metric units shall apply.

^B For referee purposes, concentration of Igepal will be consistent with the appropriate material standard. If no concentration is given, then 10 % volume solution shall be used.

^C At a temperature of 100°C, a full-strength reagent, rather than an aqueous solution of a reagent, is generally used because solutions tend to change their compositions by water evaporation losses during the period of test.

Область применения

1.1 This test method covers the determination of the susceptibility of ethylene plastics, as defined in Terminology D 883, to environmental stress-cracking when subjected to the conditions herein specified. Under certain conditions of stress and in the presence of environments such as soaps, wetting agents, oils, or detergents, ethylene plastics may exhibit mechanical failure by cracking.

1.2 The values stated in SI units are to be regarded as standard.

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 appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

Note 1—There is no similar or equivalent ISO standard.