ASTM D750-12(R2021) pdf free download

ASTM D750-12(R2021) pdf free download.Standard Practice for Rubber Deterioration Using Artificial Weathering Apparatus
1. Scope
1.1 This practice covers specific variations in the test conditions and procedures that shall be applicable when Practice G151 plus either Practice G152, G153, G154, or G155 are employed for exposure of vulcanized rubber compounds. It also covers the preparation oftest specimens and the evaluation of results. 1.2 The values stated in SI units are to be regarded as 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, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.4 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
3. Significance and Use
3.1 This practice describes procedures to use in determining the effects of an open-flame carbon-arc light source, an enclosed carbon-arc light source, a xenon-arc light source, or a fluorescent UV source along with heat and moisture on rubber specimens held in a jig or holder with or without a specified strain. The purpose is to attempt to accelerate the effects produced by light, heat, and moisture in the natural environ- ment. Exposures are not intended to simulate the deterioration caused by localized weather phenomena, such as atmospheric pollution, biological attack, and saltwater exposure. The Sig- nificance and Use section in Practice G151 and the standard for the appropriate apparatus, that is, Practices G152, G153, G154, or G155 should be consulted for additional information on significance and use of the exposure tests. 3.2 The primary criterion used in estimating resistance to weathering is the percentage decrease in tensile strength and in elongation at break. A supplementary criterion for estimating resistance to weathering is the observed extent of surface crazing and cracking. 3.3 Results obtained by use of these test procedures should not be represented as equivalent to those of any natural exposure test until the degree of quantitative correlation has been established for the material in question. 3.4 Because of differences in the spectral power distribu- tions of the exposure sources as well as the other conditions in the different types of laboratory weathering tests, the different procedures may not result in the same performance rankings or types of failure modes of the materials. Comparisons shall not be made of relative stabilities of materials exposed in different types of apparatus. 3.5 When conducting exposures in devices that use labora- tory light sources, it is important to consider how well the artificial weathering conditions will reproduce property changes and failure modes caused by end-use environments on the materials being tested. 3.6 Practices G151, G152, G153, G154, and G155 recom- mend that a similar material of known performance (a control) be exposed simultaneously with the test specimen to provide a standard for comparative purposes. Preferably, a control mate- rial known to have poor durability as well as one that has good durability should be used. The reason for using a control is that reproducibility in ranking stabilities is usually better than reproducibility of absolute changes. Therefore, the use of controls is particularly important when test materials are not being compared with one another.
4. Apparatus
4.1 Historically, this standard utilized carbon arc exposure apparatus in a test method for rubber deterioration. The options ofusing either xenon arc or fluorescent UV exposure apparatus have been added in order to update the tests with the use of light sources that give a better representation of the effects of solar radiation than carbon arcs. The xenon arc source with daylight filters, which conforms to Practice G155, gives the closest simulation of the full spectrum of terrestrial solar radiation, and the fluorescent UV/condensation test apparatus with the UVA-340 fluorescent UV lamp, which conforms to Practice G154, closely simulates the UV of terrestrial solar radiation in the 300 to 360 nm region. 4.2 The type of carbon-arc exposure apparatus preferred is the filtered open flame carbon arc, which conforms with Practice G152, but the enclosed carbon arc apparatus conform- ing with Practice G153 may be used by mutual consent of the concerned parties.