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ASTM D573 Standard Test Method for Rubber—Deterioration in an Air Oven
Last updated May 14, 2025
ASTM D573 Standard Test Method for Rubber—Deterioration in an Air Oven
ASTM D573 outlines a controlled method for determining the deterioration of rubber compounds when exposed to elevated temperatures in an air oven for a specified period. The test simulates the effects of long-term heat aging by measuring changes in physical properties such as tensile strength, elongation, and hardness. It is essential in evaluating the thermal stability and lifespan of rubber materials used in environments with sustained heat exposure. This method helps predict service life and performance degradation due to oxidative and thermal effects. It plays a critical role in product design, quality assurance, and material comparison for various rubber formulations.
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ASTM D573 Introduction
Rubber components exposed to heat over time may experience significant changes in their mechanical and physical properties. ASTM D573 provides a standardized method to evaluate these effects by aging rubber specimens in a circulating air oven under controlled temperature and time conditions. The results of this test help manufacturers assess the durability and performance of rubber materials used in seals, gaskets, hoses, and insulating products. The method applies to vulcanized rubber and thermoplastic elastomers and is typically performed alongside physical property tests before and after aging. By simulating real-world thermal exposure, ASTM D573 enables comparison between different rubber formulations and ensures material suitability for intended applications.
ASTM D573 Test Method
Aging Temperature
Typically 70°C, 100°C, or 125°C, depending on the rubber type and intended application; maintained within ±1°C.
Duration of Exposure
Specimens are aged for 70 hours, 96 hours, or longer, depending on customer or product requirements.
Property Evaluation
After aging, tensile strength, elongation at break, and hardness are measured and compared to unaged values.
ASTM D573 Equipment and Sample Preparation
Specimen Dimensions
Type C dumbbell specimens with a gauge length of 25 mm and an overall length of 115 mm are used as per the standard.
Specimen Preparation
Samples are die-cut from cured rubber sheets using a precision dumbbell-shaped cutter to minimize edge defects.
Air Oven
A forced-draft air oven capable of maintaining uniform temperature (±1°C) and free air circulation around samples.
ASTM D573 Results and Interpretation
Test results are expressed as the percentage change in physical properties such as tensile strength and elongation after aging. A significant reduction in these values indicates poor thermal aging resistance. For example, a drop of over 40% in elongation may render a material unsuitable for dynamic applications. Hardness changes, typically measured in Shore A, reflect stiffness variations due to thermal degradation. Interpretation of these changes must consider the expected service conditions and the critical performance thresholds of the product.
ASTM D412 covers the determination of tensile properties of rubber before and after aging. ASTM D2240 provides the procedure for measuring the hardness of rubber using durometers, which is essential post-aging. ASTM D865 outlines ozone resistance testing of rubber materials, which is often conducted in parallel with thermal aging studies for outdoor applications.
Applications of ASTM D573 in Industry
This test method is widely used in the automotive, aerospace, electrical insulation, and construction industries. Components such as engine mounts, gaskets, wire insulation, weatherstrips, and appliance seals are frequently subjected to this test to validate long-term performance under thermal stress.
Importance of ASTM D573
ASTM D573 is crucial for determining the thermal stability and life expectancy of rubber materials in service conditions involving heat. It provides essential data for quality control, product development, and material comparison. Without this test, failures due to unknown aging behavior could result in costly recalls or safety hazards, especially in critical sealing or insulating applications. It is a foundational test for certifying rubber performance and enhancing product reliability.