Environmental Resistance Testing
Smithers offers a wide range of environmental testing at our global ISO 17025 accredited rubber and plastic testing laboratories to suit your polymer type and their predicted service conditions.
Accelerated Weathering: Key Insights for Rubber Product Performance
For engineers and material scientists developing or utilizing rubber products, understanding their long-term durability under various environmental stressors is paramount. Accelerated weathering techniques provide critical insights into how rubber materials will perform over time, helping to ensure product reliability and mitigate costly field failures. In this short Q&A with Smithers expert Jeff Marek, we summarize key testing methods, their importance, and their impact on rubber performance.
What is accelerated weathering, and why is it particularly important for rubber products?
Accelerated weathering involves exposing materials to controlled, intensified environmental elements such as light, moisture, and temperature in a laboratory setting. For rubber products, which are often subjected to harsh outdoor or industrial conditions, this is crucial for predicting material breakdown, understanding product limitations, and assessing their lifespan. This process offers a significantly quicker turnaround time than natural weathering, provides reproducible results, and allows for the precise control of variables (e.g., temperature, humidity, irradiance) to simulate specific service environments. This foresight helps in mitigating potential product service issues and optimizing material selection.How do heat aging and fluid exposure tests specifically affect rubber performance?
Heat Aging tests accelerate the aging process by exposing rubber materials to elevated temperatures. This technique is used to determine a material's service temperature limits and is often combined with other tests to predict overall service life. For rubber, common standards include ASTM D573, ASTM D2000 (for rubber in automotive applications), and ISO 188. Exposure to high temperatures can lead to changes in rubber's physical properties such as hardness, tensile strength, and elongation, indicating a reduction in flexibility and integrity due to accelerated aging.Exposure to Fluids involves testing chemical changes in rubber caused by contact with various liquids, often accelerated by adding heat. This is vital for assessing material compatibility with substances like automotive oils, fuels, hydraulic oils, industrial cleaners, or food-related fluids. For rubber, this can result in swelling, shrinkage, degradation of mechanical properties, or chemical breakdown if the material is not compatible with the specific fluid. A few commonly used test standards include ASTM D471 and ISO 1817.
Why is ozone exposure a critical consideration for rubber, and what does this test reveal?
Ozone exposure is a highly critical test for many rubber products, especially those exposed to atmospheric or industrially produced ozone. This test assesses a rubber material's ability to withstand ozone attack. Ozone can cause a phenomenon known as "ozone cracking," where the rubber surface develops visible cracks even under slight strain, leading to premature failure. The test helps determine if a rubber compound has a sufficient antiozonant package to protect it. It can be performed under both static and dynamic strain conditions, with common standards including ASTM D1149, ASTM D1171, and ISO 1431. In addition, exposure to pure oxygen (e.g., ASTM D572) is also important for most rubber products, particularly in the tire industry, to assess deterioration.How do light exposure tests (Xenon Arc and UV Light) contribute to understanding rubber durability outdoors?
For rubber products used outdoors, exposure to sunlight is a major factor in degradation.Xenon Arc Light testing simulates the full spectrum of natural sunlight, including UV, visible, and infrared light, with controlled irradiance, humidity, and temperature. Common rubber-specific standards include ASTM D750 (Weathering Deterioration), ASTM D925 (Surface Staining), ASTM D1148 (Discoloration from UV / Heat Exposure), ISO 3865 (Staining), and ISO 4665 (Resistance to weathering) for rubber and plastic laminates.
UV Light (QUV) testing specifically simulates the damaging effects of the UV portion of sunlight. Both methods are crucial for evaluating how rubber's aesthetic and mechanical properties will hold up against prolonged solar radiation, helping to predict issues like embrittlement or surface cracking.
What essential pre- and post-weathering assessments are performed to evaluate changes in rubber performance?
To truly understand the impact of accelerated weathering, it's crucial to perform both pre- and post-weathering tests to quantify any changes. For rubber, these assessments commonly include:- Physical Properties: Evaluating changes in abrasion resistance (using methods like Rotary Drum, Taber, NBS, Pico Abrasion per ASTM D1630, D2228, D5963, ISO 4649), adhesion, tensile strength, elongation, tear strength, hardness, volume and weight changes, compressive stress relaxation, or compression set.
- Color Change/Shift: Visually and instrumentally assessing any changes in the rubber's appearance.
- Surface Degradation: Identifying and documenting issues like cracking, crazing, or chalking.
- Chemical Properties: Analyzing changes in specific gravity, bulk composition, or extractables to understand underlying chemical degradation.
Assessing materials for exposure with harsh conditions? Contact us today to design a testing program that will provide you with the guidance needed to make your most challenging development decisions.
