Rubber, as a widely used polymer material, plays an important role in various fields such as automotive, aerospace, construction, and medical. However, rubber is prone to be affected by environmental factors during use, such as oxygen, ultraviolet light, temperature, and humidity, which leads to its performance gradually deteriorating, showing phenomena such as hardening, cracking, and loss of elasticity. This phenomenon is called 'aging'. In order to evaluate the durability of rubber materials in practical applications, it is necessary to conduct scientific tests on their aging properties.



One, Mechanism of Rubber Aging



Rubber aging is mainly due to the oxidation, degradation, or destruction of cross-linking structures of its molecular chains. Common aging forms include thermal oxidation, ozone aging, photo-aging, and fatigue aging. These aging processes significantly affect the physical and mechanical properties of rubber, such as tensile strength, elongation at break, hardness, and elasticity.



Two, Common Aging Test Methods



1. Hot air aging test

This is the most common type of accelerated aging method. The rubber samples are placed in a constant temperature forced-air drying box and aged at a certain temperature for a certain period of time, then observing the changes in physical properties. Usually, the tensile strength, elongation at break, and other properties before and after aging are tested, and the performance retention rate is compared. This method is simple to operate and suitable for evaluating the resistance of rubber materials to thermal oxidation aging.



2. Ozone aging test

Rubber is prone to ozone cracking in an ozone environment, especially under tensile conditions. The ozone aging test applies a certain concentration of ozone in a special ozone aging box and applies a certain degree of tensile deformation to the sample, observing the surface cracking. This method is mainly used to evaluate the weather resistance of rubber products when used outdoors.



3. Ultraviolet (UV) aging test

Ultraviolet light is the main factor causing rubber photo-aging. The UV aging test simulates the ultraviolet radiation conditions in sunlight by using an ultraviolet aging test box to irradiate the rubber samples, observing changes in color, cracking, and decline in physical properties. This method is suitable for evaluating the stability of rubber under sunlight exposure.



4. Humid heat aging test

Humid heat environment accelerates the migration and hydrolysis reactions of certain additives in rubber. The humid heat aging test is usually carried out under high temperature and high humidity conditions to simulate the long-term use of rubber in a humid environment.



5. Fatigue aging test

Rubber products will undergo fatigue failure under repeated deformation. The fatigue aging test cycles the rubber samples by applying a certain frequency and deformation amplitude, recording their fatigue life and crack propagation behavior.



Three, Results Analysis and Evaluation



After the aging test, a systematic analysis of the appearance, mechanical properties, and chemical structure of the rubber samples is required. Common evaluation indicators include:



- Changes in appearance (such as color, cracks, bubbles, etc.)

- Changes in mechanical properties such as tensile strength, tear strength, and elongation at break

- Change in hardness

- Detect the change of chemical structure using infrared spectroscopy (FTIR) or thermogravimetric analysis (TGA)



Four, Conclusion



Through systematic aging performance testing of rubber, it can effectively evaluate its service life and stability under different environmental conditions, providing a scientific basis for product design, material selection, and quality control. With the development of material science and technology, new testing methods and evaluation methods are constantly emerging, making the research on rubber aging performance more in-depth and accurate. It is of great significance to improve the durability and reliability of rubber products.