Ageing is the phenomenon in which a material gradually deteriorates in performance during processing, storage and use under the combined action of internal and external factors, eventually losing its service value. The change is irreversible and is a universal problem for materials. Causes may be internal weaknesses such as unsaturated double bonds, branch chains, carbonyl groups and terminal hydroxyl groups, or external factors such as sunlight, oxygen, ozone, heat, water, mechanical stress, high energy radiation, industrial gases, seawater, salt mist, mould, bacteria and insects.

Types of ageing test

Ageing tests are diverse, covering high and low temperature ageing, damp heat ageing, light ageing, hot air ageing, salt mist corrosion, ozone ageing, mechanical ageing, thermal oxidative ageing, buried soil corrosion, liquid medium ageing and ageing tests to specific customer conditions. Together these cover the environmental conditions a material may meet, allowing its durability to be assessed comprehensively.

The key ageing tests are high and low temperature ageing, UV ageing, salt mist ageing, damp heat ageing, xenon arc ageing, thermal shock, ozone ageing, carbon arc ageing and gas corrosion.

1. UV ageing test. Simulates the UV component of sunlight to evaluate the ageing behaviour of polymer materials under UV exposure.

2. Salt mist ageing test. Simulates a salt mist environment to evaluate the corrosion resistance of products and metal materials. Salt mist testing includes neutral salt mist, acid salt mist, copper ion accelerated salt mist, cyclic salt mist and alternating salt mist.

3. Damp heat ageing test. Simulates a hot and humid environment to evaluate the ageing resistance of polymer materials, which can suffer swelling, hydrolysis and additive migration in such conditions.

4. Xenon arc ageing test. Simulates the thermal and optical effects of solar radiation in unshielded outdoor environments to evaluate the ageing resistance of equipment and materials.

5. Thermal shock test. Evaluates the temperature resistance of polymer materials under alternating high and low temperature and the effect of temperature change on material performance.

6. Weathering test. Exposes materials to the atmosphere to evaluate ageing behaviour and service life in the natural environment.

7. Carbon arc ageing test. Simulates light resistance under carbon arc lamps used in earlier equipment, evaluating colour degradation and structural change.

Standards for ageing tests

Ageing testing follows a series of international and national standards such as GB/T 16422.2, GB/T 3511-2008 and GB/T 1865-2009, which cover methods for different materials and products and ensure accuracy and comparability. Together they allow durability to be assessed comprehensively and provide important data for product design and improvement, ensuring reliability and safety in actual use. Ageing testing not only improves market competitiveness but also reduces the maintenance cost and environmental impact caused by material ageing, giving it considerable economic and environmental significance.