Tests on Polymers: Aging Test
Aging is the irreversible physical and chemical deformation which a material is exposed to gradually. The aging test is essential for long-lasting industrial products that will be used in polymers.
In general, the factors that are most effective on the polymer aging include temperature, exposure to ultraviolet light, visible light, atmospheric components, humidity, liquids, etc.
Aging in polymers is divided into two: physical aging and chemical aging. Their amorphous structure changes physically over time, which impairs their elastic structure. Additionally, their low molecular weight and softer structures cause them to be less resistant to aging.
The main cause of aging in polymers is the degradation of the chain structure under the influence of heat and temperature. Due to the effect of aging, intermolecular bonds become weaker and different molecules are formed in the structure. This effect is determined by measuring the molecular mass. Additionally, the surface appearance changes due to the formation of different molecules.
Aging under UV light is classified as chemical polymer aging. Bond structures are formed, which causes the material to age rapidly under UV light. The surface is oxidized when affected by UV light. Especially, PE derivative polymers undergo a very rapid degradation process under UV lights. Carbon black and/or TiO2 are widely used together with the raw material to slow down this process. However, the most reliable method is to use UV stabilizers or UV absorber additives.
For physical aging, on the other hand, the material is exposed rupture and deformation under load due to the changes on the surface caused by the breaking of bond structures. A PVC material may result in breakage due to its brittle structure especially when it is exposed to physical aging.
The aging of polymer materials takes a long time during regular service life. That is why aging tests are conducted to measure the resistance to unfavorable conditions.
Aging test is performed in specific aging cabinets in accordance with TS EN 2243, with the parameters of heat, humidity and time (30, 60, 90, etc.) adjusted.