Automotive Material Aging Test

Climate aging is (mainly photoaging) aging caused by environmental and climatic factors such as light, heat, and water.

Cars are often affected by climate and environment during use, and the performance of their interior and exterior materials, parts and car shells will gradually decrease and age over time.

The materials of interior and exterior parts for automobiles are mainly polymer materials (plastic, rubber, adhesive, fabric, etc.), and the environmental aging problem of interior and exterior parts is mainly the aging problem of polymer materials, so the analysis of environmental aging problems of interior and exterior parts is fundamental Generally speaking, it is the aging analysis of polymers.

01 Aging of polymer materials

The aging of polymer materials refers to the phenomenon that polymer materials gradually lose some of their original properties and deteriorate their performance due to the combined effects of internal and external factors during storage and use.

According to the aging reasons, polymer materials mainly have the following aging conditions:

① Photoaging: Sunlight is the main factor leading to the aging of polymer materials, especially those used outdoors. Under the action of light, the polymer compound undergoes a photochemical reaction due to the absorption of light energy, which destroys the chemical bonds. The shorter the wavelength of the light wave, the higher the energy, and the stronger the ability to destroy chemical bonds.

② Heat aging: The action of heat can not only break the covalent bonds, lead to the cracking of macromolecules, but also cause crosslinking between macromolecules, and accelerate the oxidation of polymer compounds, thereby causing thermal aging of polymer materials.

③ Oxidation: Many polymer materials are oxidized by oxygen or ozone in the atmosphere, resulting in polymer chain breakage and oxidative aging. The degree of oxidation of the polymer material is related to the chemical structure of the polymer compound, and also related to the diffusion and absorption speed of oxygen or ozone in the polymer material.

In general, polymer compounds with unsaturated carbon chains are more prone to aging than those with saturated carbon chains; polymer materials with loose structures are more likely to age than those with tight structures.

④ Erosion: Generally, polymer materials have relatively strong corrosion resistance, but some polymer materials will be eroded under certain conditions. The erosion of polymer materials includes chemical erosion and biological erosion.

When the polymer material is subjected to certain chemical substances, the polymer chain undergoes a chemical change, which degrades its performance; some microorganisms will mildew some polymer materials and undergo degradation reactions under certain temperature and humidity conditions, resulting in Ageing.

The initial aging of the photoaging process of polymer materials is slow and difficult for human eyes to observe. In the early stage of aging, the polymer mainly absorbs ultraviolet light to generate polymer free radicals, and then degrades directly or through the action of oxygen in a free radical chain mechanism. Cross-linking reaction is accompanied by the generation of degradation products such as hydroxyl and hydrocarbon groups; in the later stage of aging, due to a large number of chromogenic groups such as carboxyl and hydroxyl groups, the absorption of ultraviolet light is increased, and the aging process is accelerated, resulting in further degradation and cross-linking, making high Molecular materials discoloration, cracking, mechanical and physical properties decline.