Analysis of aging of automobile interior parts and indoor air pollution
Created on 2025.12.25
Most interior parts contain a certain amount of volatile organic compounds, which are mainly alkanes, alkenes, aromatics, acetaldehydes or ketones. The boiling points of these substances are usually in the range of 50 to 260°C.
When reaching a certain temperature, volatile substances will be released. Some will form fog and condense on the front windshield, thereby affecting the driver's vision; some will produce unpleasant odors and even cause uncomfortable reactions such as headaches, dry coughs and allergies, thereby causing harm to the occupants' bodies.
There are many sources of odor in the car, including pigments, modifiers and additives, etc. The aging and degradation of interior parts will also affect it.
Under the action of light and heat, interior parts will release some volatile substances, causing fogging and odor in the car. Research shows that possible sources of volatile substances include various additives and processing aids. In addition, by-products from the degradation of automobile interior parts and small molecule impurities in interior parts are also sources of harmful substances.
There are many reasons why additives produce odor in the car. The processes include:
- The additives migrate to the surface of the polymer. It depends on the migration and diffusion speed of the additive, which is mainly affected by the compatibility between the additive and the polymer, molecular weight and polarity.
- The additives volatilize on the polymer surface. Affected by the vapor pressure of the additive molecules, hydrogen bonds and surface energy.
- The short carbon chains produced by the aging and degradation of polymer materials will produce volatile substances such as aldehydes and ketones after being oxidized.
The sampling methods for air pollutants in cars are basically as follows:
Random environmental conditions sampling method. The comparability and reproducibility of its data are poor.
Test method for PV3938 of Volkswagen AG, Germany. The surface temperature of interior materials in the car is 65°C.
Japan Automobile Manufacturers Association's "Test Methods for VOC in Vehicles" and "Autonomous Actions to Reduce VOC in Vehicles". Heat the sealed vehicle to 40°C, hold it for a certain period of time, and then measure formaldehyde. Then start the car engine, turn on the air conditioner, and measure VOC.
China HJ/T400-2007 "Method for Sampling and Determination of Volatile Organic Compounds and Aldehydes and Ketones in Vehicles".
When determining the sampling environmental conditions of the vehicle under inspection, the following aspects will be affected:
(1) Environmental conditions that are most likely to occur in the car;
(2) The environmental conditions for VOC release in the car are relatively stable;
(3) Technically and economically feasible environmental conditions;
(4) Coordination with relevant standards.