What are the reasons for the aging of polyurethane coated wheel packaging products?

| What are the reasons for the aging of polyurethane coated wheel packaging products?

The features of polyurethane coated wheel.
2020-12-08 15:21

Mechanical force, light, oil, moisture, heat, etc. are all the keys to the aging phenomenon of polyurethane encapsulation, resulting in phenomena such as hardening, stickiness, brittleness, discoloration, and loss of strength, although aging is inevitable , but we can delay its aging process through daily maintenance and correct use, thereby extending its service life. So, what causes the aging of polyurethane encapsulated products?
1. Mechanical force: Under repeated mechanical force, the polyurethane encapsulated molecular chain will be broken to form free radicals, which will initiate oxidation chain reaction and form a mechanochemical process. In addition, it is easy to cause ozone cracking under stress.
2. Light: It is the higher energy ultraviolet rays that damage the product. The shorter the light wave, the greater the energy. In addition to directly causing the breakage and cross-linking of the molecular chain, free radicals can also be generated due to the absorption of light energy, which initiates and accelerates the oxidation chain reaction process. For samples with high gel content, network cracks will appear on both sides, the so-called "light outer layer cracks".
3. Oil: If it is in long-term contact with oily media during use, the oil can penetrate into its interior and cause it to swell, resulting in reduced strength and other mechanical properties.
4. Moisture: It is easy to age when it is exposed to rain or soaked in humid air, especially under the alternating action of water soaking and atmospheric exposure, it will accelerate the damage.
5. Heat: Too high temperature will cause thermal cracking or thermal cross-linking of the encapsulated product. But the basic function of heat is activation. This is a common aging phenomenon-thermal oxygen aging.
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