Aging and protection of rubber grommets 1
Rubber grommets aging phenomenon
In the process of processing, storage or use of rubber grommets, the phenomenon that the performance gradually deteriorates due to the influence of external environmental factors, until the loss of use value is called aging.
The occurrence and development of rubber grommets aging is a process from the surface to the inside, from quantitative to qualitative. The change in appearance after aging is that there are spots, loss of light or micro-cracks on the surface, and the hand feels soft and sticky or hard and brittle; aging causes some physical and chemical properties and electrical properties of the rubber to deteriorate. The degree of occurrence of various mechanical properties decreases, and the longer the aging time, the more significant the change.
Causes of aging of rubber grommets
The cause of aging of rubber Grommets is internal and external. The internal cause is that rubber belongs to an organic polymer material, and its chemical bond energy, bond energy of cross-linking network and cohesive energy between macromolecules are relatively low, and it is susceptible to various kinds of erosion. Damage and aging. There are three types of external factors of aging, one is physical factors, such as heat, light, electricity, high-energy radiation and mechanical stress; the other is chemical factors such as oxygen, ozone, strong oxidants, inorganic acids, alkalis, salt aqueous solutions and variable-valent metal ions. Etc.; three are biological factors such as microorganisms and ants. The damage caused by the oxidation and ozonation of rubber is the most common and most serious. In addition, factors such as heat, light, and mechanical stress often act to activate and/or catalyze oxidation and ozonation. Biological aging occurs mostly in tropical or subtropical regions.
From the actual use of rubber grommets, aging is the result of a combination of internal and external factors. On the one hand, it must be in contact with and react with oxygen in the atmosphere. At the same time, periodic stress and strain occur, mechanical loss is generated to generate heat, and heat activates oxidation reaction. On the other hand, grommets are inevitably used outdoors. Photo-oxidative aging and ozone aging occur when exposed to sunlight, wind, rain and snow, and ozone.