Why does rubber age?
Rubber is a popular elastic material that is utilized in both everyday life and business because of its superior elasticity, impact resistance, and wear resistance. But rubber is not indestructible, and with time, it will progressively lose its effectiveness-a phenomenon known as rubber aging. This post will discuss the primary causes of rubber aging and offer some practical solutions to postpone the process.
Definition of rubber aging
Rubber aging is the process by which rubber's material qualities progressively deteriorate as a result of combined mechanical, chemical, and physical stressors. Rubber ages and loses its elasticity and strength as well as having the potential to become hard, brittle, and even shatter and fracture. Rubber ages and loses its initial resilience and flexibility, sometimes making it impossible for it to continue serving its intended purpose.
Main factors leading to rubber aging
The aging process of rubber is affected by many factors, the following are the most important ones:
Oxidation
One of the primary factors for rubber aging is oxygen. Rubber molecules' double bonds readily undergo a chemical reaction with atmospheric oxygen to produce oxidation products. Rubber's molecular chain structure is destroyed by this oxidation, which makes the material less elastic, harder, and even more prone to cracking. Significant acceleration of the oxidation rate will occur, particularly in environments with high temperatures.
Oxidation performance:
Rubber surface turns white or yellow
Material hardening
Reduced elasticity
Ozone erosion
The lower atmosphere contains the extremely oxidizing gas known as ozone (O₃). More so than regular oxygen, ozone breaks down the rubber's molecular chains, causing surface fissures when the rubber is stretched or deformed. This is especially true with natural rubber, since unsaturated rubber materials are more vulnerable to ozone degradation.
Ozone erosion performance:
Obvious cracks on the surface
Rubber cracks are more serious when stretched
Ultraviolet (UV) radiation
UV radiation has a damaging effect on rubber that cannot be disregarded. When rubber items are left in the sun for an extended period of time, the UV rays cause a process called photo-oxidation, which breaks down the rubber molecules and speeds up the aging process. Ultraviolet radiation can lead to rubber cracking, discoloration, and loss of flexibility.
Performance of ultraviolet radiation:
Rubber color fades or darkens
Rubber surface cracks
Texture becomes hard
Heat effect
The aging process of rubber will be accelerated by rising temperatures. Elevated temperatures cause rubber molecules to move more quickly, hastening chemical processes such as oxidation and heat degradation. Rubber often loses its suppleness, hardens quickly, and fractures under hot conditions.
Performances of thermal aging:
Rubber hardens
Produces tiny cracks
Elasticity is significantly reduced
Mechanical stress
Rubber's molecular chain structure varies in response to mechanical stressors including stretching, compression, and bending, which in turn alters the material's performance. Long-term tension can cause stress relaxation or fatigue in the rubber material, which might ultimately result in fracture. Furthermore, rubber will eventually fail if it is repeatedly worn down and subjected to friction.
Performances of mechanical stress:
Wear on the rubber surface
Decrease in elasticity
Increase in fractures or cracks
Chemical erosion
Chemicals in some chemical conditions will degrade rubber, reducing its performance. For instance, rubber can degrade or swell more quickly in the presence of acids, alkalis, solvents, oils, and other chemicals, which will reduce the material's strength and elasticity. The right rubber material must be chosen based on the particular application environment since different types of rubber have varying chemical tolerances.
Manifestations of chemical attack:
Swelling or softening of the rubber surface
Reduction in material strength
Solvents cause molecular chains to break
How to delay rubber aging
Rubber will eventually age naturally, but taking the right steps may greatly reduce this pace and increase the useful life of rubber items. Here are a few successful anti-aging techniques:
Use of antioxidants
Antioxidants may be added while rubber is being produced. By blocking the oxygen-rubber molecular chain reaction, these substances can reduce the rate of oxidation. A variety of common antioxidants, such as phenols and amines, can significantly increase the service life of rubber.
Use of anti-ozonants
Rubber goods can have anti-ozonants added to them to stop ozone-induced fractures. By interacting with ozone, these compounds can stop ozone from directly harming rubber molecular chains. Anti-ozonation wax can also be used to isolate ozone damage by creating a protective coating on the rubber surface.
Store away from light
Rubber items should be kept as far away from prolonged sunlight exposure as possible due to the extreme damage that ultraviolet radiation does to rubber. It is advised to utilize rubber materials with UV protection features or to put an anti-UV coating to the product's surface if it will be used outside to lessen the effects of UV radiation.
Temperature control
Try to keep rubber items at a moderate temperature and stay away from areas with high temperatures when using and storing them. Selecting unique heat-resistant rubbers, including silicone rubber, fluororubber, etc., that can continue to function well at high temperatures is advised if the rubber must be utilized in an environment with high temperatures.
Reduce mechanical stress
Mechanical stress, such as excessive stretching, compression, or bending, should be minimized while installing or utilizing rubber goods. The aging of rubber will be accelerated by excessive tension. Therefore, rubber's service life may be increased by thoughtful design and installation.
Avoid chemical corrosion
Rubber goods should not come into direct touch with acids, alkalis, solvents, or oils. Chemically resistant rubber varieties, such as fluororruber or chloroprene rubber, should be chosen for usage in chemical environments. The rubber's condition should also be routinely monitored, and any potential corrosion sources should be promptly cleaned.
Conclusion
Rubber aging is a multifaceted process that results from the interaction of several elements, including as heat, mechanical stress, oxidation, ozone erosion, UV radiation, and chemical corrosion. Rubber will naturally age with time, but it may be made to age more slowly and have a longer service life by using the right materials, processing techniques, and preventative measures. In real-world applications, knowing and addressing the reasons for rubber aging is essential to guaranteeing the durability of rubber goods over time.
