Silicone rings, due to their soft, skin-friendly, safe, and durable properties, have become a popular choice for those involved in sports, fashion, and those with sensitive skin. However, many users have found that after wearing them for a while, their originally soft silicone rings gradually become hard and even crack. This phenomenon is the result of a combination of material properties, environmental factors, and manufacturing defects.
Material Properties: Silicone's "Self-Aging" Mechanism
Silicone (silicone rubber) is a polymer with silicon-oxygen bonds as its backbone. Its molecular structure determines its unique physical and chemical properties.
Silicone Oil Loss and Self-Crosslinking
Silicone's softness depends in part on the silicone oil contained within it. Over long-term use, the silicone oil gradually evaporates or migrates to the surface, reducing the internal oil content and causing the material to harden. For example, some manufacturers overuse silicone oil or softeners to achieve initial softness, but these substances are lost within a few months. Furthermore, silicone is shipped in an incompletely cross-linked state. Over time, the molecular chains continue to cross-link, forming a tighter network structure, which increases its hardness.
Vinyl Content and Crosslink Density
The hardness of silicone can be controlled by adjusting the vinyl content. Vinyl increases the tightness of silicone chains, but excessive vinyl content (e.g., exceeding the 90° limit) can lead to excessive crosslink density, resulting in a hard and brittle material. To reduce costs, some manufacturers use low-purity silicone raw materials, resulting in uneven molecular chain distribution and localized hardness abnormalities.
Environmental Factors: The "Invisible Killer" that Accelerates Aging
The hardness of silicone rings is closely related to environmental conditions. The following factors can significantly accelerate aging:
Ultraviolet Light and High Temperatures
Ultraviolet light destroys the silicon-oxygen bonds in silicone molecules, triggering free radical reactions, leading to molecular chain breakage and increased crosslinking. Prolonged exposure to sunlight (e.g., during outdoor sports) can cause silicone rings to become hard and yellow within 3-6 months. High temperatures (e.g., above 60°C) accelerate silicone oil volatilization and crosslinking reactions, causing the material to lose elasticity within weeks.
Moisture and Chemical Corrosion
Although silicone is hygroscopic, prolonged immersion in water or contact with sweat, oil, and other substances can cause water molecules to penetrate the material, disrupting the hydrogen bonds between the molecular chains and making it brittle. Furthermore, chemicals such as acids and alkalis can corrode the silicone surface, causing swelling or degradation. For example, surfactants in detergents can strip the protective layer on the silicone surface, accelerating aging.
Mechanical Stress and Fatigue
Repeated bending, squeezing, or stretching can break silicone molecular chains, forming microcracks. These cracks propagate under stress, eventually causing the material to harden and crack. For example, frequent removal and insertion of silicone rings or rubbing them against hard objects can shorten their lifespan by several months.
Process Defects: Hidden Dangers in the Production Process
Abnormal hardness in silicone rings is often closely related to the production process. The following issues require special attention:
Insufficient or Excessive Vulcanization
Vulcanization is a critical step in silicone molding. If the vulcanization time is too short or the temperature is too low, the cross-linking will be incomplete, resulting in low hardness and easy deformation. Conversely, excessive vulcanization will result in excessive cross-linking density, making the material hard and brittle.
Mold Design and Demolding
A rough mold surface or improper design (such as an overly narrow runner) can cause internal stress in the silicone during the molding process, easily leading to cracks during demolding. Furthermore, improper use of release agent (such as excessive spraying) can leave residue on the silicone surface, forming a weak layer and accelerating aging.
Raw Material and Additive Control
To reduce costs, some manufacturers use recycled materials or inferior fillers (such as calcium carbonate). These substances can disrupt the silicone's molecular structure and reduce its aging resistance. For example, one batch of silicone rings, due to excessive calcium carbonate addition, experienced a 50% increase in hardness within a month and exhibited powdering.
User Behavior: The Impact of Usage Habits
Daily usage habits can also significantly affect the lifespan of silicone rings:
Improper Cleaning and Maintenance
Using organic solvents such as alcohol and gasoline to clean silicone rings can dissolve the silicone oil on the surface and accelerate hardening. The correct cleaning method is to rinse with clean water and allow the ring to air dry.
Poor Storage Environment
Exposing silicone rings to high temperatures, humidity, or direct sunlight (such as on car dashboards or in bathrooms) for extended periods can accelerate aging. It is recommended to store them in a dry, cool place and avoid contact with sharp objects.
Incorrect Sizing
A silicone ring that is too tight can cause molecular chain breakage due to prolonged pressure, while a ring that is too loose can easily crack due to friction. Users should select the appropriate product for their finger size and regularly inspect its condition.
The hardening of silicone rings is a result of a combination of material properties, environmental factors, workmanship defects, and user behavior. To extend their lifespan, users should choose products from reputable manufacturers, avoid prolonged exposure to extreme environments, and perform regular cleaning and maintenance. Manufacturers must also optimize their production processes and strictly control the quality of their raw materials to provide more durable silicone jewelry. Through proper use and proper care, the softness and comfort of silicone rings can be maintained over time.