Summer has arrived, with temperatures rising. As the most complex and variable season of the year, extreme weather such as sustained high temperatures, heavy rainfall, hail, and even typhoons occur frequently.
At this point, improper use or maintenance of single component silicone sealant can easily lead to various quality problems after construction.
To ensure its stable and reliable performance, this article will focus on the key precautions for its use during summer and rainy seasons.
Part 01 Curing Principle
The curing reaction of single component room temperature cured silicone rubber is to react with water molecules in the air and solidify into an elastic body.
The curing process starts from the surface and gradually moves towards the interior. The curing speed depends on the curing system, temperature, humidity, and thickness of the silicone rubber layer. Increasing the temperature and humidity of the environment within a certain range can accelerate the curing process.
Using it in a conventional environment with a relative humidity of 55% RH at 25 ℃ is a reasonable and satisfactory environment that can achieve the appropriate use state of silicone gel.
Part. 02 Common Problems
- Extended drying time
- Extended deep curing time
- Colloidal surface becomes sticky
- Weakening of bonding strength per unit time
- ...........
Due to the high moisture content in the air during the rainy season, the surface of the adhesive undergoes excessive hydrolysis, resulting in a prolonged drying time and a "sticky" surface, which delays the adhesive strength for a certain period of time. However, as the curing time increases, the bonding strength will correspondingly delay until the adhesive performance is fully cured and restored.
Precautions
- Before use, remove moisture, oil stains, dirt, etc. from the surface of the adhesive material, wipe it clean, and then use it to avoid adverse reactions such as insufficient adhesive strength and curing failure.
- The bonding strength may vary greatly depending on the bonding interface, and corresponding interface bonding strength tests should be conducted before use.
- RTV silicone rubber starts to cure from the surface to the inside when it comes into contact with water molecules in the air, and the curing depth is limited. Generally, the curing depth is less than 6mm after sufficient curing. In addition, the surface drying time and depth curing time may vary with the temperature and humidity of the adhesive environment.
Part 03 Summary&Suggestions
- The curing of some RTV is related to temperature and humidity. Within a certain range of temperature/humidity, the curing depth of RTV is fast. If unilaterally cured by moisture (relative humidity above 90% RH), the colloidal surface will appear sticky.
- It is recommended to extend the storage time of the product that has been glued (the specific extension time needs to be combined with the product and application environment).
- Apply glue under environmental conditions of temperature (27 ℃± 2 ℃) and humidity (55% -70% RH).
To ensure the best use effect, please pay attention to the changes in the glue state during summer, adjust the construction plan reasonably, and give the glue sufficient curing time to avoid affecting the quality of the project due to insufficient curing.
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