Poisoning of platinum curing silicone
In this article, we delve into the world of silicone poisoning, focusing on addition-curing silicones (also known as platinum silicones). We also explore the concept of inhibition in relation to this type of poisoning.
Addition-Curing Silicones:
- These silicones undergo polymerization to harden. Short silicone molecules form long chains and networks, resulting in rubber-like silicones.
- Platinum acts as a catalyst in this process. Due to its high cost, platinum is added sparingly.
- Unfortunately, platinum also reacts with other components. If insufficient platinum remains, the silicones may not fully cure.
- The result? Sticky or even liquid silicones with less tensile strength and firmness than expected due to incomplete network formation.
Materials That React with Platinum and Poison Addition Silicones:
- Sulfur: Sulfides and their combinations (found, for example, in latex gloves). Always check your gloves!
- Nitrogen: Amines, amides, nitriles, and cyanates (present in epoxies, paints, and adhesives). Even if an epoxy or paint appears fully cured, there’s a significant chance it isn’t.
- Tin: Tin salts and similar compounds (commonly used in condensation silicones).
- Phosphorus: Phosphine and phosphite (used in the metal industry for corrosion protection).
- Other Substances: Solvents like alcohols and esters, as well as certain unsaturated compounds and primers.
Condensation Silicones:
- These silicones often use a tin compound as a catalyst.
- They usually cure unless there’s insufficient moisture in the air or system, or if moisture is drawn out (e.g., in very dry river clay).
Note: Avoid exposing silicones to toxic substances, clean surfaces before application, and use appropriate primers to prevent inhibition. For more details, refer to the full document here.
