Industry Insights · Medical Polymers & Silicone
Choosing a silicone cure system: platinum / peroxide / condensation
The cure system decides whether a silicone can be formed in your process, how much it shrinks, whether it leaves byproducts and whether it needs a post-cure. Know the three families before you choose.
All three at a glance
The table summarizes the key differences (training-level overview; verify cure schedules against product TDS):
| Property | Addition (Pt) | Peroxide | Condensation |
|---|---|---|---|
| Mechanism | Catalytic addition | Free radical | Moisture-dependent |
| Byproducts | None | Acid or alcohol | Acid or oxime |
| Shrinkage | <1% | 2–5% | 2–5% |
| Post-cure | Optional | Required | Optional |
| Thick sections | Excellent | Limited | Limited |
| Work time | Adjustable | Long | Hours to indefinite |
| Cost | Higher | Lower | Lower |
Why platinum cure gets 'poisoned'
- Amines, sulfur, organotin and some drug-containing/nitrogen-bearing formulations inhibit platinum catalysis, causing no cure or incomplete cure;
- Mitigate: test compatibility before scaling / increase platinum loading / switch to tin condensation or peroxide (especially for amine-containing drugs).
How to choose: by scenario
- Medical implants, precision thick parts, low shrinkage → platinum addition;
- HCR extruded tubing/profiles, transfer molding → peroxide (mind the post-cure);
- One-part no-mix, self-leveling seals/coatings on thin sections → condensation RTV;
- Drug delivery (DDS) → depends on the drug: clean drugs can use platinum; amine-containing drugs favor tin condensation or peroxide, tested formulation-by-formulation.
The BIO angle
FAQ
Which cure is most common for medical devices?
Platinum addition: no byproducts, low shrinkage, cures thick sections, fast with heat, long implant history.
What 'poisons' platinum cure?
Amines, sulfur, organotin and some drug/nitrogen-bearing substances inhibit platinum; do compatibility testing or switch cure systems.
Why does peroxide cure need a post-cure?
To remove decomposition byproducts (acids, etc.) and stabilize properties; common for HCR extruded parts.
What is condensation cure good for?
One-part no-mix, self-leveling seals/coatings on thin sections; not for thick parts (moisture cannot reach the core).
Which cure for drug-eluting (DDS) products?
Depends on the drug: clean drugs can use platinum; amine-containing drugs tend to inhibit platinum, favoring tin condensation or peroxide, tested per formulation.
Related reading
- Silicone, Silicone Oil, Silicone Resin: How They Relate, in 3 Minutes | BIO Insights
- Medical Polymers: Which Biocompatibility Tests Do You Actually Need? | BIO Insights
- Biodegradable Medical Implants: Reshaping Future Practice (Literature Brief) | BIO Insights
Note: an original analysis compiled from public industry information; figures and conclusions per official/original sources. Not investment advice.
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