Addition-Cured RTV-2 Silicones: Formulators Guide - News

Formulating High‑Performance Addition‑Cured RTV‑2 Silicones: A Practical Raw‑Material Guide with BRB Solutions

Addition‑cured (platinum‑cure) RTV‑2 silicone elastomers underpin demanding applications—from electronics potting and mold making to industrial tooling—thanks to their thermal stability, precision curing, and long‑term reliability. The right selection of raw materials is essential to deliver consistent processing and end‑use performance. BRB supports formulators with a comprehensive portfolio of silicone building blocks and additives designed for robust, scalable formulations.

1. Base Polymers: Vinyl‑Terminated PDMS
Vinyl‑terminated silicone polymers define viscosity, mechanical properties, and cure behavior. Select grades with appropriate vinyl functionality and viscosity to match target hardness, tear, and elongation. BRB supplies vinyl‑functional PDMS suitable for low‑ to high‑modulus systems and compatible with hydride crosslinkers.

2. Hydride‑Functional Crosslinkers & Modifiers (Si–H)
Crosslink density—and thus hardness and elasticity—is governed by the vinyl:hydride ratio. Linear and resin‑modified hydride crosslinkers enable tuning from soft, flexible gels to high‑strength elastomers. BRB hydride materials offer controlled Si–H content to support predictable cure kinetics.

3. Platinum Catalyst
RTV‑2 addition curing relies on platinum catalysis (e.g., Karstedt)). BRB raw materials are engineered for compatibility with commonly used Pt catalysts and process conditions.

4. Reinforcing Fillers
High‑surface‑area fumed silica—often surface‑treated—delivers mechanical reinforcement. Pre‑dispersed silica in vinyl PDMS can reduce mixing time and improve stability. BRB can support with dispersions and processing guidance to reach target rheology and mechanicals.

5. Silicone Fluids
Low‑viscosity silicone fluids help tune flow, degassing behavior, softness, and processing latitude without compromising compatibility. Select fluids to balance pot life and cure profile.

6. Specialty Additives
Additives enable application‑specific performance: inhibitors for pot‑life control, adhesion promoters for substrate bonding, silicone resins for hardness and thermal resistance, and silicone polyethers for improved wetting.

Figure 1. Key building blocks that synergize in a platinum-cured RTV-2 silicone system

A Modular Approach to Performance
Using BRB’s compatible silicone building blocks, formulators can assemble targeted solutions for: fast‑cure casting, low‑viscosity potting, high‑tear mold materials, high‑temperature elastomers, and precision duplication compounds. The modular approach accelerates development without sacrificing quality.

Practical Formulation Tips

Balance vinyl:hydride ratio to reach target durometer—verify with small‑scale stoichiometry sweeps.
Use inhibitors to manage pot life in warm or humid environments; calibrate to the processing window.
Optimize silica surface treatment and loading for tear strength vs. viscosity trade‑offs.
Degas both parts and assembled mixes to minimize voids in potting/casting applications.
Consider encapsulated Pt catalysts for delayed cure in complex casting or long open‑time processes.

Partner with BRB: Samples & Technical Support
Ready to accelerate your next RTV‑2 silicone? BRB offers:

**Application‑matched samples** of vinyl‑functional PDMS, hydride crosslinkers, fluids, and additives.

**Support** consultations to guide you through your formulation process.

Conclusion
A robust addition‑cured RTV‑2 system starts with the right building blocks. With BRB’s breadth of silicone polymers, crosslinkers, fillers, fluids, and specialty additives—backed by expert support—formulators can deliver reliable performance from lab to production.