SEMISIL R200 Reinforcing Hydrophobic Fumed Silica (HMDZ-Treated)
SEMISIL R200 is a hexamethyldisilazane (HMDZ)-treated hydrophobic fumed silica with a post-treatment BET surface area of 160–220 m²/g, specifically engineered as a reinforcing filler for high-consistency silicone rubber (HTV) and room-temperature-vulcanizing (RTV) silicone systems. The HMDZ surface treatment provides a higher carbon loading (2.5–6.0 Wt%) that improves polymer-filler interaction and compatibility in PDMS matrices, achieving tensile strengths above 8 MPa at standard loading levels of 25–45 phr.
Technical Specifications
| Properties and Test Methods | Unit | Typical Value | Standardization |
|---|---|---|---|
| Specific surface area (BET) | m²/g | 160 ~ 220 | GB/T 10722 |
| Carbon content | Wt% | 2.5 ~ 6.0 | GB/T 20020 |
| pH (1% in methanol/water 4:1) | – | 6.0 ~ 8.5 | Internal method |
| Loss on drying (2h @ 105°C) | Wt% | ≤ 0.5 | GB/T 5211.3 |
| Sieve residue (45 μm) | % | ≤ 0.05 | GB/T 5211.14 |
| Methanol wettability | % | ≥ 50 | Internal method |
| Silica content (ignited material) | Wt% | ≥ 98.5 | GB/T 20020 |
Application Suggestions
HTV Silicone Rubber Reinforcement
The primary application — SEMISIL R200 is used at 25–45 phr loading in high-consistency rubber (HCR/HTV) silicone compounds to deliver tensile strength >8 MPa, elongation >300%, and tear strength >25 kN/m. The high BET and HMDZ surface chemistry prevent crepe hardening, maintaining compound processability during milling and calendering.
RTV-2 Silicone Systems
Delivers in-situ reinforcement in two-component RTV silicone mold-making compounds and encapsulants. The hydrophobic surface ensures compatibility with both Part A and Part B without premature curing or viscosity drift, and produces optically clear compounds at moderate loadings.
Liquid Silicone Rubber (LSR)
Provides the reinforcing filler backbone for injection-moldable LSR systems requiring high mechanical performance, optical transparency, and biocompatibility. SEMISIL R200's controlled particle size and surface chemistry produce consistent LSR viscosity and curing profiles.
Silicone Foam and Sponge
Reinforces silicone foam and sponge products used in automotive sealing, electrical gaskets, and acoustic insulation. The hydrophobic surface promotes uniform cell structure and prevents foam collapse during vulcanization.
Technical Support & FAQ: SEMISIL R200
+Q1: What are the key features and applications of SEMISIL R200?
SEMISIL R200 is the high-performance HMDZ-treated reinforcing silica for silicone rubber:
- Core Functions: In-situ silicone rubber reinforcement, crepe hardening prevention, LSR transparency
- Key Features: BET 160–220 m²/g post-treatment; carbon 2.5–6.0%; high-strength PDMS compatibility
- Primary Applications: HTV/HCR silicone rubber, RTV-2 mold-making, LSR injection molding, silicone foam
+Q2: How does SEMISIL R200 compare with SEMISIL R272?
| Property | SEMISIL R272 | SEMISIL R200 |
|---|---|---|
| Treatment | DDS | HMDZ |
| BET after treatment (m²/g) | 90–130 | 160–220 |
| Carbon content (Wt%) | 1.5–3.5 | 2.5–6.0 |
| Primary use | Rheology control (sealants, coatings) | Silicone rubber reinforcement |
| Tensile strength contribution | Moderate | High (>8 MPa at 30 phr) |
Equivalent to: AEROSIL® R202 (Evonik), HDK® H30 (Wacker).
+Q3: What factors influence the pricing of SEMISIL R200?
- Production Costs: HMDZ treatment is more costly than DDS; higher reagent consumption for dense surface coverage
- Quality Standards: BET post-treatment tolerance and carbon content range are critical for silicone rubber compound consistency
- Logistics: PE-lined bags essential to prevent moisture ingress; premium packaging cost
+Q4: What are the typical lead times and payment terms?
- Lead Time: Typically 7–14 days (Annual supply volume: 15,000 tons)
- Payment Terms: Flexible options including T/T, L/C at sight, and D/P
- Sample Support: Free samples (200g–1kg) available for silicone compound trials
Packing & Storage Information
Storage Conditions
SEMISIL® R200 must be stored in tightly sealed containers away from moisture and humidity. Ideal storage: dry warehouse, <30°C, relative humidity <60%. Use within 2 years of manufacture date.