Complete technical data sheets for every SEMISIL fumed silica grade — BET, particle size, pH, and application parameters in one library.
SEMISIL hydrophilic fumed silica grades span BET surface areas from 150 m²/g (SEMISIL 150) to 380 m²/g (SEMISIL 380), all with silanol-rich surfaces (≥2 OH/nm²) that drive hydrogen bonding in polar systems. Higher BET grades deliver stronger thixotropy at lower loading — SEMISIL 380 achieves target viscosity at roughly 40% less addition than SEMISIL 150 in epoxy formulations. Each TDS includes loss on ignition (
SEMISIL hydrophobic grades are surface-treated with DDS, HMDS, or PDMS to cap surface silanols, reducing moisture pickup and enabling compatibility with non-polar resins. SEMISIL R272 (DDS-treated, BET 100 m²/g) targets RTV silicone sealants and printing inks; SEMISIL R620 (HMDS-treated, BET 200 m²/g) suits high-demand LSR/HTV silicone rubber; SEMISIL R202 (PDMS-treated, BET 100 m²/g) prevents structuring in rubber and viscosity aging in polar resins. TDS documents specify carbon content, methanol wettability, and storage stability data that hydrophilic datasheets do not cover.
SEMISIL H100 is a surface-treated fumed silica matting grade (BET 230–270 m²/g) engineered specifically for matting in UV and solvent-borne coatings — a direct alternative to Evonik ACEMATT TS 100. Its high oil absorption (300–380 g/100 g) and controlled particle size (d50 8.0–11.0 µm) create consistent micro-roughness for efficient gloss reduction at low loadings. The TDS includes particle size distribution curves, gloss reduction charts at varying loadings, and compatibility data for UV-acrylate and alkyd systems.
Each SEMISIL technical data sheet follows a standardized format: physical form, BET surface area (ISO 9277), primary particle size (TEM), tamped density (ISO 787-11), pH in suspension, loss on ignition, and SiO₂ content. For hydrophobic grades, carbon content and methanol wettability are added. BET surface area is the single most important parameter — it directly determines thixotropic efficiency. A 200 m²/g grade in an epoxy at 2% loading will roughly match the viscosity build of a 380 m²/g grade at 1.2% loading, but the higher-BET grade may reduce optical clarity.
The table below summarizes key specifications across all eight SEMISIL grades. Use BET surface area as the primary selection criterion: higher BET means stronger thixotropy per unit loading but potentially higher dispersion energy required.
| Grade | Surface | BET (m²/g) | Primary Particle (nm) | pH (4% susp.) | Key Application |
|---|---|---|---|---|---|
| SEMISIL 150 | Hydrophilic | 150±25 | ~15 | 3.6–4.5 | General thickening |
| SEMISIL 200 | Hydrophilic | 200±25 | ~12 | 3.6–4.5 | Adhesives, sealants |
| SEMISIL 300 | Hydrophilic | 300±30 | ~9 | 3.6–4.5 | Reinforcement |
| SEMISIL 380 | Hydrophilic | 380±30 | ~7 | 3.6–4.5 | Max thixotropy |
| SEMISIL R272 | Hydrophobic (DDS) | 100±20 | ~16 | 4.0–7.0 | Silicone sealants, inks |
| SEMISIL R620 | Hydrophobic (HMDS) | 200±20 | ~12 | 5.5–8.0 | LSR/HTV silicone rubber |
| SEMISIL R202 | Hydrophobic (PDMS) | 100±20 | ~16 | 4.0–7.0 | Rubber, polar resins |
| SEMISIL H100 | Matting (treated) | 230–270 | d50 8–11 µm | 6.0–9.0 | Matting agent |
Request the SEMISIL TDS for your target grade to confirm BET surface area, dispersion parameters, and surface chemistry match your formulation requirements — specification alignment at the datasheet level prevents costly trial-and-error in production.
Each SEMISIL TDS lists BET surface area, primary particle size, SiO₂ purity (≥99.8%), pH in 4% suspension, loss on ignition, and tamped density. Hydrophobic grades add carbon content and methanol wettability values. All measurements follow ISO test methods referenced on the sheet.
SEMISIL 200 is the standard recommendation for epoxy adhesives at 1.5–3% loading. It delivers consistent anti-sag behavior without excessive viscosity increase. For higher-gap-fill applications, SEMISIL 300 provides stronger thixotropy at lower loading but requires higher shear during dispersion.
Hydrophilic grades have silanol-rich surfaces that bond via hydrogen bonding in polar systems like epoxies and waterborne coatings. Hydrophobic grades are surface-treated with HMDS or DDS to replace silanols with methyl groups, making them compatible with non-polar resins and moisture-sensitive formulations.
Higher BET surface area means more silanol groups per gram, creating stronger inter-particle hydrogen-bond networks. A 380 m²/g grade achieves target viscosity at roughly 40% lower loading than a 150 m²/g grade. However, higher BET also demands more dispersion energy and may reduce optical clarity.
SEMISIL H100 is optimized for matting with a controlled particle size (d50 8.0–11.0 µm) that creates surface micro-roughness. It provides some rheological effect but at lower efficiency than SEMISIL R620 for thixotropy. For dual function, consider combining H100 for matting with a small addition of SEMISIL 200 for anti-settling.
High-shear dispersers (tip speed ≥15 m/s) or three-roll mills deliver consistent deagglomeration. Planetary mixers work for high-viscosity systems above 50 Pa·s. The TDS for each grade specifies minimum dispersion energy — under-dispersion leaves agglomerates that cause grittiness and inconsistent rheology.
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