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AEROSIL® 200

AEROSIL® 200 is a hydrophilic fumed silica with a specific surface area of 200 m²/g.

Brand: AEROSIL (33 products)

INCI Name: Silica

Chemical Name: Pyrogenic Silica, Silica gel, pptd., cryst.-free

Functions: Anti-Settling Agent, Rheology Modifier, Thickener, Viscosity Modifier

CAS Number: 112926-00-8

Chemical Family: Silica

Enhanced TDS

Enhanced TDS

Knowde-enriched technical product data sheet

Identification & Functionality

Features & Benefits

Benefit Claims
Labeling Claims
Agrochemicals Features
CASE Ingredients Features
Fluids & Lubricants Features
Materials Features
Product Features
  • Optimum adjustment of rheology during processing
  • Reinforcement of silicone elastomers
  • Thickening of non-polar liquids
  • Free-flow of industrial powders
  • High chemical purity
  • Excellent insulation properties, even at high and low temperatures

Applications & Uses

Markets
Applications
Application Format
Compatible Polymers & Resins
Fluids & Lubricants Type
AP/Deo Applications
Fluids & Lubricants End Use
Oral Care Applications
Plastics & Elastomers End Uses
Plastics & Elastomers Processing Methods
Cable Gel Applications

Use of AEROSIL® fumed silica for cable gels gives excellent performance when it comes to shear-thinning, providing quick recovery and the gel does not require heat to be applied. AEROSIL® fumed silica improves properties of oil-based filling compounds for wire and cables to protect fibers (e. g. optical fibers) as it:

  • Supports to isolate sensitive optical fi bers from external forces
  • Protects the fi bers from moisture
  • Provides thickening to help the gel to stay where it is placed
  • Helps to form a seal to keep out contaminants like dust, dirt and water
  • Is non-conductive / does not negatively infl uence di-electrical properties
Lubricating Grease Applications

The use of AEROSIL® fumed silica is recommended for lubricating greases used in industrial applications, automotive, electrical as well as food grade.

Electrical

  • High thixotropic effect
  • High temperature stability
  • Dielectric properties

Industrial

  • High thixotropic effect
  • High temperature stability
  • Wear resistance
  • Extreme pressure resistance

Automotive

  • High thixotropic effect
  • High temperature stability
  • Wear resistance
  • Reduced friction

Food - Hydrophilic AEROSIL® are generally recognized as safe (GRAS; direct food contact)

  • High thixotropic effect
  • High temperature stability
  • Wear resistance

AEROSIL® Fumed Silica in Lubricating Greases

AEROSIL® fumed silica helps to build a stable matrix to increase viscosity and suppress oil separation in lubricating greases. It can be used in the following systems:

  • In non-soap greases, used in high-temperature applications up to 230° C as well as for extreme-pressure and multipurpose greases.
  • In soap greases, thickened by fatty acid soaps of lithium, calcium, sodium or aluminum, AEROSIL® fumed silica can be used to further improve the performance of the lubricating grease.
  • Hydrophilic fumed silica provides optimized thickening effects in non-polar oils.
  • Hydrophobic fumed silica provides viscosity control and increased water repellency in semi-polar to polar oils.
  • The surface area of the silica and the volume fraction of the silica in the fi nal mass play a role in the long term storage and heat stability.

Properties

Physical Form
Appearance
Fluffy white powder
Physico-Chemical Properties
ValueUnitsTest Method / Conditions
Unit Weight (Netto)10kg-
Sieve Residue⁶ (45 μm)max. 0.05wt %By Mocker
HCI Content⁸,¹¹max. 0.025wt %-
TiO₂ Content⁸max. 0.030wt %-
Fe₂O₃ Content⁸max. 0.003wt %-
Al₂O₃ Content⁸max. 0.050wt %-
Loss on Ignition⁴,⁷ (2h at 1000°C)max. 1.0wt %-
Densified Material (Suffix „V“, „VV“)120¹²g/l-
Behavior Towards WaterHydrophilic--
Tamped Density*approx. 50g/l-
Specific Surface Area (BET)175 - 225m²/g-
SiO₂ Content (based on ignited material)min. 99.8%-
pH Value (in 4% dispersion)3.7 - 4.5--
Loss on Drying* (at 105 °C, 2 hours)max. 1.5%-
Note

1 - According to DIN 9277
² - According to DIN EN ISO 787/11, JIS K 5101/20 (not sieved)
3 - According to DIN EN ISO 787/2, ASTM D 280, JIS K 5101/23
4 - According to DIN EN ISO 3262-20, ASTM D 1208, JIS K 5101/24
5 - According to DIN EN ISO 787/9, ASTM D 1208, JIS K 5101/26
6 - According to DIN EN ISO 787/18, JIS K 5101/22
7 - Based on dried substance (2 hours at 105 °C)
8 - Based on ignited substance (2 hours at 1000 °C)
9 - Special moisture-protective packaging
10 - in water: methanol = 1:1
11 - HCI-content is a part of ignition loss
12 - Packaging of densed material: 20 kg

Regulatory & Compliance

Technical Details & Test Data

AEROSIL® Fumed Silica
  • AEROSIL® fumed silica is a highly dispersed, amorphous, very pure silica manufactured by high-temperature hydrolysis of silicon tetrachloride in an oxyhydrogen gas flame. The primary particles formed in the AEROSIL® process are virtually spherical and free of pores.
  • During the formation of the primary particles, aggregates are formed which further accumulate into agglomerates. Under shear, these agglomerates can be returned back into smaller aggregates.
  • Figure shows a transmission electron micrograph (TEM) of AEROSIL® 200, in which the primary particles, aggregates and agglomerates can be clearly seen. Depending on the AEROSIL® grade, the specific surface areas range between 50 and 380 m²/g.

AEROSIL® 200 - Aerosil® Fumed Silica

Transmissions electron micrograph (TEM) of AEROSIL® 200

Test Methods

Four different types of oils used in cable gels were selected for the tests:

  • Mineral oil Drakeol® 35 (Penreco, USA)
  • Polybutene Napvis® DE 10 (H&R, UK)
  • Silicone oil Baysilon® M 1000 (Bayer, Germany)
  • Polypropylene glycol (molar mass ~700 g/mol), (Aldrich, USA)

Using a laboratory disperser (Cowles disk, d = 5 cm), the silicas were first thoroughly wetted into the various oils at 6% and 12% at 1000 rpm and then dispersed for 5 minutes at 3000 rpm. The air bubbles introduced into the system by the dispersion process were removed by vacuum.

Rheological measurements

  • The Haake RV 20 tester using the CV 20 N measuring system was utilized for the rheological measurements. Rotational measurements were obtained using PK 20.4° and PK 30.4° cones and oscillation measurements were obtained using the Q 30 plate (clearance 1 mm) with a deformation of 5 % at a constant temperature of 25°C. The following ramp function in the rotational measurements was determined after initial shearing (18 sec. at 1 s-1 and 18 sec. at rest).
  • In the first test, the shear rate was increased linearly within 2 minutes from approx. 0.3 s-1 to 10 s-1, held constant for 1 minute at 10 s-1, and decreased linearly within 2 minutes from 10 s-1 to approx. 0.3 s-1.
  • The flow curve (down) was used to calculate each yield point in accordance with the Casson regression model; the viscosi- ties were also calculated at 2.5 s-1 using the flow curve down).
  • In a second test sequence (to determine the recovery of viscosity) the substances were first subjected to shearing at 1 s-1 for 0.5 min., then at 100 s-1 for 0.5 min. and again at 1 s-1 for 0.5 min. The oscillation measurements were carried out as a function of frequency. To do this, the frequency was increased from 0.1 Hz to 9.8 Hz at a constant deformation of 5%. These measurements were used to calculate the loss and storage module.

Rotational and oscillatory measurements

  • The measured yield points and viscosities of the various samples are shown in Tables below.
  • The hydrophilic type AEROSIL® 200 exhibits the highest yield points and viscosities in the nonpolar mineral, silicone and polybutene oils as compared with the hydrophobic AEROSIL® grades.
  • In the case of AEROSIL® 200, despite a 12% concentration, hardly any thickening and thixotropic effect was noticeable in the polar polypropylene glycol.

Table 1 - Yield points and viscosities of Drakeol 35 (mineral oil) and Baysilon M 1000 (silicone oil), thickened with 6 % and 12 % different AEROSIL® grades.

Mineral oil Silicone oil
Silica grade and
concentration
Yield point
in Pa
Viscosity at
2.5 s-1 in Pas
Silica grade and
concentration
Yield point
in Pa
Viscosity at
2.5 s-1 in Pas
6 % AEROSIL® 200 198 116 6 % AEROSIL® 200 461 218
Mineral oil 0.0 0.135 Silicone oil 0.0 0.960

Table 2 - Yield points and viscosities of Napvis DE 10 (polybutene) and polypropylene glycol, thickened with 6 % and 12 % different AEROSIL® grades

Polybutene oil

Polypropylene glycol

Silica grade and
concentration
Yield point
in Pa
Viscosity at
2.5 s-1 in Pas
Silica grade and
concentration
Yield point
in Pa
Viscosity at
2.5 s-1 in Pas
6 % AEROSIL® 200 670 560 12 % AEROSIL® 200 0.3 0.9
Polybutene oil 0 25 Polypropylenglycol 0 0.11

The flow curves in Figures below graphically illustrate this fact once more. All samples show pseudoplastic flow behavior. The samples thickened with 6% AEROSIL 200 (mineral oil) and 6% AEROSIL® R 202 (polypropylene glycol) also exhibit distinctive thixotropy.

AEROSIL® 200 - Test Methods

Flow curves of mineral oils thickened with different AEROSIL® grades.

AEROSIL® 200 - Test Methods - 1

  • The following paragraphs explain the thickening effect of AEROSIL®, which depends on the polarity of the oil, as well as the mechanisms of thickening and thixotropy of the different silicas in liquids. The specific test results are also diskussed.
  • The thickening and thixotropic effect result from the forma- tion of a threedimensional network of AEROSIL® particles in the system. With the addition of shearing forces (shak- ing or stirring), the network is broken down, depending on the intensity and duration of the stress, and the viscosity is reduced accordingly. At rest, the network reforms and the system recovers to its original viscosity.
  • The interactions between the silanol groups of different AEROSIL® particles are responsible for the formation and stability of the network. The hydrogen bonds between the AEROSIL® particles have their full effect in nonpolar liquids such as hydrocarbons or polydimethyl siloxanes. As soon as the liquid molecules exhibit a greater or lesser affinity to the silanol groups as determined by their structure, solvation of the AEROSIL® particles occurs and with it destabilization of the spatial network. For this reason the thickening of polar liquids such as ethanol or water, or in this case polypropyl- ene glycol, is only possible with relatively large quantities of hydrophilic AEROSIL® grades.
  • If we now compare the thickening effect of the hydrophobic AEROSIL® grades in the three non-polar oils, the highest yield points and viscosities are achieved in all three oils (mineral, silicone and polybutene oil) when AEROSIL® R 805 is used, while AEROSIL® R 972 exhibits only a minimal thickening effect.
  • It is only with a concentration of 12% that AEROSIL® R 972 comes close to a yield point of 93 Pa in mineral oil, which is comparable to the yield point of 92 Pa at a 6% concentra- tion of AEROSIL® R 805. In comparison to AEROSIL® R 972, AEROSIL® R 974 is more effective in terms of thickening in all three non-polar oils. This is due to its greater surface area of 170 m²/g as compared to 110 m2/g for AEROSIL® R 972 with the same functional surface groups. The physical mixing of AEROSIL® 200 and AEROSIL® R 202 in a ratio of 1:1 also pro- duces very high yield points and viscosities in mineral, silicone and polybutene oils.
  • This model explains the superior thickening effect of AEROSIL® R 202 and AEROSIL® R 805 as compared with AEROSIL® 200, AEROSIL® R 972 and AEROSIL® R 974 in the polar polypropylene glycol and other polar systems such as epoxy resins and vinyl ester resins (3, 4).
  • Table below shows the measured loss and storage modulus for the mineral and silicone oil and the loss factor tan d calculated at an angle velocity of 10 s-1. Loss modulus G" is a measure of the viscous component, whereas storage modulus G' is a measure of the elastic component in the system. For the sake of clarity, the two moduli have been calculated at a constant angle velocity of 10 s-1 and not shown as a function of the angle velocity. Loss factor tan d is the ratio G" / G'; if it is greater than 1, the viscous components in the system are greater, and if it is smaller than 1, the elastic components are greater.
  • The test results in Table show, that when the AEROSIL® grades are used, different viscoelastic properties can be obtained in the thickened oils. Figure shows that there is a good correlation between the elastic properties and the yield points of the thickened min- eral and silicone oils. In these oils, as the storage modulus G' increases, so does the yield point.

AEROSIL® 200 - Test Methods - 2

Correlation of elastic modulus and yield point of oils thickened with various AEROSIL® grades.

  • Beyond that, the loss factors tan d are less than 1 for all sam- ples with high yield points and greater than 1 for all samples with low yield points. Based on these measurements the following additional mechanism is being suggested for rheological effect. When the thickened oil is suddenly subjected to shearing forces, the three-dimensional network of silica particles reacts because of its elastic properties and absorbs the deforming energy.
  • Initially, there is resistance against being deformed; the system indicates solid-like behavior. For elastic like behav- iour to occur, we must assume that the hydrophilic AEROSIL® particles exhibit hydrogen bonding while the hydrophobic AEROSIL® particles react due to Van-der-Waals attractions. Furthermore, we must consider also steric circumstances.

Table - Elastic modulus G', loss modulus G" and tan d of Drakeol 35 (mineral oil) and Baysilon M 1000 (silicone oil) at 10 s-1, thickened with 6% and 12% different AEROSIL® grades.

Mineral oil Silicone oil
Silica grade and
concentration
Elastic modulus
G' in Pa loss
Modulus
G'' in Pa
tan δ
(calculated)
Silica grade and
concentration
Elastic modulus
G' in Pa loss
Modulus
G'' in Pa
tan δ
(calculated)
6 % AEROSIL® 200 3150 810 0.26 6 % AEROSIL® 200 4300 1050 0 0.24

At rates of deformation higher than the yield point, the silica particles move in the shear field and disarrange each other, assuming a configuration that is adverse to a normal thermo- dynamic conformation. Under these higher shear rates, the thixotropic oil indicates predominantly viscous behavior and begins to flow. After removing the shearing deformation, the elastic properties of the visco-elastic system dominate. The energy, which is absorbed by the elastic deformation, is released and the three-dimensional network of silica particles forms again. The yield point recovers almost to its original value.

Electrical measurements

The methods used to measure the dielectric properties are described in (8). The dielectric constant, as measured at 1 MHz and 25°C, was 2.17 for mineral oil, 2.19 for polybutene oil and 2.67 for silicone oil. When the AEROSIL® grades tested here are used in these oils the dielectric constant remains practically unchanged. The dielectric loss factor tan d was less than 0.001 in all the samples. Good dielectric properties are particularly important for filler compounds used in copper cable (8).

Packaging & Availability

Country Availability
Packaging Type
Regional Availability
  • North America
Packaging Information

AEROSIL 200 is supplied in multiple layer 10 kg bags.

Storage & Handling

Shelf Life
2 years
Storage Conditions

Recommend to store the product in closed containers under dry conditions and to protect the material from volatile substances. AEROSIL® 200 should be used within 2 years after production.