Kaolin

Catalog NumberACM1332587-22

CAS Number1332-58-7

CategoryNano Flame Retardant

Description	USP grade, pure natural mineral (anhydrous aluminum silicate) composed of kaolinite with low iron content (synonyms: china clay, nacrite, kaolinite, calcined kaolin, metakaolin). Consists of 44-46% silicon dioxide, 37-40% aluminum oxide, 0.2-0.4% magnesium oxide, 0.03-0.06% calcium oxide, 0.2-0.4% ferric oxide, and 1.5-2.0% titanium dioxide. Average particle size 1.0-1.4 micrometers.
Synonyms	Bolus, Aluminum silicate hydroxide, Hydrated aluminum silicate, Kaolin
Molecular Weight	258.160437
Molecular Formula	~Al2Si2O5(OH)4
Purity	99%, 99.9%, 99.99%, 99.999%
Density	1.8-2.6 g/cm³
Solubility	Water-insoluble
Appearance	Off-white fine powder, odorless
Application	Face powders, face masks, creams and lotions for oily skin, bath powders, foundation cake makeup, dry rouges, deodorants, soaps.
Storage	Store in a closed container at a dry place at room temperature
MDL Number	MFCD00062311
Packaging	1, 2.5 kg in poly bottle 500 g in poly bottle
pH	3.5-5.0 (20% in water)

Download COA Download MSDS

Case Study

Kaolin as a Synergistic Flame Retardant for Polypropylene/Intumescent Flame Retardant Composites

Zhang, Sheng, et al. Polymers for advanced technologies 25.9 (2014): 912-919.

Kaolin acts as an effective synergist in polypropylene (PP)/intumescent flame retardant (IFR) systems, significantly enhancing fire performance by promoting compact char formation and reducing heat release.
Fabrication Process: PP was melt-blended with IFR (ammonium polyphosphate-based) and kaolin at varying ratios. The optimal formulation contained 38 phr IFR and 2 phr kaolin, prepared by melt compounding followed by compression molding.
Performance Evaluation: The PP/IFR/kaolin composite achieved a limiting oxygen index (LOI) of 33.0% (vs. 30.0% for PP/40 phr IFR) and UL-94 V-0 rating without dripping. Cone calorimetry showed peak heat release rate (PHRR) decreased from 318 kW/m² (PP/IFR) to 222 kW/m², and time to PHRR was prolonged from 390 to 655 s. Smoke production rate also decreased. TGA revealed increased char residue (from 12.5% to 14.0% at 2 phr kaolin). SEM and FTIR demonstrated that kaolin formed a compact, defect-free char layer. XPS analysis confirmed the formation of Si-O-P bonds between kaolin and IFR, indicating chemical interaction that strengthens the char structure.
Application Significance: Kaolin enables partial replacement of IFR while improving flame retardancy, offering a cost-effective and efficient synergist for PP composites.

Kaolin as a Synergistic Flame Retardant for Low-Density Polyethylene/Intumescent Flame Retardant Composites

Ou, Hongxiang, et al. Polymer 221 (2021): 123586.

Urea-modified kaolin (KU) acts as an effective synergistic agent for intumescent flame retardant (IFR) in low-density polyethylene (LDPE), enhancing flame retardancy, smoke suppression, and thermal stability while improving mechanical properties.
Fabrication Process: Kaolin was intercalated with urea via mechanochemical ball milling (1:1 mass ratio, 2000 rpm for 30 min, then heated at 100 °C for 48 h) to obtain KU with an intercalation rate of 63%. LDPE was melt-blended with IFR (SiO2@MAPP/DPER, 2:1) and KU at 150 °C. The optimal formulation contained 3 wt% KU.
Performance Evaluation: XRD and FTIR confirmed successful urea intercalation. The LDPE/IFR/3 wt% KU composite achieved a limiting oxygen index (LOI) of 27.2% (vs. 24.1% without KU) and UL-94 V-1 rating. Smoke density test showed luminous flux increased from 31.96% to 56.01%, indicating effective smoke suppression. TGA revealed char residue increased from 7.67 wt% to 15.53 wt%, and Tmax shifted from 477 °C to 486 °C. Raman analysis showed a decrease in R value from 2.23 to 0.96, indicating higher graphitization of char. SEM demonstrated a dense, continuous char layer. Tensile strength increased from 16.1 to 16.6 MPa and elongation at break from 512% to 554%.
Application Significance: Kaolin provides a cost-effective, eco-friendly synergistic route to high-performance flame-retardant LDPE composites.

Kaolinite as a Synergistic Flame Retardant for Intumescent Flame-Retardant Polyurea Composites

Sun, Yaru, et al. Polymer Degradation and Stability 197 (2022): 109842.

Kaolinite (K0) acts as an effective synergist for intumescent flame retardant (IFR) in polyurea (PUA), simultaneously enhancing flame retardancy, thermal stability, and mechanical properties.
Fabrication Process: Kaolinite was incorporated into PUA/IFR system by melt blending. The optimal formulation contained 1.0 wt% kaolinite and 24 wt% IFR (ammonium polyphosphate and char forming agent). Composites were prepared by mechanical mixing followed by compression molding.
Performance Evaluation:The PUA/IFR/1.0 wt% kaolinite composite achieved a limiting oxygen index (LOI) of 36.0% (vs. PUA/IFR without kaolinite). Time to flame out decreased by 32.0%, and total heat release (cone calorimetry) reduced by 16.0%. The linear ablation rate under oxyacetylene flame was significantly lowered, indicating excellent fire protection. Tensile strength increased by 4.8% and elongation at break by 36.9% compared to PUA/IFR. The plate-like kaolinite particles promote char densification and act as a physical barrier, while also reinforcing the polymer matrix through mechanical interlocking.
Application Significance: Kaolinite offers a low-cost, efficient synergist for intumescent flame-retardant polyurea, with promising potential for aerospace insulation coatings.

If the product of interest is not available in our catalog, please contact us to see if there is any relevant stock or other purchase channels.