About Kaolin Flame Retardant Additive
Kaolin is a naturally occurring mineral that has been widely used in various industries due to its unique properties. One of its remarkable applications is the enhancement of flame retardancy in different materials. Kaolin has emerged as an attractive flame retardant due to its abundant availability, low cost, and inherent thermal stability. The addition of kaolin to various flame retardant systems has been shown to improve their efficiency, making it a valuable and versatile component in fire safety applications.
How Does Kaolin Enhance Flame Retardancy?
- Physical Barrier Mechanism
Kaolin's primary flame retardant mechanism involves the formation of a physical barrier between the flame and the combustible material. Upon exposure to heat, kaolin undergoes a phase transformation leading to the formation of a protective ceramic layer. This layer acts as a heat shield, promoting thermal insulation and reducing the heat transfer to the underlying material. - Smoke Suppression
Apart from its physical barrier properties, kaolin also contributes to smoke suppression. During combustion, kaolin undergoes an endothermic dehydration process, absorbing heat energy from the surrounding environment. This process lowers the temperature of the flame and reduces the flammability of combustible gases, ultimately leading to a reduction in smoke emission.
Synergistic Flame Retardancy of Kaolin
Kaolin exhibits synergistic flame retardant effects with many compounds, such as phosphinates, ammonium polyphosphate, and hydroxyl aluminum oxalate. Here are some examples of kaolin synergistic flame retardant research and application:
- In polyamide 6 (PA6), the interaction between kaolin and phosphinate-based flame retardants can improve the thermal degradation and flammability of PA6. [1]
- Nano-kaolin and nano-HAO (hydroxyl aluminum oxalate) can synergistically improve the flame retardant properties of low-density polyethylene (LDPE)/ethylene propylene diene rubber (EPDM) blends. [2]
- Kaolin can be used as an intumescent flame retardant (IFR) synergist to enhance the thermal stability, mechanical properties and flame retardancy of intumescent flame retardant polyurea (PUA/IFR) composite materials. [3]
Innovative Modification of Kaolin Flame Retardant
- Urea (KU) intercalation modified kaolin
Hongxiang Ou et al. used mechanochemical methods to prepare urea intercalated modified kaolin, and compounded it with intumescent flame retardant (IFR) as a low-density polyethylene (LDPE) flame retardant. The insertion of functional particles can expand the distance between layers and change the environment between layers. [4]
- Glycine (GLY) intercalation modified kaolin
Glycine intercalated kaolin (Kaol-GLY) can be prepared by introducing glycine into the kaolinite layer through intercalation and substitution. The obtained Kaol-GLY is further introduced into intumescent flame retardant (IFR) polypropylene (PP) composite materials through melt blending, which can effectively improve its flame retardancy and thermal stability. [5]
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References
- Batistella, M. A., et al. Applied Clay Science, 2018, 157, 248-256.
- Chang, Zhi-Hong, et al. Polymer degradation and stability, 2007, 92(7), 1204-1212.
- Yaru Sun, et al. Polymer Degradation and Stability, 2022, 197, 109842.
- Ou, Hongxiang, et al. Polymer, 2021, 221, 123586.
- Tang, Wufei, et al. Applied Clay Science, 2022, 217, 106411.
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