Polydimethylsiloxane (PDMS) is a silicone flame retardant. In addition to imparting excellent flame retardant properties to the substrate, it can also improve other properties of the substrate (such as processing performance, mechanical properties, resistance to corrosion, and thermal performance, etc.). In this article, Alfa Chemistry focuses on the research and development progress of various PDMS-based flame retardant composite materials.
Flame Retardant Mechanism of Polydimethylsiloxane
Generally speaking, the flame retardant effect of PDMS is based on the condensed phase flame retardant mechanism, and its flame retardant effect is achieved by generating a cracked carbon layer and improving the oxidation resistance of the carbon layer.
- On the one hand, the silicon-oxygen links can promote the material to form carbon at high temperatures, and the silicon-oxygen links in the carbon layer help to form a continuous, oxidation-resistant silicate protective layer.
- On the other hand, the silicone links contained in the polymer main chain can also improve the material's moisture resistance and chain flexibility, and improve the material's performance.
- In addition, when PDMS polymer is thermally decomposed, it generates CO2, water vapor and SiO2, making it an environmentally friendly flame retardant material.
Polydimethylsiloxane for Polypropylene Flame Retardant
Pin Lv et al. studied the effect and pyrolysis of PDMS in intumescent flame-retardant polypropylene (PP) containing melamine phosphate (MP). The addition of PDMS effectively reduces the LOI value of the composite material. According to UL-94 test results, PP/MP/PDMS composites containing 30% PDMS can achieve V-0 level flame retardancy. [1]
Polydimethylsiloxane Synergistic Flame Retardant Aluminum Diethylphosphinate
PDMS is a flexible, durable, transparent and inexpensive polymer. Hydrophobic surfaces can be easily prepared using PDMS to further enhance the flame retardant properties of aluminum diethylphosphinate (ADP). PDMS-modified ADP was added to polyamide 6 to prepare PA6/PDMS-ADP flame retardant composites. The composite material can pass the UL-94 V-0 flame retardant rating, and the peak heat release is reduced to 192kW/m2, which is 70.4% lower than pure PA6.
PDMS-modified ADP flame retardant. [2]
Polydimethylsiloxane/Silica Aerogel Flame Retardant Material
Thanks to its flexible Si-bonded structure, PDMS can be used to impregnate modified silica aerogels to create flexible thermal insulation composites. To ensure that the silica aerogel maintains its low thermal conductivity and unique porous structure within the PDMS matrix, a pore repair method was employed. The best PDMS composite exhibits superior thermal insulation (0.018 W/m·K) and flame retardancy.
PDMS/silica aerogel flame retardant material. [3]
Polydimethylsiloxane/Multi-Walled Carbon Nanotube Composites
PDMS/multiwall carbon nanotube (MWCNT) nanocomposites have diverse applications such as antifouling coatings, metamaterials, microwave shielding, pressure-resistant films, and wearable pressure sensors. Furthermore, a novel PDMS/CNT nanocomposite film has been designed for flame retardant applications. 2 wt% MWCNT-COOH and liquid surfactant were mixed, followed by three-roller grinding with PDMS, and then spin coating to prepare nanocomposite films. According to the cone calorimetry and LOI test evaluation results, the obtained nanocomposite exhibits excellent flame retardant properties, and its LOI value can be increased to 31.5.
PDMS/ MWCNT nanocomposites. [4]
References
- Lv, Pin, et al. Journal of polymer research, 2009, 16, 81-89.
- Pan, Ying, et al. Journal of Applied Polymer Science, 2020, 137(35), 49027.
- Lee, Hyeseong, et al. Composites Part A: Applied Science and Manufacturing, 2019, 123, 108-113.
- Kabir, Imrana I., et al. Journal of Materials Science, 2021, 56, 2192-2211.
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