The Flame Retardant and Synergistic Effects of Antimony Trioxide for Materials

Antimony Trioxide Flame Retardant and Synergist

Antimony trioxide (Sb2O3) has been widely employed as a flame retardant and synergist due to its superior ability to reduce the flammability of various materials and enhance the effectiveness of other flame retardants. Sb2O3 functions through various mechanisms to reduce the flammability of materials. These mechanisms can include the formation of a protective char layer on the material's surface, catalytic action to suppress flame propagation, and interference with the degradation of volatile gases within the combustion processes.

Here, Alfa Chemistry focuses on the application and research progress of Sb2O3 flame retardant systems in various materials, such as polypropylene, epoxy resin, polyvinyl chloride and other polymer composite materials.

Antimony Trioxide Flame Retardant and Synergist

Sb2O3 Synergistic Intumescent Flame Retardant System for Polypropylene

In the polypropylene (PP) resin matrix, ammonium polyphosphate (APP)/pentaerythritol (PER)/Sb2O3 intumescent system is used to improve the flame retardant properties of PP composite materials. In this system, APP serves as the acid source and blowing agent, PER serves as the carbonific agent and Sb2O3 serves as the synergist. When the addition amount of Sb2O3 is 2wt %, the limiting oxygen index (LOI) of the PP composite increases from 27.8% to 36.6%, meeting the UL-94 V-0 standard.

Schematic of the reaction between APP and Sb2O3.Schematic of the reaction between APP and Sb2O3. [1]

Epoxy/Sb2O3 Nanocomposites

Sb2O3 nano-powder with a particle size of 20-30 nm was added to the epoxy resin at (0, 2, 4, 6, 8, 10) wt%. The effectiveness of Sb2O3 in improving the flammability of epoxy resin was evaluated through LOI, burning rate (R.B) and maximum flame height (H) tests. The results show that 10wt% Sb2O3 has good effect as a flame retardant for epoxy resin, and has the activity of inhibiting combustion and reducing flammability. [2]

Nano-Sb2O3 Used for Flame Retardant of Polyvinyl Chloride

Due to the good synergistic flame retardant effect of nano-Sb2O3 and halogen flame retardants, it is reasonable to use it as a flame retardant additive for chlorine-containing polyvinyl chloride (PVC). In order to improve the good interfacial compatibility and dispersion of Sb2O3 nanoparticles in PVC, surface modification with dioctyl phthalate (DOP) is one of the effective ways. DOP-modified Sb2O3 nanoparticles can effectively improve the flame retardancy and tensile strength of PVC-based composite materials.

The modification of nano-Sb2O3 particles.The modification of nano-Sb2O3 particles. [3]

Sb2O3 Used in ABS Composite Materials

In an acrylonitrile-butadiene-styrene (ABS) matrix, the combination of Sb2O3/huntite/hydromagnesite can improve the thermal stability and char-forming ability of the composite through synergistic effects. The flame-retardant nanocomposite material composed of Sb2O3/huntite/hydromagnesite can effectively reduce the flammability of ABS composite materials and reach the UL94/V-0 level. [4]

Alternatives and Innovations

As concerns grow about the environmental and health impacts of Sb2O3 flame retardants, there is significant interest in developing alternative solutions. Research is currently underway to find effective and safer flame retardants, such as phosphorus-based compounds or nanomaterials. Ye-Tang Pan et al. developed a nanoscale zinc carbonate (nano- ZnCO3) through a one-step hydrothermal synthesis reaction of zinc nitrite and urea. Replacing 75% Sb2O3 with nano-ZnCO3 in flexible polyvinyl chloride (PVC) significantly improved the dripping behavior in the UL-94 test, increased the LOI value, and greatly reduced the peak heat release rate and total heat release. [5]

Alternatives and Innovations

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  1. Li N, et al. Polymer Degradation and Stability, 2012, 97(9), 1737-1744.
  2. Dheyaa B M, et al. Journal of Physics: Conference Series, 2018, 1003(1), 012078.
  3. Xu J, et al. Materials Research, 2021, 23(6).
  4. Yurddaskal M, et al. Journal of Materials Science: Materials in Electronics, 2018, 29, 4557-4563.
  5. Pan Y T, et al. Rsc Advances, 2015, 5(35): 27837-27843.
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