Red phosphorus (RP) particles are commercially available as a flame-retardant additive for polymers. Conventionally, RP is encapsulated with a protective organic coating. In the present work, we propose an alternative approach for the encapsulation of RP with an inorganic SiO2 shell (SiO2@RP), to be employed in textiles. The silica shell was obtained by two steps sol-gel of tetraethyl orthosilicate (TEOS) precursor in RP aqueous dispersion. A homogenous silica shell was consistently achieved. The chemical structure and morphology of the as-obtained powder were characterized by Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effect of the silica coating on the thermal stability of RP was investigated through thermogravimetric coupled-differential thermal analysis (DT-TGA) that revealed improved thermo-oxidative stability. The application of the prepared coated and uncoated RP as flame retardant additives for fabric back-coating is then investigated. Only the fabrics treated with SiO2@RP successfully self-extinguished the flame during flammability test, based on BS-5852 normative, achieving the no-ignition classification required for a practical application. The proposed fully inorganic encapsulation strategy opens up to new and efficient flame retardant solutions based on RP that can potentially be exploited in several application fields.

Silica-encapsulated red phosphorus for flame retardant treatment on textile

Gibertini E.;Aykanat K.;Accogli A.;Panzeri G.;Magagnin L.
2021-01-01

Abstract

Red phosphorus (RP) particles are commercially available as a flame-retardant additive for polymers. Conventionally, RP is encapsulated with a protective organic coating. In the present work, we propose an alternative approach for the encapsulation of RP with an inorganic SiO2 shell (SiO2@RP), to be employed in textiles. The silica shell was obtained by two steps sol-gel of tetraethyl orthosilicate (TEOS) precursor in RP aqueous dispersion. A homogenous silica shell was consistently achieved. The chemical structure and morphology of the as-obtained powder were characterized by Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effect of the silica coating on the thermal stability of RP was investigated through thermogravimetric coupled-differential thermal analysis (DT-TGA) that revealed improved thermo-oxidative stability. The application of the prepared coated and uncoated RP as flame retardant additives for fabric back-coating is then investigated. Only the fabrics treated with SiO2@RP successfully self-extinguished the flame during flammability test, based on BS-5852 normative, achieving the no-ignition classification required for a practical application. The proposed fully inorganic encapsulation strategy opens up to new and efficient flame retardant solutions based on RP that can potentially be exploited in several application fields.
2021
Anti-flame
Coating
Fabrics
Red phosphorus
SiO2
Sol-gel
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/1203176
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