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Novel PEPA-functionalized graphene oxide for fire safety enhancement of polypropylene

View Article: PubMed Central - PubMed

ABSTRACT

Polypropylene (PP) is a general-purpose plastic, but some applications are constrained by its high flammability. Thus, flame retardant PP is urgently demanded. In this article, intumescent flame retardant PP (IFRPP) composites with enhanced fire safety were prepared using 1-oxo-4-hydroxymethyl-2,6,7-trioxa-1-phosphabicyclo [2.2.2] octane (PEPA) functionalized graphene oxide (PGO) as synergist. The PGO was prepared through a mild chemical reaction by the covalent attachment of a caged-structure organic compound, PEPA, onto GO nanosheets using toluene diisocynate (TDI) as the intermediary agent. The novel PEPA-functionalized graphene oxide not only improves the heat resistance of GO but also converts GO and PEPA from hydrophobic to hydrophilic materials, which leads to even distribution in PP. In our case, 7 wt% addition of PGO as one of the fillers for IFRPP composites significantly reduces its inflammability and fire hazards when compared with PEPA, by the improvement of first release rate peak (PHRR), total heat release, first smoke release rate peak (PSRR) and total smoke release, suggesting its great potential as the IFR synergist in industry. The reason is mainly attributed to the barrier effect of the unburned graphene sheets, which protects by the decomposition products of PEPA and TDI, promotes the formation of graphitized carbon and inhibits the heat and gas release.

No MeSH data available.


TGA (a) and DTG (b) patterns of GO and PGO in air and nitrogen atmosphere.
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Figure 6: TGA (a) and DTG (b) patterns of GO and PGO in air and nitrogen atmosphere.

Mentions: The functionalization and reduction of GO improved the thermal stability of GO [39–41]. Figure 6 shows TGA and DTG patterns of GO and PGO in nitrogen and air atmosphere, respectively. As figure 6 shows GO is thermally unstable with the first peak from 50 to 100 °C due to the removal of water, and its main mass loss of 65% at around 225 °C, which belongs to the decomposition of the functional groups (–OH and –COOH) and the graphene structure. The PGO has the first peak as well as GO from 50 to 100 °C in nitrogen atmosphere, but the peak intensity is much lower than that of GO, it demonstrates that the functionalization process reduces the hydroscopicity of GO, which is consistent with the results of the solubility studies mentioned above. In contrast, the thermal decomposition of PGO is divided into two steps (320 and 390 °C) in figure 6, which are much higher than that of GO, and exhibit much less mass losses than that of GO. The TGA results of GO and PGO in nitrogen or air atmosphere are consistent, except for behavior above 500 °C, which might be the oxidation of carbon materials. The significant enhancement of the thermal stability of GO is due to the decoration of PEPA and TDI on the surface of GO, they decompose first around 320 °C, and the cross-linked residual carbon of the decomposition covers on the surface of GO sheets could protect it from decomposing at this temperature. The improvement of the thermal stability of PGO is beneficial for its application as a flame retardant nano-filler.


Novel PEPA-functionalized graphene oxide for fire safety enhancement of polypropylene
TGA (a) and DTG (b) patterns of GO and PGO in air and nitrogen atmosphere.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5036477&req=5

Figure 6: TGA (a) and DTG (b) patterns of GO and PGO in air and nitrogen atmosphere.
Mentions: The functionalization and reduction of GO improved the thermal stability of GO [39–41]. Figure 6 shows TGA and DTG patterns of GO and PGO in nitrogen and air atmosphere, respectively. As figure 6 shows GO is thermally unstable with the first peak from 50 to 100 °C due to the removal of water, and its main mass loss of 65% at around 225 °C, which belongs to the decomposition of the functional groups (–OH and –COOH) and the graphene structure. The PGO has the first peak as well as GO from 50 to 100 °C in nitrogen atmosphere, but the peak intensity is much lower than that of GO, it demonstrates that the functionalization process reduces the hydroscopicity of GO, which is consistent with the results of the solubility studies mentioned above. In contrast, the thermal decomposition of PGO is divided into two steps (320 and 390 °C) in figure 6, which are much higher than that of GO, and exhibit much less mass losses than that of GO. The TGA results of GO and PGO in nitrogen or air atmosphere are consistent, except for behavior above 500 °C, which might be the oxidation of carbon materials. The significant enhancement of the thermal stability of GO is due to the decoration of PEPA and TDI on the surface of GO, they decompose first around 320 °C, and the cross-linked residual carbon of the decomposition covers on the surface of GO sheets could protect it from decomposing at this temperature. The improvement of the thermal stability of PGO is beneficial for its application as a flame retardant nano-filler.

View Article: PubMed Central - PubMed

ABSTRACT

Polypropylene (PP) is a general-purpose plastic, but some applications are constrained by its high flammability. Thus, flame retardant PP is urgently demanded. In this article, intumescent flame retardant PP (IFRPP) composites with enhanced fire safety were prepared using 1-oxo-4-hydroxymethyl-2,6,7-trioxa-1-phosphabicyclo [2.2.2] octane (PEPA) functionalized graphene oxide (PGO) as synergist. The PGO was prepared through a mild chemical reaction by the covalent attachment of a caged-structure organic compound, PEPA, onto GO nanosheets using toluene diisocynate (TDI) as the intermediary agent. The novel PEPA-functionalized graphene oxide not only improves the heat resistance of GO but also converts GO and PEPA from hydrophobic to hydrophilic materials, which leads to even distribution in PP. In our case, 7 wt% addition of PGO as one of the fillers for IFRPP composites significantly reduces its inflammability and fire hazards when compared with PEPA, by the improvement of first release rate peak (PHRR), total heat release, first smoke release rate peak (PSRR) and total smoke release, suggesting its great potential as the IFR synergist in industry. The reason is mainly attributed to the barrier effect of the unburned graphene sheets, which protects by the decomposition products of PEPA and TDI, promotes the formation of graphitized carbon and inhibits the heat and gas release.

No MeSH data available.