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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.

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FTIR spectra of the residual char of IFRPP composites. The curves of samples 4, 5, and 7 are offset vertically by 0.45, 0.2, and 0%, respectively.
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Figure 11: FTIR spectra of the residual char of IFRPP composites. The curves of samples 4, 5, and 7 are offset vertically by 0.45, 0.2, and 0%, respectively.

Mentions: To clarify the cross-linked network char residue formation mechanism at the intumescent outer surface, FTIR (figure 11) and Raman (figure 12) spectroscopies were employed to characterize the residue char for samples 4, 5 and 7. As shown in FTIR results, there is no clear distinction among the samples with and without GO. The peaks around 1630 cm−1 correspond to the stretching vibration of phenyl, indicating the formation of polyaromatic species or graphitic structures during combustion [25]. The absorption bond at 1149 cm−1 is attributed to P–C–O structure in P–C complex, and the peak around 1000 cm−1 is for the symmetric vibration of P–O bond in P–O–C group [51]. Based on FTIR analysis of residue chars, the chemical structures of all samples are basically similar.


Novel PEPA-functionalized graphene oxide for fire safety enhancement of polypropylene
FTIR spectra of the residual char of IFRPP composites. The curves of samples 4, 5, and 7 are offset vertically by 0.45, 0.2, and 0%, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 11: FTIR spectra of the residual char of IFRPP composites. The curves of samples 4, 5, and 7 are offset vertically by 0.45, 0.2, and 0%, respectively.
Mentions: To clarify the cross-linked network char residue formation mechanism at the intumescent outer surface, FTIR (figure 11) and Raman (figure 12) spectroscopies were employed to characterize the residue char for samples 4, 5 and 7. As shown in FTIR results, there is no clear distinction among the samples with and without GO. The peaks around 1630 cm−1 correspond to the stretching vibration of phenyl, indicating the formation of polyaromatic species or graphitic structures during combustion [25]. The absorption bond at 1149 cm−1 is attributed to P–C–O structure in P–C complex, and the peak around 1000 cm−1 is for the symmetric vibration of P–O bond in P–O–C group [51]. Based on FTIR analysis of residue chars, the chemical structures of all samples are basically similar.

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.


Related in: MedlinePlus