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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.


TEM image of 7 wt% PGO loaded in IFRPP composite (a), enlarged TEM image of (b).
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Figure 7: TEM image of 7 wt% PGO loaded in IFRPP composite (a), enlarged TEM image of (b).

Mentions: As a polymer additive, PGO is supposed to act as a char-forming agent as well as barrier preventing the transfer of combustion gases to the flame zone and energy feedback, thus the evenly distributed of the fillers in matrix is necessary. TEM images shown in figure 7 are IFRPP composite containing 7 wt% PGO powder, which characterize the distribution of the PGO in PP matrix. It is found that the layered graphene sheets with a high aspect ratio showing the same orientation arrangement and no large aggregation, which demonstrates the good dispersion of PGO in IFRPP composite. It could be attributed to the elimination of polar functional groups, which enhances the interfacial interactions among graphene and PP. And the layered graphene material, shown in figure 7, could act as a physical barrier which slows down the diffusion of gases and degradation products.


Novel PEPA-functionalized graphene oxide for fire safety enhancement of polypropylene
TEM image of 7 wt% PGO loaded in IFRPP composite (a), enlarged TEM image of (b).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 7: TEM image of 7 wt% PGO loaded in IFRPP composite (a), enlarged TEM image of (b).
Mentions: As a polymer additive, PGO is supposed to act as a char-forming agent as well as barrier preventing the transfer of combustion gases to the flame zone and energy feedback, thus the evenly distributed of the fillers in matrix is necessary. TEM images shown in figure 7 are IFRPP composite containing 7 wt% PGO powder, which characterize the distribution of the PGO in PP matrix. It is found that the layered graphene sheets with a high aspect ratio showing the same orientation arrangement and no large aggregation, which demonstrates the good dispersion of PGO in IFRPP composite. It could be attributed to the elimination of polar functional groups, which enhances the interfacial interactions among graphene and PP. And the layered graphene material, shown in figure 7, could act as a physical barrier which slows down the diffusion of gases and degradation products.

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.