Synthesis of a Phosphorus/Nitrogen/Sulphur Containing Phosphazene Micro-Nanotube and Its Flame Retardancy on Epoxy Nanocomposite†

doi:10.7503/cjcu20170227

Abstract

Abstract:

A highly cross-linked poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol)(PZS) nanotubes were synthesized via an in situ template method using cyclotriphosphazene(HCCP) and 4,4'-sulfonyldiphenol(BPS) as raw materials. PZS micro-nanotubes were applied on epoxy resin(EP) and the flame retarded mechanism was studied. The PZS micro-nanotubes were characterized by SEM, TEM, EDS and element Mapping. The thermalstability of PZS/EP nanocomposites were explored through TG, as compared to that of EP, and the flammability was investigated by microscale combustion calorimeter(MCC) and limit oxygen index(LOI) tests. The TGA results showed that a decreased initial degradation temperature, the residue chars were greatly improved. The flame retardancy was significantly enhanced by the addition of PZS micro-nanotubes. The residue char was improved 46% and the heat release rate was reduced 40% under addition of PZS micro-nanotubes(5%). The LOI value was also improved from 26.0% to 30.6%. The mechanical strength was also improved by the addition of PZS micro-nanotubes. The improvement of flame retardancy can be ascribed to the good dispersion and the formation of graphene-like structure during combustion of PZS/EP nanocomposites. In conclusion, PZS micro-nanotube is a kind of excellent flame retardant with potential application value.

Key words: Phosphorus/Nitrogen/Sulphur containing phosphazene micro-nanotube, Flame retardancy, Epoxy, Poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol)

CLC Number:

O631.2

TrendMD:

ZHAO Shishi, HE Meng, SONG Wenyao, ZHANG Chong, XU Jianzhong, MA Haiyun. Synthesis of a Phosphorus/Nitrogen/Sulphur Containing Phosphazene Micro-Nanotube and Its Flame Retardancy on Epoxy Nanocomposite^†[J]. Chem. J. Chinese Universities, 2017, 38(12): 2337.

Figures/Tables 11

Scheme 1 Synthetic routes of the PZS nanotubes and EP/PZS nanocomposites

Fig.1 FTIR spectra of HCCP(a), BPS(b) and PZS nanotubes(c)

Fig.2 SEM(A), TEM(B), EDS(C) and element mapping(D) images of the PZS nanotubes

Fig.3 TG(A) and DTG(B) curves of PZS nanotubes, EP, EP/PZS nanocomposites at a heating rate of 10 ℃/min under N2 atmospherea. PZS; b. EP; c. EP/PZS-1%; d. EP/PZS-3%; e. EP/PZS-5%.

Table 1 Thermogravimetric properties of PZS nanotubes, EP and EP/PZS nanocomposites

Sample	T_5%/℃	T_max/℃	Char residue at 800 ℃/(%)	Sample	T_5%/℃	T_max/℃	Char residue at 800 ℃/(%)
Neat EP	366.4	381.4	15.4	EP/PZS-3%	330.3	381.2	20.5
PZS	395.0	503.9	46.0	EP/PZS-5%	324.6	342.9	22.5
EP/PZS-1%	341.6	382.4	17.8

Fig.4 LOI values(A) and HRR curves(B) of EP and PZS/EP nanocomposites a. EP; b. EP/PZS-1%; c. EP/PZS-3%; d. EP/PZS-5%.

Fig.5 Residue chars of EP and EP/PZS nanocomposites at the end of LOI tests(A) EP; (B)EP/PZS-1%; (C) EP/PZS-3%;(D) EP/PZS-5%.

Fig.6 SEM(A), TEM(B), HRTEM(C) and EDS(D) images of the chars of PZS nanotubes at a heating rate of 10 ℃/min under N2 atmosphere Inset of (C): TEM electron diffraction image.

Fig.7 XRD profiles(A) and FTIR spectra(B) of chars of EP(a) and PZS nanotubes(b)

Fig.8 Typical stress-strain curves of the EP and EP/PZS nanocompositesa. EP; b. EP/PZS-1%; c. EP/PZS-3%; d. EP/PZS-5%.

Fig.9 SEM images of fracture section of EP(A) and EP/PZS nanocomposites(3%)(B)

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