Flame retardancy and smoke suppression of rigid polyurethane foam coated with chitosan⁃sulfonated graphene through layer⁃by⁃layer self⁃assembly

doi:10.19491/j.issn.1001-9278.2024.03.007

Abstract

Abstract:

In this paper， a bio⁃based flame⁃retardant coating with different chitosan⁃sulfonated graphene layers was constructed on the surface of a RPUF by using a water⁃based layer⁃by⁃layer self⁃assembly method （LBL）. The influence of different layers on the flame retardancy and smoke suppression of the RPUF was intensively investigated. The results indicated that the RPUF coated with the flame⁃retardant coating exhibited excellent flame⁃retardant performance， high thermal stability， and good smoke suppression， which were also affecting by the numbers of coating layers. The 5⁃layer⁃self⁃assembly coated RPUF （RPU⁃5BL） reached a UL 94 V⁃0 rating in the vertical burning test along with a limiting oxygen index of 35.1 vol% and a char yield of 34.9 wt% at 800 ℃， which were increased by 78.2 % and 85.6 %， respectively， compared to the untreated RPUF. Moreover， the RPU⁃5BL exhibited a peak heat release rate of 163.9 kW/m²， a total smoke production of 9.1 m²， a maximum smoke density of 22.9 %， and a smoke density grade of 14.9， which decreased by 30.6%， 14.2%， 61.9%， and 120.1%， respectively， compared to the controlled sample.

Key words: polyurethane, foam, flame retardant, smoke suppression, sulfonated graphene, layer?by?layer self?assembly

CLC Number:

TQ323.8

XU Jinjia, HUANG Teng, BAI Zhicheng, SHEN Jiahao, XIE Qingyi, ZHU Junhui, DAI Jinfeng, LIU Yuanqiang, ZHAN Xianxu. Flame retardancy and smoke suppression of rigid polyurethane foam coated with chitosan⁃sulfonated graphene through layer⁃by⁃layer self⁃assembly[J]. China Plastics, 2024, 38(3): 38-43.

Figures/Tables 12

Fig.1. Diagram of preparation of layer⁃by⁃layer self⁃assembled flame retardant RPUF

Fig.2. Layer⁃by⁃layer self⁃assembled flame retardant coating RPUF cross⁃section

Fig.3. Mass variation diagram of RPUF⁃xLB with different layers （a） and interface topography （b）

样品	RPUF	RPUF⁃1BL	RPUF⁃3BL	RPUF⁃5BL
d/μm	0	18.59	22.32	27.17

Tab.1. Thickness of different RPUF⁃xLB

Fig.4. LOI of RPUF⁃xLB with different self⁃assembly layers （a） and the process photographs of UL 94 vertical burning tests（b）

样品	T₁/s	T₂/s	UL 94级别	LOI/%
RUPF	-	-	无	19.7±0.5
RUPF⁃1BL	-	-	V⁃2	26.5±0.5
RUPF⁃3BL	7.1±1.2	12.4±0.8	V⁃1	32.6±0.5
RUPF⁃5BL	3.8±0.4	5.4±0.4	V⁃0	35.1±0.5

Tab.2. The flame retardant performance of RPUF⁃xLB with different self⁃assembly layers

Fig.5. TGA（a） and DTG curves（b） of RPUF⁃xLB with different layers

样品	T_d5%/℃	R_peak/T_peak（%·min^-1·℃^-1）	800 ℃残炭量/%
RPUF	293	13.2/352	18.8
RPUF⁃1BL	293	13.2/359	24.8
RPUF⁃3BL	283	11.2/406	31.6
RPUF⁃5BL	275	10.7/399	34.9

Tab.3. TGA data of RPUF⁃xLB with different layers

Fig.6. Curves of RPUF⁃xLB absorption rate （a） and maximum smoke density and smoke density grade （b） of different assembly layers

Fig.7. RPUF⁃xLB heat release rate （a）， total heat release （b）， total smoke generation （c） and mass loss （d） of different layers

样品	RPUF	RPUF⁃1BL	RPUF⁃3BL	RPUF⁃5BL
TTI/s	3±0.7	5±0.5	11±0.5	17±0.5
pHRR/kW·m^-2	236.1±5.2	180.4±3.2	164.1±2.5	163.9±2.3
THR/MJ·m^-2	45.8±1.2	42.1±1.1	40.0±1.1	39.0±0.8
残炭量/%	15.8±0.5	20.2±0.3	23.2±0.3	24.2±0.3
TSP/m²	10.6±0.1	9.7±0.1	9.3±0.1	9.1±0.1

Tab.4. Cone data of RPUF⁃xLB with different layers

Fig.8. SEM of the residual carbon layer after combustion of RPUF⁃XLB with different layers

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