Synergistic effect of zinc borate and aluminum diethylphosphinate on flame retardancy of PA6

doi:10.19491/j.issn.1001-9278.2022.01.018

Abstract

Abstract:

Zinc borate （ZB） as a synergistic flame retardant was compounded with aluminum diethylhypophosphonate （ADP） for flame?retarding nylon 6. The flame retardant properties and mechanical properties of the resultant compounds were evaluated， and their flame retardant mechanism was investigated using vertical combustion， limiting oxygen index， cone calorimetry， thermogravimetric analysis， scanning electron microscopy and Raman spectroscopy. The results indicated that the synergistic flame?retardant effect resulting from ZB and ADP was remarkable. When 1.5 % Zb and 8.5 % ADP were added into PA6， obtained composites achieved a flame?retardant level classification of UL 94 V?0 with a limi?ting oxygen index of 29.8 vol % Compared to the samples without a synergistic agent， their peak heat release rate， average heat release rate， and mass loss rate decreased by 42.7 %， 27.3 % and 32.7 %， respectively. The cone calorimetry analysis indicated that the introduction of ZB into the ADP flame retardant system not only generated a flame?retardant effect of the vapor phase， but also promoted the flame retardancy of condensed phase. This was attributed to a synergistic flame retardant mechanism， mainly based on the gas?phase flame retardancy together with the condensed?phase flame retardancy

Key words: polyamide 6, aluminum diethylhyphosphonate, zinc borate, synergy

CLC Number:

TQ323.6

YANG Zheng, WANG Zhenhua, LU Shike, LIU Yang, FANG Xiaoming, LI Jiantong, LIU Baoying, DING Tao. Synergistic effect of zinc borate and aluminum diethylphosphinate on flame retardancy of PA6[J]. China Plastics, 2022, 36(1): 120-127.

Figures/Tables 10

样品编号	PA6 含量/%	ADP 含量/%	ZB 含量/%	PTFE 含量/%	抗氧剂含量/%
PA6	99.2	0	0	0.3	0.5
0^#	89.2	10.0	0	0.3	0.5
1^#	89.2	9.5	0.5	0.3	0.5
2^#	89.2	9.0	1.0	0.3	0.5
3^#	89.2	8.5	1.5	0.3	0.5
4^#	89.2	8.0	2.0	0.3	0.5

Tab. 1. Formulation of PA6 composite material

样品	熔滴现象	UL 94				极限氧指数/%
样品	熔滴现象	t₁/s	t₂/s	t₁₀/s	等级	极限氧指数/%
PA6	是	-^①	-^①	-^①	-	25.7
0^#	是	22.9	14.2	185.5	V?2	27.8
1^#	否	1.2	3.9	25.5	V?0	29.7
2^#	否	2.9	3.0	29.6	V?0	29.6
3^#	否	1.5	2.0	19.4	V?0	29.8
4^#	否	4.6	1.1	28.6	V?0	28.9

Tab. 2. Data of flame retardant properties of PA6 composites

Fig.1. TG and DTG curves of PA6 composites

样品	T_{5 %}/℃		T_{10 %}/℃		T_{50 %}/℃		T _max/℃		800 ℃残炭率/%
样品	氮气	空气	氮气	空气	氮气	空气	氮气	空气	氮气	空气
PA6	389	377	406	396	440	440	444	442	1.6	1.2
10 %ADP	385	366	405	394	438	439	439	437	4.2	5.2
1.5 %ZB	392	379	406	398	436	436	434	434	7.4	7.6

Tab. 3. TG data of PA6 composites

Fig.2. HRR， THR， SPR and TSP curves of PA6 composites

样品s

TTI/s

PKHRR/

kW $?$ m^-2

AvHRR/

kW $?$ m^-2

THR/

MJ $?$ m^-2

Mean EHC/

MJ $?$ kg^-1

AvMLR/

g $?$ （m² $?$ s）^-1

SEA/

m² $?$ kg^-1

样品s

TTI/s

PKHRR/

kW $?$ m^-2

AvHRR/

kW $?$ m^-2

THR/

MJ $?$ m^-2

Mean EHC/

MJ $?$ kg^-1

AvMLR/

g $?$ （m² $?$ s）^-1

SEA/

m² $?$ kg^-1

TSP/m²

残炭率/%

PA6

717.8

234.8

102.3

16.1

27.5

53.3

3.2

10 %ADP

621.7

276.8

150.1

21.2

21.8

325.8

20.4

4.9

1.5 %ZB

356.0

201.3

136.9

20.1

14.7

342.4

20.7

9.2

Tab.4. Combustion characteristic parameters of PA6 composite i?CONE test

Fig.3. Carbon layer image of PA6 composite after i?CONE test

Fig.4. SEM of carbon layer of PA6 composite after i?CONE test

Fig.5. Raman diagram of PA6 composite after i?CONE test

样品	拉伸强度/MPa	弯曲强度/MPa	弯曲模量/ MPa	冲击强度/kJ·m^-2
0^#	73.9±0.6	94.9±0.6	3 159.3±14.5	6.6±0.3
1^#	74.0±0.4	95.3±1.0	3 174.7±39.8	5.7±0.8
2^#	73.5±1.6	96.2±1.0	3 181.7±76.4	6.4±0.1
3^#	73.9±0.4	95.9±1.1	3 188.4±38.8	6.8±0.8
4^#	74.6±1.2	96.2±1.1	3 181.3±54.0	6.4±0.2

Tab. 5. Data of mechanical properties of PA6 composites

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