Study on flame⁃retardant epoxy resins and mechanism based on catalysis of bamboo⁃based porous carbon and aluminum diethylphosphinate

doi:10.19491/j.issn.1001-9278.2023.10.010

Abstract

Abstract:

The flame retardancy and mechanism of bamboo⁃based porous carbon （PCM） and aluminum diethylphosphonate （AlPi） for epoxy resins （EP） were studied through using renewable resources as synergies. Combustion test results indicated that the flame⁃retardant EP obtained a significant increase in the LOI value when 3 wt% PCM and 4.4 wt% AlPi was introduced. A V⁃0 classification was also achieved for the flame⁃retardant EP， and its peak heat release rate decreased by 60.7 %. This means that there is a remarkable catalytic effect of PCM and AlPi on the flame⁃retardant EP. TG⁃FTIR， TG⁃MS， XPS， and Raman spectra indicated that owing to the catalysis of PCM， the diethyl phosphinic acid released by AlPi could capture free radicals in the gas phase to form alumina， aluminum phosphate， and aluminum pyrophosphate in the condensed phase. This improves the resistant thermal oxidation property of char and promotes the formation of graphite⁃like char.

Key words: porous carbon material, aluminum diethylphosphinate, epoxy resin, synergic effect, flame retardancy mechanism

CLC Number:

TQ317.2

WANG Fang, HAO Jianwei. Study on flame⁃retardant epoxy resins and mechanism based on catalysis of bamboo⁃based porous carbon and aluminum diethylphosphinate[J]. China Plastics, 2023, 37(10): 70-76.

Figures/Tables 10

样品	AlPi 含量/%	P^* 含量/%	PCM 含量/%	EP 含量/%
EP	-	-	-	100
EP/4.4AlPi	4.4	1.0	-	95.6
EP/1PCM	-	-	1.0	99.0
EP/3PCM	-	-	3.0	97.0
EP/5PCM	-	-	5.0	95.0
EP/4.4AlPi/1PCM	4.4	1.0	1.0	94.6
EP/4.4AlPi/3PCM	4.4	1.0	3.0	92.6
EP/4.4AlPi/5PCM	4.4	1.0	5.0	90.6
EP/2.2AlPi/1.5PCM	2.2	0.5	1.5	96.3

Tab.1. Formula of EP and EP composites

Fig.1. SEM and EDS images of EP/4.4AlPi and EP/4.4AlPi/3PCM

样品	UL 94垂直燃烧测试				$L O I e x p a)$ /%	$L O I c a l b)$ /%	ΔLOI^c）/%
样品	第一次有焰燃烧时间/s	第二次有焰燃烧时间/s	熔融滴落	垂直燃烧级别	$L O I e x p a)$ /%	$L O I c a l b)$ /%	ΔLOI^c）/%
EP	火焰燃至夹具	火焰燃至夹具	是	无级别	24.6	⁃⁃	⁃⁃
EP/2.2AlPi	10.4	5.8	否	V⁃1	35.1	⁃⁃	⁃⁃
EP/4.4AlPi	2.8	2.0	否	V⁃0	38.0	⁃⁃	⁃⁃
EP/1PCM	>60	⁃⁃	否	无级别	24.7	⁃⁃	⁃⁃
EP/1.5PCM	>60	⁃⁃	否	无级别	25.9	⁃⁃	⁃⁃
EP/3PCM	>60	⁃⁃	否	无级别	27.6	⁃⁃	⁃⁃
EP/5PCM	火焰燃至夹具	火焰燃至夹具	否	无级别	29.7	⁃⁃	⁃⁃
EP/4.4AlPi/1PCM	2.3	1.8	否	V⁃0	39.5	38.1	1.4
EP/4.4AlPi/3PCM	0.8	1.1	否	V⁃0	42.6	41.0	1.6
EP/4.4AlPi/5PCM	5.4	3.2	否	V⁃0	42.5	43.1	-0.6
EP/2.2AlPi/1.5PCM	6.4	3.2	否	V⁃0	39.2	36.4	2.8

样品	UL 94垂直燃烧测试				$L O I e x p a)$ /%	$L O I c a l b)$ /%	ΔLOI^c）/%
样品	第一次有焰燃烧时间/s	第二次有焰燃烧时间/s	熔融滴落	垂直燃烧级别	$L O I e x p a)$ /%	$L O I c a l b)$ /%	ΔLOI^c）/%
EP	火焰燃至夹具	火焰燃至夹具	是	无级别	24.6	⁃⁃	⁃⁃
EP/2.2AlPi	10.4	5.8	否	V⁃1	35.1	⁃⁃	⁃⁃
EP/4.4AlPi	2.8	2.0	否	V⁃0	38.0	⁃⁃	⁃⁃
EP/1PCM	>60	⁃⁃	否	无级别	24.7	⁃⁃	⁃⁃
EP/1.5PCM	>60	⁃⁃	否	无级别	25.9	⁃⁃	⁃⁃
EP/3PCM	>60	⁃⁃	否	无级别	27.6	⁃⁃	⁃⁃
EP/5PCM	火焰燃至夹具	火焰燃至夹具	否	无级别	29.7	⁃⁃	⁃⁃
EP/4.4AlPi/1PCM	2.3	1.8	否	V⁃0	39.5	38.1	1.4
EP/4.4AlPi/3PCM	0.8	1.1	否	V⁃0	42.6	41.0	1.6
EP/4.4AlPi/5PCM	5.4	3.2	否	V⁃0	42.5	43.1	-0.6
EP/2.2AlPi/1.5PCM	6.4	3.2	否	V⁃0	39.2	36.4	2.8

Tab. 2. LOI and UL 94 vertically burning test data of EP and EP composites

Fig.2. Cone test curves of EP and EP composites

样品	TTI/s	pk⁃HRR/ W·m^-2	THR /MJ·m^-2	CO产率（COY）/ kg·kg^-1	EHC/ MJ·kg^-1	MLR/ g·s^-1	pk⁃HRR/TTI/ kW·（m^-2·s^-1）	THE/TML /MJ·（m^-2·g^-1）
EP	95	1357	68.0	0.07	35.1	20.9	14.3	2.95
EP/3PCM	69	1401	69.4	0.09	33.5	12.5	20.3	3.03
EP/4.4AlPi	68	765	45.1	0.14	26.0	13.4	11.3	2.74
EP/4.4AlPi/3PCM	67	533	40.2	0.15	24.2	10.2	8.0	2.20

Tab.3. Cone test data of EP and EP composites

Fig.3. Digital photos in Cone test process and SEM images of char of EP and EP composites

Fig.4. FTIR of gas phase products of EP/4.4AlPi and EP/4.4AlPi/3PCM by TG⁃FTIR as a function of temperature

Fig.5. Particle flow curves of gas phase decomposition products of EP/4.4AlPi and EP/4.4AlPi/3PCM by TG⁃MS

Fig.6. Fitting curves of O1s and P2p of EP/4.4AlPi/3PCM at 500 ℃

Fig.7. Raman spectra of char of EP and EP composites at 500 ℃

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