Effects of graphite type and size on flame retardancy of high⁃impact polystyrene and it’s action mechanism

doi:10.19491/j.issn.1001-9278.2022.03.005

Abstract

Abstract:

Graphites with different types and particle sizes were incorporated into high?impact polystyrene （PS?HI） matrix through melt compounding. The effects and flame?retarding mechanism of graphite type and particle size on the flame retardancy of PS?HI were investigated. The results indicated that the flame?retarding effect of natural graphite （NG） on PS?HI was not significant， and the particle size of NG presented a small impact on its flame?retardant performance. The PS?HI/NG composite still showed poor flame?retardant performance even if the loading of NG reaches 50 wt%. In contrast to NG， expandable graphite （EG） exhibited much higher flame retardant efficiency， resulting in a significant improvement in the flame?retardant performance of PS?HI. The larger the EG particle size is， the higher is the flame retardant efficiency and the more noticeable is the smoke?suppressing effect of EG. The introduction of suitable amount of microencapsulated red phosphorus （MRP） into the PS?HI/EG system could improve the flame retardant efficiency of EG and therefore reduced the loading of flame retardant considerably. When the EG particle size is 270 μm， the PS?HI system achieved excellent flame?retardant performance with the addition of 20 wt% flame retardant at a PS?HI/EG/MRP mass ratio of 80/15/5. The PS?HI/EG/MRP composites generated a continuous and compact intumescent char layer.

Key words: graphite, high?impact polystyrene, particle size, microencapsulated red phosphorus, intumescent char layer, flame?retardant mechanism

CLC Number:

TQ323.8

GUO Yiming, DONG Xiaochen, LIANG Shitong, WANG Sen, LIU Jichun. Effects of graphite type and size on flame retardancy of high⁃impact polystyrene and it’s action mechanism[J]. China Plastics, 2022, 36(3): 26-32.

Figures/Tables 9

Fig.1. LOI of different PS?HI/graphite composites

Fig.2. HRR and SPR curves of different composites with graphite content of 30 %

样品名称	点燃时间/s	PHRR/ kW·m^-2	AHRR/ kW·m^-2	THR/ MJ·m^-2	平均有效燃烧热/ MJ·kg^-1	TSR/ m²·m^-2	FPI/ 10^⁃3s·m²·kW^⁃1	残炭率/%
PS⁃HI	63	738	280	119	34	5 112	85	1.9
PS⁃HI/EG50	45	131	95	77	35	578	344	45.0
PS⁃HI/EG150	50	230	105	76	35	1 222	217	41.1
PS⁃HI/NG50	50	436	118	94	32	3 786	115	30.6
PS⁃HI/NG150	57	378	123	97	32	4 103	151	30.8

Tab. 2. Some cone calorimeter data for different composites with graphite content of 30 %

Fig.3. SEM images of single graphite particles after burned in flame for 2 min

样品名称	LOI/%	UL 94等级
PS⁃HI	18.1	NR
PS⁃HI/EG50	24.0	NR
PS⁃HI/NG50	20.2	NR
PS⁃HI/EG50/MRP	25.0	V⁃0
PS⁃HI/NG50/MRP	22.4	V⁃2

Tab.2. Burning testing results of several different PS?HI composites with 20 % loading of flame retardant

Fig.4. HRR and THR curves of different composites with 20 % flame retardant

Fig.5. Digital photos of the burnt residue of different composites of 20 % flame retardant after cone calorimeter test

Fig.6. SEM images of residue surface morphology of different composites with 20 % flame retardant after cone calorimeter test

Fig.7. TG and DTG curves of surface intumescent char in air for two different flame retardant composites with expandable graphite after cone calorimeter test

References 22

1	CULLIS C F， HIRSCHLER M M， TAO Q M. The effect of red phosphorus on the flammability and smoke⁃producing tendency of poly（vinyl chloride） and polystyrene ［J］. European Polymer Journal， 1986， 22（6）： 161⁃167.
2	ROBERT H N， PARTTYWISIAN N. Poly（alky/arylphosphazenes） and their precursors ［J］. Chemical Reviews， 1988， 88（3）： 541⁃562.
3	LEE K， KIM J. Studies on the thermal stablilzation enhancement of ABS： synersistic effect by triphenyl phosphate and epoxy resin mixtures ［J］. Polymer， 2002， 43（8）： 2 249⁃2 253.
4	刘继纯，常海波，李晴媛，等. Mg（OH）₂/聚苯乙烯复合材料的阻燃机制［J］，复合材料学报， 2012， 29（5）： 32⁃40.
	LIU J C， CHANG H B， LI Q Y， et al. Flame retardant mechanism of Mg（OH）₂/polystyrene composites ［J］. Acta Materiae Compositae Sinica， 2012， 29（5）： 32⁃40.
5	CUI W G， GUO F， CHEN J F. Preparation and properties of flame retardant high impact polystyrene ［J］. Fire Safety Journal， 2007， 42（3）： 232⁃239.
6	LIU H， YI J H. Polystyrene/magnesium hydroxide nanocomposite particles prepared by surface⁃initiated in⁃situ polymerization ［J］. Applied Surface Science， 2009， 255（11）： 5 714⁃5 720.
7	MANZI⁃NSHUTI C， CHEN D， SU S P， et al. Structure⁃property relationships of new polystyrene nanocomposites prepared from initiator⁃containing layered double hydroxides of zinc aluminum and magnesium aluminum ［J］. Polymer Degradation and Stability， 2009， 94（8）： 1 290⁃1 297.
8	LIU J C， LI H， CHANG H B， et al. Effect of water erosion on flame retardancy of high impact polystyrene/magnesium hydroxide composite and its mode of action ［J］. Fire and Materials， 2020， 44（2）： 180⁃188.
9	LU H D， WILKIE C A. Study on intumescent flame retarded polystyrene composites with improved flame retardancy ［J］. Polymer Degradation and Stability， 2010， 95（12）： 2 388⁃2 395.
10	焦清介，吴中伟，臧充光，等. 膨胀型无卤阻燃HIPS热分解动力学及阻燃机理研究［J］. 化学学报， 2009， 67（2）： 151⁃156.
	JIAO Q J， WU Z W， ZANG C G， et al. Thermal degradation kinetics of intumescent halogen⁃free flame⁃retarding HIPS and its retarding mechanism ［J］. Acta Chimica Sinica， 2009， 67（2）： 151⁃156.
11	SU S P， JIANG D D， WILKIE C A. Novel polymerically⁃modified clays permit the preparation of intercalated and exfoliated nanocomposites of styrene and its copolymers by melt blending ［J］. Polymer Degradation and Stability， 2004， 83（2）： 333⁃346.
12	ZHENG X X， JIANG D D， WANG D Y， et al. Flammability of styrenic polymer clay nanocomposites based on a methyl methacrylate oligomerically⁃modified clay ［J］. Polymer Degradation and Stability， 2006， 91（2）： 289⁃297.
13	ISITMAN N A， KAYNAK C. Tailored flame retardancy via nanofiller dispersion state： synergistic action between a conventional flame⁃retardant and nanoclay in high⁃impact polystyrene ［J］. Polymer Degradation and Stability， 2010， 95（9）： 1 759⁃1 768.
14	ATTIA N F， AFIFI H A， HASSAN M A. Synergistic study of carbon nanotubes， rice husk ash and flame retardant materials on the flammability of polystyrene nanocomposites ［J］. Materials Today： Proceedings， 2015， 2（7）： 3 998⁃4 005.
15	边策，曹金波，毕立，等. 不同无卤阻燃剂对PPO/HIPS合金性能影响研究［J］. 上海塑料， 2021， 49（2）： 27⁃31.
	BIAN C， CAO J B， BI L， et al. Effect of different halogen⁃free flame retardants on properties of PPO/HIPS alloy ［J］. Shanghai Plastics， 2021， 49（2）： 27⁃31.
16	刘继纯，罗洁，郑喜俊，等. 微胶囊红磷和聚苯醚对高抗冲聚苯乙烯的协同阻燃作用［J］. 复合材料学报， 2013， 30（4）： 44⁃52.
	LIU J C， LUO J， ZHENG X J. Synergistic effect of MRP and PPO on the flame retardancy of HIPS ［J］. Acta Materiae Compositae Sinica， 2013， 30（4）： 44⁃52.
17	YAO H Y， MCKINNEY M A， DICK C. Crossing⁃lin⁃king of polystyrene by friedel⁃crafts chemisty： reaction of p⁃hydroxymethylbenzyl chloride with polystyrene ［J］. Polymer Degradation and Stability， 2001， 72（3）： 399⁃405.
18	SUZUKI M， WILKIE C A. The thermal degradation of acrylonitrile⁃butadiene⁃styrene terpolymer grafted with methacrylic acid ［J］. Polymer Degradation and Stability， 1995， 47（2）： 223⁃228.
19	PRICE D， BULLETTA K J， CUNLIFFEA L K.et al. Cone calorimetry studies of polymer systems flame retarded by chemically bonded phosphorus［J］. Polymer Degradation and Stability， 2005， 88（1）： 74⁃79.
20	王星，胡立嵩，夏林，等. 石墨资源概况与提纯方法研究［J］. 化工时刊， 2015， 29（2）： 19⁃22.
	WANG X， HU L S， XIA L， et al. Graphite resources and graphite purification methods research ［J］. Chemical Industry Times， 2015， 29（2）： 19⁃22.
21	SCHARTEL B， HULL T R. Development of fire⁃retarded materials—interpretation of cone calorimeter data ［J］. Fire and Materials， 2007， 31（5）： 327⁃354.
22	AI L H， YANG L， HU J F， et al. Synergistic flame retardant effect of organic phosphorus⁃nitrogen and inorganic boron flame retardant on polyethylene ［J］. Polymer Engineering and Science， 2020， 60（2）： 414⁃422.

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