Construction of hierarchical structure of carbon nanotube-encapsulated ammonium polyphosphate/Mg(OH)2 and the synergistic effect on the fire safety of ethylene-vinyl acetate copolymer
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摘要: 本文采用微胶囊法制备了具有多层次结构的碳纳米管包裹聚磷酸铵(APP@CNT)阻燃剂，在此基础上与Mg(OH)2复配，采用纳米复合技术制备了火安全的电线电缆用阻燃乙烯-醋酸乙烯酯共聚物(EVA)复合材料(APP@CNT/EVA-Mg(OH)2)。采用SEM、TGA、极限氧指数(LOI)、垂直燃烧(UL-94)、微型锥形量热仪(MCC)，电子万能拉伸机和高阻计对阻燃EVA复合材料的结构与性能进行系统研究。结果表明，APP@CNT/EVA-Mg(OH)2的残炭率从2.4%上升至43.9%，氧指数高达38%，垂直燃烧达到UL-94 V-0级，热释放峰值(PHRR)比纯EVA下降了57.85%，总热释放(THR)下降了57.80%，屈服强度提高了408%，复合材料体积电阻率仍高达3.9×1015 Ω·cm。以上数据表明多层次结构APP@CNT协同Mg(OH)2阻燃EVA复合材料(APP@CNT/EVA-Mg(OH)2)具有良好的火安全性能。Abstract: In this paper, a hierarchical structure of carbon nanotube-encapsulated ammonium polyphosphate (APP@CNT) flame retardant was synthesized, and Mg(OH)2 was used in conjunction with nano-composite technology to prepare fire-safe wire and cable flame-retardant ethylene-vinyl acetate copolymer (EVA) composite material (APP@CNT/EVA-Mg(OH)2). The structure and performance of flame-retardant ethylene-vinyl acetate composite materials were studied by using SEM, TGA, limiting oxygen index (LOI), vertical combustion (UL-94), microscale combustion colorimeter (MCC), universal stretching machine and high resistance meter. The results show that the residual carbon rate of EVA increases from 2.4% to 43.9%, the peak heat release decreases by 57.85% compared with pure EVA, the total heat release decreases by 57.80%, and the yield strength increases by 408%. At the same time, the volume resistivity of APP@CNT/EVA-Mg(OH)2 is still as high as 3.9×1015 Ω·cm, indicating that the EVA composite material after flame retardant treatment is still an ideal wire and cable material. In addition, the oxygen index of APP@CNT/EVA-Mg(OH)2 has reached 38%, and the vertical combustion UL-94 has also reached the V-0 level, which further illustrates the hierarchical structure of APP@CNT and magnesium hydroxide. Flame-retardant ethylene-vinyl acetate composite material has high fire safety performance.
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Key words:
- ethylene-vinyl acetate /
- carbon nanotube /
- hierarchical structure /
- flame retardant /
- synergistic effect
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图 1 碳纳米管包裹聚磷酸铵(APP@CNT)的合成路线图
APTES-APP—KH550 modified APP
Figure 1. Synthesis route of carbon nanotube-encapsulated ammonium polyphosphate (APP@CNT)
图 2 APP、CNT和APP@CNT的FTIR图谱 (a) 和空气下的TGA (b)、DTG曲线 (c)
Figure 2. FTIR spectra of APP, CNT and APP@CNT (a), TGA curves (b) and DTG curves (c) under air atmosphere
图 3 APP粉体 (a)，APP@CNT ((b), (c)) 的SEM图像和CNT的TEM图像 (d)
Figure 3. SEM images of APP (a) and APP@CNT ((b), (c)) and TEM image of CNT (d)
图 4 纯EVA (a)、CNT/EVA (b)、EVA-Mg(OH)2 (c)、APP/EVA-Mg(OH)2 (d) 和APP@CNT/EVA-Mg(OH)2 (e) 的内部微观形貌
Figure 4. SEM cross-sectional images of EVA composites pure EVA (a), CNT/EVA (b), EVA-Mg(OH)2 (c), APP/EVA-Mg(OH)2 (d), APP@CNT/EVA-Mg(OH)2 (e)
图 6 EVA和EVA复合线缆材料的应力应变拉伸曲线 (a) 和拉伸强度、屈服强度柱状图 (b)
Figure 6. Stress-Strain curves (a) and tensile strength and yield strength (b) of EVA and EVA composites
图 7 EVA和阻燃EVA体系总热释放(THR)曲线 (a) 和热释放速率(HRR)曲线 (b)
Figure 7. Total heat release (THR) (a) and heat release rate (HRR) (b) curves of EVA and EVA composites
图 8 EVA及EVA复合材料的TGA (a) 及DTG (b) 测试曲线
Figure 8. TGA (a) and DTG (b) curves of EVA and EVA composites
表 1 阻燃乙烯-醋酸乙烯酯共聚物(EVA)复合材料的原料配比
Table 1. Formulations of the ethylene-vinyl acetate copolymer (EVA) and EVA composites
Sample EVA/wt% Mg(OH)2/wt% APP/wt% APP@CNT/wt% EVA 100 0 0 0 EVA-Mg(OH)2 40 60 0 0 APP/EVA-Mg(OH)2 40 58 2 0 APP@CNT/EVA-Mg(OH)2 40 58 0 2 
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表 2 EVA和阻燃EVA复合材料的力学拉伸测试数据
Table 2. Mechanical properties of EVA and EVA composites
Samples Yield strength/MPa Tensile strength/MPa Elongation at break/% EVA 2.64±0.38 14.6±0.26 611±50 EVA-Mg(OH)2 8.59±0.50 9.60±0.32 107±46 APP/EVA-Mg(OH)2 9.33±0.23 10.5±0.15 108±61 APP@CNT/EVA-Mg(OH)2 10.78±0.15 11.7±0.11 123±33
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表 3 EVA和阻燃EVA复合材料的MCC数据
Table 3. MCC data and flame retardant test results of EVA and EVA composites
Sample THR/(kJ·g−1) Peak HRR/(W·g−1) LOI/vol% UL-94 EVA 37.2 851.9 18 NR EVA-Mg(OH)2 16.2 358.6 36 V-1 APP/EVA-Mg(OH)2 16.1 351.4 37 V-0 APP@CNT/EVA-Mg(OH)2 15.7 359.1 38 V-0 Notes: NR—No rating; THR—Total heat release; Peak HRR—Peak heat release rate; LOI—Limiting oxygen index; UL-94—Test for flammability of plastic materials for parts in devices and appliances.
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表 4 EVA复合线缆材料的阻燃性能与文献报道的数据对比
Table 4. Comparison of EVA composites among this work and literatures
Samples LOI/vol% Peak HRR/(W·g−1) Reference APP@CNT/EVA-Mg(OH)2 38 359.1 This work MH/MgAl-LDH/EVA 35 Not reported [29] MCAPP/MCPER/EVA 33 Not reported [30] PPUAPP/EVA 32.5 320 [31] CDAPP/EVA 29 408 [32] Notes: LDH—Layered double hydroxide; MCAPP—Silica gel microencapsulated ammonium polyphosphate; MCPER—Microencapsulated pentaerythritol; PPUAPP—Polyurethane@expandable graphite microencapsulated ammonium polyphosphate; CDAPP—Cyclodextrin microencapsulated ammonium polyphosphate.
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表 5 EVA及EVA复合材料的热重测试数据
Table 5. TGA data of EVA and EVA composites
Sample T5wt%/℃ Tmax/℃ Residues at 700℃/% T1max T2max EVA 318.1 351.5 462.7 2.4 EVA-Mg(OH)2 333.0 372.4 469.4 43.6 APP/EVA-Mg(OH)2 330.4 365.0 469.5 43.7 APP@CNT/EVA-Mg(OH)2 333.5 363.8 468.9 43.9 Notes: T5wt%—Temperature when the samples loss 5wt%; Tmax—Temperature at the max decomposition rate; T1max and T2max—First and second stage temperature at the max decomposition rate, respectively.
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[1] 汤龙其, 令旭霞, 王士华, 等. 聚吡咯/碳纤维纸电热复合材料的制备及性能[J]. 复合材料学报, 2020, 37(6):1426-1433.TANG Longqi, LING Xuxia, WANG Shihua, et al. Preparation and properties of polypyrrole/carbon fiber paper electrothermal composites[J]. Acta Materiae Compositae Sinica,2020,37(6):1426-1433(in Chinese). [2] SHUAIY, CHIANG K, LINH et al. Performance enhancement of metal nanowirebased transparent electrodes by electrically driven nanoscale nucleation of metal oxides[J]. Nanoscale,2015,7:12698-12705. doi: 10.1039/C5NR02780B [3] 陈志杰, 郑玉婴, 张延兵, 等. 无卤阻燃乙烯-醋酸乙烯酯共聚物泡沫复合材料的制备及性能表征[J]. 复合材料学报, 2015, 32(3):649-656.CHEN Zhijie, ZHENG Yuyin ZHANG Yanbing, et al. Preparation and property characterization of halogen-free fire retardant ethylene-vinyl acetate copolymer foam compo-sites[J]. Acta Materiae Compositae Sinica,2015,32(3):649-656(in Chinese). [4] MENZEL R, BARG S, MIRANDA M, et al. Joule heating characteristics of emulsion-templated graphene aerogels[J]. Advanced Functional Materials,2015,25:28-36. doi: 10.1002/adfm.201401807 [5] 刘继纯, 李行, 贺云鹏, 等. 纳米Mg(OH)2微胶囊红磷/乙烯-乙酸乙烯酯共聚物阻燃复合材料的性能[J]. 复合材料学报, 2019, 36(11):2530-2540.LIU Jichun, LI Xing, HE Yunpeng, et al. Properties of nano Mg(OH)2-microencapsulated red phosphorus/ethylene-vinyl acetate copolymer flame-retardant composites[J]. Acta Materiae Compositae Sinica,2019,36(11):2530-2540(in Chinese). [6] CHAI F, WANG G, LIU F, et al. Preparation and properties of flame-retardant neutron shielding material based on eva polymer reinforced by radiation modification[J]. Radiation Physics and Chemistry, 2020, 174: 108984. [7] ZHANG Y, HU Y, WANG J, et al. Engineering carbon nano-tubes wrapped ammonium polyphosphate for enhancing mechanical and flame retardant properties of poly(butylene succinate)[J]. Composites Part A: Applied Science & Manufacturing,2018,115:215-227. doi: 10.1016/j.compositesa.2018.09.020 [8] ZOU N, NIE Q, ZHANG X, et al. Electrothermal regeneration by Joule heat effect on carbon cloth based MnO2 catalyst for long-term formaldehyde removal[J]. Chemical Engineering Journal,2019,357:1-10. doi: 10.1016/j.cej.2018.09.117 [9] XING W, YANG W, YANG W, et al. Functionalized carbon nanotubes with phosphorus and nitrogencontaining agents: Effective reinforcer for thermal, mechanical, and flame-retardant properties of polystyrene nanocompo-sites[J]. ACS Applied Materials & Interfaces,2016,8:39, 26266-26274. [10] CHENG T, ZHANG Y, LAI W, et al. High-performance stretchable transparent electrodes based on silver nanowires synthesized via an eco-friendly halogen-free 1method[J]. Journal of Materials Chemistry C,2014,2(48):10369-10376. doi: 10.1039/C4TC01959H [11] WANG J, ZHANG D, ZHANG Y, et al. Construction of multifunctional boron nitride nanosheet towards reducing toxic volatiles (CO and HCN) generation and fire hazard of thermoplastic polyurethane[J]. Journal of Hazardous Materials,2019,362:482-494. doi: 10.1016/j.jhazmat.2018.09.009 [12] KONO A, SHIMIZU K, NAKANO H, et a1. Positive temperature-coefficient effect of electrical resistivity below melting point of poly(vinylidene fluoride) (PVDF) in Ni particle dispersed PVDF composites[J]. Polymer,2012,53(8):1760-1764. doi: 10.1016/j.polymer.2012.02.048 [13] CHEN B, GAO W, SHEN J, et al. The multilayered distribution of intumescent flame retardants and its influence on the fire and mechanical properties of polypropylene[J]. Composites Science and Technology,2014,93:54-60. doi: 10.1016/j.compscitech.2013.12.022 [14] PALACIOS J, PERERA R, ROSALES C, et al. Thermal degradation kinetics of PP/OMMT nanocomposites with mPE and EVA[J]. Polymer Degradation and Stability,2012,97(5):729-737. doi: 10.1016/j.polymdegradstab.2012.02.009 [15] ZHAO H, WU Z, WANG S, et a1. Concrete pavement deicing with carbon fiber heating wires[J]. Cold Regions Science and Technology,2011,65(3):413-420. doi: 10.1016/j.coldregions.2010.10.010 [16] YANG T, YANG Z, SINGLA M, et a1. Experimental study on carbon fiber tape-based deicing technology[J]. Journal of Cold Regions Engineering,2012,26(2):55-70. doi: 10.1061/(ASCE)CR.1943-5495.0000038 [17] ASTM. Standard test method for measuring the minimum oxygen concentration to support candle-like combustion of plastics (Oxygen index): ASTM D2863—2017[S]. West Conshohocken: ASTM, 2017. [18] ASTM. Standard test method for measuring the comparative burning characteristics of solid plastics in a vertical position: ASTM D3801[S]. West Conshohocken: ASTM, 2010. [19] ASTM. Standard test methods for vulcanized rubber and thermoplastic elastomers-Tension: ASTM D412—2015[S]. West Conshohocken: ASTM, 2015. [20] SINGLA M, CHANG C, SONG G, et a1. Automatic controls for the carbon fiber tape-based deicing technology[J]. Journal of Cold Regions Engineering,2014,28(1):1-17. [21] RAFIEE F, OTADI M, GOODARZI V, et al. Thermal and dynamic mechanical properties of PP/EVA nanocomposites containing organo-modified layered double hydroxides[J]. Composites Part B: Engineering,2016,103:122-130. doi: 10.1016/j.compositesb.2016.08.013 [22] ZHANG W, BI E, LI M, et al. Synthesis of Ag/RGO compo-site as effective conductive ink filler for flexible inkjet printing electronics[J]. Colloids Surfaces A: Physicochemical Engineering Aspects,2016,490(12):232-240. [23] ALOTAIBI F, TUNG T, NINE M, et al. Silver nanowires with pristine graphene oxidation barriers for stable and high performance transparent conductive films[J]. ACS Applied Nano Materials,2018,1:2249-2260. doi: 10.1021/acsanm.8b00255 [24] LAN W, CHEN Y, YANG Z, et al. Ultraflexible transparent film heater made of Ag nanowire/PVA composite for rapid-response thermotherapy pads[J]. ACS Applied Materials & Interfaces,2017,9:6644-6651. [25] GUPTA R, RAO K, SRIVASTAVA K, et al. Spray coating of crack templates for the fabrication of transparent conductors and heaters on flat and curved surface[J]. ACS Applied Materials & Interfaces,2014,6:13688-13696. [26] 程博, 李定华, 吴凡等. 不同蒙脱土Al(OH)3/乙烯-醋酸乙烯酯复合材料力学性能和阻燃性能的影响[J]. 复合材料学报, 2017, 34(12):2715-2721.CHENG Bo, LI Dinghua, WU Fan et al. Effect of montmorillonite type on mechanical and flame retarded properties of Al(OH)3/ethylene vinyl acetate copolymer composites[J]. Acta Materiae Compositae Sinica,2017,34(12):2715-2721(in Chinese). [27] WANG B, ZHOU K, WANG L, et al. Enhancement on physical properties of flame retarded ethylene-vinyl acetate copolymer/ferric pyrophosphate composites through electron beam irradiation[J]. Composites Part B: Engineering,2012,43:641-646. doi: 10.1016/j.compositesb.2011.08.027 [28] WANG B, SHENG H, SHI Y, et al. Recent advances for microencapsulation of flame retardant[J]. Polymer Degradation and Stability,2015,113:96-109. doi: 10.1016/j.polymdegradstab.2015.01.008 [29] DING Y, GUI Z, ZHU J, et al. Exfoliated poly(methyl methacrylate)/mgfe layered double hydroxide nanocomposites with small inorganic loading and enhanced properties[J]. Materials Research Bulletin,2008,43:3212-3220. doi: 10.1016/j.materresbull.2008.03.002 [30] WANG B, TAI Q, NIE S, et al. Electron beam irradiation cross linking of halogen-free flame-retardant ethylene vinyl acetate (EVA) copolymer by silica gel microencapsulated ammonium polyphosphate and char-forming agent[J]. Industry Engineering Chemistry Research,2011,50:5596-5605. doi: 10.1021/ie102394q [31] WANG B, HU S, ZHAO K, et al. Preparation of polyurethane microencapsulated expandable graphite, and its application in ethylene vinyl acetate copolymer containing silica-gel microencapsulated ammonium polyphosphate[J]. Industry Engineering Chemistry Research,2011,50:11476-11484. doi: 10.1021/ie200886e [32] WANG B, WANG X, TANG G, et al. Preparation of silane precursormicro encapsulated intumescent flame retardant and its enhancement on the properties of ethylene-vinyl acetate copolymer cable[J]. Composites Science and Technology,2012,72:1042-1048. doi: 10.1016/j.compscitech.2012.03.022 [33] LU J, ZHANG Y, TAO Y, et al. Self-healable castor oil-based waterborne polyurethane/MXene film with outstanding electromagnetic interference shielding effectiveness and excellent shape memory performance[J]. Journal of Colloid and Interface Science,2021(558):164-174. [34] TIAN W, ZHANG Y, LIU J, et al. Rapid electrothermal response and excellent flame retardancy of ethylene-vinyl acetate electrothermal film[J]. Polymer of Advanced Technologies,2020,31:1088-1098. doi: 10.1002/pat.4843 -
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