Synergistic flame retardancy of nano-BN and ZnO on wood flour-polyvinyl chloride composites
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摘要: 为提高木粉-聚氯乙烯(WF-PVC)木塑复合材料的阻燃抑烟性能，本文将纳米BN与ZnO加入到WF-PVC木塑复合材料中，通过热压成型方法制备了阻燃WF-PVC木塑复合材料，研究了复合材料热分解、燃烧性能和力学性能。热重分析(TG)测试表明，BN和ZnO的加入一定程度上降低了复合材料的初始热分解温度，但明显提高了复合材料的热解残余物质量，BN和ZnO的质量比为1∶2时，复合材料的残炭量增加了21.7%。锥形量热仪燃烧测试表明，纳米BN和ZnO的加入能够显著提高复合材料的阻燃性能，与纯WF-PVC相比，BN与ZnO的加入能有效降低WF-PVC复合材料燃烧时的热释放和烟释放，复合材料的总热释放量和总烟气释放量最高分别降低18.2%和48.9%。通过万能力学试验机对材料进行力学性能测试，结果表明阻燃剂的加入一定程度上降低了复合材料的力学性能，对阻燃剂进行一定比例的复配，可有效减少对复合材料力学性能的损害，单独添加ZnO时，复合材料弯曲强度降低了29.5%，而BN和ZnO以2∶1的质量比复配时，复合材料的弯曲强度降低了9.9%。Abstract: The effects of the nano BN and ZnO on the thermal decomposition, combustion and mechanical properties of wood flour-polyvinyl chloride (WF-PVC) composites were investigated. The flame retarded WF-PVC composites with nano-BN and ZnO were prepared by hot pressing. Thermogravimetric analysis (TG) test results show that the addition of BN and ZnO reduces the initial thermal degradation temperature of the composites, while significantly increases the pyrolysis residues of the composites. When the mass ratio of BN to ZnO is 1∶2, the residues content of the composites increases by 21.7%. The cone calorimeter combustion test results show that the addition of nano-BN and ZnO significantly improves the flame retardant properties of the composites. Compared with the pure WF-PVC, the addition of BN and ZnO effectively decreases the heat release and smoke release during combustion of the composites, the total heat release and total smoke emission are decreased by 18.2% and 48.9%, respectively. The mechanical properties of the composites were tested by the universal mechanical testing machine. The results show that the addition of the flame retardants has some negative effects on the mechanical properties of the composites. However, the flame retardants were compounded in a certain proportion, which could effectively reduce the damage to the mechanical properties of the composites. The flexural strength of the composites is reduced by 29.5% when the ZnO is added alone, while the flexural strength of the composites is decreased by 9.9% when the mass ratio of BN to ZnO is 2∶1.
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Key words:
- polyvinyl chloride /
- BN /
- ZnO /
- flame retardant /
- smoke suppression
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图 2 WF-PVC复合材料的热释放率(HRR)与总热释放量(THR)曲线
Figure 2. Heat release rate (HRR) and total heat release (THR) curves of WF-PVC composites
图 4 WF-PVC复合材料锥形量热仪燃烧后残炭形貌图
Figure 4. Char residue of WF-PVC composite after cone calorimeter test ((a) WF-PVC; (b) WF-PVC-BN; (c)WF-PVC-ZnO; (d) WF-PVC-BN-ZnO(2∶1); (e) WF-PVC-BN-ZnO(1∶2); (f) WF-PVC-BN-ZnO(1∶1))
图 5 WF-PVC复合材料燃烧残炭SEM图像及能谱图
Figure 5. SEM images and energy spectrum of WF-PVC composites ((a) WF-PVC-BN; (b) WF-PVC-ZnO; (c) WF-PVC-BN-ZnO(1∶1))
表 1 木粉-聚氯乙烯 (WF-PVC)复合材料的物料配比
Table 1. Formulations of the wood flour-polyvinyl chloride (WF-PVC) composites
wt% PVC WF BN ZnO Heat stabilizers WF-PVC 69 27 0 0 4 WF-PVC-BN 62 25 9 0 4 WF-PVC-ZnO 62 25 0 9 4 WF-PVC-BN-ZnO (2∶1) 62 25 6 3 4 WF-PVC-BN-ZnO (1∶2) 62 25 3 6 4 WF-PVC-BN-ZnO (1∶1) 62 25 4.5 4.5 4 
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表 2 N2气氛下WF-PVC复合材料的热重分析数据
Table 2. Thermogravimetric analysis data of WF-PVC composites under N2
Sample Initial temperature/℃ First stage Second stage Residue
at 750℃/
%Temperature
range/
%Maximum
temperature/
℃Mass loss
fraction/
wt%Temperature
range/
%Maximum
temperature/
℃Mass
residual/
%WF-PVC 274 204-394 307 56.0 436-553 476 17.0 17.4 WF-PVC-BN 268 209-388 301 49.7 432-562 480 14.2 29.0 WF-PVC-ZnO 230 212-302 238 39.3 450-583 510 11.0 35.5 WF-PVC-BN-ZnO(2:1) 231 212-323 236 43.7 453-545 495 7.5 38.4 WF-PVC-BN-ZnO(1:2) 231 208-315 236 40.8 460-552 505 7.3 39.1 WF-PVC-BN-ZnO(1:1) 236 218-288 240 36.9 449-619 500 16.3 35.3
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表 3 WF-PVC复合材料锥形量热仪燃烧数据
Table 3. Cone calorimeter data of WF-PVC composites
TTI/s PHRR/
(kW·m−2 )THR/
(kJ·g−1)Residue/
wt%MLR/
(g·s−1)av-SEA/
(m2·kg−1)TSP/
(m2·m−2)WF-PVC 32 115.1 32.7 21.0 0.090 560.3 23.1 WF-PVC-BN 45 183.8 34.2 32.1 0.092 378.7 13.9 WF-PVC-ZnO 61 94.1 16.1 39.3 0.077 407.6 12.5 WF-PVC-BN-ZnO(2∶1) 98 130.8 18.8 38.5 0.099 257.1 10.5 WF-PVC-BN-ZnO(1∶2) 115 111.6 17.4 38.6 0.081 124.2 11.8 WF-PVC-BN-ZnO(1∶1) 66 98.0 18.8 39.5 0.084 346.9 12.3 Notes: TTI—Ignition time; PHRR—Peak heat release rate; Residue is the amount of residual carbon; MLR—Mass loss rate; av-SEA—Average specific extinction area of smoke; TSP—Total smoke release.
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表 4 WF-PVC复合材料的力学性能
Table 4. Mechanical properties of WF-PVC composites
Sample Bending strength/MPa Bending modulus/GPa Impact strength/(kJ·m−2) WF-PVC 61.6±4.67 4.37±0.04 8.04±0.28 WF-PVC-BN 53.9±2.57 4.97±0.39 4.82±0.40 WF-PVC-ZnO 43.4±4.51 3.04±0.07 4.31±0.73 WF-PVC-BN-ZnO(2∶1) 55.5±0.46 4.74±0.08 5.13±0.39 WF-PVC-BN-ZnO(1∶2) 42.3±2.89 4.21±0.14 3.74±0.37 WF-PVC-BN-ZnO(1∶1) 53.7±4.73 4.03±0.38 7.56±0.80
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