Influence of phosphomolybdic acid-based ionic liquid and layered double hydroxide on the properties of intumescent flame-retardant thermoplastic polyurethane elastomer composites
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摘要: 采用离子交换的方法合成了磷钼酸基离子液体(PMAIL),并与水滑石(LDH)复配,添加到膨胀阻燃热塑性聚氨酯弹性体(IFR/TPU)复合材料中,研究了PMAIL和LDH对IFR/TPU复合材料阻燃性能、热稳定性和加工流动性的影响。结果表明,PMAIL和LDH复配使用提高了IFR/TPU复合材料的阻燃性能和热稳定性;当PMAIL、LDH和IFR的质量比为0.2∶1.0∶8.8且总添加量为10wt%时,PMAIL-LDH-IFR/TPU复合材料的极限氧指数为30.1%,垂直燃烧测试达到UL-94 V-0级,热释放速率峰值和总热释放量与纯TPU相比分别下降88.06%和45.88%;平衡扭矩、熔融指数和熔融温度等数据变化表明,PMAIL-LDH-IFR/TPU复合材料具有良好的加工流动性。Abstract: The phosphomolybdic acid-based ionic liquid (PMAIL) was synthesized by ion-exchange method, and it was compounded to the intumescent flame-retardant thermoplastic polyurethane elastomer (IFR/TPU) compo-sites together with layered double hydroxide (LDH). The effect of PMAIL and LDH on the flame retardant properties, thermal stability and processing fluidity of IFR/TPU composites was investigated. The results show that the combination of PMAIL and LDH improve the flame retardancy and thermal stability of IFR/TPU composites. When the mass ratio of PMAIL, LDH and IFR is 0.2∶1.0∶8.8 and the total addition amount is 10wt%, the limiting oxygen index of the PMAIL-LDH-IFR/TPU composites is increased to 30.1% and the vertical burning test reach UL-94 V-0 rating. Moreover, the peak heat release rate and total heat release of PMAIL-LDH-IFR/TPU sample are reduced by 88.06% and 45.88% respectively compared with that of control TPU. The changes in the results such as the balanced torque, melt index and melting temperature indicate the improvement of processing fluidity for PMAIL-LDH-IFR/TPU composites.
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表 1 PMAIL-水滑石/膨胀阻燃热塑性聚氨酯弹性体(PMAIL-LDH-IFR/TPU)复合材料的配比
Table 1. Formulation of PMAIL-hydrotalcite/expanded flame-retardant thermoplastic polyurethane elastomer (PMAIL-LDH-IFR/TPU) composites
No. Sample IL/wt% PMAIL/wt% LDH/wt% IFR/wt% TPU/wt% 1# TPU 0 0 0 0 100 2# IFR/TPU 0 0 0 10.0 90 3# IL-IFR/TPU 0.2 0 0 9.8 90 4# PMAIL-IFR/TPU 0 0.2 0 9.8 90 5# PMAIL-LDH-IFR/TPU 0 0.2 1.0 8.8 90 Note: IFR—Mixture of ammonium polyphosphate and pentaerythritol with a ratio of 3∶1. 表 2 PMA、IL和PMAIL的TG数据
Table 2. TG data of of PMA, IL and PMAIL
Sample T5%/℃ Tmax/℃ Char residue at 800℃/% PMA 68.65 796.38 71.10 IL 271.69 365.21 16.70 PMAIL 373.71 445.22 60.00 Notes: T5%—Temperature at 5% mass loss; Tmax—Temperature at maximum mass loss rate. 表 3 TPU、IFR/TPU、IL-IFR/TPU、PMAIL-IFR/TPU和PMAIL-LDH-IFR/TPU复合材料的极限氧指数(LOI)和UL-94垂直燃烧等级
Table 3. Limiting oxygen index (LOI) and UL-94 vertical burning test rating of TPU, IFR/TPU, IL-IFR/TPU, PMAIL-IFR/TPU and PMAIL-LDH-IFR/TPU composites
Sample LOI/% UL-94 (t1+t2)/s Dripping Cotton ignition Rating TPU 23.7 2.3 Y(1/6) Yes V-2 IFR/TPU 28.2 3.6 Y(1/7) Yes V-2 IL-IFR/TPU 28.4 3.4 Y(1/5) Yes V-2 PMAIL-IFR/TPU 29.2 3.5 Y(1/10) No V-0 PMAIL-LDH-IFR/TPU 30.1 3.0 Y(1/8) No V-0 Notes: t1—Self-extinguishing time after the first ignition; t2—Self-extinguishing time after the second ignition. 表 4 TPU、PMAIL-IFR/TPU和PMAIL-LDH-IFR/TPU复合材料的锥形量热测试结果
Table 4. Cone calorimeter test results of TPU, PMAIL-IFR/TPU and PMAIL-LDH-IFR/TPU composites
Sample pHRR/
(kW·m−2)THR/
(MJ·m−2)ITF/
spSPR/
(m2·s−1)pCOP/
(g·s−1)pCO2P/
(g·s−1)FPI/
(m2·s·kW−1)FIGRA/
(kW·m−2·s−1)TPU 1106.96 91.77 300 0.11 0.014 0.86 0.02 9.71 PMAIL-IFR/TPU 317.80 66.14 788 0.06 0.008 0.17 0.08 11.77 PMAIL-LDH-IFR/TPU 132.15 49.67 845 0.06 0.002 0.02 0.14 5.75 Notes: pHRR—Peak of heat release rate; ITF—Time from ignition to flameout; pSPR—Peak of smoke production rate; pCOP—Peak of carbon monoxide production; pCO2P—Peak of carbon dioxied production; FPI—Defined by TTI/pHRR; FIGRA—defined by pHRR/pHRR. 表 5 TPU、IFR/TPU、IL-IFR/TPU、PMAIL-IFR/TPU和PMAIL-LDH-IFR/TPU复合材料在N2中的TG数据
Table 5. TG data of TPU, IFR/TPU, IL-IFR/TPU, PMAIL-IFR/TPU and PMAIL-LDH-IFR/TPU composites in N2
Sample T5%/℃ T50%/℃ Tmax1/℃ Tmax2/℃ Tmax3/℃ Char residue at 800℃/% TPU 330.47 397.50 327.28 428.34 — 2.29 IFR/TPU 302.76 361.82 336.58 354.99 474.80 18.93 IL-IFR/TPU 308.28 368.13 338.29 360.54 471.64 18.71 PMAIL-IFR/TPU 307.16 366.73 341.16 357.58 483.49 18.76 PMAIL-LDH-IFR/TPU 312.53 373.52 343.86 364.44 487.53 19.87 Note: T50%—Temperature at 50% mass loss. 表 6 TPU、IFR/TPU、IL-IFR/TPU、PMAIL-IFR/TPU和PMAIL-LDH-IFR/TPU复合材料的熔体特性数据
Table 6. Melt characteristic data of TPU, IFR/TPU, IL-IFR/TPU, PMAIL-IFR/TPU and PMAIL-LDH-IFR/TPU composites
Sample Maximum torque/(N·m) Balanced torque/(N·m) Melting index/(g·(10 min)−1) Melting temperature/℃ TPU 10.8 6.5 2.04 144.46 IFR/TPU 10.3 4.1 22.00 132.41 IL-IFR/TPU 9.8 3.4 24.00 131.31 PMAIL-IFR/TPU 9.6 3.2 21.90 132.43 PMAIL-LDH-IFR/TPU 9.3 2.8 29.52 129.66 -
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