Flame retardant effect of phosphotungstic acid intercalated ZnAl layered double hydroxides and intumescent flame retardant on epoxy-polyamide resin
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摘要: 采用[PW12O40]3−离子柱撑插层共沉淀法合成的ZnAl硝酸根(NO3-ZnAl)层状双金属氢氧化物(LDHs),制备了PW12O40-ZnAl LDHs,并利用XRD、FTIR、电感耦合等离子体(ICP)、SEM等进行组成和结构的表征。将NO3-ZnAl LDHs和PW12O40-ZnAl LDHs分别与含聚磷酸铵、三聚氰胺、季戊四醇的膨胀阻燃剂(IFRs)复合阻燃环氧-聚酰胺树脂(EP-PA),采用TGA、背温实验和锥形量热实验评价不同ZnAl LDHs与IFRs复合阻燃EP-PA的热及烟气的释放规律。TGA结果表明,PW12O40-ZnAl-IFRs/(EP-PA)复合材料的最大降解速率最小,残炭率最高,说明PW12O40-ZnAl LDHs提高了IFRs/(EP-PA)复合材料高温下的抗氧化能力。背温实验表明,相同热辐射强度下,PW12O40-ZnAl-IFRs/(EP-PA)复合材料的背温达到200℃和300℃用时最长,具有最低的背温升温速率,说明PW12O40-ZnAl LDHs使IFRs/(EP-PA)复合材料耐火能力明显增强。从锥形量热实验数据可知,PW12O40-ZnAl-IFRs使PW12O40-ZnAl-IFRs/(EP-PA)复合材料具有最低的热释放速率峰值(PHRR)、平均热释放速率(MHRR)、平均有效燃烧热(MEHC)和总热释放量(THR),其火势增长指数(FGI)仅为IFRs/(EP-PA)复合材料的14.5%,烟释放总量(TSP)比NO3-ZnAl-IFRs/(EP-PA)复合材料减少了27.6%,比IFRs/(EP-PA)复合材料减少了55.3%。说明PW12O40-ZnAl-IFRs比NO3-ZnAl-IFRs更能有效地减少EP-PA的热量释放,抑制烟气生成。
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关键词:
- ZnAl层状双金属氢氧化物 /
- 插层改性 /
- 环氧-聚酰胺树脂 /
- 阻燃 /
- 背温速率
Abstract: The PW12O40-ZnAl layered double hydroxides(LDHs) was prepared by using [PW12O40]3− ion pillared intercalation NO3-ZnAl LDHs. The composition and structure were analyzed by XRD, FTIR, inductively coupled plasma(ICP) and SEM. The flame retardant epoxy-polyamide resin(EP-PA) were prepared by NO3-ZnAl LDHs or PW12O40-ZnAl LDHs compound with intumescent flame retardants(IFRs) containing ammonium polyphosphate, melamine, pentaerythritol. The heat and smoke release rules of different ZnAl LDHs-IFRs flame retardant EP-PA were evaluated by back temperature experiment and cone calorimetry experiment. TGA result shows that the maximum degradation rate of PW12O40-ZnAl-IFRs/(EP-PA) composite is the lowest, and the carbon residue rate is the highest, which indicate that PW12O40-ZnAl LDHs improve the oxidation resistance of PW12O40-ZnAl-IFRs/(EP-PA) composite at high temperature. The back temperature experiment results show that under the same heat radiation intensity, the back temperature of PW12O40-ZnAl-IFRs/(EP-PA) composite reaches to 200℃ and 300℃ with the longest time and the lowest rate of back temperature rise. The results show that PW12O40-ZnAl LDHs can obviously enhance the fire resistance of EP-PA. From cone calorimetry experimental data, it can be seen that PW12O40-ZnAl-IFRs makes PW12O40-ZnAl-IFRs/(EP-PA) composite have the lowest peak of heat release rate(PHRR), mean heat release rate(MHRR), mean effective heat of combustion(MEHC) and total heat release(THR). Its fire growth index (FGI) is only 14.5% of IFRs/(EP-PA) composite, and the total smoke production (TSP) is 27.6% lower than NO3-ZnAl-IFRs/(EP-PA) composite and 55.3% lower than IFRs/(EP-PA) composite. The results suggest that PW12O40-ZnAl-IFRs is more effective than NO3-ZnAl-IFRs in reducing the heat release and inhibiting the generation of flue gas. -
表 1 层状双金属氢氧化物-膨胀阻燃剂/(环氧-聚酰胺树脂)(LDHs-IFRs/(EP-PA))复合材料配比
Table 1. Proportion of layered double hydroxides- intumescent flame retardants/(epoxy-polyamide resin) (LDHs-IFRs/(EP-PA)) composites
Sample EP/g PA/g IFRs/g LDHs/g NO3-ZnAl PW12O40-ZnAl IFRs/(EP-PA) 10 10 5.00 0 0 NO3-ZnAl-IFRs/(EP-PA) 10 10 3.75 1.25 0 PW12O40-ZnAl-IFRs/(EP-PA) 10 10 3.75 0 1.25 表 2 NO3-ZnAl LDHs 和 PW12O40-ZnAl LDHs的XRD衍射参数
Table 2. XRD parameters of NO3-ZnAl LDHs and PW12O40-ZnAl LDHs
Crystal face NO3-ZnAl LDHs PW12O40-ZnAl LDHs 2θ/(°) d/nm 2θ/(°) d/nm (003) 9.94 0.8888 7.96 1.1090 (006) 19.92 0.4452 18.24 0.4858 (009) 33.76 0.2651 33.36 0.2682 (110) 60.30 0.1533 60.40 0.1531 a/nm 0.3066 0.3061 c/nm 2.6660 3.3270 Notes:d—Interplanar distance; θ—Angle of deviation; a=2d(110); c=3d( 003). 表 3 NO3-ZnAl LDHs和PW12O40-ZnAl LDHs的元素分析结果
Table 3. Elemental analysis results of NO3-ZnAl LDHs and PW12O40-ZnAl LDHs
Sample Zn/wt% Al/wt% W/wt% Chemical formula NO3-ZnAl LDHs 5.57 42.80 – ${\rm{Z}}{{\rm{n}}_{{\rm{0}}{\rm{.76}}}}{\rm{A}}{{\rm{l}}_{{\rm{0}}{\rm{.24}}}}{{\rm{(OH)}}_{\rm{2}}}{{\rm{(N}}{{\rm{O}}_{\rm{3}}}{\rm{)}}_{{\rm{0}}{\rm{.24}}}} \cdot {\rm{0}}{\rm{.59}}{{\rm{H}}_{\rm{2}}}{\rm{O}}$ PW12O40-ZnAl LDHs 3.47 22.50 37.13 ${\rm{Z}}{{\rm{n}}_{{\rm{0}}{\rm{.73}}}}{\rm{A}}{{\rm{l}}_{{\rm{0}}{\rm{.27}}}}{{\rm{(OH)}}_{\rm{2}}}{{\rm{(P}}{{\rm{W}}_{{\rm{12}}}}{{\rm{O}}_{{\rm{40}}}}{\rm{)}}_{{\rm{0}}{\rm{.037}}}}{{\rm{(N}}{{\rm{O}}_{\rm{3}}}{\rm{)}}_{{\rm{0}}{\rm{.16}}}}$ $ \cdot {\rm{0}}{\rm{.58}}{{\rm{H}}_{\rm{2}}}{\rm{O}}$ 表 4 IFRs/(EP-PA)、NO3-ZnAl-IFRs/(EP-PA)和PW12O40-ZnAl-IFRs/(EP-PA)复合材料的TG数据
Table 4. TG data of IFRs/(EP-PA), NO3-ZnAl-IFRs/(EP-PA) and PW12O40-ZnAl-IFRs/(EP-PA) composites
Sample T5%/℃ T50%/℃ T70%/℃ Rmax1/(%·℃−1) Residue at 700℃/% IFRs/(EP-PA) 104.9 329.1 410.2 0.71 3.47 NO3-ZnAl-IFRs/(EP-PA) 86.1 328.3 415.7 0.69 4.42 PW12O40-ZnAl-IFRs/(EP-PA) 95.1 330.1 426.2 0.66 6.05 Notes: T5%, T50%, T70%—Temperature corresponding to 5%, 50% and 70% of degradation mass, respectively; Rmax1—Maximum degradation rate. 表 5 IFRs/(EP-PA)、NO3-ZnAl-IFRs/(EP-PA)和PW12O40-ZnAl-IFRs/(EP-PA)复合材料的背温实验结果
Table 5. Back temperature test results of IFRs/(EP-PA), NO3-ZnAl-IFRs/(EP-PA) and PW12O40-ZnAl-IFRs/(EP-PA) composites
Sample Fire resistance time/s V200℃/(℃·s−1) V300℃/(℃·s−1) t200℃ t300℃ IFRs/(EP-PA) 459.5 942.5 0.44 0.33 NO3-ZnAl-IFRs/(EP-PA) 618.0 916.0 0.32 0.32 PW12O40-ZnAl-IFRs/(EP-PA) 764.0 1 526.0 0.26 0.20 Notes: V200℃—Back temperature rising rate at 200℃;V300℃—Back temperature rising rate at 300℃. 表 6 IFRs/(EP-PA)、NO3-ZnAl-IFRs/(EP-PA)和PW12O40-ZnAl-IFRs/(EP-PA)复合材料的锥形量热实验数据
Table 6. Cone calorimetry test data of IFRs/(EP-PA), NO3-ZnAl-IFRs/(EP-PA) and PW12O40-ZnAl-IFRs/(EP-PA) composites
Sample TTI/$ \mathrm{s} $ PHRR/
(kW·m−2)MHRR/
(kW·m−2)THR/
(MJ·m−2)MEHC/
(MJ·kg−1)TSP/
(m2·m−2)FGI/
(kW·(s·m2)−1)IFRs/(EP-PA) 154.0 388.3 140.8 60.6 20.3 4.7 2.35 NO3-ZnAl-IFRs/(EP-PA) 227.0 317.5 118.5 39.4 20.2 2.9 1.48 PW12O40-ZnAl-
IFRs/(EP-PA)281.0 136.3 62.3 28.2 14.5 2.1 0.34 Notes: TTI—Ignition time; PHRR—Peak of heat release rate; MHRR—Mean heat release rate; THR—Total heat release; MEHC—Mean effective heat of combustion; TSP—Total smoke produce; FGI—Fire growth index. 表 7 EP-PA、IFRs/(EP-PA)、NO3-ZnAl-IFRs/(EP-PA)和PW12O40-ZnAl-IFRs/(EP-PA)复合材料的力学性能
Table 7. Mechanical properties of EP-PA, IFRs/(EP-PA), NO3-ZnAl-IFRs/(EP-PA) and PW12O40-ZnAl-IFRs/(EP-PA)composites
Sample Tensile strength/MPa Tear strength/(N·mm−1) Elongation at break/% EP-PA 11.47 42.83 10.87 IFRs/(EP-PA) 8.12 31.40 16.93 NO3-ZnAl-IFRs/(EP-PA) 7.86 30.23 19.60 PW12O40-ZnAl-IFRs/(EP-PA) 8.03 30.62 19.39 -
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