Study on the properties of flame-retardant epoxy resin HPCTP-DOPS/EP with double groups synergistic flame retardant effect
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摘要: 单一的磷杂菲、磷腈类阻燃剂的阻燃效果有限,为了改善9,10-二氢-9-氧杂-10-磷杂菲-10-硫化物(DOPS)对环氧树脂(EP)的阻燃效果,将DOPS和六苯氧基环三磷腈(HPCTP)复配应用于EP。在总含P量为1.2wt%时,通过调整磷杂菲和磷腈阻燃剂中含P量的比例,将DOPS和HPCTP复配添加到EP中,制备EP复合材料。利用极限氧指数(LOI)、垂直燃烧(UL-94)、热重(TG)、锥形量热(CONE)、扫描电镜-能量色散X射线谱(SEM-EDS)、热重-红外光谱联用(TG-IR)等测试手段研究不同比例的磷杂菲和磷腈基团对EP热稳定性和阻燃性能的影响,探究双基协同阻燃规律和机制。研究结果表明:P、S元素之间存在协同阻燃作用,当总含P量为1.2wt%时,复合体系中随着含S量的增加,HPCTP-DOPS/EP的LOI值和UL-94等级逐渐升高,当HPCTP和DOPS中的含P量比为0.2∶1时,HPCTP-DOPS/EP的LOI值为30.4%,达到UL-94 V-0级,总热释放量(THR)和热释放速率峰值(PHRR)显著降低,燃烧后形成了更加致密、稳定的膨胀炭层,优于两种阻燃剂单独使用对EP的阻燃效果,即磷腈和磷杂菲两种阻燃剂之间存在着协同阻燃效应。从阻燃机制看,DOPS和HPCTP分别在气相和凝聚相发挥协同阻燃作用。
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关键词:
- 9,10-二氢-9-氧杂-10-磷杂菲-10-硫化物(DOPS) /
- 六苯氧基环三磷腈(HPCTP) /
- 复配 /
- 环氧树脂 /
- 协同效应
Abstract: The flame retardant effect of single phosphaphenanthrene and phosphazenes was limited. In order to improve the flame retardant effect of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-sulfide (DOPS) on epoxy resin (EP), DOPS and hexa (phenoxy) cyclotriphosphazene (HPCTP) were compounded and applied in EP. When the total P content was 1.2wt%, DOPS and HPCTP were added to EP by adjusting the ratio of P content in the phosphaphenanthrene and phosphazene groups to prepare EP composites. The limiting oxygen index test (LOI), vertical flame test (UL-94), thermogravimetric analysis (TGA), cone calorimeter test (CONE), scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS) and thermogravimetric-infrared spectroscopy analysis (TG-IR) were used to study the effects of different proportions of phosphaphenanthrene and phosphazene groups on the thermal stability, and combustion performance of EP, and explored the law and mechanism of double groups synergistic flame retardancy. The results show that there is synergistic flame retardancy between P and S elements. When the total P content is 1.2wt%, the LOI value and UL-94 grade of HPCTP-DOPS/EP increase with the increase of S content in the composite system. and the ratio of P content between HPCTP and DOPS is 0.2∶1, the LOI of HPCTP-DOPS/EP composite system is 30.4%, reaching UL-94 V-0 grade, the total heat release (THR) and peak heat release rate (PHRR) decreased significantly, The EP/HPCTP/DOPS composite has a more dense and stable expanding carbon layer after combustion, which is superior to the flame retardant effect of the two flame retardants on EP solely, there is a synergistic flame retardant effect between the phosphazene and phosphaphenanthrene flame retardants. From the perspective of flame retardant mechanism, DOPS and HPCTP plays a flame retardant role in gas phase and condensed phase respectively. -
表 1 阻燃环氧树脂(EP)复合材料(总含P量1.2wt%)的配方设计
Table 1. Formulation of flame retardant epoxy resin (EP) composites (Total P content 1.2wt%)
Sample P/wt% S/wt% EP/g DDS/g HPCTP/g DOPS/g P(HPCTP)∶P(DOPS) EP 0.0 3.09 100 31.6 — — 0∶0 1.2HPCTP/EP 1.2 2.82 100 31.6 12.94 0.00 1.2∶0 1.0HPCTP/0.2DOPS/EP 1.2 3.03 100 31.6 10.79 2.17 1.0∶0.2 0.8HPCTP-0.4DOPS/EP 1.2 3.23 100 31.6 8.63 4.33 0.8∶0.4 0.6HPCTP-0.6DOPS/EP 1.2 3.44 100 31.6 6.47 6.50 0.6∶0.6 0.4HPCTP-0.8DOPS/EP 1.2 3.65 100 31.6 4.31 8.66 0.4∶0.8 0.2HPCTP-1.0DOPS/EP 1.2 3.85 100 31.6 2.16 10.83 0.2∶1.0 1.2DOPS/EP 1.2 4.06 100 31.6 0.00 13.00 0∶1.2 Notes: DDS—4,4'-diaminodiphenyl sulfone; HPCTP—Hexa (phenoxy) cyclotriphosphazene; DOPS—9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-sulfide; P(HPCTP)∶P(DOPS)—Ratio of P content in flame retardants HPCTP and DOPS. 表 2 EP及其复合材料的极限氧指数(LOI)和垂直燃烧(UL-94)数据
Table 2. Limiting oxygen index test (LOI) and vertical flame test (UL-94) data of EP and EP composites
Sample LOI/% UL-94 t1/t2(s) Dripping Rating EP 22.2 —/— No N.R. 1.2HPCTP/EP 28.8 4.58/— No N.R. 1.0HPCTP-0.2DOPS/EP 29.4 2.73/47.08 No V-1 0.8HPCTP-0.4DOPS/EP 29.5 5.30/32.52 No V-1 0.6HPCTP-0.6DOPS/EP 29.9 5.44/11.57 No V-1 0.4HPCTP-0.8DOPS/EP 30.0 2.17/10.22 No V-1 0.2HPCTP-1.0DOPS/EP 30.4 2.63/7.28 No V-0 1.2DOPS/EP 29.7 4.93/10.99 No V-1 Notes: t1/t2—First and second combustion time in UL-94 test. 表 3 EP及其复合材料在N2下的TG和DTG数据
Table 3. TG and DTG data of EP and EP composites in N2
Sample T5%/℃ TP1/℃ TP2/℃ Rmax1/(%·℃−1) Rmax2/(%·℃−1) Char residue at
600℃/%DOPS 205.71 221.20 379.30 0.30 0.82 7.45 HPCTP 341.33 424.67 — 1.65 — 3.51 EP 376.84 411.08 — 1.93 — 14.18 1.2HPCTP/EP 307.02 377.69 — 1.09 — 23.43 0.2HPCTP-1.0DOPS/EP 296.97 377.83 — 0.81 — 26.06 1.2DOPS/EP 287.91 378.60 — 0.84 — 22.22 Notes: T5%—Temperature corresponding to mass loss 5wt% of material; TP—Temperature corresponding to maximum thermal degradation rate; Rmax—Maximum thermal degradation rate. 表 4 EP及其复合材料的锥形量热测试数据
Table 4. Cone calorimeter test data of EP and EP composites
Sample TTI/s PHRR/
(kW·m−2)THR/
(MJ·m−2)av-EHC/
(MJ·kg−1)TSR/
(m2·m−2)av-CO2Y/
(kg·kg−1)av-COY/
(kg·kg−1)EP 75 1235.10 116.49 30.67 2250.92 4.39 0.42 1.2HPCTP/EP 72 525.34 93.74 30.77 1976.23 3.32 0.55 0.2HPCTP-1.0DOPS/EP 63 513.57 99.21 27.92 2197.75 3.37 0.45 1.2DOPS/EP 59 583.18 103.87 27.28 2271.40 3.80 0.53 Notes: TTI—Time to ignition; PHRR—Peak heat release rate; THR—Total heat release; av-EHC—Average effective heat of combustion; TSR—Total smoke release; av-CO2Y—Average carbon dioxied yield; av-COY—Average carbon monoxide yield. 表 5 EP及其复合材料残炭的EDS数据
Table 5. EDS data of char residue of EP and EP composites
Sample C/wt% O/wt% P/wt% S/wt% EP 78.78 20.97 ─ 0.25 1.2HPCTP/EP 56.28 35.85 7.38 0.49 0.2HPCTP-1.0DOPS/EP 75.81 17.23 5.50 1.46 1.2DOPS/EP 73.33 22.02 3.73 0.92 -
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