环交联聚磷腈包覆羟基锡酸锶杂化纳米棒的合成及阻燃环氧树脂研究

doi:10.15541/jim20180493

摘要/Abstract

摘要：

为了开发新型无机-有机杂化的阻燃消烟剂, 本研究采用共沉淀法合成了棒状纳米羟基锡酸锶(SrSn(OH)₆), 并用环交联聚磷腈(PZS)对其进行包覆, 得到一种核壳结构的有机无机杂化纳米阻燃剂(PZS@SrSn(OH)₆)。通过扫描电镜、透射电镜和红外光谱研究了PZS@SrSn(OH)₆的微观形貌和化学结构。通过热重分析研究了PZS@SrSn(OH)₆及EP/PZS@SrSn(OH)₆阻燃复合材料的热降解行为。采用极限氧指数和锥形量热对复合材料阻燃性能进行测试, 用X射线衍射、扫描电镜、能谱分析及红外光谱对EP/PZS@SrSn(OH)₆的阻燃机理进行分析。结果表明PZS@SrSn(OH)₆在环氧树脂中展现出高阻燃效率和抑烟效果, 且PZS与SrSn(OH)₆之间存在显著的协同阻燃效应。与纯环氧树脂相比, 仅添加3wt%的PZS@SrSn(OH)₆时, 极限氧指数(LOI)值从26.2%增加到29.6%。锥形量热结果表明热释放速率峰值降低了约29%, 烟释放速率峰值降低了约37%, 残炭率提高了242%。PZS@SrSn(OH)₆在高温下形成致密结构炭层, 隔绝分解产物及热量和氧气交换, 从而显著提高环氧树脂的阻燃效果。

关键词: 磷腈, 羟基锡酸锶, 杂化, 阻燃, 纳米复合材料

Abstract:

To develop a novel hybrid organic-inorganic flame retardant and smoke suppressant, strontium hydroxystannate (SrSn(OH)₆) nanorods were synthesized via a co-precipitation method, and then the SrSn(OH)₆ were encapsulated by cyclomatrixpolyphosphazene (PZS) to prepare a novel core-shell organic-inorganic hybrid nano-flame retardant (PZS@SrSn(OH)₆). The micromorphology and chemical structure were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and fourier transform infrared spectroscopy (FT-IR). The thermal degradation of PZS@SrSn(OH)₆and EP/PZS@SrSn(OH)₆ composites was investigated by thermogravimetry analysis (TGA). The flame retardancy properties were studied by limited oxygen index (LOI) and CONE calorimetry tests. The flame retardant mechanism was determined by X-ray diffraction (XRD), SEM, energy-dispersive X-ray spectroscopy (EDS), and FT-IR. The results showed that PZS@SrSn(OH)₆ exhibited high flame retardant and smoke suppression efficiency. Significant synergy between PZS and SrSn(OH)₆ was found to enhance the flame retardancy of EP compared with pure EP, the LOI value was increased from 26.2% to 29.6% with 3wt% addition of PZS@SrSn(OH)₆. CONE calorimetry tests indicated that 3% incorporation of PZS@SrSn(OH)₆ brought about 29% and 37% maximum reduction in peak heat release rate and peak smoke production rate, and 242% improvement of char residue, respectively. A dense char structure is formed after combustion under elevated temperature for PZS@SrSn(OH)₆, and the char layer blocks the exchange between the decomposed fragments and oxygen, then protect EP matrix and improve the flame retardancy.

Key words: polyphosphazene, strontium hydroxystannate, hybrid, flame retardancy, nanocomposites

中图分类号:

O631

张冲, 耿晓维, 高香迪, 张欣, 郭娆, 王宇静, 徐建中, 马海云. 环交联聚磷腈包覆羟基锡酸锶杂化纳米棒的合成及阻燃环氧树脂研究[J]. 无机材料学报, 2019, 34(7): 761-767.

ZHANG Chong, GENG Xiao-Wei, GAO Xiang-Di, ZHANG Xin, GUO Rao, WANG Yu-Jing, XU Jian-Zhong, MA Hai-Yun. Strontium Hydroxystannate Nanorods Encapsulated by Hybrid Polyphosphazene: Synthesis and Flame Retardancy on Epoxy Resin[J]. Journal of Inorganic Materials, 2019, 34(7): 761-767.

图/表 10

图1 SrSn(OH)6及PZS@SrSn(OH)6的合成路线图

Fig. 1 Synthetic routes of the SrSn(OH)6 and PZS@SrSn(OH)6

图2 SrSn(OH)6及PZS@SrSn(OH)6的微观形貌及其元素分布图 (a, b) SrSn(OH)6; (c, d, e) PZS@SrSn(OH)6

Fig. 2 Morphologies and element distribution map of SrSn(OH)6 and PZS@SrSn(OH)6

图3 PZS, SrSn(OH)6和PZS@SrSn(OH)6在N2氛围中测得的热失重曲线(a)和失重微分曲线(b)

Fig. 3 TG (a) and DTG (b) curves of SrSn(OH)6, PZS and PZS@SrSn(OH)6 tested in N2 atmosphere

图4 EP纳米复合材料在N2氛围中测得的热失重曲线(a)和失重微分曲线(b)

Fig. 4 TG (a) and DTG (b) curves of EP nanocomposites tested in N2 atmosphere

表1 PZS, SrSn(OH)6, PZS@SrSn(OH)6及其EP纳米复合材料的热降解数据

Table 1 Thermogravimetric properties of PZS, SrSn(OH)6, PZS@SrSn(OH)6 and EP nanocomposites

Sample	T_5%/℃	T_max/℃	Residue at 800 ℃/wt%	Theoretical residue at 800 ℃/wt%
PZS	442.8	507.9	48.2	—
SrSn(OH)₆	217.3	237.7	80.4	—
PZS@SrSn(OH)₆	218.5	487.5	69.4	—
Pure EP	364.2	375.3	13.0	—
3% EP/SrSn(OH)₆	354.0	367.3	16.2	15.0
3% EP/PZS@SrSn(OH)₆	360.0	368.6	17.0	14.7

图5 EP及其纳米复合材料的极限氧指数及测试后残炭形貌

Fig. 5 LOI values and residue chars at the end of LOI tests of EP, EP/SrSn(OH)6 and EP/PZS@SrSn(OH)6 nanocomposites

图6 EP及其纳米复合材料的热释放速率(a), 质量损失(b), 烟释放速率(c)和CO释放速率(d)

Fig. 6 Heat release rate (HRR) (a), specimen mass (b), smoke production rate SPR (c), and CO production rate (d) curves of the samples in CONE tests

表2 EP及其纳米复合材料的锥形量热数据

Table 2 Cone calorimetry data for EP composites

Sample	Pure EP	1wt% EP/SrSn(OH)₆	3wt% EP/SrSn(OH)₆	1wt% EP/PZS@SrSn(OH)₆	3wt% EP/PZS@SrSn(OH)₆
Char residue/g	5.6	13.2	12.4	13.8	19.2
THR/(MJ·m^-2)	100.4	93.2	92.6	93.1	88.9
PHRR/(kW·m^-2)	1141.1	971.7	888.9	777.3	809.7
PSPR/(m²·s)	0.33	0.25	0.24	0.22	0.21
TSP/m²	27.6	23.7	23.9	25.1	21.2

图7 EP及其纳米复合材料锥形量热后残炭宏观形貌

Fig. 7 Digital photos of the char residues for composites after cone calorimeter tests (a,f) EP; (b,g) 1wt% EP/SrSn(OH)6; (c,h)3wt% EP/SrSn(OH)6; (d,i) 1wt% EP/PZS@SrSn(OH)6; (e,j) 3wt% EP/PZS@SrSn(OH)6

图8 EP及其纳米复合材料残炭的XRD(a), EDS(b)及FTIR(c)图谱

Fig. 8 XRD (a), EDS (b) and FT-IR (c) spectra of the char residue of EP samples

参考文献 18

[1]	SHAO Z B, ZHANG M X, LI Y , et al. A novel multi-functional polymeric curing agent: synthesis, characterization, and its epoxy resin with simultaneous excellent flame retardance and transparency. Chem. Eng. J., 2018,345:471-482. DOI URL
[2]	QIAN L J, QIU Y, WANG J Y , et al. High-performance flame retardancy by char-cage hindering and free radical quenching effects in epoxy thermosets. Polymer, 2015,68:262-269. DOI URL
[3]	JIAN X Y, HE Y, LI Y D , et al. Curing of epoxidized soybean oil with crystalline oligomeric poly(butylene succinate) towards high performance and sustainable epoxy resins. Chem. Eng. J., 2017,326:875-885. DOI URL
[4]	WANG P, XIA L, JIAN R K , et al. Flame-retarding epoxy resin with an efficient P/N/S-containing flame retardant: preparation, thermal stability, and flame retardance. Polym. Degrad. Stabil., 2018,149:69-77. DOI URL
[5]	CHEN T, CHEN X M, WANG M J , et al. A novel halogen-free co-curing agent with linear multi-aromatic rigid structure as flame- retardant modifier in epoxy resin. Polym. Advan. Technol., 2018,29(1):603-611. DOI URL
[6]	XIE H L, LAI X J, LI H Q , et al. Fabrication of ZrP nanosheet decorated macromolecular charring agent and its efficient synergism with ammonium polyphosphate in flame-retarding polypro-pylene. Compos. Part A-Appl. S., 2018,105:223-234. DOI URL
[7]	YANG Y Y, LIU J, CAI X F . Antagonistic flame retardancy between hexakis(4-nitrophenoxy) cyclotriphosphazene and potassium diphenylsulfone sulfonate in the PC system. J. Therm. Anal. Calorim., 2016,126(2):571-583. DOI URL
[8]	SHI X X, PENG X F, ZHU J Y , et al. Synjournal of DOPO-HQ-functionalized graphene oxide as a novel and efficient flame retardant and its application on polylactic acid: thermal property, flame retardancy, and mechanical performance.[J]. Colloid. Interf. Sci., 2018,524:267-278. DOI URL
[9]	YANG W, TAWIAH B, YU C , et al. Manufacturing, mechanical and flame retardant properties of poly(lactic acid) biocomposites based on calcium magnesium phytate and carbon nanotubes. Compos. Part A-Appl. S., 2018,110:227-236. DOI URL
[10]	CHEN G G, HU Y J, PENG F , et al. Fabrication of strong nanocomposite films with renewable forestry waste/montmorillonite/ reduction of graphene oxide for fire retardant. Chem. Eng. J., 2018,337:436-445. DOI URL
[11]	ZHANG B, LIU H, HAN J . Synthesis of zinc hydroxystannate microcapsule for improving flame retardancy and smoke suppression of poly(lactic acid). Mater.Lett., 2018,213:35-39. DOI URL
[12]	XU R, DENG B, MIN L , et al. CuSn(OH)₆ submicrospheres: room-temperature synthesis and weak antiferromagnetic behavior. Mater. Lett., 2011,65(4):733-735. DOI URL
[13]	GAO T T, SANG B, SHAO B , et al. Flame retardancy and mechanical properties of a novel zinc hydroxystannate/epoxy resin nanocomposite. J. Nanosci.Nanotech no., 2017,17(12):8856-8863. DOI URL
[14]	QIU S L, MA C, WANG X , et al. Melamine-containing polyphosphazene wrapped ammonium polyphosphate: a novel multifunctional organic-inorganic hybrid flame retardant.[J]. Hazard. Mater., 2018,344:839-848. DOI URL
[15]	YANG R, WANG B, HAN X F , et al. Synthesis and characterization of flame retardant rigid polyurethane foam based on a reactive flame retardant containing phosphazene and cyclophosphonate. Polym. Degrad. Stabil., 2017,144:62-69. DOI URL
[16]	ZHAO S S, HE M, SONG W Y , et al. Synthesis of a phosphorus/ nitrogen/sulphur containing phosphazene micro-nanotube and its flame retardancy on epoxy nanocomposite. Chem. J. Chinese U., 2017,38(12):2337-2343.
[17]	LI P, FU H, ZHAO O , et al. Influence of polyphosphate flame retardant couple with ammonium polyphosphate on epoxy resin. Chem. J. Chinese U., 2017,38(2):294-302.
[18]	WEN P Y, WANG X F, XING W Y , et al. Synthesis of a novel triazine- based hyperbranched char foaming agent and the study of its enhancement on flame retardancy and thermal stability of polypropylene. Ind. Eng. Chem. Res., 2013,52(48):17015-17022. DOI URL