【作者】 张璇；

【导师】 毛志平；

【作者基本信息】 东华大学 ， 纺织化学与染整工程， 2014， 博士

【摘要】 材料的阻燃是长期以来科学研究中的重要课题。传统卤素阻燃剂在阻燃过程中会产生有毒物质,为了满足目前对环境保护的要求,阻燃剂的无卤化已成为发展趋势。近年来,含磷阻燃剂因其优异的阻燃性能,逐渐成为研究者的研究热点。环三磷腈化合物是一类由磷、氮原子以单、双键交替键合而成的环状化合物,分子中有三个磷原子,通过在磷原子上连接不同的官能团,得到不同的功能性化合物。磷腈类化合物其结构中的磷、氮元素具有协同阻燃效应,故可得到较好的热稳定性和阻燃性能,而且在热分解时不产生毒性较大的物质,符合人们对阻燃剂低毒、低污染、低腐蚀性的要求。聚酯(PET)和聚氨酯(PU)是两种重要的聚合物,因其优异的综合性能,广泛地用于服装面料、包装材料、工程塑料、电子工业、汽车工业和石油工业等领域。但是PET和PU极易燃烧,限制了其在某些方面的应用,因此开发阻燃PET和阻燃PU尤为重要。对于PET和PU来说,含磷阻燃剂是一类较为有效的阻燃剂,常用的阻燃剂有磷酸酯、氧化磷、有机磷酸盐等。本论文分别用4-硝基苯酚、对羟基苯甲醛取代六氯环三磷腈,合成了两种磷腈阻燃剂,改进了合成方法,对其结构进行了表征；分别研究了两种阻燃剂对PET和PU的阻燃性能影响,探讨了阻燃机理；研究了阻燃剂六(4-硝基苯氧基)环三磷腈(HNCP)和增容剂马来酸酐接枝乙烯-辛烯共聚物(POE-g-MA)对PET的协同抗熔滴作用。(1)环三磷腈衍生物的合成及表征采用一种新体系制备环三磷腈衍生物,以六氯环三磷腈、4-硝基苯酚或对羟基苯甲醛为原料,K2CO3作缚酸剂,丙酮或四氢呋喃为溶剂,合成六(4-硝基苯氧基)环三磷腈(HNCP)和六(4-醛基苯氧基)环三磷腈(HAPCP),简化了合成过程,缩短了反应时间。研究了六(4-硝基苯氧基)环三磷腈还原制备六(4-氨基苯氧基)环三磷腈(HACP)的反应。采用水合肼作还原剂,Pd/C为催化剂,消除了传统反应中黑色不溶物的影响,提高了产率。通过傅立叶变换红外光谱(FTIR)、核磁共振(NMR)氢谱、磷谱、元素分析(EA)对反应产物进行了结构分析表征。(2)环三磷腈阻燃剂在PET中的应用及性能研究利用合成的磷腈阻燃剂HNCP和HAPCP分别对PET进行阻燃改性,通过熔融共混法制备阻燃PET复合材料。通过热重分析(TGA)研究了两种阻燃剂对PET热稳定性能的影响,结果表明两种阻燃剂的加入,均可降低PET的起始分解温度和最大降解速率；在氮气和空气气氛中,600℃下,HNCP和HAPCP都可以提高PET的残炭量,HAPCP的成炭效果更优。通过极限氧指数(LOI)、垂直燃烧测试(UL-94)研究了阻燃剂对PET阻燃性能的影响。结果表明：PET/HNCP阻燃复合材料的LOI值最高可达35.1%,通过垂直燃烧实验,UL-94等级达到V-0等级；PET/HAPCP阻燃复合材料的LOI值最高可达34.3%,UL-94测试中仅当HAPCP含量为10wt.%时,可达V-0等级,其余样品均为V-2级,但HAPCP的加入,缩短了PET的余焰和余燃时间。SEM结果表明,HNCP和HAPCP阻燃的PET燃烧后形成的炭层表面平滑致密、内部疏松多孔,这种炭层结构有利于阻碍基材与外界环境之间的物质交换,起到隔热、隔氧的作用,是理想的防护结构。热降解动力学的研究说明,阻燃剂HNCP、HAPCP在降解初期可降低PET的降解活化能,促进PET成炭。在高降解转化率时,阻燃PET的降解活化能比纯PET的高,这是由于阻燃PET在降解前期形成了热稳定性能较高的炭层。(3) HNCP和POE-g-MA在PET中的协同抗熔滴作用在PET/10wt.%HNCP阻燃复合材料中添加增容剂POE-g-MA,研究了HNCP与POE-g-MA在PET中的协同抗熔滴作用。TGA结果表明,POE-g-MA不能提高PET的热稳定性能和残炭量,而HNCP可以有效地提高PET的热稳定性能并促进PET成炭。因此,HNCP的加入使得PET/10wt.%HNCP/POE-g-MA复合材料的热稳定性能优于纯PETo PET/10wt.%HNCP/POE-g-MA的LOI值最高可达28.3%,当POE-g-MA含量达3wt.%时,阻燃PET熔滴现象消失。DSC测试结果证明, POE-g-MA可改善HNCP与PET的相容性。SEM测试发现,PET/10wt.%HNCP/POE-g-MA复合材料燃烧后炭层的内部孔径较小,且分散均匀。这说明POE-g-MA改善了HNCP与PET的相容性,有利于HNCP在燃烧时形成连续平整的保护炭层,从而提高PET的阻燃性能和抗熔滴性能。HNCP可与POE-g-MA产生协同作用,有效地提高了PET的抗熔滴性能。(4)环三磷腈阻燃剂在PU中的应用及性能研究分别将HNCP和HAPCP加入到聚氨酯涂膜液中,采用湿法成膜制备了阻燃PU。TGA实验结果表明,在氮气和空气中,HNCP和HAPCP阻燃PU的热稳定性能和成炭能力都得到了提高,并且HAPCP促进PU成炭的效果更为明显。HNCP和HAPCP都可以提高PU的极限氧指数,但阻燃PU的熔滴严重,没有通过垂直燃烧测试,UL-94等级为VTM-2级；续燃和阴燃时间均大大缩短,提高了PU的离火自熄性能。炭渣的FTIR表明,阻燃剂中的磷、氮元素仍留在残渣中。SEM测试显示,两种阻燃PU的炭层表面虽没有孔洞,但不太平滑,这种炭层结构隔热、隔氧效果不够理想,因此阻燃性能没有显著提升。热降解动力学研究发现,阻燃剂HNCP和HAPCP均可在降解前期降低PU的降解活化能；在降解后期,阻燃PU形成稳定性更高的炭层,因此降解活化能要高于纯PU。更多还原

【Abstract】 The preparation of flame resistant materials has been an important issue in scientific research for a long time. The traditional halogen flame retardants produce toxic gas and smoke as burning. It needs to develop non-halogenated flame retardants to meet the requirements of environmental protection. Over the past decade, there is a sustained research interest on the phosphorus-containing flame retardants which have excellent flame retardant properties. Cyclotriphosphazene is a kind of ring material which contains alternating phosphorus and nitrogen atoms. There are three phosphorus atoms in a cyclophosphazene molecule which are active to be substituted by different nucleophiles. Multifunctional compounds can be obtained by replacing the chlorine groups with various functional substituents. Phosphazenes exhibit good thermal stability and flame retardancy for the synergistic flame retardant effect of phosphorus and nitrogen. Due to less toxic gas and smoke as burning, the phosphazene-based materials are able to fulfill the requirements of flame retardant which have low toxicity, pollution and corrosive. Poly (ethylene terephthalate)(PET) and polyurethane (PU) are two important polymers in modern industry. For the outstanding properties, PET and PU are widely used in various areas such as surface coatings, fibers, electronic industry, automobile industry, petroleum engineering and barrier materials. However, the flammability of PET and PU polymers limit their applications in some special fields. Therefore, it is important to develop flame retardancy of PET and PU. Phosphorus-containing flame retardants are effective to PET and PU, containing phosphate, phosphorus oxide, organic phosphate and so on. In this paper, two kinds of cyclotriphosphazene flame retardants are synthesized via a simple method, and the structure of the flame retardants are investigated. The effects of flame retardants on the thermal and flame retardancy of PET and PU are mainly investigated. And then, the synergic effect of hexakis (4-nitrophenoxy) cyclotriphosphazene (HNCP) and maleic anhydride grafted ethylene-octene copolymer (POE-g-MA) on the anti-dripping of PET is also studied.(1) The synthesis and characteristic of cyclotriphosphazene derivativesCyclotriphosphazene derivatives were synthesized in a new system. Hexakis (4-nitrophenoxy) cyclotriphosphazene (HNCP) and hexakis (4-formacylphenoxy) cyclotriphosphazene (HAPCP) were prepared by reacting hexachlorocyclotriphospha zene with4-nitrophenol, p-hydroxybenzaldehyde respectively, using potassium carbonate as acid binding agent, acetone or tetrahydrofuran as solvent. It was simplified the reaction process and shortened the reaction time. It was restudied the reduction of hexakis (4-nitrophenoxy) cyclotriphosphazene to hexakis (4-aminophenoxy) cyclotriphosphazene (HACP). The reduction was catalyzed by Pd/C in tetrahydrofuran, using hydrazine hydrate as reducing agent. This method eliminated the influence of dark insoluble matters and improved the yield. The structures of products were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and element analysis (EA).(2) Application of cyclotriphosphazene flame retardants in PET and study of the properties of flame retarded PETThe cyclotriphosphazene flame retardants HNCP and HAPCP were added into PET to improve its flame retardancy by melt blending. The effects of HNCP and HAPCP on the thermal stability of PET were investigated by TGA. The results revealed that the addition of flame retardants could reduce the initial degradation temperature and the maximum mass loss rate while the char formation of PET was improved by HNCP and HAPCP both in nitrogen and in air atmosphere. The flame retardancy of the flame retarded PET was studied by LOI and vertical burning test (UL-94test). It was found that the LOI value of PET/HNCP was up to35.1%and could pass UL-94V-0. For the PET/HAPCP, the value of LOI was up to34.3%. Although the UL-94grade was V-2except the sample which the content of HAPCP was10wt.%, the afterflame time and the afterglow time were reduced. SEM graphs showed the outer of residue of flame retarded PET after burning appeared smooth and compact but the inner was frothy and swollen. This structure of char layer was an ideal insulation structure. It was helpful to hinder the exchange between the substrate and external environment. The degradation behavior of flame retarded PET was studied by TGA. The results declared that HNCP and HAPCP could reduce the degradation activation energies (E) of flame retarded PET and promote the char formation in the early degradation. While the E of flame retarded PET was higher than that of PET at high degradation conversion degree. It meant that flame retarded PET had a better thermal stability of char formed than PET.(3) The synergistic effect of HNCP and POE-g-MA on the improvement of the dripping resistance of PETPOE-g-MA was added to PET/10wt.%HNCP composite by melt blending. The synergic effect to improve the dripping resistance of PET was investigated. TGA results suggested POE-g-MA had no improvement on the thermal stability and the final char yield of PET while the presence of HNCP would promote charring processes. The thermal stability of PET/10wt.%HNCP/POE-g-MA was better than PET meanwhile the LOI value was up to28.3%. When the loading of POE-g-MA increased to3wt.%, the flame retarded PET achieved a V-0rating with no dripping. DSC illustrated POE-g-MA improved the compatibility between PET and HNCP. It was found that the inner side of the char layer of PET/10wt.%HNCP/POE-g-MA was a frothy internal structure with many uniform microporous cells. That was to say the presence of POE-g-MA increased the compatibility and dispersion between PET and HNCP. It was in favor of forming a more continuous char layer by HNCP which was effective to improve the flame retardancy and anti-dripping of PET in fire. The flame retarded PET with anti-dipping property was obtained by the synergic effect of HNCP and POE-g-MA.(4) Application of cyclotriphosphazene flame retardants in PU and study of the properties of flame retarded PUThe flame retarded PU was prepared by incorporating HNCP and HAPCP into the PU coating solution through wet film forming process, respectively. TGA results showed that the thermal stability and the char formation of PU were enhanced with HNCP and HAPCP both in nitrogen and in air atmosphere. HAPCP was more effective than HNCP on promoting the char formation of PU. Both HNCP and HAPCP could improve the LOI value of PU though they did not pass the vertical burning test and UL-94grade was VTM-2for the heavy dripping. The afterflame time and afterglow time were reduced greatly which meant self-extinguishing property of PU was improved. The FTIR spectra provided evidence that phosphorus and nitrogen elements still remained in the residue of PU after burning. SEM graphs revealed the outer of residue of flame retarded PU after burning was not smooth. It was not an ideal char structure for insulation. So, the flame retardancy properties of PU were not significantly enhanced. In the study of the degradation behavior of flame retarded PU, it was found the degradation activation energies (E) of flame retarded PU were reduced by HNCP and HAPCP at the early degradation stage. E of flame retarded PU increased at high degradation conversion degree in comparison with pure PET due to the formation of char with better thermal stability.更多还原