【作者】 夏新年；

【导师】 徐伟箭；

【作者基本信息】 湖南大学 ， 应用化学， 2006， 博士

【摘要】 环氧树脂由于具有粘接强度高、电绝缘性能好、优良的耐化学腐蚀性和良好的加工性能等,广泛应用在国民经济的各个领域,可用作涂覆材料、增强材料、浇涛材料及胶粘剂等。但由于环氧树脂的易燃性使其应用受到限制,开发阻燃环氧树脂成了环氧树脂的重要研究方向。磷、氮系阻燃环氧树脂由于具有无卤、低烟、低毒、高阻燃效率等特性,且符合当今生态环境保护的要求,已越来越被国际阻燃界广泛重视。本文在含磷、氮环氧固化物的合成与应用方面进行了深入的研究和讨论。本论文共分六个部分,内容包括:绪论;有机磷杂环化合物2-(5,5-二甲基-4-苯基-2-氧代-1,3,2-二氧磷杂环已烷膦酸酯基)-对苯二酚(DPODB)的合成、表征及性能研究;含马来酰亚胺环氧固化剂的合成与性能研究;含磷、氮自膨胀型阻燃环氧固化剂的合成与性能及热分解机理的研究;阻燃环氧树脂的热降解行为及成炭机理研究;结论。有机磷杂环化合物具有磷杂环的特殊的环状结构及较高的耐热稳定性、耐氧化等特点,将其引入到环氧树脂分子骨架中可有效提高环氧固化物的耐热性和阻燃性,因此合成反应型含磷杂环氧体系日益受到人们的重视。本论文从苯甲醛、异丁醛、三氯化磷和对苯醌出发,首次合成了一种新型的有机磷杂环二元酚DPODB,采用元素分析、红外光谱(FTIR)、1H NMR、31P NMR及质谱法对DPODB的分子结构进行了表征;并用DPODB作为扩链剂合成了一种分子结构中含磷的环氧树脂,采用元素分析、FTIR和凝胶渗透色谱法(GPC)对树脂的结构和分子量分布进行了表征。用热失重法(TG-DTG)与示差扫描量热法(DSC)对相应环氧固化物体系的热性能进行了研究。结果显示,该含磷固化体系具有较高的热分解温度,热分解速率缓慢且分解温区很宽(335~605℃);阻燃性能测试表明该含磷化合物阻燃效率较高,当树脂中含磷量仅为2.83%时,固化体系的阻燃与含溴量为17.12%的树脂固化体系相当。酚醛树脂由于其优异的性能而常用作环氧树脂的固化剂,向酚醛树脂分子链上引入阻燃官能团,并将这种酚醛树脂用作环氧固化剂,则可大大提高树脂的阻燃性能。本文将结构性阻燃官能团N-马来酰亚胺作为环氧固剂,合成了一系列含N-马来酰亚胺的酚醛树脂(PMF)。研究了PMF/CNE(酚醛环氧)固化体系的热稳定性,阻燃性能、耐溶剂性及抗拉伸性能。对比研究得出,PMF/CNE体系具有良好的热稳定性和阻燃性能以及较优的抗拉伸性能。磷-氮膨胀型阻燃体系因其独特的阻燃机体和高阻燃效率,近年来成为国际阻燃领域广泛关注的新型复合阻燃剂。而自膨胀型阻燃体系由于较添加型体系具有更优的相溶性、更强的耐水性和更好的热稳定性等特点,这一体系在今后将取得长足的发展。本文利用反应型阻燃剂与不饱和高聚物反应,首次合成了两种含磷的马来酰亚胺酚醛树脂,并将其作为环氧固化剂制备阻燃性的环氧固化物。采用热分析法、极限氧指数法对相应环氧固化物的耐热性能和阻燃性能进行了表征。研究结果表明:该含磷聚合物作为环氧树脂的固化剂,对稳定固化物骨架碳的结构和交联成炭能力的提高起到了增强作用;环氧固化物具有较高的玻璃化转变温度(145.4℃)和较高的热稳定性(T5% 308℃),极限氧指数显示其具有较好的阻燃性能。利用热-红联用的方法分析了几种不同阻燃体系,即含氮体系(酚醛环氧树脂/马来酰亚胺酚醛,CNE/PMF)、含磷体系(含DOPO环氧树脂/邻甲酚醛树脂(DOPO-CNE/PN))、含磷氮体系((DOPO-CNE/PMF)和CNE/DOPO-PMF(含磷酚醛树脂))的高温热氧化机理。研究结果表明:环氧固化物的热降解过程与聚合物的结构、阻燃元素的种类及元素存在的结构状态有密切的关系。P/N体系在较低温度下有磷酸胺官能团出现,参与交联成炭反应,但在高温下出现C=N,形成氮杂环化合物结构。采用X-光射线光电子能谱(XPS)测定了不同P/N体系,即DOPO-CNE/PMF和CNE/DOPO-PMF固化体系在不同温度下的碳层结构谱图,并对C1s、N1S吸收峰进行了曲线拟合。研究结果显示:P/N阻燃体系在降解过程都有NOP结构出现,并发现环氧树脂中NOP出现速率与残炭含量成正比例关系;同时发现所研究体系同时存在凝聚和气相阻燃两种阻燃机理。利用扫描显微镜(SEM)对含不同阻燃元素的阻燃体系如CNE/PMF固化物、DOPO-CNE/PN和DOPO-CNE/PMF固化物的燃烧残炭结构进行了研究,并对残留炭层的结构加以详细的阐述。此外,本文在动力学方面作了许多研究工作:采用动态DSC法,对含DPODB环氧树脂(DPODB-EP)/4,4’-二胺基二苯砜(DDS),CNE/PMF体系固化反应进行了非等温动力学研究,用Kissinger法和积分法分别计算了它们的表观活化能和表观指前因子;采用FTIR法对PMF/CNE的固化机理进行了研究;用Rogers方法对DSC数据进行处理,计算了PMF与含磷化合物的反应活化能;并以10℃的热失重曲线为基础,利用九种常见的机理函数推断了DOPO-PMF/CNE的热分解机理。更多还原

【Abstract】 Epoxy resins are widely used as structural adhesives, coatings, and advanced composite matrices in the aerospace and electronic industries because of their high tensile strength and modulus, low shrinkage on cure, high adhesion to many substrates, excellent chemical and corrosion resistance, and good dimensional stability. The flammability of epoxy resins, however, is a major hazard in their applications.Therefore, many flame retardants have been developed to improve their flame retardancy. Among them, organophosphorous compounds, generating negligible amounts of toxic gas and smoke, have demonstrated high efficiency as flame retardants for epoxy polymers. The research work of this dissertation is mainly involving the synthesis, application and mechanism about the phosphorous-containing, nitrogen- containing or phosphorous-nitrogen epoxy resins.There are five parts in this dissertation: introduction; synthesis and characterize of an novel phosphorous-containing biphenol DPODB and its application as flame- retardant in epoxy resin; synthesis and application of an novel curing agent used for epoxy resins bearing N-(4-hydroxyphenyl) maleimide (HPM); study on properties and mechanism about curing reaction of a self-intumescent flame retardant epoxy resin cured with an new phosphorous-nitrogen phenolic resins; investigation on thermal decomposition performance and mechanism about cured epoxy resins with different elements; conclusions. Among the organophosphorous flame retardants, phosphorinane compounds with higher thermal stabilities have been in great favor for phosphorous-containing epoxy resin, and many investigations have been done about them. A novel phosphorous- containing biphenol, 2-(5,5-dimethyl-4-phenyl-2 -oxy-1,3,2-dioxa- phosphorin-6-yl)1, 4-benzenediol(DPODB), was prepared by the addition reaction between 5,5-dimethyl-4- phenyl-2-oxy-1,3,2-dioxaphos-phorinane phosphonate (DPODP) and p-benzoquinone ( BQ ). The compound (DPODB) was used as a reactive flame-retardant in o-cresol formaldehyde novolac epoxy resin (CNE) for electronic application. The structure of DPODB was confirmed by FTIR and NMR spectra. Thermal properties of cured epoxy resin were studied using differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The flame-retardance of cured epoxy resins was tested by UL-94 vertical test and achieved UL-94 vertical tests of V-0 grade (nonflammable). The most studied approach to toughen epoxy resin was the use of polyimides which have high degree of thermal stability, excellent mechanical properties and chemical resistance. In this study, we made another approach to prepare an novel epoxy/polyimide cured resins, in which the curing agent is a maleimide-functional novolac copolymer resin synthesized through the copolymerization of HPM with phenol and formaldehyde. The modified epoxy films excellent solvent resistance; The tensile measurements of the films showed that, with the increase of the maleimide content, tensile properties of the film increased but were not changed significantly which reflects their independence on the HPM content on the film within the ratios used in this study. The thermal properties and thermal degradation behaviors of the PMF-CNE cured epoxy resins were also studied thermogravimetric analysis. Extremely high thermal stability (above 380℃) and high char yields (700℃48.6%) were observed for the PMF-CNE (o-cresol novolac epoxy)-based resins. Thermo gravimetric analysis also showed the increase of the thermal stability with the increase of the maleimide content.phosphorous-nitrogen intumescent flame retardants especially self-intrumescent flame retardant have been attracting so many interests in the fields of compound flame retardant, for the reason that their better compatibility, better flame retardance, good solvent resistance and tensile properties.Through the electrophilic addition reaction of -P(O)-H and C=C, a series of novel phosphorus-containing phenolic resins bearing maleimide (P-PMFs) were synthesized and used as curing agent for preparing high performance and flame retardancy epoxy resins. The structure of the resin was confirmed with FTIR and elemental analysis. Thermal properties and thermal degradation behaviors of the thermosetted resin was investigated by using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The epoxy resins exhibited high glass transition temperature (143-156℃) , goof thermal stability (>330℃) and retardation on thermal degradation rates. High char yields (700℃52.9%) and high limited oxygen indices (30.6-34.8) were observed, indicating the resins’good flame retardance for the P-PMFs/CNE cured resins. The developed resin may be used potentially as“green”in electronic fields.The thermal degradation property of flame-retarded systems was investigated by means of FTIR. It is found that the thermal decomposition process is closely related to the structure of polymers, the types of flame-retarded elements and the structure of elements. TG and FTIR results demonstrate that the flammability and thermal stability of the system are all improved as a results of cross-linking in the process of thermo-oxidative degradation. The C=N bonds appeared and took part in the cross-linking reaction in the higher temperature, which contrast to the appearance of phosphorate groups in the lower temperature during the decomposition process of phosphorous-nitrogen intumescent flame retarded epoxy systems. The possible composition of intumescent char of phosphorous-nitrogen epoxy systems was suggested based on the XPS measurement. It was found that there was NOP group appeared during the decomposition process and the char yields is in proportion to the rate of NOP. Moreover, the morphology of char residues was examined by SEM.Moreover, the dynamic research is another important point in this dissertation. FTIR, dynamic TG and DSC were used to calculate the active energy and other kinetics parameters of curing reaction with various methods, and asserted their mechanistic function of thermal decomposition. The mechanistic function of curing reaction was also investigated by in-situ FTIR.更多还原