摘要
本文系统的研究了聚合物包覆纳米SiO2的制备工艺与方法,采用无皂乳液聚合法和预聚物包覆法分别成功制备了聚甲基丙烯酸甲酯(PMMA)和三聚氰胺-甲醛树脂(MFR)包覆改性纳米SiO2粒子,并采用红外光谱、热分析、扫描电镜、粒度分析等方法对其性能、结构、组成等进行了分析。在此基础上,通过对改性SiO2/IFR/EVA复合材料的力学性能、阻燃性能及热降解行为的分析,考查了包覆改性SiO2在膨胀EVA体系中的作用,重点研究了不同包覆改性SiO2对成炭性能的影响。
本论文的研究表明:(1)以包覆量结合粒度分析为评价标准时,能够更好评价包覆效果,具有最大包覆量的纳米SiO2的粒径最小,说明在此条件下SiO2的分散情况最好;(2)红外光谱、热分析和扫描电镜的研究表明,成功制备了PMMA、三聚氰胺-甲醛树脂、丁醇改性三聚氰胺-甲醛树脂包覆改性的SiO2粒子,未改性的纳米SiO2在EVA中团聚现象比较严重,改性后的纳米SiO2在EVA中的分散性明显改善;(3)复合体系的热降解过程的研究结果表明,不同包覆改性粒子具有不同的成炭作用,三聚氰胺-甲醛树脂包覆的纳米SiO2更有利于促进体系的热降解成炭过程,其体系表现出较低的热失重速率和较高的成炭量;(4)氧指数和力学性能的测试结果表明,改性纳米SiO2体系力学性能和阻燃性能在很大程度上取决于粒子的分散状态和表面状态。
Modification of nano-silica coated with poly(methyl methacrylate)(PMMA), melamine formaldehyde resin (MFR) and butanol modified melamine formaldehyde resin (BMFR) by emulsion polymerization method and prepolymer coating method was investigated in the dissertation. Composition, structure and properties of modified silica were analyzed by means of Fourier transform infrared spectroscopy(FTIR), thermogravimetric analysis(TG), scanning electron microscopy(SEM) and particle size analyzer. Modified silica was used in intumescent flame retardant EVA composites(EVA/IFR) and its effects on tensile properties, flame retardant properties and thermal degradation behaviors were studied. Emphasis was given to effects of modified silica on charring properties of the system.
The following conclusions could be drawn: (1) Modification degree could be better evaluated by combination of encapsulated mass and particle size. The modified silica with the most encapsulated mass possessed the smallest particle size, which could be interpreted as the better dispersed silica particles. (2) The results of FTIR and TG revealed successful modification of silica coated with PMMA, MFR and BMFR. As observed by SEM, conglomeration of nano-silica particles was lessened and dispersibiliby of silica in EVA was improved after modification. (3) Study on thermal degradation of composites indicated enhanced charring by modified silica, among which MFR coated silica possessed best charring effects according to lower weight loss rate and more residue left. (4) Tensile properties and flame retardant properties of the composites were affected by the dispersibility and surface structure of modified silica.
引文
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