Synthesis And Application Of Talc-based High-temperature-resistant Flame Retardants

Recently layered silicate/polymer composites have drawn great attention due to good mechanical properties and thermodynamic stability. One of the layered talc powder as an excellent packing has been employed in a variety of polymers because of its low surface energy, low thermal conductivity and high heat resistant characteristics. However, the low flame retardant efficiency is still great challenge when used it alone, resulting in a limited application. On the other hand, ammonium polyphosphate is a highly efficient flame retardant, but its disadvantage is low decomposition temperature. Herein, aiming to the above problems, this thesis is focused on the synthesis of talc-based high-temperature-resistant flame retardant via polymerization between talc and phosphoric acid and urea. Furthermore, it is used in ethylene-vinyl-acetate (EVA) and polypropylene (PP) as flame retardant to prepare two composite materials. Their flame retardant efficiency and mechanical strength were also investigated. The main points of this dissertation are as follows:(1) Talc-based high-temperature-resistant flame retardant is synthesized via polymerization between talc and phosphoric acid and urea. The microstructure of as-prepared composite particles was investigated through infrared spectroscopy (FT-IR), X ray powder diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis. The yield of flame retardant was also discussed through different raw materials ratio, reaction temperature, reaction time. When ratio of talc:urea:phosphoric acid is equal to1:1.5:1, the reaction temperature was125℃and the reaction time was40min, the yield of flame retardant reached48.85%. Meanwhile, the heat-resistance of as-prepared flame retardant is analyzed, its decomposition temperature is improved200℃than normal nitrogen/phosphorus flame retardants.(2) Composite flame retardant is further modified by silane coupling agent for preparation of flame retardant/EVA composite materials. The effect of silane coupling agent amount is discussed. Analysis results indicated that0.8%of the silane coupling agent is proper for flame retardant. The performance of composite materials is much better than the industry standard of EVA composites. Furthermore, the mechanism of as-prepared flame retardant is also proposed.(3) Composite flame retardant is employed to highly processing temperature PP composite materials. The microstructure of composite materials was investigated through small angle XRD, SEM and thermogravimetric analysis(TG). When composite flame dosage50wt%, the tensile strength of composite materials is29.11MPa, elongation at break is19.8%, bending strength is 38.15MPa, limiting oxygen index of31.5%and achieve UL94V-0rating, respectively. The performance could meet the requirements of the domestic automotive indicators.