| Polypropylene has good properties of anti-bending, heat-resisting and chemical stability. It is a kind of main resin matrix for making plastic production. Foamed polypropylene was used widely due to the properties of low density, sound insulation and heat preservation. Foamed polypropylene is a hot spot in research field, its’ low density and high strength of foamed polypropylene have important impact to motor and spaceflight industry. In this dissertation, sodium bicarbonate was treated by anti-solvent crystallization, and carbon fiber reinforced polypropylene which foamed by modified sodium bicarbonate were prepared by injection molding method. The diameter of sodium bicarbonate, the thermal performance of modified sodium bicarbonate and the mechanical properties of the carbon fiber reinforced foamed polypropylene were investigated. The main contents and conclusions in this dissertation are listed in the following:(1) Sodium bicarbonate was recrystallized by octadecanamine-isopropyl alcohol as anti-solvent, the particles size of recrystallized sodium bicarbonate was smaller than original sodium bicarbonate. The particles size was smallest at the 1% of concentration. Particles size decreased after washing by ethanol.(2) Sodium bicarbonate was modified with citric acid by solution coating method. This method has notable effect for increasing the decomposition temperature. When the mass of citric acid was equal to sodium bicarbonate, the foam agent has highest decomposition temperature which raised 34.35℃, and faster rate of decomposition.(3) Acid and coupling agent were used to treat the surface of carbon fibers, both of them could improving the infiltration between carbon fibers and polypropylene matrix. The well combination was helpful to reinforce polypropylene. Cells have smaller size and better shape after adding carbon fibers. The effect of improving mechanical properties and shape of cells is not significant when the content of carbon fibers is over 10%. |
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