Copolymerization Of Styrene And Methyl Methacrylate Preparation Gasification Materials Research

Evaporative pattern casting is a technology which can realize precise, efficient, volume, cleaner production, and obtain the required casting. Foamable styrene / methyl methacrylate copolymer beads are one of the raw materials that are used to prepare gasification mode shape.In the thesis, styrene and methyl methacrylate were used as the raw materials, dibenzoyl peroxide was used as initiator, basic magnesium carbonate and polyvinyl alcohol were used as composite dispersant, methacrylic acid was used as the functional monomer that improve the foaming properties, which prepared the foamable copolymer beads by suspension polymerization. Then, the gasification mode of styrene / methyl methacrylate copolymer was prepared by foaming method, and the optimum conditions for the synthesis were explored. The microstructure of the polymer was characterized and analyzed by using scanning electron microscope, thermal degradation behavior of the polymer was characterized and analyzed by using thermogravimetric analysis, and the thermal oxidative degradation of polymer materials was also discussed. In addition, the situation of foaming polymer materials, residual monomer, and the final residue of burning material were tested. Then, several conclusions were got as following.(1) The volume ratio was 7: 4: 1 of styrene: methyl methacrylate: methacrylic acid for preparation of styrene / methyl methacrylate copolymer. The optimal conditions for preparing qualified particle size of styrene / methyl methacrylate beads were obtained as follows: water-oil ratio was 6:1, stirring speed was 450r/min, temperature was 85℃. Styrene / methyl methacrylate copolymer beads were uniform and the particle size was 500μm.(2) Under the same foaming conditions, the foaming ratio of polystyrene/polymethyl methacrylate copolymer beads was just 32.8 times, while the foaming ratio of polystyrene/methyl methacrylate copolymer beads with functional monomer was near 39.3 times, which improved 21 %. The surface aperture of polystyrene / methyl methacrylate copolymer and polystyrene / polymethyl methacrylate / polymethyl methacrylate copolymer beads were 1μm ~ 8μm. The pore diameter of polystyrene / methyl methacrylate copolymer were 20μm ~ 80μm. The addition of methacrylic acid as foaming functional monomer significantly increased its bore diameter, the bore diameter of polystyrene / polymethyl methacrylate / polymethyl methacrylate copolymer were 40μm ~ 100μm.(3) Residual rate of polystyrene/methyl methacrylate copolymer and polystyrene/polymethyl methacrylate/polymethyl methacrylate copolymer is less than 0.5%, which meets the standard of residual monomer QBT4009-2010 ratio requirements. Its burning residual rate in order were: Polystyrene>PMMA>styrene/methyl methacrylate copolymer>styrene/methyl methacrylate / methacrylic acid copolymers.(4) TGA results show that polystyrene/polymethyl methacrylate/polymethyl methacrylate copolymer at 400~450 ℃ thermal decomposition fastest, 450 ℃ thermal decomposition weight loss of 95%. The result of simulate thermal degradation kinetics by Ozawa method indicated that the calculated values of Pyrolysis activation energy is 75-105 k J/mol.