Study On Polymethacrylimide And Its Nanocomposite

For recent 40 years, polyimides have been developed rapidly and applied in manyhigh performance fields, such as aerospace, microelectronics, and so on.Polyimide exhibitted outstanding thermal and mechanical properties, especially at elevated temperature.Polymethacrylimide(PMI) was a type developed rather rapidly among polyimides, good process ability was gained besides keeping function advantage.In this thesis, MAN-MAA copolymer was prepared by copolymerization of methacrylic acid(MAA) and methacrylonitrile(MAN), PMI was formed via the imidation(cyclization, i.e.) of the copolymer to polyimide.PMI/montmorillorite nanocomposite was prepared by in-situ intercalate polymerization to enhance the properties of PMI afterwards.The stucture and property of the material mentioned above were characterized by FT-IR,DSC-TGA and SEM.The work was composed in following parts:First of all, MAN-MAA copolymer were synthesized by solution polymerization and bulk polymerization, parameters such as reaction temperature, monomer ratio and initiator were investigated in polymerization.The preferable condition of polymerization was gained by characterization of thermal and mechanical properties.The mechanism of cyclization was studied at the mean time, and the preferable cyclization condition of the MAN-MAA copolymer was acquired via the controlling of time and temperature.For the sake of nano MMT's homogeneous dispersion , high macromolecule poly(Methyl-Methacrylate) was synthesized via suspension polymerization, the influences of temperature, concentration of initiator, and conversion rate on molecular weight were analysed. In this way, the viscosity of the monomer reaction solution was improved.Based on the above work, influence of nano MMT to the property the copolymer was studied. Thanks to this special structure, the thermal and mechanical properties of the nano composite formed by PMI and MMT taken on a great improvement comparing to PMI.Furthermore, nano composite prepared by Acrylonitrile-Methacrylic acid(AN-MAA) copolymer/MMT was produced , after the same cyclization procedure as the methacrylonitrile-methacrylic acid copolymer, a structure named half-PMI was formed, compared to PMI/MMT nano composite , the glass-transition temperature of the half-PMI/MMT nano composite descended little, the bending intensity of the former descended 20%.