Synthesis And Characterization Of PMMA/MMT Composites By Suspension Polymerization

Poly(methyl methacrylate)(PMMA) is an important member in the family of poly(acrylic ester)s and widely used in plastics products in many areas due to its excellent physical and chemical properties. PMMA prepared by suspension polymerization is widely used as dental materials such as denture base powder and denture powder, but it doesn't yet satisfy the requirement of the dental materials completely because of the low flexural strength, low surface hardness and low abradability. How to improve these properties becomes the research focus. Since Okada first prepared nylon6/layered silicate nanocomposite, researchers pay much attention to intercalation technology.In this study, montmorillonite(MMT) which was modified with different intercalation agents intercalated by MMA, and then PMMA/MMT composites were synthesized via in situ suspension polymerization. X-ray diffraction(XRD) and transmission electron microscopy(TEM) were used to study nanostructure of the composites, and Fourier transform infrared spectroscopy(FT-IR) was used to investigate the interaction between PMMA and MMT. The molecular weight of PMMA in the compounds, the particle shape and size of compounds and the mechanical and thermal properties of the composite prepared by different conditions were discussed.The results indicate that, PMMA/MMT nanocomposites could be successfully synthesized via suspension polymerization, when dodecylamine(12CNH) and hexadecylallyldimethyl ammonium chloride(HADC) were used as modifiers, and P-12CNH exhibits a mixed intercalated-exfoliated structure, while P-HADC only exhibits intercalated structure, but the interaction between PMMA and MMT was strongest in P-HADC. The presence of MMT layers influenced the molecular weight of PMMA and the shape and size of compounds particles, but didn't change the general laws that synthesis condition affected on molecular weight. The presence of MMT layers performed a positive effect on the mechanical and thermal properties of composites, and the properties of composites were determined by their nanostructure and the interaction between PMMA and MMT. Among the composites prepared in this study, mechanical and thermal properties of P-HADC were optimized.