Synthesis and characterization of LDHs/PMMA nanocomposites: Effect of two different intercalated anions on the mechanical and thermal properties

摘要

Poly(methyl methacrylate) (PMMA)/layered double hydroxides (LDH) nanocomposites were synthesized by in situ bulk polymerization. The LDHs were synthesized by coprecipitation method. Eight LDHs having different compositions were produced, varying the divalent/trivalent cations (Zn/Al, Mg/Fe), the ratio between these cations (2: 1 and 4: 1) and the LDH intercalated anions (dodecyl sulfate and laurate). The LDH percentage (wt ) in the PMMA was fixed at 1. The thermal properties of the nanocomposites were evaluated by thermal analysis (thermogravimetric-TGA and differential scanning calorimetry-DSC). Most of the nanocomposites presented higher thermal resistance than PMMA and the best results were presented by the following nanocomposites: PMMA/(Zn/Al 2: 1 laurate) and PMMA/(Zn/Al 4: 1 laurate). The dynamic mechanical properties of the nanocomposites were investigated and compared to those obtained for PMMA. It was noticed that PMMA/(Mg/Fe 4: 1 laurate) nanocomposite presented an elastic modulus 2.2 times higher than PMMA at 40°C. This investigation demonstrated that the addition of low concentrations of selected LDHs can enhance some desired properties of PMMA.