Effect of Layered Hydroxide Salts, Produced by Two Different Methods, on the Mechanical and Thermal Properties of Poly(Methyl Methacrylate)

In this study, eight different layered hydroxide salts (LHSs) based on copper and zinc, intercalated with stearate, myristate, azelate, and poly(ethylene glycol) (PEG) monolaurate, were prepared. All the LHSs were produced according two different methods: co-precipitation (direct method) and synthesis of zinc hydroxide nitrate (ZHN) and copper hydroxide nitrate (CHN) followed by exchange reaction (indirect method). The synthetic layered compounds were characterized by X-ray diffraction (XRD) and thermogravimetric analysis (TGA). TGA results revealed that higher thermal stability was observed for the LHSs synthesized by direct method. The effects of all these LHSs on the thermal and mechanical properties of poly(methyl methacrylate) (PMMA) nanocomposites were investigated. The LHSs percentage (wt%) in the PMMA was fixed at 1%. PMMA and PMMA nanocomposites were produced by in situ bulk polymerization. Compared to PMMA, all the nanocomposites exhibited higher thermal stability. The nanocomposite containing ZHN(stearate) by indirect method revealed both [T.sub.50] (temperature at which a 50% loss of mass occurs) and [T.sub.90] (temperature at which a 90% loss of mass occurs) 71[degrees]C higher than PMMA. Compared to PMMA, the nanocomposite with ZHN(PEG monolaurate) exhibited an increase of 14% in the elastic modulus, at 30[degrees]C.
INTRODUCTION Polymer/clay nanocomposites have been shown to provide enhancements in physical properties of polymers such as increased tensile strength, tensile modulus, flexural strength, thermal stability, and corrosion protection due to [...]