Effect of Organo-modified Layered Silicates on the Properties of Poly(Methyl Methacrylate) Nanocomposites

Abstract

Poly(methyl methacrylate) (PMMA)/layered silicate nanocomposites were prepared using melt intercalation technique. Commercially modified nanoclays such as Cloisite 30B (C30B), Cloisite 20A (C20A), and Bentone 109 (B109) have been used as organoclays for the preparation of nanocomposites. PMMA matrix has been grafted with maleic anhydride to modify the interfacial region and improve the interfacial adhesion between organoclays and PMMA matrix. Mechanical tests revealed an increase in the tensile modulus of PMMA/C30B (5%) nanocomposite to about 35% as compared to virgin PMMA matrix. Thermal measurements employing differential scanning calorimetry and thermogravimetric analysis also showed improved thermal stability and marginal increase in Tg of PMMA matrix with the incorporation of nanoclays. Wide angle X-ray diffractograms revealed an increase in d-spacing of C30B nanoclay from 18.5 to 39.4 Å in PMMA/C30B nanocomposites, thus confirming intercalated structure. The dispersion characteristics of organoclay within PMMA matrix was also investigated using transmission electron microscopy. Furthermore, dynamic mechanical analysis shows a substantial increase in storage modulus of PMMA matrix with the incorporation of organoclays. Additionally, an improved fire retardancy of PMMA was also observed in PMMA/B109 (5 wt%) nanocomposites with an evidence of reduced horizontal rate of burning.