Foams based on low density polyethylene/hectorite nanocomposites:: Thermal stability and thermomechanical properties

Novel polymer nanocomposite foams made by a two step compression molding method are analyzed in this article. Nanocomposites of low density polyethylene and an organo-modified hectorite were first melt compounded and then foamed using a compression molding method. To study the influence of the presence and the amount of hectorite in both mechanical and thermal properties, samples with 3% and 7% content of hectorite were prepared. Polyethylene crystalline characteristics and thermal stability of the samples were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. Mechanical properties of foams and solid nanocomposites were analyzed by using dynamical mechanical analysis (DMA). Thermal expansion of the samples was analyzed by thermomechanical analysis. The results indicate that the exfoliation of hectorite platelets was achieved after the foaming process, but not during the melt mixing step. Foams with hectorite nanoparticles exhibit improved thermal stability and mechanical properties when compared with neat polymeric foams. (c) 2007 Wiley Periodicals, Inc.