Morphology and interaction of nanocomposite foams formed with organo-palygorskite and ethylene-vinyl acetate copolymers

Abstract

To obtain excellent mechanical properties of polymer nanocomposite foams without sacrificing the lower density through popular and friendly means. Organically modified palygorskite (OPal) was prepared with γ-aminopropyltriethoxysilane on the surface of rod-shaped Pal particles, and nanocomposite foams based on ethylene-vinyl acetate (EVA) copolymer was prepared by melt-blending EVA with OPal. Fourier transform infrared spectroscopy (FTIR) was used to investigate the interaction between OPal and EVA matrix, and the OPal/EVA nanocomposites were also characterized by X-ray photoelectron spectra (XPS), X-ray diffraction analysis (XRD) and differential scanning calorimetry (DSC). The dispersivity of OPal in the EVA matrix and the morphology of the foams were investigated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), and the OPal/EVA nanocomposite foams were also characterized by thermogravimetric analysis (TGA). The effect of OPal content in the foam samples on the cellular structure and mechanical properties was investigated. Our studies indicate that the OPal nanofibers could be used as a heterogeneous nucleation agent to reduce the average cell diameter. The uniformity of cell structure of the foams was improved, and the physical properties of OPal/EVA nanocomposite foams were enhanced by the addition of OPal. The density of OPal/EVA nanocomposite foams was decreased to 0.133 g/cm3. Also, the best tear strength, peel strength and compression set values of nanocomposite foams were 4.65, 2.65 N/mm and 25.5 %, which were improved by 36.0, 54.3 and 12.0 %, respectively, compared with those of the initial foam.