Synthesis and characterization of LLDPE/sepiolite nanocomposites using melt blending

LLDPE/Sepiolite nanocomposites were prepared by melt blending using unmodified and silane modified sepiolite. Following two methods were used to modify sepiolite; modification before heat mixing (ex situ) and modification during heat mixing (in situ). The characterization was performed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC). FTIR spectra of nanocomposites showed new peaks confirming the development of new covalent bond between the components. The scanning electron micrographs of the nanocomposites exhibited the homogeneous dispersion and distribution of nano-sized sepiolite particles in the LLDPE matrix. TGA results showed the higher thermal stability of nanocomposites than pure LLDPE. The modulus and stress at break of the nanocomposites containing unmodified and ex situ modified sepiolite nanocomposites was also improved; whereas elongation at break was reduced in all nanocomposites. Increased crystallization temperature of ex situ modified nanocomposites revealed heterogeneous nucleation effect resulted by sepiolite which can be exploited for shortening of cycle time during processing. (author)