Effect of nanosilica on the morphology of polyethylene investigated by AFM

Nanocomposites from low density polyethylene (PE) and nanosilica (NS) with and without a compatibilizer were prepared via direct melt blending. Their morphology and mechanical properties were investigated in relation to that of neat PE using peak force QNM (quantitative nanomechanics) analysis. A suppression of spherulitic development as compared to neat PE was observed in PE/NS nanocomposites. NS induced no modification in the lamellar thickness of PE but a slight decrease of the crystallinity was detected. Changes in the thickness and distribution of the amorphous strips were emphasized in samples containing the compatibilizer. For the first time the nanomechanical properties of PE–NS interface were quantitatively characterized. AFM investigation of fractured samples revealed different mechanisms involved in deformation and breaking of neat PE and composites.