Enhanced tensile creep stability of immiscible poly(l-lactide)/poly(ethylene vinyl acetate) blends achieved by adding carbon nanotubes

Creep stability is usually adopted to evaluate the dimensional stability of polymers under the load condition. However, the creep behavior of polymer blend composites, which has been already used in many fields, is seldom investigated. In this work, immiscible poly(l-lactide) (PLLA)/poly(ethylene vinyl acetate) (EVA) blend composites with different contents of carbon nanotubes (CNTs) were prepared. The crystalline structure of matrix, the dispersion of CNTs as well as the morphologies of the blend composites were comparatively investigated. The results demonstrated that CNTs selectively located at the blend interface and induced the morphological changes from quasi-cocontinuous structure to cocontinuous structure. Mechanical property measurements demonstrated that CNTs exhibited toughening effect for the immiscible PLLA/EVA blends. The creep behavior was investigated under different external forces. The results demonstrated that the creep stability of the blend composites was apparently enhanced by adding CNTs. The mechanisms for the enhanced creep stability were then proposed.