Essential Work of Fracture Parameters of in-situ Microfibrillar Poly(ethylene terephthalate)/Polyethylene Blend: Influences of Blend Composition

An in-situ microfibrillar blend based on poly(ethylene terephthalate) (PET) and polyethylene (PE) was fabricated through slit die extrusion, hot-stretching and quenching. The morphology of the PET in-situ microfibers, which were observed after the matrix was etched away, appears to be dependent on the blend composition at a fixed hot stretch ratio. The well-defined in-situ fibers were generated at the PET concentrations ranging from 15 to 25 wt.-%. The fracture toughness of the microfibrillar blend was evaluated using deeply double-edge notched tension (DDENT) specimens according to the essential work of fracture procedure. Initially, the increase of PET concentration makes w(e), rise. At 15 wt.-% of PET concentration there exists a maximum w(e), Further increase of PET microfibers causes a rapid decrease of w(e), On the other hand, incorporation of PET microfibers at a low concentration to PE makes w(p) rise slightly. As it exceeds 10 wt.-%, wp decreases substantially. It was believed that the characteristics of the PET microfibers were responsible for the fracture behaviors of the microfibrillar blend.