Solid-state microcellular foaming of PE/PE composite systems, investigation on cellular structure and crystalline morphology

摘要

This novel research aims to develop, for the first time, microcellular polyethylene fiber-reinforced polyethylene (PE/PE) clay containing nano-composites during a solid-state microcellular foaming process using supercritical nitrogen (scN_2) as a foaming agent. Results show that by employing clay nanoparticles in the matrix, expansion ratio of the microcellular processed composites enhance, because of the nucleating effect of nanoparticles. Microcellular nano-homocomposite has an average cell size of 0.5 μm. Trans-crystalline layer of composites with a length of about 3 μm; remain intact during the foaming process but the bulk matrix crystalline structure alters to a more oriented "quasi-fibrillar" structure after foaming. Microcell growth in the amorphous interlamellar regions exerts a tension on the neighboring lamellas which cause some orientation on them. The DSC studies show the emerging of new crystalline sectors with a lower melting point which affirms the creation of a less perfect crystalline morphology due to cell wall movements during cell growth step and subsequent stabilization period of the cells.