From our previous work, it has already been clarified that physical degradation is the main cause of the deterioration of mechanical properties in recycled plastic. In addition, the physical degradation is related to the changes of inner structure of plastics from molding process history which can be regenerated by the optimization of molding condition. We have developed an additional device namely as "Molten resin reservoir" which is connected at the end of screw part of a general twin-screw extruder. This molten resin reservoir unit affected the relaxation from shear deformation of screw mixing zone and secure time for polymer entanglement. Based on our studies, it can be found that the mechanical properties of recycled polyethylene were regenerated by re-extrusion with this new type of twin-screw extruder. In this study, virgin polyethylene was used to investigate the mechanism of recovery of physical properties by using this new type of twin-screw extruder with an additional molten resin reservoir. The re-extrusion condition will be optimized. The mechanical properties and inner structure of the re-pelletized products were evaluated by tensile test, dynamic mechanical analysis (DMA), and small angle X-ray scattering (SAXS). This study is expected to find the relationship between mechanical properties, inner structure, and the optimized re-extrusion condition of virgin polyethylene by using a special type twin-screw extruder in order to improve the properties of mechanical recycling plastic products.