Porous Shish-Kebab Structure Prepared from Oriented UHMWPE Films by Processing in Supercritical CO₂

For the first time, a highly crystalline porous shish-kebab structure with a high degree of crystallinity was obtained by using a combination of two methods for the formation of porous polymeric materials. A treatment procedure using supercritical carbon dioxide (scCO(2)) was carried out for oriented ultrahigh molecular weight polyethylene (UHMWPE) films, which provided special conditions for the crystallization of dissolved UHMWPE macromolecules on the surface of oriented UHMWPE crystals. The prepared porous materials were investigated by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The particularity of the obtained porous shish-kebab is the absence of the amorphous phase between lamellar crystals (kebabs). The obtained pores had an oval shape, and they were oriented in the orientation direction of the UHMWPE macromolecules. The pore size ranged from 0.05 mu m to 4 mu m. Controlling the conditions for the crystallization of the UHMWPE macromolecules using supercritical CO2 gives the possibility to control the size of both lamellar disks and pores formed.