The role of PTFE in-situ fibrillation on PET microcellular foaming

Microcellular polyethylene terephthalate (PET) foams were fabricated by introduced poly (tetrafluoroethylene) (PTFE) fibrils. The existence of PTFE network impeded the mobility of PET chains while increased the crystal nucleation sites. The crystallization temperature, crystallization rate and viscoelastic behavior of PET were promoted effectively by the introduction of PTFE fibrils. It reached to a rheological percolation value when the content of PTFE increased to 1 wt%. During foaming process, the presence of physical PTFE fibrils network structure promoted the nucleation of crystallization and restrict the growth of cells. In addition, the PET foams with 1 wt% PTFE possessed the smallest cell diameter and the highest cell density. The cell diameter with 1 wt% PTFE could reduce from 22 μm to 2 μm, and the cell density could increase by three orders of magnitude that from 108 cells/cm3 to 1011 cells/cm3.