Unusually high temperature transition and microporous structure of polytetrafluoroethylene fibre prepared through film fibrillation

• The molecular constraints created through the processes existed in the PTFE fibre.
• PTFE fibre has a reversible high temperature transition at 380 °C.
• The rectangular and rhombus porous structures of PTFE fibre have been produced.
• The molecular constraints resulted in forming the microporous PTFE fibre.

The melting behaviour and structure of polytetrafluoroethylene (PTFE) fibre prepared through film fibrillation were investigated in this study. An unusually high temperature transition of PTFE fibre was observed using a differential scanning calorimeter and a hot stage polarising microscope. The network rectangular porous channel structure framed with fibrils and membranes in the PTFE fibre was obtained after an axial tear failure. It was suggested that the extruding, rolling, and drawing processes be beneficial for molecular constraints between crystals and have contributed to the presence of the unusually high temperature transition of PTFE and the formation of a rectangular porous channel structure in the PTFE fibre. The development of the microporous structure of PTFE fibre is present in diagrams in this paper.

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