Manufacturing of polytetrafluoroethylene fine fibers by waterjet impacting

Abstract

Due to unique anti-erosion properties and excellent thermal stability, polytetrafluoroethylene (PTFE) fibers are regarded as an ideal material to manufacture filters for industrial dust purification. Based on weak interactions between PTFE molecular chains, we applied a high-pressure waterjet to cause normal PTFE split-film fibers to split fibers again. Four kinds of PTFE split-film fibers and sintered films with different molecular weights were produced. Afterward, waterjets were introduced to impact PTFE sintered films and split-film fibers under different pressures and jets, and we analyzed variations in the sintered film morphology and fiber diameter. When the molecular weight was increased, the visible light transmittance of four different PTFE sintered films at the wavelength of 382 nm decreased from 85.7% to 77.6% and then increased to 95.1%, which was consistent with light–dark characteristics in light micrographs of sintered films. The four PTFE sintered films split into fibers under the waterjet impact force. In particular, MW49 PTFE sintered film was split into microscale fibers using waterjets at 110 bar and 5 jets. Finally, waterjets were applied to impact normal PTFE split-film fibers to force the original fibers to split into fine fibers. Different PTFE split-film fibers exhibited a significant decrease in the average diameter. In particular, in the case of MW49 PTFE split-film fibers, the average diameter of fibers impacted by 5 jets at 110 bar decreased from 27.4 to 15.7 μm, confirming the suitability of high-pressure waterjets for the splitting of PTFE split-film fibers into microscale fibers.