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Improving the Continuous Microcellular Extrusion Foaming Ability with Supercritical CO2 of Thermoplastic Polyether Ester Elastomer through In-Situ Fibrillation of Polytetrafluoroethylene

by Rui Jiang 1,2, Tao Liu 1, Zhimei Xu 1, Chul B. Park 2 and Ling Zhao 1,3,*
1
State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China
2
Microcellular Plastics Manufacturing Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON M5S 3G8, Canada
3
College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046, China
*
Author to whom correspondence should be addressed.
Polymers 2019, 11(12), 1983; https://doi.org/10.3390/polym11121983
Received: 31 October 2019 / Revised: 22 November 2019 / Accepted: 25 November 2019 / Published: 2 December 2019
(This article belongs to the Special Issue Supercritical Fluids Technology for Polymer Applications)
In-situ fibrillated polytetrafluoroethylene (PTFE) enhanced nanocomposites were successfully prepared by mixing thermoplastic polyether ester elastomer (TPEE) and PTFE using a twin-screw extruder. Well-dispersed, long aspect ratio PTFE nanofibrils with a diameter of less than 200 nm were generated and interwoven into networks. Differential scanning calorimetry and in-situ polarized optical microscopy showed that the PTFE nanofibrils can greatly accelerate and promote crystallization of the TPEE matrix and the crystallization temperature can be increased by 6 °C. Both shearing and elongational rheometry results confirmed that the introduction of PTFE nanofibrils can significantly improve the rheological properties. The remarkable changes in the strain-hardening effect and the melt viscoelastic response, as well as the promoted crystallization, led to substantially improved foaming behavior in the continuous extrusion process using supercritical CO2 as the blowing agent. The existing PTFE nanofibrils dramatically decreased the cell diameter and increased cell density, together with a higher expansion ratio and more uniform cell structure. The sample with 5% PTFE fibrils showed the best foaming ability, with an average diameter of 10.4–14.7 μm, an expansion ratio of 9.5–12.3 and a cell density of 6.6 × 107–8.6 × 107 cells/cm3. View Full-Text
Keywords: supercritical carbon dioxide; extrusion foaming; in-situ fibrillation; TPEE supercritical carbon dioxide; extrusion foaming; in-situ fibrillation; TPEE
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MDPI and ACS Style

Jiang, R.; Liu, T.; Xu, Z.; Park, C.B.; Zhao, L. Improving the Continuous Microcellular Extrusion Foaming Ability with Supercritical CO2 of Thermoplastic Polyether Ester Elastomer through In-Situ Fibrillation of Polytetrafluoroethylene. Polymers 2019, 11, 1983.

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