Influence of fibrillated poly(tetrafluoroethylene) on microcellular foaming of polyamide 6 in the presence of supercriticalCO₂

Abstract

In this article, PA6/poly(tetrafluoroethylene) (PTFE) composites were prepared by internal mixer with high rotor speed. The existence of PTFE nano‐fibrillation network structure was observed by scanning electron microscopy (SEM) analysis. The effect of PTFE on crystallization and rheological behavior of PA6 was evaluated. The result showed that the PTFE fibrils improved the crystallization properties of PA6 and do not change the crystal structure. The PTFE effectively enhanced the melt strength of PA6 by fibrillation. The PA6/PTFE composites were then foamed assisted by supercritical CO2. The PTFE was used as cell nucleating agent, crystal nucleating agent and melt strength enhancement agent in the foaming process. Finally, the microcellular PA6 foams were successfully obtained with the cell density higher than 109 cells/cm3, the cell size of ca. 14 μm and the volume expansion ratio of 16.

Preparing low-Density microcellular polystyrene foam by in-Situ fibrillated PTFE and supramolecular nucleator TMC-300 in the presence of sc-CO2

“…26,27 PTFE fibers have effectively improved the crystallization and melt strength performances of PA6. 28 Wang et al 29 also demonstrated that PTFE fiber networks significantly improved the melt viscoelasticity of polybutylene terephthalate (PBT) wherein the fibers promoted crystallization kinetics and changed the PBT crystallization structure. Meanwhile, nascent PTFE is a highly crystalline polymer with low chain entanglement density which can undergo fibrillation during matrix shearing.…”

Fabrication of polyamide 12T micro‐cellular foams with ultra‐high compressive strength via in situ polytetrafluoroethylene fibrillation using supercritical carbon dioxide foaming

“…After fiber addition, the cell diameters decreased from 22 to 2 μm and cell density increased by three orders of magnitude. 26,27 Peng et al added PTFE to poly(propylene carbonate) (PPC) and polystyrene (PS) using a three-screw extrusion method. The cell density of PPC increased by four orders of magnitude and the PS/PPC/PTFE foam exhibited excellent mechanical properties.…”

“…Previously, we demonstrated that PTFE fibers in polyethylene terephthalate (PET) and PA6 effectively promote the formation of cellular structures of the resulting PET/PTFE and PA6/PTFE foams. After fiber addition, the cell diameters decreased from 22 to 2 μm and cell density increased by three orders of magnitude 26,27 . Peng et al added PTFE to poly(propylene carbonate) (PPC) and polystyrene (PS) using a three‐screw extrusion method.…”

The Preparation of Monomer Casting Polyamide 6/Thermotropic Liquid Crystalline Polymer Composite Materials with Satisfactory Miscibility

“…However, its poor notched impact toughness (especially at low temperatures) restricts its overall performance, which limits its applications in modern plastic industries and newly emerging fields [ 5 , 6 , 7 , 8 , 9 ], e.g., wearable fabrics [ 4 ], self-supporting water purification films [ 9 ], and nanofiltration membrane [ 7 ], etc. To solve this issue, PA6 matrix has been modified by reinforcing materials, such as hydrogenated acrylonitrile-butadiene-styrene (ABS) [ 10 ], styrene-co-acrylonitrile (SAN) [ 11 ], hydrogenated styrene-butadiene-styrene (SEBS) [ 12 ], polyamide 66 [ 13 ], poly(tetrafluoroethylene) (PTFE) [ 14 ], and thermotropic liquid crystalline polymer (TLCP) [ 15 ], etc. For those reinforcing monomers or polymers, they have similar functional groups to that of PA6, which is advantageous to obtain compatible polymer composites to overcome the phase separation problem at the interface of PA6 and reinforcing additives through chemical and physical interactions or adhesions between them.…”

“…As we know, among those polymer modifiers [ 10 , 11 , 12 , 13 , 14 , 15 ], TLCP is one promising choice. Because of the peculiar rigid-rod chemical structures, TLCP in the solid form possesses many unique properties, e. g., low melt viscosity and high mechanical modulus in the oriented direction.…”