Open-Celled Foams from Polyethersulfone/Poly(Ethylene Glycol) Blends Using Foam Extrusion

Abstract

Polyethersulfone (PESU), as both a pristine polymer and a component of a blend, can be used to obtain highly porous foams through batch foaming. However, batch foaming is limited to a small scale and is a slow process. In our study, we used foam extrusion due to its capacity for large-scale continuous production and deployed carbon dioxide (CO2) and water as physical foaming agents. PESU is a high-temperature thermoplastic polymer that requires processing temperatures of at least 320 °C. To lower the processing temperature and obtain foams with higher porosity, we produced PESU/poly(ethylene glycol) (PEG) blends using material penetration. In this way, without the use of organic solvents or a compounding extruder, a partially miscible PESU/PEG blend was prepared. The thermal and rheological properties of homopolymers and blends were characterized and the CO2 sorption performance of selected blends was evaluated. By using these blends, we were able to significantly reduce the processing temperature required for the extrusion foaming process by approximately 100 °C without changing the duration of processing. This is a significant advancement that makes this process more energy-efficient and sustainable. Additionally, the effects of blend composition, nozzle temperature and foaming agent type were investigated, and we found that higher concentrations of PEG, lower nozzle temperatures, and a combination of CO2 and water as the foaming agent delivered high porosity. The optimum blend process settings provided foams with a porosity of approximately 51% and an average foam cell diameter of 5 µm, which is the lowest yet reported for extruded polymer foams according to the literature.

Extrusion foaming of multiphasic polyethylene/ethylene-vinyl acetate copolymer/carbon nanotube mixtures: Tailoring foam properties by selective localization of nanoparticles

“…27 Controlling the extrusion foaming process is complicated due to the number of influential parameters that affect the foamability of a molten extrudate including polymer type, melt rheological behavior, FA type, barrel and die temperatures, die pressure, screw design and die geometry. 27,28…”

“…27 Controlling the extrusion foaming process is complicated due to the number of influential parameters that affect the foamability of a molten extrudate including polymer type, melt rheological behavior, FA type, barrel and die temperatures, die pressure, screw design and die geometry. 27,28 By considering this fact, it will be obvious that the extrusion foaming process of a multi-component polymeric systems such as PE/EVA/CNT nanocomposites is accompanied by larger extent of complexity. Attempts have been made, in this study, to show that the effect of the nanoparticles localization state in a biphasic polymeric system on the processability and structural properties of the extruded foams is of great significance.…”