Fabrication‐controlled morphology of poly(butylene succinate) nano‐microcellular foams by supercritical CO₂

Abstract

Poly(butylene succinate) urethane ionomer (PBSUIs) foams with nano‐microcellular morphology were fabricated using supercritical CO2 (sc‐CO2) at different parameters. Effect of urethane ionic group (UIG) content (ranged from 1% to 5%) on the rheology and crystallization of PBSUIs were evaluated by intrinsic, dynamic rheological, X‐ray diffraction, and differential scanning calorimetry measurements. The results show that the complex viscosity of PBSUIs vastly improved, while their intrinsic viscosity and crystallinity decreased. They also evidenced that CO2 promoted the formation of crystallites in the amorphous and increased the Xc of PBSU and PBSUIs foams. Scanning electron microscope was employed to explore the influences of UIG content and foaming parameters on the morphologies of PBSUIs microcellular foams, and it revealed that UIG content was the dominated factor. The cell size and cell densities of PBSUIs microcellular foams were smaller than 5.0 micrometers and higher than 1.5 × 1010 cells/cm3, respectively, even foamed at diverse variations of foam temperature and pressure. Interestingly, PBSUIs with 3% and 5% UIG content achieved microcellular foams in nano‐cells, high‐stretched elliptical shape. The mechanism was ascribed that these PBSUIs with high melt viscosities could retard the CO2 bubbles to merge during the foam process and induce the cells to stretch and orient in depressururization direction. This study proposed a novel method for fabricating PBS nano‐microcellular foams.

Fabrication of open‐porous PCL/PLA tissue engineering scaffolds and the relationship of foaming process, morphology, and mechanical behavior

“…Also, as the amount of dissolved gas in the polymer increased, the interaction of carbon dioxide and the polymer lead to a decrease in the glass transition temperature of the polymer, the motion of molecular chains increased and the melt viscosity of the composite materials decreased, so that the resistance of the polymer to the process of cell nucleation and growth was reduced, which promoted the nucleation and growth of bubbles. Therefore, the performance of the foaming system was improved, and it was easier to obtain cells with a uniform size and cell structure …”

“…Therefore, the performance of the foaming system was improved, and it was easier to obtain cells with a uniform size and cell structure. 20 3.1.3 | Influence of CO 2 dissolution time on cell morphologies of PCL/PLA blends With an increase in the CO 2 dissolution time, the dissolution of carbon dioxide in the composites increased before foaming, which increased the number of nucleation points inside the blends, and the nucleation efficiency increased, so that the cell density increases and the average cell diameter was reduced. 21 Also, as the amount of dissolved gas in the polymer increases and the interaction of carbon dioxide and the polymer leaded to an increase in the motion of molecular chains, so the melt viscosity of the composite materials decreased, and the resistance to the process of cell nucleation and growth was reduced, which promoted the nucleation and growth of bubbles, so that it was easier to obtain cells with a uniform size and cell structure.…”

Effects of dicumyl peroxide on cross‐linking pure poly(butylene succinate) foaming materials for high expansion and high mechanical strength

“…11 Due to these outstanding performances, PBS is an appropriate foaming raw material and have been applied in some fields, such as the package and tissue engineering material; 12,13 however, these PBS foaming materials have large cellular size, collapsed cells, poor structural shape ability, and low mechanical strength, which restrict their widespread use in package and tissue engineering fields application. 14,15 To improve these properties, PBS is proposed to be equipped with microcellular and high mechanical strength characters. However, due to the low-melt strength and surface tension, PBS is restricted to fabricate microcellular foams with high compressive strength.…”

Simple and feasible strategy to fabricate microcellular poly(butylene succinate) foams by chain extension and isothermal crystallization induction

“…Microcellular polymer foams exhibit some specific structures, in which their cell density is great than 10 9 cells cm −3 and their cell size is less than 10 μm . Consequently, they have many virtues such as low price, lightweight, heat insulation, and high impact resistance . These superior properties made them appropriate for a versatile of applications, including acoustic absorption, thermal insulation, impact resistance, and scaffolds for tissue engineering …”

“…Up to now, a large number of literatures about microcellular polymer foaming technology have been reported, including microcellular polypropylene, polyethylene (PE), and polystyrene (PS) foams . Among them, microcellular PE and PS foams were used most widely in the world, but their low heat distortion temperature and no degradability were harmful to their applications in many fields.…”