Study of microcellular foaming of polystyrene aided with 45 kHz of ultrasound waves energy

Polymer Supercritical CO2 Foaming under Peculiar Conditions: Laser and Ultrasound Implementation

“…In melt foaming, the two previous effects (on No and Φ) were noted in extruded PP foamed by a chemical blowing agent in the presence of talc [9]. In solid-state foaming, these US effects were slight as noted by one previous work on PS foams [12]. Our work on neat PMMA foams is thus consistent with these two studies.…”

“…Regarding the foaming process, the literature contains rather few examples of US-aided microcellular foaming processing, usually by heating simultaneously the gas-saturated polymer and employing ultrasound waves in a solid state. Adam et al [12] foamed PS using a temperature-induced batch foaming assisted by sc-CO 2 . The nucleation was triggered by the elevation of the temperature of the super-saturated sample, in this case, the ultrasound were applied during this stage.…”

Ultrasonic-assisted Dunlop method for natural rubber latex foam production: Effects of irradiation time on morphology and physico-mechanical properties of the foam

“…Furthermore, Wang et al explained that when the cell density was too high, foam growth was restricted, leading to a lower foam expansion ratio [23] . Several researchers reported that transient cavitation caused not only foam collapse, but also cell rupture in rigid polymer foams, such as those of PUR [32] , PLA [35] and PS [36] . The effects of transient cavitation on the foaming behaviors of flexible elastomeric foams in aqueous media have never been reported.…”

The degradation of cellulose in ionic mixture solutions under the high pressure of carbon dioxide

“…The process of the formation of acoustic cavitation bubbles is as follows (in sequence and simultaneously): bubble formation, successive growth, collapse, and microjet formation. [21][22][23] The theoretical estimation of the bubble collapse temperature and pressure can reach 5300 C and 310 bar, respectively, and the H and OH radical fraction produced per collapse event is higher 24,25 (the value set for the sonication frequency was 20 kHz). The microjets intensively pierce and attack the cellulose surface, damaging the cellulose solids.…”