Dynamic behavior of nucleation in supercritical N2 foaming of polystyrene-aluminum oxide nanocomposite

Polymer ferroelectret based on polypropylene foam: piezoelectric properties prediction using dynamic mechanical analysis

“…Polypropylene‐foamed films were produced through physical foaming using supercritical N 2 . Saturated polymers with an inert gas in its supercritical state followed by a rapid pressure drop are known to result in the creation of a large number of small cells, which can grow to produce microcellular foams . Supercritical fluids, because of their low viscosity and negligible surface tension, have high mass transfer rates into polymers, and this principle was used to produce microcellular foams.…”

“…Saturated polymers with an inert gas in its supercritical state followed by a rapid pressure drop are known to result in the creation of a large number of small cells, which can grow to produce microcellular foams. [23] Supercritical fluids, because of their low viscosity and negligible surface tension, have high mass transfer rates into polymers, [45][46][47] and this principle was used to produce microcellular foams. It is also known that the presence of a well-dispersed nucleating agent in the polymer matrix substantially improves the nucleation rate creating a higher number of uniform nucleation sites (heterogeneous nucleation) in comparison with a neat polymer (homogeneous nucleation), thus leading to a more uniform cellular structure.…”

“…It is also known that the presence of a well-dispersed nucleating agent in the polymer matrix substantially improves the nucleation rate creating a higher number of uniform nucleation sites (heterogeneous nucleation) in comparison with a neat polymer (homogeneous nucleation), thus leading to a more uniform cellular structure. [23] Physical foaming was performed through continuous extrusion on a Leistritz ZSE18HP co-rotating twin-screw extruder (diameter = 18 mm and length/diameter = 40). A slit die with dimensions of 15 cm by 0.5 mm and a calendaring system including three rolls having a width of 20 cm and set at 40°C was used to produce the foamed PP films.…”

“…Polymer foams are materials including a solid polymer matrix as the continuous phase and gas bubbles as the dispersed phase . But a tailor‐made cellular structure can be achieved by controlling the nucleation step . Foams can be produced by using chemical or physical blowing agents.…”

“…[22] But a tailor-made cellular structure can be achieved by controlling the nucleation step. [23] Foams can be produced by using chemical or physical blowing agents. In comparison with chemical blowing agents, physical ones like inert gases have several advantages such as chemical inertness, non-toxicity, and non-flammability.…”