Solid-state microcellular acrylonitrile-butadiene-styrene foams

Microcellular ABS foams are a novel family of materials with the potential to significantly reduce material costs in a number of applications that currently use solid polymer. ABS foams were produced using carbon dioxide in a solid-state process. Solubility and diffusivity of CO2 in ABS was measured, and the latter was found to depend significantly on the gas concentration. The useful range of process-space for ABS-CO2 was characterized. Closed cell ABS foams were produced with densities ranging from 1.03 g/cm3 (almost completely solid) to 0.09 g/cm3. It was determined that there are many different processing conditions that can produce microcellular ABS foams that have the same density. The cell nucleation density was of the order of 1011 cells per cm3, and the average cell sizes observed ranged from 0.5 μm to 5.6 μm.