Expanded polyamide 12 bead foams (ePA) thermo-mechanical properties of molded parts

Abstract

The demand for bead foam products, typically made from expanded polystyrene (ePS) or expanded polypropylene (ePP), has risen sharply in the past. Bead foam products made from engineering thermoplastics with superior thermomechanical properties compared to existing products, such as a polyamide could open up completely new fields of application. Like other engineering thermoplastics, polyamide shows challenging properties with regard to foaming, such as a low melt strength and a narrow processing window. The present work shows the thermo-mechanical properties of expanded bead foams from polyamide 12 (ePA). The molded parts, with a density less than 100 g/l, were compared to commercially available ePP in three-point bending tests. The bending modulus is about 4 times higher compared to ePP, although the molding can be still improved. Furthermore, the thermo-mechanical properties are tested with dynamic mechanical analysis. ePA exhibit a good thermal stability up to 150 °C, with nearly unchanging dynamic mechanical properties in the tested range. In comparison to ePP, with a thermal resistance up to 100 °C, ePA bead foams show significantly better properties and could displace commonly used compact polyamide parts as well as ePP parts in the car.