Issue 01 | 2021
Polymeric foams are widely used in applications such as cushioning, packaging, and insulation, due to their unique energy absorption behaviour and good thermal or acoustic insulation properties. They keep their bending stiffness, though a part of the material is exchanged by gas and so reduces the part’s mass at the same time. Currently, extruded PS (XPS) is one of the most important representatives of foams worldwide. In some countries, there have already been attempts to ban food packaging made of petroleum-based XPS foams. As a result, alternatives to foams made of PS are coming into focus. One possible alternative is polylactide (PLA). PLA is a biobased polyester that is biodegradable under certain conditions, approved for use in the food industry, available at competitive prices, and has mechanical properties similar to those of PS. However, PLA also has a number of disadvantages, which pose a particular challenge for foaming. In addition to its low melt strength and viscosity, its crystallization behaviour is also responsible for the fact that unmodified PLA is difficult to foam.