Polystyrene Balls

These light-as-a-feather white foam balls are made from expanded polystyrene, otherwise known as styrofoam: a useful and ubiquitous material that has had a profound impact on the world. From coffee cups to surfboards, beanbag chairs to building insulation, this handy stuff can be found in almost all areas of life. Inert, insulating and cheap to use, polystyrene foam is one of the preferred choices for takeaway food containers and packing materials. As a thermoplastic, polystyrene is incredibly adaptable, meaning it can be formed into all shapes and sizes.

Polystyrene doesn’t start life as a squeaky, lightweight foam though. It all begins with tiny, rigid pellets of polystyrene resin that are infused with an expanding agent (usually pentane) and steamed at very high temperatures. The heat causes this expanding agent to vaporise into a gas, expanding the plastic into tiny balls of bubbled material. These foamy balls are left to age in silos, allowing any residual gas to evaporate and allowing the balls to reach a consistent size. Once aged the foamed pellets can then be moulded into the desired shape. Steam is used again to expand these pieces even more and fuse them together into a homogenous and durable product, without the need for additional binders.

The discovery of polystyrene is thought to date back to the early 19th century. German chemist Eduard Simon was busy distilling storax resin from the Liquidambar tree when he noticed an interesting material that appeared upon cooling and solidification. He named his new material styrol, and it was only when another chemist, Herman Staudinger, accurately described this process as polymerization that the material was renamed polystyrene.

Industrial-scale production of polystyrene began in Germany in the 1930s, and soon after in the USA and beyond. Large scale production was made possible by changing the raw material from naturally-derived storax to synthetically-derived ethylbenzene, as this meant synthetic styrene could be produced from processing crude oil. 

Ethylbenzene is still widely used today, contributing to 90% of polystyrene production. However, with global environmental concerns driving an increase in legislation against single-use plastics, the future of polystyrene is facing change and will likely become less prevalent in everyday life, at least in the form that we know it. Take a look at our mycelium foam to see what alternatives to polystyrene foam are currently being explored.