Expandable polystyrene, otherwise known as EPS, is one of the most revolutionary materials ever invented. Its unique combination of physical properties and recycle ability make it a highly desirable rigid foam product.
EPS’s life cycle is worth looking at in greater detail to better understand the unique nature of this material. Know this: EPS has come a long way in recent years. It is a fantastic insulator, a lightweight and easy-to-work-with material, and more sustainable than ever before.
Manufacturing Expandable Polystyrene
Expandable polystyrene is manufactured using a multi-step process that transforms simple beads into a lightweight, rigid foam material. Watching the polystyrene beads transform into what is an excellent insulating and protective material is simultaneously exciting and fascinating. Here are the four steps in the process:
1. Material Preparation
The first step involves preparing raw materials. Manufacturers begin with a polystyrene resin presented in the form of tiny beads. The beads are a combination of polystyrene, a blowing agent, and other materials. Blowing agents tend to be compounds like pentane and cyclopentane.
2. Pre-Expansion
Moving on to the second step, the beads are exposed to steam in a specialized vessel. Steam softens the beads and simultaneously heats the blowing agent in excess of its boiling point. Once the blowing agent reaches that boiling point, it begins to expand.
The blowing agent partially vaporizes while expanding the beads up to forty times their original volume. You end up with much larger beans filled with millions of air pockets.
3. Aging
Following pre-expansion, the material is stored for up to 24 hours so that it can properly age. During aging, the beads cool and any residual blowing agent liquifies. This creates a partial vacuum that allows air to diffuse into the beads. The entire material stabilizes in both size and density.
4. Molding
Finally, properly aged beads are fed into molds where they are once again exposed to steam. They expand further while also bonding to create a solid block, panel, etc. The mold is cooled to solidify the material within before the actual product is removed and trimmed to meet requirements. An EPS block or panel can be cut into any number of shapes and finished to offer a smooth surface.
Quality control is obviously important. Finished products are rigorously tested for density, strength, and other properties. Any finished materials that do not meet specifications can be returned to the production process.
Recycling Expandable Polystyrene
Despite what many people believe about expandable polystyrene, it is a highly recyclable material. It can, and does, play a vital role in the circular economy. Here is what you need to know about it:
1. Recycling Potential
Expandable polystyrene is 100% recyclable. It can be recycled repeatedly with no significant loss of integrity. Note that it is not easily distinguishable from other polymers that can only be partially recycled or ultimately end up as waste. So recycling it requires diligence.
2. Recycling Is Fairly Easy
EPS is fairly easy to recycle. It is collected, cleaned, and densified. It is then processed to create new raw materials in the form of pellets or billets.
3. Recycling Is Catching On
Recycling programs are embracing EPS recycling with greater frequency. More than 30% is recaptured in North America. Furthermore, 50% EPS products are now common. They can be made from post-consumer recycled material.
We are thrilled to be an industry leader in expandable polystyrene. This incredible material has transformed how we approach plastic resins for insulating applications. Its combination of properties, performance, and recyclability make it a dynamic manufacturing material for the 21st century.