Expanded Polystyrene Foam: Its Uses, Qualities and Manufacturing Process

As one of the world’s most popular materials, we use polystyrene daily, often times without even noticing. Beyond the visible goods we encounter (cups, food trays, coolers, toys and packaging material), polystyrene is also used as a component in insulation, flotation devices, and construction. Its versatility, practicality, and affordability is why Foam Factory, Inc. offers polystyrene in 4-pack quantities to suit commercial, residential, or personal needs, whatever they may be.

Expanded Polystyrene Sheet

Expanded Polystyrene Sheet

There are two main varieties of polystyrene foam, defined by their forming process, which results in slightly different structural makeups. Expanded polystyrene foam sheets, known as EPS, and extruded polystyrene foam, known as XPS, are both closed-cell foams with slightly different feels, densities and hardnesses. Foam Factory only carries EPS, but possesses manufacturing capabilities to produce products from XPS should a customer provide raw XPS for finishing. Polystyrene is often incorrectly referred to in generic terms as “Styrofoam,” which is actually a specific variety of polystyrene owned by the Dow Chemical Company. Though frequently used when referring to all-polystyrene products like drinking cups and packaging, Styrofoam is almost exclusively used as insulation and in crafting applications.

EPS is created through polymerization, where by chemical reaction, very small beads expand greatly from heat and steam until they fuse together to form a solid material, made of tiny, expanded pellets of foam. Due to this dramatic expansion, EPS can be as much as 98 percent air, depending on the variety.  XPS foam is manufactured through a slightly different process. Crystals of polystyrene are blended with other chemicals and then fed into an extruder to produce high levels of heat and pressure. This combines the compounds into a thick, fluid mass. This mass is sent through dies that mold its shape as it expands from a combination of air contact and chemical reactions. Both materials have the potential to be formed into sheets or large blocks that can be manufactured into products like foam insulation or packaging. They can also be forced into unique molds while in a liquid state to produce end products immediately, like drinking cups.

Being very similar structurally, both types of foam have many applications, but the slight difference in manufacturing gives each type particular characteristics that make them suitable for different uses.

XPS is a denser material because of its less-airy structure. It is also typically more consistent because of its manufacturing process. This makes it an excellent insulating material with a high R-Value, a measure of thermal insulation. EPS however, has shown it is better at maintaining its R-Value over the course of its lifetime (EPS Industry Alliance: Source).

Expanded Polystyrene Cake Dummy

Expanded Polystyrene Cake Dummy

Foam Factory makes three different densities of EPS available, each having qualities that make it beneficial for certain applications. 1LB EPS, the most easily manipulated foam density, functions as cost-effective insulation because of its relatively high R-Value and excels in crafting and personal project applications. The 1LB density EPS can be cut or formed into numerous toys like airplane gliders or models. Additionally, it has found a niche in baking as a cake support for large or detailed projects and as a cake dummy for decorating practice or competitions.

Foam Factory’s most popular EPS, the 2LB density, provides increased strength, resistance and insulation while maintaining affordability. One of the best uses for this EPS density is as a hot tub cover. It has a higher R-Value than the 1LB density, with nearly total resistance from water, moisture and vapors and it will not rot, mold, mildew or attract fungi. This is true of all EPS products. The 2LB density is also used for its increased insulation properties. Detailed 3-D business signs are a particularly unique product that Foam Factory can manufacture from EPS foam. A foam sign, made on precision computer programmed machines, can replicate any logo or design, is paintable, and holds up to the elements.

The greatest density Foam Factory carries is the 3LB EPS. This product is best used for industrial insulation and construction purposes. However, if desired, personal or residential products that can be produced using the other two densities may also be produced in the 3LB, with an increased R-Value and durability.

Additionally, all of these products excel as packaging materials and flotation foam. Large blocks of EPS foam have been used in the past to float building materials into place for bridges and other marine construction projects. Floating docks frequently utilize EPS as a flotation material, and some boats utilize it in hull construction to maintain flotation in case of emergency. Its moisture resistant characteristics increase its practicality in all marine situations. EPS is also used in the food industry, as cups, trays and boxes.

Foam Factory utilizes a variety of machines for manufacturing EPS products as well. Most frequently used is the hot wire cutter, which creates smooth contours and 3-D designs from a block of foam. Blade cutters are used for slicing products into sheets, typically into polystyrene insulation and routers can produce angles, cuts and designs in EPS products.

So, the next time you’re soaking in the hot tub, enjoying leftovers from a restaurant, or staying comfortable in the heat or air conditioning of your home, remember that it’s polystyrene that helped make it possible.

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