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So you need to find out what the best glue for polystyrene is? Or what the best glue for styrofoam is? Heck, is there even a difference between the two you should be concerned about?
Due to their similar textures and compositions, it’s easy to confuse styrofoam for polystyrene and vice versa. In reality, these two chemicals are quite different!
For starters, one is a brand of the other. They also differ in uses too! If you want to know about the differences between polystyrene and styrofoam, keep reading!
What is Styrofoam and Polystyrene?
Styrofoam
Styrofoam is a brand name of polystyrene. More accurately put, it’s a brand of closed-cell extruded polystyrene foam and is also known as “Blue Board.” Styrofoam is made of styrene monomers. Generally, styrofoam is used as a form of insulation.
The Dow Chemical Company owns this material, and it’s primarily used as a water barrier and thermal insulation between roofs, foundations, and walls.
In colloquial terms, styrofoam is used to refer to another material that’s generally white in colour and constructed of expanded polystyrene foam. Keep in mind, that’s expanded, not extruded.
Styrofoam brand polystyrene foam can be differentiated by the “crunch” it makes and the roughness of its texture. In addition, it’s somewhat soluble in cyanoacrylate, organic solvents, and the solvents and propellants of spray paint – which is a fancy way of saying it has a melting point in certain solvents so you need to be careful what you’re working with!
Polystyrene
A versatile plastic by nature, polystyrene is used to make a large variety of consumer goods. It’s this hard, solid plastic that is often used to make products requiring like food packaging or even the stuff you find a lot of your packages will come with to protect them during transit! If you’ve ever bought something online, I’m sure you’ve had to throw out a mountain of the stuff before!
Polystyrene comes in both solid and foam forms and it is technically what’s known as a synthetic aromatic hydrocarbon polymer featuring a monomer construction (which is a fancy way again of saying its made up of lots of little bits of ‘monomer’ or molecules) The monomer, in this case, is named styrene.
So it’s a scientific way of mashing or polymerizing lots of bits of this molecule they call styrene together, to get polystyrene that you is which is also how it got its name.
Much like the name suggests, polystyrene is made by polymerizing or stringing styrene (a chemical building block utilized in manufacturing consumer products) together.
When made into a foam material, it’s called EPS expanded polystyrene, or XPS which is extruded polystyrene. XPS has cushioning and insulation properties.
Foam polystyrene (styrofoam) can be about 95% air and is used to make appliances and home insulation, surfboards, lightweight packaging, food and foodservice packaging, automobile parts, and more.
What is the Difference between Styrofoam and Polystyrene?
While polystyrene is whats known as a synthetic aromatic hydrocarbon polymer, Styrofoam is one of the trademark brands of polystyrene. Polystyrene seems transparent but many forms of PS are known to have different colours due to the mixing of colourants. For instance, styrofoam features a light blue hue.
One more difference between the two is the availability. Polystyrene is available in solid products as well as foam products whereas Styrofoam can be found as foam products only. There is a big difference between their uses too.
Styrofoam is made and designed to work as an insulation material between roads and buildings while generic polystyrene products are used in everything from insulation to food packaging.
Last but not least, it’s also claimed that EPS (expanded polystyrene) isn’t biodegradable, which is true to a certain extent. However, this doesn’t mean that it can’t be recycled.
EPS foam packaging can be turned into solid polystyrene pellets which can then be used to make goods like foodservice packaging, picture frames, coat hangers and more.
So what does all that mean for you? Well, that means that there is in fact the best glue for polystyrene and the best glue for styrofoam and you have to at least have some idea of which one you’re using!
The Best Glue for Polystyrene or Styrofoam
The best, most compatible glues with Styrofoam are the actual glues made for the brand. Think USU Styrofoam glue, 3M 77, and Weldbond.
Styrofoam glue can be found in both sprays and tubes. The adhesive sprays such as 3M 77 make craft projects easier and anyone can use them without creating a mess.
With 3M 77, it dries relatively faster and has a better bonding capacity than the other.
In contrast, the Weldbond glue takes longer to bond. You have to wait for it to become tacky enough before attaching the surfaces to ensure it doesn’t emit toxic fumes or dissolve the foam.
What Should Not Be Used with Styrofoam and Polystyrene?
You shouldn’t use glues that feature solvents since these adhesives will melt the styrofoam. Plus, it will release toxic fumes. Never use hot glue on styrofoam because when applied to the material directly, hot glue causes styrofoam to melt. Alternatively, find some form of polystyrene instead that doesn’t have a low melting point.
If you’re in a pinch and can’t work with anything except hot glue, which is fine, just apply it to the object you want to stick to instead. Wait for it to develop a tacky texture and then attach it to the styrofoam. Steer clear of hot glue if you want to stick two styrofoam bits together.
Another glue we don’t recommend at all is the LePage Pres-tite Cement. This solvent-based glue will melt the styrofoam. But there is one variant of this – the LePage Pres-tite Green Cement that seems to work well with styrofoam. Don’t go for the general Contact version of this adhesive though.
Safety Precautions working with styrofoam glue
Polystyrene has not been classified as a hazardous substance by the Globally Harmonized System (GHS). But, it may be harmful if inhaled, absorbed through the skin, or if swallowed. Moreover, it can cause skin, eye or respiratory tract irritation.
Keeping that in mind, there are some safety instructions when handling polystyrene. You should only use this in well-ventilated areas. Don’t inhale fumes, dust, or vapors. When the material is in a raw state, wear proper protective gear to handle it. Avoid contact with skin, eyes, or clothing.
At What Temperature Does Styrofoam Melt?
As it’s made from expandable polystyrene, styrofoam doesn’t accommodate heat well. Usually, it begins to soften at 212° Fahrenheit/100° Celsius and melt at 464° Fahrenheit/240° Celsius. Never put styrofoam cookware in the microwave or the oven!
How Long Does Styrofoam Adhesive Take to Dry?
Drying time varies from one glue to another. As a rule of thumb, you should wait 24 hours to let the glue cure completely. Some cyanoacrylate adhesives dry faster, so wait times can be between a few minutes to a few hours. Spray-on adhesives don’t take very long to dry. In contrast, industrial adhesives require longer drying times. So if you’re doing something as simple as building out a model train layout, you can probably give it half an hour to adhere to the surface and then just be a bit careful with it for the next day or two before it really cures to the new surface!
As you can see, calling polystyrene styrofoam or the other way around isn’t scientifically correct. Their uses vary a lot, and both have fairly different properties. So, choosing the best glue for polystyrene or styrofoam will depend on the uses.
Peter has been building model trains for longer than he can remember. An avid fan of HO and O scale this blog is a creative outlet to allow him to dive further into other scales and aspects of the model train community and hobby.
