Differences Between Polyurethane and Polystyrene

Differences Between Polyurethane and Polystyrene Looking for strategies that will lower your home heating and cooling costs while raising your comfort level? If so, the benefits of foam insulation may interest you. Spray foam (polyurethane) insulation and rigid foam (polystyrene) are the two main types available. Both polystyrene and polyurethane are polymers, synthetic materials made from long molecular chains. Most of the atoms in these molecules are hydrogen and carbon. These materials are manufactured by industry and used to create various everyday objects. Polystyrene, also known as foam, is frequently used particularly in packaging boxes for electronic devices for extra protection. However, polyurethane is replacing polystyrene in some cases, particularly where additional flexibility is required. Although the two can sometimes be confused, there are differences between them in composition, heat conduction of the finished products, resistance to chemicals, and thickness tolerances.

Composition Differences

Polystyrene is typically a polymer containing molecules made up of carbon and hydrogen atoms. Polyurethane's molecular formula, on the other hand, represents a much more complex polymer made up of molecules containing nitrogen, oxygen, carbon, and hydrogen. Polyurethane's polymers can be ordered in various ways to produce materials with varying degrees of flexibility, unlike polystyrene which creates a rigid plastic.

Thermal Resistance

The thermal resistance of a building material is measured by its R-value. Polyurethane, an excellent material for electrical insulation, achieves heat resistance nearly twice that of polystyrene. Polyurethane's flexibility is maintained even at extremely cold temperatures. However, this resistance varies according to the thickness and density of both materials.

Degradation, Chemical Resistance, and Wear

While solvents such as gasoline and some insecticides damage polystyrene, polyurethane is resistant to almost all chemicals. In terms of resistance to oxidation and atmospheric degradation caused by sunlight, this polymer performs better than polystyrene. In addition, polyurethane is more resistant to physical impact and stress factors than polystyrene.

Load Support and Sound Insulation

Polyurethane can be used to produce load-bearing wheels, mechanical fasteners, couplings, and machine mounts because it mimics both rubber and plastic. Polystyrene lacks the flexibility required for these tasks. Because polyurethane shares certain properties with rubber, it helps achieve mechanical sound reduction. This material provides significantly quieter gears.

Rigid Polystyrene Foam Insulation

The most common places to apply rigid foam are unfinished walls, roofs, and foundations. Compared with other insulation types, this dense material offers a high R-value that provides exceptional performance with a very thin thickness. Rigid foam installation reduces thermal bridging, increases the R-value of wall or roof assembly, and significantly reduces air leakage.

Insulation Made from Rigid Polystyrene Foam

EPS or expanded polystyrene: EPS is a good material for home insulation use because it has an R-value of 3.6 to 4.2 per inch. It is a more affordable option and best suited for top-tier applications. Extruded polystyrene (XPS): XPS is ideal insulation for below-grade applications and foundation walls thanks to its notable R-5 per-inch value, strong compression resistance, and water resistance.

Insulation Made with Polyurethane Spray Foam

Spray foam is the best insulation to minimize air leakage. Because it foams in place, you can fill every crack. For this reason, spray foam is excellent for filling voids around irregularly shaped cracks as well as floor and wall penetrations. However, because spray foam must be applied in place and with the use of special protective clothing, installation should be performed by specialists.  

Spray Foam Insulation Made from Polyurethane

Open-cell polyurethane foam: An R-value of 3.6 per inch is expected. Open-cell foam is airtight but permits moisture vapor. This makes it perfect for inward-drying roof systems that require insulation. Closed-cell polyurethane foam: Closed-cell foam provides the highest R-value per any insulation thickness, roughly 6.5 R per inch. Its consistency resembles adhesive and provides structural integrity to the wall or ceiling it is applied to. Although this alternative is more expensive than open-cell foam, it may be a better choice under the required conditions because it offers a higher R-value per inch and also acts as a vapor retarder. Polystyrene Rigid Foam Panels: Benefits and Drawbacks Polystyrene has a greater R-value than fiberglass, cellulose, or mineral wool. It is also lightweight and easier to use and contains no fibers that can irritate skin. Rigid panels are resistant to sagging, provide good resistance to water and wind, and are easy to cut and shape with a knife. Disadvantages of polystyrene include weak chemical resistance particularly to organic solvents and sensitivity to damage from UV light (which restricts its outdoor use).

Benefits and Drawbacks of Polyurethane Spray Insulation

Polyurethane spray foam can reach some of the highest R-values of any typical insulation, namely R-6 per inch. It is applied as a liquid, expands to fill voids, and creates a strong bond with surrounding surfaces. This results in tight air sealing and increased structural integrity. Because closed-cell polyurethane is highly water-resistant, it can be used to successfully waterproof various surfaces. Polyurethane insulation requires an experienced professional to mix and apply properly, a requirement that may mean the insulation application is more costly. Compiled by: B. Serhat Cengiz Sources https://byjus.com/chemistry/polystyrene/ https://www.ibpportland.com/blog/polystyrene-vs-polyurethane-insulation https://sciencing.com/hdpe-vs-ldpe-5968206.html