Plastics have a reputation for being lightweight materials, but is this always the case? Also, how do they compare to traditional materials when it comes to weight? In this article, we’ll examine the difference between the weight of various types of plastics and that of traditional materials (metals and glass). We’ll also suggest plastic options that are lighter and stronger than standard glass, along with some that are more durable than steel and aluminum.
Finally, we’ll provide a brief overview of the benefits related to system component weight reduction.
Hard yet extremely brittle, glass can often be replaced by acrylic, better known under the trade name of Plexiglas®, or by polycarbonate, also known as LEXAN®, two thermoplastics with excellent optical properties and good transparency.
Besides reducing system weight, these two plastics offer excellent impact resistance. Indeed, acrylic is 17 times more impact resistant than glass. As for polycarbonate, it’s even more prized for its impressive impact resistance, which is 250 times greater than glass.
Density of transparent materials
| Materials | Density (kg/m³) |
| Standard glass | 2,500 |
| Polycarbonate | 1,200 |
| Acrylic | 1,190 |
To learn more about how to maintain and clean polycarbonate, see our article, Cleaning Polycarbonate.
Some plastics can be used to replace metal parts or components. For example, while steel is known for its strength and excellent mechanical properties, it’s a very heavy material that doesn’t prevent corrosion.
FRP (fiber reinforced plastic) is a composite material that has excellent mechanical properties while being 70% lighter than steel. It’s used to make walkways, ladders and structural components that never rust because of its excellent chemical resistance.
| Materials | Density (kg/m³) |
| Steel | 7,500–8,100 |
| Stainless steel | 8,010 |
| Aluminum | 2,700 |
| FRP (gratings) | 2,025 |
To learn more about FRP, see our following articles:
FRP: An Alternative to Steel for More Durable Structures
FRP in the Food Sector
4 Questions to Help You Choose the Right Structural Material
Mechanical parts made of stainless steel can also be replaced by high-performance plastic equivalents. For example, by replacing a stainless piston with one made of acetal, you can easily increase its durability while reducing its weight by 5 times.
Density of other plastics
| Materials | Density (kg/m³) |
| Polytetrafluoroethylene (Teflon®) | 2,160 |
| PVDF | 2,025 |
| PVDF | 1,780 |
| PET-P (Ertalyte®) | 1,410 |
| PEEK (Ketron® 1000) | 1,310 |
| Polycarbonate | 1,200 |
| Acrylic | 1,190 |
| Nylons (NYLOIL®) | 1,140 |
| ABS | 1,080 |
| HDPE | 960 |
| UHMW | 953 |