Is it True That Plastic Materials Are Lightweight?
Overall, plastic materials are known to be lightweight, but is it always the case? Although most plastic materials are very lightweight when compared to traditional materials (metal, glass, concrete and wood), the plastic weight will vary greatly depending on their category. To find out if a plastic material is lightweight, one will have to refer to its volumetric density mass (volumetric mass density = kg/m3). As a reference, the water has a density of 997 kg/m3. Thus, any material that has mass density lower than that of water will float while a material with a density mass greater than 997 kg/m3 will not float. Some plastic materials are heavier than others, but when compared to more traditional materials such as metals, they will always be lighter.
Comparison With Other Materials
As weight could be a very relative measure, the most effective method to accurately illustrate the weight of a material is to compare it with other materials. A metal can be described as a “lightweight” material when compared with other metals, but this does not mean that it is a lightweight material. Similarly, a plastic material of a specific category may be very lightweight, but when compared to other more specialty plastics, it will probably be considered as a weighty material. Overall, we can conclude that even the heaviest in weight plastics will be far lighter than aluminum. Teflon®, which is considered as one of the heaviest plastic materials, has a volumetric mass density of 540 kg/m3, which is much lower than that of aluminum, in addition to having an outstanding strength.
Acrylic: 1,190 kg/m3
Aluminum: 2,700 kg/m3
Concrete: 2,200 kg/m3
Polycarbonate: 1,200 kg/m3
Polypropylene: 946 kg/m3
Polytetrafluoroethylene (Teflon®): 2,160 kg/m3
Stainless steel: 8,010 kg/m3
Standard glass: 2,500 kg/m3
Steel: 7,500 - 8,100 kg/m3
UHMW: 941 - 965 kg/m3
Why Choose a Lightweight Plastic Material?
The volumetric mass density listed above demonstrates why high-performance plastic materials can be very effective solutions to reduce the weight of mechanical parts and structural components. Lightweight material provides concrete benefits including reducing maintenance and energy costs. Lightweight parts require less energy to be set in motion. For example, let's take a mechanical part made of stainless steel (volumetric mass density of 8,000 kg/m3) that could be replaced by a part made of high-performance plastic material such as acetal. The weight of the acetal part would be lower (volumetric mass density of 1,410 kg/m3) in addition to providing an outstanding wear resistance. The result would be an energy-efficient part, easily replaceable and above all, cheaper in cost. A lightweight part offers many advantages, including reduced maintenance and risk of accidents during maintenance. In addition, a food-quality acetal formulation is available, compliant with FDA standards.
To learn more about plastics designed for the food industry, consult our free guide: Performance Plastics for the Food Industry
While plastic materials are lightweight, they still have very significant mechanical properties and ability to withstand various stresses. Performance plastics have a much higher power-weight ratio than more traditional materials such as metal and glass. This means that for a much lower weight, their mechanical properties will also or if not be greater than those of traditional materials.