Many thermoplastic polymers are hygroscopic in nature. The absorption of water in these polymers can affect their material properties including the mechanical strength, dielectric loss, and electrical conductivity. Water adsorption is the attachment of individual water molecules on the surface of plastics. This gathering of molecules on the surfaces of medical plastics is important as it can prevent protein adsorption onto the devices surface which is unwanted in some applications.
D570-98 (reapproved 2018)
This standard covers the testing methods for measuring water absorption of plastics when immersed in water for different time periods and conditions. This testing can help determine the amount of water that can be absorbed by a material, and the products uniformity as the density of the plastic can affect the water absorption. Water absorption of the sample is determined by weighing the sample before and after immersion and is recorded as a percentage increase in weight.