Pendulum hardness is one of the static measurement methods of viscoelasticity, and the hardness values measured at different temperatures cannot compared. The damping in the determination of pendulum hardness mainly comes from the absorption of mechanical energy by the paint film, that is, the loss modulus. The loss modulus is lower in both the glass and rubber regions and higher at T. The hardness of the pendulum is related to the thickness of the paint film. When it is too thin, the substrate will be affected . The advantage of the pendulum damping test method is that it does not damage the coating film.
Common pendulum damping Testers include Konig pendulum, referred to as K pendulum; Persoz pendulum, referred to as Р pendulum. These two Testers have been adopted by CHINA's national standard GB 1730-88 "Determination of Paint Film Hardness Pendulum Damping Test".
The pendulum damping hardness method uses two steel balls embedded under the cross bar of the pendulum to contact the coating film sample. When the pendulum swings, the fixed mass of the pendulum presses the film to make the film resist . The time to determine the hardness of the coating film, the K pendulum is from 6° to 3°, and the P pendulum is from 12° to 4°. The standard time for K pendulum on a polished flat glass plate is 250s±10s, and for Р pendulum is 420s. Both Testers are equipped with a photoelectric control counting device to automatically record the damping time.
