The true specific gravity of PVC is about 1.4, which is comparatively heavy among plastics, as is the case for PET. This can be a disadvantage depending on the application.
By taking advantage of the fact that PVC does not float in water, it is used in water sealing sheets for agricultural water reservoir or swimming pools, or lining materials for rivers. Regarding flexible PVC products, the specific gravity falls within the 1.1~1.3 range depending on the amount of plasticiser used, which is slightly lower than that of rigid PVC.
