EPDM is a synthetic rubber, or elastomer. Although it's made from the same family of polymers as plastics, its elastic properties differentiates it from plastics. Different combinations of additives and processing methods create structurally distinct molecules that produce its unique material characteristics.
While some plastics are somewhat flexible, that characteristic often depends on the addition of chemicals known as plasticizers, such as phthalates. The molecular structure of elastomers, in contrast, can stretch and bounce back into shape without any chemical additives.
