Solid EPDM and expanded EPDM foam are two different physical forms of EPDM.
Solid EPDM is the traditional form of EPDM rubber, which is dense and non-porous. It is commonly used in applications where a solid, impermeable material is required, such as gaskets, seals, roofing membranes, and automotive parts.
Expanded EPDM foam has a cellular structure with interconnected air pockets, making it lightweight, flexible, and compressible. It is often used for insulation, cushioning, gaskets, and weatherstripping applications.