Great question! Its super simple, it is ONLY the length of the hydrocarbon chain, a better quality natural rubber has really long chains (10,000+ atoms long) that last a LONG time and are VERY stretchy. Synthetic rubber (or plastic) is shorter (1,000 atoms long) and doesn't last as long.
Thats it, it is the exact same "product" just a chain that gets longer and longer and changes its physical properties as it grows.
Thats it, it is the exact same "product" just a chain that gets longer and longer and changes its physical properties as it grows.