Complex sentence: Of these theories, the Scavenger Theory is the most common and most important however, more than one theory can act at the same time and the theory that takes place depends on the protective materials, the polymer and surrounding environment.
Split into simpler sentences: Of these theories, the Scavenger Theory is the most common and most important. However, more than one theory can act at the same time and the theory that takes place depends on the protective materials, the polymer and surrounding environment.