Complex sentence: In the paint industry, benzoyl peroxide is used as a hardener in order to start the polymerization process in resins for instance PMMA resins can be polymerized with benzoyl peroxide.
Split into simpler sentences: In the paint industry, benzoyl peroxide is used as a hardener in order to start the polymerization process in resins. For instance, PMMA resins can be polymerized with benzoyl peroxide.