Free-Radical Polymerization Initiation step: O---O兰O benzoyl peroxide phenyl radicals styrene benzylie radical Copyright2010 Pearson Prentice Hall,Inc. Propagation step: many more styrene molecules H HH growing chain styrene elongated chain polystyrene n=about 100 to 10,000 Copyright 2010 Pearson Prentice Hall,Inc. Chapter 26 6 Chapter 26 6 Free-Radical Polymerization Initiation step: Propagation step: