143589.fig.003
Figure 3: (a) Dibenzoyl peroxide commonly known as benzoyl peroxide or BPO dissociates into two molecules to provide (b) benzoyl free radicals (R). (c) In liquid form, styrene monomer with vinyl-group C7 and C8 (C=C) double pi (π) bond upper left of molecule is attacked by R to add a benzoyl group on one of the carbon atoms. (d) Subsequent styrene radical formation depicted by “e” on the opposite vinyl carbon atom can now enter into a reaction with a new styrene molecule C=C vinyl group. (e) A second styrene molecule can add the benzoyl-styrene radical on the C=C vinyl group for the growing chain to form a free radical again as “e” on the opposite vinyl carbon atom. Free-radical additions through the liquid styrene monomer C=C vinyl groups continue the polymerization process by the reactive secondary sequence method a multitude of times to eventually form a solid.