© 2006 by Taylor & Francis Group, LLC

16 Corrosion Control Through Organic Coatings
TABLE 2.1
Main Reactions Occurring in Free Radical Chain Addition Polymerization
• Transfers the free radical to another polymer, a solvent, or a chain transfer
agent, such as a low-molecular-weight mercaptan to control molecular
weight
This process, excluding transfer, is depicted in Table 2.1 [4].
Some typical initiators used are listed here and shown in Figure 2.3.
• Azo di isobutyronitrile (AZDN)
• Di benzoyl peroxide
• T-butyl perbenzoate
• Di t-butyl peroxide
Typical unsaturated monomers include:
• Methacrylic acid
• Methyl methacrylate
• Butyl methacrylate
• Ethyl acrylate
• 2-Ethyl hexyl acrylate
Radical Polymerization
I = Initiator; M = Monomer
Initiator breakdown I:I ➔ I + I
Initiation and propagation I + M n ➔ I(M) n
Termination by combination I(M) n + (M) mI ➔ I(M) m+nI
Termination by disproportionation I(M) n + (M) nI ➔ I(M) n−1+n(M−H) + I(M) m−1(M+H)
Data from: Bentley, J., Organic film formers, in Paint and Surface Coatings Theory and Practice,
Lambourne, R., Ed., Ellis Horwood Limited, Chichester, 1987.
CH3 CH3 A. CH3 C N = N C CH3 CN CN
B.
C.
D.
tBu
CO O
O O
O OC
FIGURE 2.3 Typical initiators in radical polymerization: A = AZDN; B = Di benzoyl peroxide;
C = T-butyl perbenzoate; D = Di t-butyl peroxide.
© 2006 by Taylor & Francis Group, LLC
CO
tBu O O tBu