Cure Kinetics of Neat Unsaturated Polyester

10 min i, and 2 = 4.94x 10 J/mol (see Eq. (14.2)). It should be mentioned that one encounters kj = 0 when the rate of cure reaction of an unsaturated polyester is relatively slow and k Q when an accelerator (e.g., A(,A/-dimethylaniline) is added to speed up the cure reaction of an unsaturated polyester, even at relatively low cure temperatures. 

Horie et al. (1969) pointed out that the cure reaction of unsaturated polyester can be analyzed using the approach of free-radical polymerization. It should be pointed out that the cure reaction of unsaturated polyester involves the formation of three-dimensional 

BPO as initiator and 1.9 wt % A,A-dimethylaniline as accelerator at various isothermal cure temperatures ( C) (O) 40, (A) 45, ( ) 50, (V) 55, and (O) 60. (Reprinted from Han and Lem, Journal of Applied Polymer Science 28 3155. Copyright 1983, with permission from John Wiley Sons.) 

other investigators (Han and Lee 1987a, 1987b Huang et al. 1990b) employed the same approach to obtain slightly different rate expressions. 

The curing reaction of unsaturated polyester resin involves the copolymerization of unsaturated polyester and styrene in the presence of an organic initiator. Like any other free-radical polymerization (e.g., bulk polymerization of methyl methacrylate), the organic initiator first decomposes to form an initiator radical [/ ], which will then react with unsaturated polyester to form a polyester radical [ ] and with styrene monomer to form a styrene radical [S ]. Therefore, the curing reaction can be treated by a free-radical polymerization approach. Below, we describe briefly the mechanistic kinetic model for unsaturated polyester (Han and Lee 1987a, 1987b Stevenson 1986). 

---