162
8.1.1.4 Final Reactions of Reactive UP
The main reactive site for UP to produce the mature product is the double bond.
There are other functional reactive groups in the UP but they do not participate in
the final reactions. The double bonds react with styrene in the presence of peroxides
as initiator. Peroxides such as di-benzoyl peroxide, di-cumyl peroxide, di-t-butyl
peroxide, methyl ethyl ketone peroxide and t-butyl peroxybenzoate (Fig. 8.3) are
being widely used (Dodiuk and Goodman 2013). Depending on the peroxide used,
different temperatures are needed to dissociate the peroxide in order to produce free
radical (Kunwen et al. 2016). The radicals formed in the propagation stage react
with styrene or the present double bond in the main chain of polyester. Then, these
active pieces react again with styrene or the double bond to obtain the final product
(Yu and Ma 1993).
The peroxides can also be activated at room temperature by using accelerator
compounds. Accelerator materials are mainly based on cobalt complexes or tertiary
amine compounds (Nakagawa et al. 1992). The cobalt complexes, such as cobalt
naphthenate and cobalt octoate, are frequently used to reduce the initiation temperature of the reaction to the room temperature (Nakagawa et al. 1992). On the other
hand, tertiary amine compounds are used on a more extended scale than cobalt
complexes. Compounds such as N,N-dimethoxy-p-toluidine, N,N-dimethyl aniline
(DMA) and N,N-dimethyl-p-toluidine (DMPT) are being used on a large scale
(Landau et al. 1979; Cambien 2014).
8.1.1.5 Uses and Applications
UPs have a wide range of applications such as filled composite materials, polymer
concrete, powder coatings and reinforced materials (Penczek et al. 2005). Polymer
concrete is a composite in which cement is replaced by polymeric materials such as
Fig. 8.3 The peroxides
used for curing UPs: (a)
di-benzoyl peroxide, (b)
di-t-butyl peroxide, (c)
di-cumyl peroxide, (d)
methyl ethyl ketone
peroxide and (e) t-butyl
peroxybenzoate
M. Akbari and R. Najjar
8.1.1.4 Final Reactions of Reactive UP
The main reactive site for UP to produce the mature product is the double bond.
There are other functional reactive groups in the UP but they do not participate in
the final reactions. The double bonds react with styrene in the presence of peroxides
as initiator. Peroxides such as di-benzoyl peroxide, di-cumyl peroxide, di-t-butyl
peroxide, methyl ethyl ketone peroxide and t-butyl peroxybenzoate (Fig. 8.3) are
being widely used (Dodiuk and Goodman 2013). Depending on the peroxide used,
different temperatures are needed to dissociate the peroxide in order to produce free
radical (Kunwen et al. 2016). The radicals formed in the propagation stage react
with styrene or the present double bond in the main chain of polyester. Then, these
active pieces react again with styrene or the double bond to obtain the final product
(Yu and Ma 1993).
The peroxides can also be activated at room temperature by using accelerator
compounds. Accelerator materials are mainly based on cobalt complexes or tertiary
amine compounds (Nakagawa et al. 1992). The cobalt complexes, such as cobalt
naphthenate and cobalt octoate, are frequently used to reduce the initiation temperature of the reaction to the room temperature (Nakagawa et al. 1992). On the other
hand, tertiary amine compounds are used on a more extended scale than cobalt
complexes. Compounds such as N,N-dimethoxy-p-toluidine, N,N-dimethyl aniline
(DMA) and N,N-dimethyl-p-toluidine (DMPT) are being used on a large scale
(Landau et al. 1979; Cambien 2014).
8.1.1.5 Uses and Applications
UPs have a wide range of applications such as filled composite materials, polymer
concrete, powder coatings and reinforced materials (Penczek et al. 2005). Polymer
concrete is a composite in which cement is replaced by polymeric materials such as
Fig. 8.3 The peroxides
used for curing UPs: (a)
di-benzoyl peroxide, (b)
di-t-butyl peroxide, (c)
di-cumyl peroxide, (d)
methyl ethyl ketone
peroxide and (e) t-butyl
peroxybenzoate
M. Akbari and R. Najjar