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UP. When UP is used as a binder for polymer concrete, MMA is a better option than
styrene as a reactive monomer, as it shows excellent outdoor stability (Yeon et al.
2017). Bulk molding compounds and sheet molding compounds are used to produce reinforced plastics for cars, buildings, transportation, etc. (Önder and Robinson
2018). The manufacture of industrial pipe and polymer concrete buttons are other
important applications of UPs (Weatherhead 2012; Affolter et al. 2018; Hashemi
et al. 2018).
8.1.2 Saturated Polyesters
8.1.2.1 Introduction
The reactive polyesters to be discussed in this section are low Mw polymers which
are produced by step-growth polymerization (Jones et al. 2017). These polyesters
are almost always end-capped functionalized with hydroxyl or carboxylic acid
groups. There are many ways to convert reactive polyesters into mature product,
between them by using melamine-formaldehyde (MF), polyisocyanates and epoxy
resins as a crosslinker or hardener (Jones et al. 2017).
8.1.2.2 Monomers
The final properties of polyester depend on the selection of monomers. The selection of the monomer in the polyester affects the color of the polyester, the esterification rate, the glass transition temperature (T g ), the hydrolysis resistance, the
reactivity against curing agent, the resistance to ultraviolet (UV) rays, the viscosity
and finally the cost of the final product (Swanson et al. 2017). In general, two types
of monomer are used to synthesize polyester: glycols and dicarboxylic acids or
anhydrides.
8.1.2.2.1 Glycols
There are many types of industrially available glycols to produce saturated polyester. Depending on the final use of the polyester, a narrow range of glycols should be
chosen because each glycol has a unique property. Glycols such as BD, DEG, EG,
HD and NPG, CHDM as difunctional glycol, and TMP and glycerol (Fig. 8.4) as
trifunctional glycols are widely used (Jung et al. 1998). NPG is almost always used
in polyester synthesis due to its exclusive properties. It should be noted that polyester is susceptible to hydrolysis even in mild acidic or basic conditions. For this reason, NPG is used to prevent water and other active species to reach the ester bond
(because the two methyl groups on the sides of water-repellent NPGs) (Deligny and
Tuck 2000). In addition, NPG does not have β hydrogen capable of forming
8 Reactive and Functional Polyesters and Polyurethanes
UP. When UP is used as a binder for polymer concrete, MMA is a better option than
styrene as a reactive monomer, as it shows excellent outdoor stability (Yeon et al.
2017). Bulk molding compounds and sheet molding compounds are used to produce reinforced plastics for cars, buildings, transportation, etc. (Önder and Robinson
2018). The manufacture of industrial pipe and polymer concrete buttons are other
important applications of UPs (Weatherhead 2012; Affolter et al. 2018; Hashemi
et al. 2018).
8.1.2 Saturated Polyesters
8.1.2.1 Introduction
The reactive polyesters to be discussed in this section are low Mw polymers which
are produced by step-growth polymerization (Jones et al. 2017). These polyesters
are almost always end-capped functionalized with hydroxyl or carboxylic acid
groups. There are many ways to convert reactive polyesters into mature product,
between them by using melamine-formaldehyde (MF), polyisocyanates and epoxy
resins as a crosslinker or hardener (Jones et al. 2017).
8.1.2.2 Monomers
The final properties of polyester depend on the selection of monomers. The selection of the monomer in the polyester affects the color of the polyester, the esterification rate, the glass transition temperature (T g ), the hydrolysis resistance, the
reactivity against curing agent, the resistance to ultraviolet (UV) rays, the viscosity
and finally the cost of the final product (Swanson et al. 2017). In general, two types
of monomer are used to synthesize polyester: glycols and dicarboxylic acids or
anhydrides.
8.1.2.2.1 Glycols
There are many types of industrially available glycols to produce saturated polyester. Depending on the final use of the polyester, a narrow range of glycols should be
chosen because each glycol has a unique property. Glycols such as BD, DEG, EG,
HD and NPG, CHDM as difunctional glycol, and TMP and glycerol (Fig. 8.4) as
trifunctional glycols are widely used (Jung et al. 1998). NPG is almost always used
in polyester synthesis due to its exclusive properties. It should be noted that polyester is susceptible to hydrolysis even in mild acidic or basic conditions. For this reason, NPG is used to prevent water and other active species to reach the ester bond
(because the two methyl groups on the sides of water-repellent NPGs) (Deligny and
Tuck 2000). In addition, NPG does not have β hydrogen capable of forming
8 Reactive and Functional Polyesters and Polyurethanes