Reactive and Functional Polyesters and Polyurethanes
The reactive polyesters are organic compounds based primarily on carboxyl, hydroxyl and double bond functional groups, which are produced by polycondensation or ring opening polymerization (ROP). Depending on the functional group, they can react with diff
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Reactive and Functional Polyesters and Polyurethanes Morteza Akbari and Reza Najjar
Abstract The reactive polyesters are organic compounds based primarily on carboxyl, hydroxyl and double bond functional groups, which are produced by polycondensation or ring opening polymerization (ROP). Depending on the functional group, they can react with different types of curing agents such as 2- hydroxyalkylamides, amines, atmospheric oxygen, diisocyanates, epoxies, melamine-formaldehyde (MF) and polyols to produce the final product on an industrial scale. The polymers resulting from the polyesters and curing agents have many applications such as adhesives, coatings, composites, elastomers, foams and sealants. One of the main applications of reactive polyesters is the preparation of diisocyanate-cured PUs. There are several types of reactive PUs which are produced by reacting a polyol with an isocyanate compound. The reactive site is often isocyanate end-capped groups. However, other functional groups such as amine, carboxyl and hydroxyl can be used as the reactive site. This chapter aims to analyze reactive polyester and polyurethane. Keywords Curing agent · Diisocyanate · Functionalization · Unsaturated polymer
8.1 Polyesters The discovery of polyesters was achieved when Carothers successfully synthesized this type of polymers by the reaction of glycols and dicarboxylic acids. Due to a high viscosity problem, Carothers was unable to obtain high molecular weight (Mw) polyester (Smith and Hounshell 1985). Other researchers carried out their work using long chain glycols or polyols to produce high Mw polyesters. The first commercial polyester was introduced in 1941 under the trade name of Dacron. Since then, much progress has been made in the industrial production of polyesters.
M. Akbari · R. Najjar (*) Polymer Research Laboratory, Faculty of Chemistry, University of Tabriz, Tabriz, Iran e-mail: [email protected] © Springer Nature Switzerland AG 2020 T. J. Gutiérrez (ed.), Reactive and Functional Polymers Volume One, https://doi.org/10.1007/978-3-030-43403-8_8
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M. Akbari and R. Najjar
Today, there are many types of commercially available polyesters. Two types of reactive polyesters based on the functional group are known in the art: unsaturated and saturated polyesters.
8.1.1 Unsaturated Polyesters (UPs) 8.1.1.1 Introduction UPs have double reactive bonds in their structure. UPs are synthesized by a polycondensation of dicarboxylic acids (or anhydrides) with glycols and usually water as the by-product is removed from the reaction medium. In order to produce UPs, which can be crosslinked in the final stage by vinylic monomer (e.g. methyl methacrylate -MMA, styrene), there must be a double bond in the polymer backbone. This double bond is almost always introduced by dicarboxylic acids or anhydrides which have a double bond in their structure by using of compounds such as fumaric acid or maleic anhydride (MA). By varying the ratio of unsaturated dicarboxylic acid (or anhydride) to glycols, a wide ran
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