Hydroxylated polyesters structure

A general idealized structure of a hydroxylated polyester based on 2 mol of trimethylolpropane, 9 mol of 1,6-hexanediol, and 10 mol of isophthalic acid is the following (11. 12) ... 

The polyester structure has been adapted for use in radiation-cured coatings. Low molecular weight, linear polyesters have been made in which the terminal hydroxyl groups have been esterified with acrylic acid. These oligomers have low viscosity and are used increasingly in coatings cured by UV or electron-beam radiation (21). 

Block copolymers with materials such as a polyester (PE) (qv) can be prepd by the reaction of diisocyanate-terminated polyesters with hydroxyl-terminated PMMA according to Wilkes and Grezlak (Ref 21). The basic structure was found to be PMMA-PE-FMMA, with a mw of from 7500 to 47000. The purpose of the work was to produce a stronger copolymer (in terms of stress-strain) by tailoring the amt of each monomer used to produce the copolymer Further information on polymerization can be found in Refs 2a 6a... 

The largest single use of maleic anhydride is in the preparation of unsaturated polyester resins. It is first esterihed with a polyalcohol (two or more hydroxyls) and then the double bond is copolymerized (crosslinked) with a vinyl monomer such as styrene to form a rigid structure. Such resins are usually reinforced with hberglass (FRP). Maleic anhydride is also used to make oil additives and agricultural chemicals. 

This publication established that crosslinking of the polystyrene was not necessary to support the pore structure in monolith nanoporous samples, that mild chemical degradation of an aliphatic polyester is a practical methodology for the generation of bulk porous samples, and that the hydroxyl group derived from the juncture of the PS-PLA material decorated the pore walls of the material. 

Fig. 10. Complex dynamic viscosity as function of temperature for three different aliphatic hyperbranched polyesters based on bismethylol propionic acid and having different end-group structure - (O) propionate end-groups, ( ) benzoate end-groups, ( ) hydroxyl end-groups [118]...

Figure 12 presents q as a function of temperature for three hyperbranched polyesters with different end groups. A comparison shows that the properties of hyperbranched polymers are greatly affected by the structure of the terminal groups. The Tg decreases from 35 °C with terminal hydroxyl groups to 15 0 for benzoates and -20 °C for propionates. 

Since the early days of polyurethane discovery, the technology has focused on isocyanate reactions with polyesters or polyethers. The differences will be discussed in later sections. These reactions are responsible for the growth of the polyurethane industry. The polyesters of interest to polyurethane chemists terminate in hydroxyl groups and are therefore polyols produced by the polycondensation of dicarboxyhc acids and polyols. An example is a polyol with a polycarbonate structure (Figure 2.3). 

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