TRIMETHYLOLPROPANE DIALLYL ETHER

This has led to chemical modification of the polyesters, in particular the introduction of allyl ether groups into the resins. Amongst the monomers figuring prominently in the literature are allyl glyceryl ether I, trimethylolpropane diallyl ether II (1,1-diallyloxypropanol) and pentaerythritol triallyl ether III (2,2,2-trial-lyloxyethanol), as shown in Figure 25.32. 

Real-Time FTIR. For our IR studies, we utilized a stoichiometrically equivalent amount of a trifunctional thiol, trimethylolpropane tris(2-mercaptoacetate), with a difunctional allyl, trimethylolpropane diallyl ether. The thiols were protected from oxidative polymerization by the addition of hydroquinone. The monomers and hydroquinone were purchased from Aldrich Chemicals and were used as received. This formulation was mixed for five minutes and then a commercial photoinitiator, Esacure TZT (Sartomer Inc.), which contained a blend of methyl benzophenones, was added at a level of 1.0% by weight of monomers to the formulation. Stirring was maintained for a further five minutes following the addition of the photoinitiator. The final formulation contained 2.0% by weight of hydroquinone. The samples were prepared prior to each experiment in order to ensure reproducibility of sample history. 

Figure 7. IR spectra of the trimethylolpropane tris(2-mercaptoacetate)/ trimethylolpropane diallyl ether system for three different UV exposure times (0 s, 713 s, 8995 s) showing S-H stretching (2570 cm 1), C=C stretching (1646 cm 1), and aromatic out-of-phase C-H deformation (830 cm 1) peaks. The thiol peak is monitored to calculate the extent of reaction while the C-H deformation peak is used as an internal standard.

In another approach, to minimize air inhibition, reactive oxygen species are added to the system, which preferentially consume oxygen before it can interfere with the curing reaction. Allyl ethers such as trimethylolpropane diallyl ether, pentaerythritol monoallyl ether and allyl glycidyl ether are normally used for this purpose. 

UV-curable UPRs are mainly used in coatings, waterborne ones in particular. Por that purpose, imsaturated polyesters were synthesized from ethylene glycol, diethylene glycol and 1,2-propylene glycol combined with dicarboxylic acids or acid anhydrides fumaric acid, tetrahydrophthalic anhydride, tereph-thahc acid and trimelUtic anhydride [177] trimethylolpropane diallyl ether was incorporated into the polyester as an air inhibitor of cure. Moreover, tri-ethylamine was added to neutralize the unreacted carboxyUc groups, whereas... 

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