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International Journal of Analytical Chemistry
Volume 2019, Article ID 2879869, 8 pages
Research Article

Analysis of the Possibility and Conditions of Application of Methylene Blue to Determine the Activity of Radicals in Model System with Preaccelerated Cross-Linking of Polyester Resins

1Rzeszow University of Technology, Faculty of Chemistry, Department of Biotechnology and Bioinformatics, Al. Powstancow Warszawy 6, 35-959 Rzeszow, Poland
2Rzeszow University of Technology, Faculty of Chemistry, Department of Organic Chemistry, Al. Powstancow Warszawy 6, 35-959 Rzeszow, Poland

Correspondence should be addressed to Karol Hęclik; lp.ude.zrp@kilcehk

Received 20 February 2019; Revised 15 April 2019; Accepted 19 May 2019; Published 1 August 2019

Academic Editor: Bogusław Buszewski

Copyright © 2019 Karol Hęclik et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Unsaturated polyester resins are usually processed using a curing system consisting of initiator and accelerator introduced into the resin. Actually, the producers apply built-in amine accelerators which can be named as preaccelerators. Commonly used preaccelerators for unsaturated resins are tertiary aromatic amines of which incorporation into resin structure may bring better stability. It also causes shorter gelation time of resins because of formation of active RO• radicals that initiate polymerization. Investigated radical reactions are too fast and there is no possibility of freezing it (in unsaturated polyester) to measure with Electron Paramagnetic Resonance (EPR). The analytical methodology on radicals activity measurement in model of preaccelerated unsaturated polyester resin reaction with methylene blue as indicator was presented. Using methylene blue as indicator allows us to determine the activity of forming radicals in three-component system (cobalt salt, amine preaccelerator, peroxide, or hydroperoxide) during the reaction of radicals generating. Changes in radicals activity using methylene blue as interceptor can be observed by changes of transmittance in the UV-Vis spectrum in the range 400-950 nm.