University of Pardubice Faculty of Chemical Technology

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The effect of cobalt-free promoters on curing of unsaturated polyester resins at ambient temperature

Authors: Matušková Eliška | Honzíček Jan | Vinklárek Jaromír

Year: 2022

Type of publication: ostatní - přednáška nebo poster

Page from-to: nestránkováno

Titles:

Language	Name	Abstract	Keywords
eng	The effect of cobalt-free promoters on curing of unsaturated polyester resins at ambient temperature	Our study is focused on behaviour of cobalt-free transition metal compounds as curing promoters for unsaturated polyester resins (UPR). The curing process is based on a free radical polymerization including transformation from the liquid state into the rigid structure. If the curing process is performed at ambient temperature, accelerator and initiator need to be added. As initiators, organic peroxides are commonly used, for example methyl ethyl ketone peroxide (MEKP). Accelerators, particularly complexes of transition metals, are effective in decomposing of peroxides, which serve as sources of free radicals [1]. With increasing environmental pressure on the producers, it is important to find a cobalt-free alternative for the sustainable future of polyester resins [2]. The catalytic power of potential promoters has been verified by determination of gelation time on a commercial polyester/styrene/methyl ethyl ketone peroxides system. In case of exothermic behaviour, we focused on a different situation during the curing of UPR. At thermally isolated system, the curing process was followed by a K-type thermocouple, which enabled to observe inhibition of the curing process at high concentration of promoters and verify their thermal stability. In case of isothermal conditions, consumption of styrene and unsaturated polyester double bonds was followed by real-time near-infrared spectroscopy. Subsequently, a kinetic model was established for precise quantification of catalytic effect for each promoter. Temperature of glass transition was determined by using thermomechanical analysis in order to verify the ability of tested promotors to reach similar degree of cure as a commercially used promotor based on cobalt carboxylates. All tested promoters were proved to be capable of catalysing the curing process of the unsaturated polyester resin with a potential for future use.	unsaturated polyester