Microwave-Assisted Synthesis of Solid Epoxy Resins: Study of Molecular Weight by GPC and MALDI-TOF/MS
2016
Bogdal, Dariusz | Gorczyk, Jaroslaw | Kwasek, Beata
A new method of preparation of solid epoxy resins (SER) with desired epoxy-group content via an advanced process under microwave irradiation is presented together with the results of molecular weight measurements for narrow oligomeric fractions obtained from chromatographic separation of SER. All the measurements were performed using gel permeation chromatography (GPC) and matrix-assisted laser desorption ionization spectrometry–time of flight mass spectrometry (MALDI-TOF/MS). In the GPC analysis, two types of calibration were used: the first was a standard calibration based on polystyrene standards, while the second was done on the basis of a chromatograms of epoxy resins synthesized from bisphenol A (BPA) and diglycidyl ether of bisphenol A (EDBPA). On the basis of the MALDI-TOF analysis, it was assumed that the purity of starting materials, i.e., low molecular weight epoxy resin, clearly determined the structure of the SER. In order to obtain an SER with linear chain structures and an even number of polymerization degrees, the low molecular weight epoxy needs to be characterized by a high content of diglycidyl ether of bisphenol A (EDBPA) as it was observed for Rutapox 0162. In the case of low molecular weight epoxy resins that contained a higher oligomeric fraction of diglycidyl ether of bisphenol A (EDBPA) like Epikote 828, one can observe an even and odd polymerization degree which resulted in the branching of chain structures. Eventually, the procedure of chromatographic separation of SER allowed a better correlation of results from MALDI-TOF/MS and the GPC.
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