Study of hyperbranched poly(ethyleneimine) polymers of different molecular weight and their interaction with epoxy resin

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Defense date2018-03-09
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Abstract
Two different commercial hyperbranched poly(ethyleneimine)s (HBPEI), with molecular weights (MW) of 800 and 25,000 g/mol, and denoted as PEI800 and PEI25000, respectively, as well as the mixtures with a Diglycidyl Ether of Bisphenol-A (DGEBA) epoxy resin, have been studied using thermal analysis techniques (DSC, TGA), dielectric relaxation spectroscopy (DRS), and dynamic mechanical analysis (DMA). Only a single glass transition is observed in these mixtures by DSC. DRS of the HBPEIs shows three dipolar relaxations: ¿, ß, and a. The average activation energy for the ¿-relaxation is similar for all HBPEIs and is associated with the motion of the terminal groups. The ß-relaxation has the same average activation energy for both PEI800 and PEI25000; this relaxation is attributed to the mobility of the branches. The a-relaxation peak for all the HBPEIs is an asymmetric peak with a shoulder on the high temperature side. This shoulder suggests the existence of ionic charge trapped in the PEI. For the mixtures, the ¿- and ß-relaxations follow the behaviour of the epoxy resin alone, indicating that the epoxy resin dominates the molecular mobility. The a-relaxation by DRS is observed only as a shoulder, as a consequence of an overlap with conductivity effects, whereas by DMA, it is a clear peak.
CitationRoman, F., Colomer, P., Calventus, Y., Hutchinson, J.M. Study of hyperbranched poly(ethyleneimine) polymers of different molecular weight and their interaction with epoxy resin. "Materials", 9 Març 2018, vol. 11, núm. 3 (410), p. 1-26.
ISSN1996-1944
Publisher versionhttp://www.mdpi.com/1996-1944/11/3/410
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