Thermal curing of an epoxy-anhydride system modified with hyperbranched poly(ethylene imine)s with different terminal groups

• Published in: Journal of thermal analysis and calorimetry Vol. 127; no. 1; pp. 645 - 654
• Main Authors: Morancho, J. M., Fernández-Francos, X., Acebo, C., Ramis, X., Salla, J. M., Serra, À.
• Format: Journal Article Publication
• Language: English
• Published: Dordrecht Springer Netherlands 2017; Springer Nature B.V; Springer
• Subjects: Analytical Chemistry; Anhydrides; Calorimetry; Chemical synthesis; Chemistry; Chemistry and Materials Science; Curing; Differential scanning calorimetry; Dynamic mechanical analysis; Dynamical systems; Enginyeria dels materials; Epoxy networks; Fourier transforms; Glass transition temperature; Hyperbranched polymers; Inorganic Chemistry; Isocyanates; Kinetics; Materials plàstics i polímers; Mathematical models; Measurement Science and Instrumentation; NMR; Nuclear magnetic resonance; Parameter modification; Phenyls; Physical Chemistry; Polyethyleneimine; Polymer Sciences; Polymers; Polímers; Reaction kinetics; Ressonància magnètica nuclear; Storage modulus; Temperature; Thermal curing; Thermogravimetric analysis; Thermogravimetry; Àrees temàtiques de la UPC; Epoxy networks; Kinetics; Thermal curing; Hyperbranched polymers
• ISSN: 1388-6150; 1588-2926; 1572-8943
• DOI: 10.1007/s10973-016-5376-z

New hyperbranched polymers (HBP) have been synthesized by reaction of a poly(ethylene imine) with phenyl and t -butyl isocyanates. These HBPs have been characterized by 1 H-NMR (nuclear magnetic resonance of hydrogen) and Fourier transform infrared spectroscopy. Their influence on the curing and properties of epoxy-anhydride thermosets has been studied by different techniques: differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and thermogravimetry (TG). The curing kinetics has been studied with DSC. Integral isoconversional method and the Šesták–Berggren model have been used to determine the activation energy and the frequency factor. The kinetic parameters are very similar for all the studied systems at the middle stage of the process, but changes are observed at the beginning and at the end of the process when these modifiers are used. The HBPs reduce the glass transition temperature of the cured materials. In addition, from the DMA analysis it can be seen that the HBP modifier obtained from phenyl isocyanate hardly changes the storage modulus, but the obtained ones from t -butyl isocyanate decrease it. TG analysis reveals a decrease in the onset temperature of the degradation process upon addition of the HBPs.