TY - THES

T1 - Isothermal and Non-Isothermal DSC Analysis towards the Formulation of a Low-Temperature Curing Epoxy-Alcohol Resin

AU - Lang, Johanna

N1 - embargoed until 11-03-2026

PY - 2024

Y1 - 2024

N2 - Sustainability issues regarding conventional epoxy resins from non-renewable resources led to investigations of bio-based alternatives. One of these alternatives, based on renewable feedstocks, is eugenol, which can be epoxidised at the allyl functionality. In this thesis, the curing behaviour of this monomer was compared to the most frequently used epoxy resin, diglycidyl ether of bisphenol A (DGEBA), with the aid of dynamic and isothermal differential scanning calorimetry (DSC) measurements. The anionic ring-opening homo- and copolymerisation of these monomers in various ratios was initiated by tertiary amines, namely 1-methylimidazole (1-MI) and 2,4,6-tris(dimethylaminomethyl)phenol (K54). This thesis aimed to develop a low-temperature curing epoxy-alcohol formulation without amine co-curing agents. The homopolymerisation showed that K54 was advantageous for low-temperature curing, while 1-MI performed better at elevated temperatures. This was also confirmed by a proton nuclear magnetic resonance (1H NMR) study with phenyl glycidyl ether (PGE) as a soluble model compound. The apparent activation energies calculated based on the Kissinger and Ozawa method were about 10 kJ mol-1 lower for K54 than for 1 MI. Moreover, the dynamic DSC revealed that formulations with epoxidised eugenol (EE) exhibited lower onset temperatures than DGEBA alone. The acceleration of the curing reaction due to hydroxyl groups was even more prevalent in isothermal DSC measurements at 80 °C than in dynamic DSC analysis. The same trends were observed during the copolymerisation of DGEBA and EE. A significant acceleration of the epoxy polymerisation by hydroxyl groups was found for an EE content of only 10 mol%. However, the acceleration due to the phenolic hydroxyl of EE was not confirmed at room temperature in an 1H NMR study. Finally, benzyl alcohol was investigated as an alternative alcohol with a more promising reactivity at room temperature. To conclude, K54 was found to be beneficial for curing at low temperatures and the acceleration of an epoxy-alcohol formulation was shown at 80 °C. However, a monomer with more reactive functionalities than EE should be used for room temperature curing.

AB - Sustainability issues regarding conventional epoxy resins from non-renewable resources led to investigations of bio-based alternatives. One of these alternatives, based on renewable feedstocks, is eugenol, which can be epoxidised at the allyl functionality. In this thesis, the curing behaviour of this monomer was compared to the most frequently used epoxy resin, diglycidyl ether of bisphenol A (DGEBA), with the aid of dynamic and isothermal differential scanning calorimetry (DSC) measurements. The anionic ring-opening homo- and copolymerisation of these monomers in various ratios was initiated by tertiary amines, namely 1-methylimidazole (1-MI) and 2,4,6-tris(dimethylaminomethyl)phenol (K54). This thesis aimed to develop a low-temperature curing epoxy-alcohol formulation without amine co-curing agents. The homopolymerisation showed that K54 was advantageous for low-temperature curing, while 1-MI performed better at elevated temperatures. This was also confirmed by a proton nuclear magnetic resonance (1H NMR) study with phenyl glycidyl ether (PGE) as a soluble model compound. The apparent activation energies calculated based on the Kissinger and Ozawa method were about 10 kJ mol-1 lower for K54 than for 1 MI. Moreover, the dynamic DSC revealed that formulations with epoxidised eugenol (EE) exhibited lower onset temperatures than DGEBA alone. The acceleration of the curing reaction due to hydroxyl groups was even more prevalent in isothermal DSC measurements at 80 °C than in dynamic DSC analysis. The same trends were observed during the copolymerisation of DGEBA and EE. A significant acceleration of the epoxy polymerisation by hydroxyl groups was found for an EE content of only 10 mol%. However, the acceleration due to the phenolic hydroxyl of EE was not confirmed at room temperature in an 1H NMR study. Finally, benzyl alcohol was investigated as an alternative alcohol with a more promising reactivity at room temperature. To conclude, K54 was found to be beneficial for curing at low temperatures and the acceleration of an epoxy-alcohol formulation was shown at 80 °C. However, a monomer with more reactive functionalities than EE should be used for room temperature curing.

KW - Epoxy

KW - DGEBA

KW - Epoxidised eugenol

KW - Tertiary amines

KW - DSC

KW - Kissinger

KW - Epoxy

KW - DGEBA

KW - Epoxidiertes Eugenol

KW - Tertiäre Amine

KW - DSC

KW - Kissinger

U2 - 10.34901/mul.pub.2024.095

DO - 10.34901/mul.pub.2024.095

M3 - Master's Thesis

ER -