Role of amines in microstructure tuning for synergistic damping and mechanical properties in epoxy resins

[Display omitted] •Low temperature curing novel interpenetrating polymer networks (IPNs) having varying degree of micro phase separation is developed in this work.•The early stage of curing process is a kinetically controlled one which later turned to diffusion controlled mechanism.•Nanoscopic Phase separation of nanostructures contributes for excellent toughness and damping behaviour of the epoxy matrix.•Interfacial interactions and internal frictions between the interpenetration networks boosted the damping properties to 1.02 and 1 in 40wt% m-CA/ER/MI and 30wt% s-CA/ER/MI systems respectively. A novel epoxy(ER)/(imidazole)MI/caproamine(CA)interpenetrating polymer networks (IPNs) having varying degree of micro phase separation was prepared. The FTIR results demonstrated that there were two main reactions occurring in the curing process of the CA/ER/MI system. The DSC thermograms of the CA/ER/MI exhibited cure regime in the temperature range of 100–130 °C, Ea was obtained from Kissinger method and the toughened epoxy systems fitted well into a first order linear relation with the average apparent activation energy of 50.5 kJ/mol for m-CA/ER/MI and 63 kJ/mol for s-CA/ER/MI system. The cure index of m- CA/ER/MI was found to obey the condition for good cure, whereas the s-CA/ER/MI system showed poor cure index at lower heating rate and at higher heating rate the system transformed into an excellent cure index. It was interesting to notice that the concentration of CA played a vital role in tuning the microstructure of the overall CA/ER/MI system exhibiting nanoscopic phase separation when CA> 20 wt% with higher percentage of phase separation phenomenon. The 30 wt% m-CA/ER/MI system and 40 wt% s-CA/ER/MI system exhibited excellent damping value of 1.02 and 1 respectively. The tensile strength and the respective elongation at break of 40 wt% m-CA/ER/MI and 30 wt%s-CA/ERMI are 31.25 MPa with14.4 % elongation at break and 27.8 MPa with 30.57 % elongation at break respectively thereby suggesting the potential applications in the field of vibration damping to meet the demands of high performance engineering materials.