Synthesis, characterization and qualitative assessment of self-healing capacity of PU microcapsules containing TDI and IPDI as a core agent

Abstract This paper shows the results obtained during the synthesis, characterization and self-healing qualitative capacity assessment microcapsules made of polyurethane (PU) shell, a product of emulsion polymerization reaction between diphenylmethane diisocyanate (MDI) and 1,4-butanediol, and within it, as the "encapsulated" self-healing agent, toluene diisocyanate (TDI) or isophorone diisocyanate (IPDI). Microcapsules synthesis and self-healing agent encapsulation were possible due to the difference of diisocyanates reactivity applied in the process, while its self-healing capacity was achieved by the interaction between encapsulated agent (TDI and IPDI) with active groups present in the epoxy matrix. The characterization was performed by means of experimental techniques such as: Universal Attenuated Total Reflection in the middle infrared region (FT-MIR / UATR), Scan Differential Calorimetry (DSC), Optical Microscopy (OM), Scanning Electron Microscopy (SEM) and Thermogravimetric Analysis (TGA) to monitor the synthesis, morphology and thermal stability of the microcapsules. Self-healing qualitative capacity was evaluated through dynamometric test to monitor its effectiveness when it is added in a proportion of 5% in epoxy matrix. The results were satisfactory considering the proposed study about synthesis and characterization of PU microcapsules containing TDI and IPDI as a core agent and the compatibility of core agents with the epoxy matrix.