Reaction Kinetics and Mechanical Properties of Reversible Epoxies by Diels-Alder reaction

<p>Epoxies are an important class of thermosetting polymers for many long-term applications such as adhesives, structural materials, and coatings. Epoxies have durable and robust mechanical properties; but, they are difficult to remove, recycle and rework. Epoxies capable of reversible polymerization could solve these problems. In this experiment, reversible epoxies were synthesized by introducing the Diels-Alder reaction groups to epoxy monomers. 1,1'-(Methylenedi-4,1-phenylene) bismaleimide and furfuryl glycidyl ether were reacted to form a Diels-Alder cycloadduct. This cycloadduct was confirmed using Fourier Transform-Infrared (FTIR) Spectrometry. The forward and reverse Diels-Alder reaction was monitored by FTIR measurements at 90 ^oC and 110 ^oC as a function of exposure time. IR absorption peaks relevant to the reverse Diels-Alder reaction grew due to longer exposure time at 90 ^oC and 110 ^oC. The equilibrium shift was observed toward the reverse reaction dominant side at higher temperature by comparison of FTIR spectra at 90 ^oC and 110 ^oC. Mechanical properties of the reversible epoxies was examined to confirm two states of reversible epoxies: a durable network at lower temperature and soft segments at higher temperature.</p>