Investigation of Capsulated Epoxy and DCPD in Epoxy Based Self-healing Composites - DFT Calculation and Experimental Analysis

Epoxy and dicyclopentadien (DCPD) are two common healing agents, which are introduced into epoxy matrix through encapsulation in order to prepare self-healing composites. In a comparative study, the compatibility of healing agents and epoxy matrix is investigated through experimental tests and DFT calculations. The interaction energy is considered to be the determinative parameter in DFT calculation. The values of total interaction energy are -0.14eV for DCPD and +0.169eV for epoxy absorbing on epoxy matrix. According to the obtained results from DFT, an attraction between DCPD and epoxy matrix is observed. DOS and charge analysis of these systems are fulfilled and demonstrated the charge transfer of 0.07 e from epoxy to DCPD. The obtained data reveal the most charge transfer is occurred in DCPD-epoxy, which affects the mechanical properties of healed composites. To examine the mechanical properties, tensile strength parameters are measured experimentally and demonstrated the improved ultimate strength of 783.49 MPa in DCPD/epoxy system rather than the ultimate strength of 571.87 MPa in epoxy/epoxy system. Also elongation at break in DCPD-epoxy system is improved to 3.44% compared to 1.84% in epoxy/ epoxy blend. These findings highlight the role of interaction energy in mechanical properties of polymeric interface, and prompt further experiments and simulations to confirm this effect.