Double cantilever beam test and micro-computed tomography as evaluation tools for self-healing of CFRPs loaded with DCPD microcapsules

Abstract

In the present study, the healing efficiency of microcapsules containing dicyclopentadiene (DCDP) was investigated on carbon fibre reinforced polymers (CFRPs) via morphological and mechanical characterisation. Micro-computed tomography (m-CT) has been used to observe in three dimensions (3D) the dynamic process of crack propagation and give CFRPs qualitative and quantitative structural and compositional information. Microcapsules with Poly(urea-formaldehyde) as shell and DCPD as healing agent in core were prepared by in situ polymerization in an oil-in-water emulsion. The morphology and thermal properties of microcapsules were examined via Optical Microscopy, Scanning Electron Microscopy (SEM), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Vacuum bagging was proved an efficient technique for the CFRPs’ manufacturing that microcapsules can endure. The morphology of heal progression of cracks, induced at the surface of microplastics, was observed through SEM, while for the mechanical response double cantilever beam (DCB) test was selected to evaluate heal efficiency. The reduction of the crack volume in the CFRPs internal structures was up to 45%, while the mechanical restoration exceeded 50% proving microcapsules’ efficiency.