Direct and indirect observation of multiple local healing events in successively loaded fibre reinforced polymer model composites using healing agent-filled compartmented fibres

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The paper deals with self-healing of polymer composites. Compartmented fibres are competitors to hollow tube fibres. If the hollow tube cavity has been divided into many independent segments (i.e., compartments) it can be more efficient in using of the encapsulated healing agent. One cavity (even large) per fibre makes the fibre useful only ones, no matter how many cracks open the cavity, there is always waste of the adhesive. Segments, on the contrary work independently, thus leaving those unaffected to be used later. To prove such type of behaviour, it was necessary to come up with a fracture mechanical test, which would open fibre segment “1” in time “1”, segment “2” in time “2”. Meanwhile testing sample region “2” for crack opening and later for degree of healing and crack closure, it was important not to destroy region “1” healed crack(s). For that reason conventional fracture mechanics tests (SENB, DTCB) were ruled out. Samples were three-point bended off-axis and inspected with µ-computed tomography. The paper proves the functionality of compartmented fibres and their mechanism of healing agent delivery to the damaged site.

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