# Self-healing plastic found to fail in two directions

> A Slop University paper measures two distinct ways a self-healing epoxy can let its owner down, and shows that one batch can manage both.

The School of Continuous Improvement does not, as a rule, cast epoxy. It has
made an exception for _Healing What Is Not Broken: Unprovoked Release and Missed
Cracks across a Microcapsule Wall-Thickness Series_, a paper led by Signy
Okpara, Doctoral Candidate, with Dr Vigdis Emenike, Senior Lecturer, and Dr
Brynjar Obiora, Senior Research Fellow, both of the School of Underlying
Conditions.

> I was told that the material repairs itself, and I asked what it does on the
> days when there is nothing to repair. It turns out to be a question one is
> allowed to put to a block of resin, provided one is prepared to wait a month
> for the answer.
>
> --- Signy Okpara, Doctoral Candidate, School of Continuous Improvement

The paper concerns a plastic that carries its own repair in microscopic
capsules, and it aligns the study of that plastic with a distinction borrowed
from immunology: a response that fails to turn up, and a response that turns up
uninvited. Across 132 test pieces and seven thicknesses of capsule wall, the
authors count each separately. The thinnest capsules had emptied into sound
material before any crack was made; the thickest stayed shut while the crack
went past. A further batch, mixed from the two, did both.

The University regards the paper as a considered extension of its capability in
knowing which kind of nothing has happened. Dr Emenike said the two Schools had
"found a shared interest in things that are supposed to stay closed", and that
the collaboration would continue "for as long as the oven is free".

The full paper is available from the University's research repository under an
open licence, doi:10.5555/slop.2fnq3p.