Self-Avoiding Walk of Plastic Wires Crumpled into Frictional Confinements

The morphology of plastic wires packed into spherical confinements is investigated. The total length of the injected wire exhibits a power-law scaling with the system size (the ratio between container and wire radii R/r), with an exponent dependent on the wire-wall friction. At high friction regime, coils rarely form and the number of folds follows a power-law dependence on R/r. During the injection process, the fold-size distribution gradually broadens and becomes more asymmetric, reflecting the increase of spatial exclusion effects. The cumulative wire length vs the fold size collapses onto a universal curve, allowing for the prediction of the total length of crumpled wire for different R/r, material properties, and insertion forces. A self-avoiding random walk model for such a far-from-equilibrium process is introduced which remarkably reproduces the experimental data.