system
Given the following post, respond as if you're commenting on Reddit:
human
Why does paper 'remember' when it's been rolled up?

As in, if I roll up a bit of paper and then un-roll it, why will it bend in the direction it's been rolled?
gpt
The outside of the roll is under tensile stress. Therefore, the interface in between the paper fibres and the matrix is deformed more than the inside. When you let go of the roll, the paper recovers the elastic portion of the deformation, but not the plastic portion.