  The process of crumpling a sheet and compacting it into a ball is dependent
on many parameters that are difficult to disentangle. We study the effect of
plasticity on the crumpling process, and disentangle the effects of plasticity
and dimensionality of compaction by performing isotropic compaction experiments
on various materials with different elastoplasticities. The force required to
crumple a sheet into a ball as well as the number of layers inside the ball
have a power-law dependence on the size of the crumpled ball, each with its own
power-law exponent. We experimentally determine both exponents and find that
they are linearly proportional to and decrease with increasing plasticity of
the material. Finally we provide a scaling argument predicting a linear
relation between the two exponents with a coefficient of 3.5 in excellent
agreement with our experimental results.
