We can easily manipulate part into any shapes. But have you ever wondered why does a fold in paper becomes permanent? What prevents it from regaining it's initial form?
Let's know,
As you all might know, paper is made by fibres of different plants material as well as it is mixed with pulp. Every material has a plastic limit and elastic limit. Till elastic limit, the material can be bend and can still refrain it's original form when the force is removed without any permanent deforestation.
When you exceed above this limit, the material enters into plastic limit where permanent deforestation is caused because of force in the material.
In case of paper, a bend or fold becomes permanent because the fundamental structure of the fibres that compose paper get damaged which pushes them beyond their elastic limit into a state of permanent physical change.
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