Paper’s mechanical properties lend themselves to folding and bending. The cellulose fibers of which it is made can be partially snapped in the area of maximum bend, allowing a permanent crease to form, while sufficient fibers remain intact for the material not to crack and fall apart. Indeed, in this state it pretty much maintains its ability to resist being pulled apart, but it can also be torn easily and accurately along the crease if a point of weakness—a small, initial tear—is opened up. This winning combination of mechanical properties allows it to assume the shape of any object through
...more
