Why does paper become wet intermolecular forces

From the pulp and paper industry, it is known as bulking state of polymer (swelling of polymer). The paper is made mainly from zellulose, and the zellulose is a amorphous-crystalline polymer. In the water there is restricted intercrystalline swelling, when the macromolecules of zellulose enlarge the distance between each other, and the molecules of water fill this space. As the result, swelled zellulose loses its strength and can be easily teared, so because that. When that water hits the paper, it tears more easily than anything because of those intermolecular forces.