Degradasi dan Biodegradasi Interpenetrating Polymer Network (IPN) Hidrogel Kitosan Poli (N-Vinil-2-Pirolidon) = Degradation and Biodegradation Interpenetrating Polymer Network (IPN) Hydrogel Based Chitosan Poly(N-Vynil-2-Pyrrolidone) (Fakultas Matematika dan Ilmu Pengetahuan Alam Universitas Indonesia, 2014)