“In point of fact, a stack of printed or handwritten sheets of paper does not become a book until it is bound. For this reason the binding cannot be seen apart from the book and differs therefore from the picture frame, with which it is sometimes compared but in which there is seldom any structural parallel with painting.” Jan Storm van Leeuwen 
Thinking of a book’s binding as something independent from “the book” as an entirety is a serious misconception. This raises some practical concerns: if a book has been disbound, and perhaps remains disbound for the purposes of display, is it no longer a book? Does it now belong in a special category of the book; a disbound book?  Much descriptive terminology adds similar qualifiers; an unbound book, a rebound book, etc…. A work of art remains a work of art if it is in its frame or not. A textblock cannot just be taken out of its binding without radically altering its ontological status as a book.
 Jan Storm van Leeuwen. Dutch Decorated Bookbinding in the Eighteenth Century, Volume 1: General Historical Introduction. Den Haag: Hes & De Graff, 2006. p. 41.
 The extreme of this might be the leaf book, a new book made to highlight a single leaf from another book. There are a number of excellent essays, including one by a lawyer/ leaf book collector who considers ethics and international law in the catalog to the exhibition Disbound and Dispersed: The Leaf Book Considered. Chicago: The Caxton Club, 2005.