A detailed discussion about different material models for polymers is available in the book “Mechanics of Solid Polymers – Theory and Computational Modeling”. The book is written by Dr. Jorgen Bergstrom from Veryst Engineering, and the book is available from Amazon. The book is very comprehensive and covers both detailed theory and hands-on practical advice on how to perform accurate FE simulations of any polymer. These topics are not discussed in any other book that is currently available. See PolymerMechanics.com for more information about the book.