“…This unique behaviour is intimately related to the uncrossability of chains which effectively leads to topological constraints between chains in the form of entanglements (deGennes, 1980;Doi and Edwards, 1988). The original reptation theory, based on the tube model, and more recent theoretical concepts have captured qualitatively and quantitatively the effect of entanglements on polymer dynamics and rheology (deGennes, 1980;Doi and Edwards, 1988;Kroger, 2004;Likhtman, 2005;Likhtman and McLeish, 2002;Marrucci, 1996;Marrucci and Ianniruberto, 2004;McLeish and Larson, 1998;Ramirez et al, 2007;Stephanou et al, 2011;Wang et al, 2012). Additionally, density is one of the key factors which affect profoundly the static, dynamic and rheological properties of entangled polymers (Daoud et al, 1975;Doi and Edwards, 1988;Edwards, 1966;Fleer et al, 1993).…”