Polymer melts Critical Molecular weight Mw.of a polymer Mw Mw;no of molten polymer is almost directly proportional to the weight average molecular weight Mw Mw>Mwe no is 。=K[MJ户4 Mw is the point where at which entanglemments become important.Below this value the chains may be considered as non-penetration spheres. Mw.depends on chain configuration and is usually on the order of tens of thousands. At higher shear complete entanglement rates chain entanglements begin to decrease and shear thinning complete alignment- occurs. Shear rate.(log scale) All the individual curves for a series of Mw's, temperatures,and shear rates can be incorprated into a master curve by plotting n versus。dhpe n。 PT where a is a constant near unity 22 Polymer melts Critical Molecular weight Mwe of a polymer Mw < Mwe ; ηο of molten polymer is almost directly proportional to the weight average molecular weight Mww Mw > Mwe ; ηο is ηo = K Mw [ ]w 3.4 Mwe is the point where at which entanglemments become important. Below this value the chains may be considered as non-penetration spheres. Mwe depends on chain configuration and is usually on the order of tens of thousands. At higher shear rates chain entanglements begin to decrease and shear thinning occurs. where is a constant near unity versus into a master curve by plotting temperatures, and shear rates can be incorprated All the individual curvesfor a series of Mw's, α ρ η γ η η α T o Mw o &