Suspensions Particles and Polymers
Suspensions Particles and Polymers
Polymer Rheology trees and plants-gum-arabic,cellulose ● seeds Guar gum,locust bean gum ● seaweed carageenan,alginates,agar ● fruit -pectins ● grains starches ● microbial xanthan gum ● animal -gelatin,keratin and petroleum -'acrylic acid,polyacrylamide,and many plastics. Kinds of Polymer Chains Long Rods Coils/Strings Branching
Polymer Rheology Kinds of Polymer Chains Long Rods Coils/Strings Branching
Polymer melts and solutions Viscosity of Polymer melts -molecular weight distribution degree of branching shear rate Temperature and Pressure Polymer solutions all of the above -concentration -solvent interactions
Polymer melts and solutions Viscosity of Polymer melts -molecular weight distribution - degree of branching - shear rate - Temperature and Pressure Polymer solutions - all of the above -concentration -solvent interactions
Polymer melts Critical Molecular weight Mwe of a polymer Mw Mwe;no ofmolten polymer is almost directly proportional to the weight average molecular weight Mww Mw>MWe;no is 。-K[Mw]4
Polymer melts Critical Molecular weight Mwe of a polymer Mw < Mwe ; ho of molten polymer is almost directly proportional to the weight average molecular weight Mww Mw > Mwe ; ho is ho KMww 3.4
Mwe 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 gradual loss of entanglements to decrease and development of alignment shear thinning complete alignment- occurs. Shear rate,y(log scale)
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