by Elsevier Science Publishers .
Written in English
|The Physical Object|
A nonlinear viscoelastic model for polymer solutions and melts—II. Vivek Sharma, Gareth H. McKinley, An intriguing empirical rule for computing the first normal stress difference from steady shear viscosity data for concentrated polymer solutions and melts, Rheologica Acta, /s, 51, 6, (), ().Cited by: Nonlinear effects in the dynamics of concentrated polymer solutions and melts. “Rhelogy of polymer solutions and melts,” Preprint No. [in Russian], Institute of Problems of Mechanics, USSR Academy of Sciences, Moscow (). “System of equations of motion of a nonlinear viscoelastic fluid suitable for describing the flow of Cited by: This book presents detailed studies of flows in elastic liquids, from theory, through experiment, to applications. Falling into the category of elastic liquids in particular, are the melts and concentrated solutions of such flexible-chain polymers as polyethylene, polyisobutylene and polypropylene, all of which are widely used in polymer processing.
We compare viscoelastic properties of several polystyrene solutions and melts with the same number of entanglements. It is demonstrated that the modulus and time can be shifted such that the linear viscoelastic properties are identical provided the number of entanglements are identical. However the nonlinear properties in strong extensional flow are different with polymer solutions showing. The rheological behavior of a concentrated solution of well-characterized, broad molecular weight distribution polystyrene in step strain flows is examined at large deformations. Mechanical and optical techniques are used to obtain the full stress tensor in terms of the shear stress, first normal stress difference, and second normal stress difference. Stress relaxation data on this novel. An extremely important property of linear viscoelastic materials is that of superposition. Superposition principles occur in several domains in viscoelasticity as will be seen shortly (including nonlinear viscoelasticity), but the first one to consider is superposition of responses to linear viscoelastic materials, the strain responses to two different stress inputs applied. Polymer melts and solutions exhibit very complicated stress relaxation and flow behavior in response to a deformation. Unlike simple viscous liquids or elastic solids, polymeric liquids are viscoelastic, which means that the stress is a function of the whole deformation history rather than just of deformation rate (as in simple liquids) or of deformation amplitude (as in simple solids).
Nonlinear dynamics of viscoelastic flow in axisymmetric abrupt contractions. Gareth H Dheur, J. & Crochet, M. J., Interfacial effects in the flow of viscous and elastico-viscous liquids R. B. & DeAguiar, J. R., An encapsulated dumbbell model for concentrated polymer solutions and melts; I theoretical development and. Extensional Flow Behavior of Melts and Concentrated Solutions Linear, Monodisperse Polymers Effect of Polydispersity Linear Low-Density Polyethylene Effect of Long-Chain Branching Randomly Branched Polymers and LDPE Experimental Methods for Extensional Flow Basic Techniques Approximate Methods. In literature there are many papers in which the best fitting of the peculiar viscoelastic functions using a fractional model is performed. However there are not present studies about best fitting of relaxation function and/or creep function of materials that exhibit a non-linear viscoelastic behavior, as polymer melts, using a fractional model. An experimental study has been carried out to specify the nonlinear viscoelastic behavior of noncrystalline peroxide-cured EPDM networks covering a range in .