Viscoelastic properties of polymer solutions

Abstract

In a cOllcentrated polymer solution, the entanglement of long-chain molecules results in a transient network structure, to which may be attribu ted certain aspects of the viscoelastic behavior of such a system. A sui table mechanical model for rcpresenting this network a s a first approximat ion is a retarded Maxwell element with one spring and two dashpots.Experimental measurements of mechanical properties of polymer solut ions may be made eit h er by periodic deformat ion under conditions where inertia forces can be neglected or by propagation of transverse waves. Th e data are expr essed in terms of frequency-dependent parameters from which can be d erived the constants of t he correspo!1ding m echanical model. A solution o f polystyrene in xylene is cited as an exampl e. In this case, analysis in term s of a . recent theory of Kuhn suggests t hat elastic energy may be stored in the network strands by twist a gains t t he potential hindering free rotation about bonds in t he chains. I. Entanglement in Concentrated SolutionsThe polymer solutions discussed in this paper lie in the concen t ration range from 5 to 50 percent-more concentrated than the very dilute solutions commonly used for measurements of viscosity and osmotic pressure and other properties from which the behavior of single molecules is deduced, but more dilute than the usual commercial plastic, which may contain from 50 to 100 percen t of polymer mixed with a plasticizer. Solutions in this range are u sed in plastics technology-in spinnin g, extrusion , and coating processes. Aside from their technical importance, they are of interest because of their remarkable mechanical, optical, and dielectric properties. Their mechanical properties are intermediate between those of solids and liquids; these solutions are both viscous and elastic.Examples may be cited to illustrate three very different types. Lightly vulcanized rubber swollen in cyclohexane to a concentration of 20 percent is a quivery, elastic gel. A variety of evidence shows that th e long-chain molecules are bound togeth er at widely spaced points by primary chemical bonds, forming a network: that can be broken only by ch emical deeomposition; but there I Thi~as presented as part of tbe 1946--47 series of lectures on t be P ropert ies of Hi gh Pol ymers given at the Kational Bureau of Stand ards., Department of Chemistry, U ni versity of Wisconsin .Viscoelastic Properties is· very little hindrance to motion of the chains except for these occasional cross-links. Polyvinyl chloride dissolved in cyclohcxanone at the same concentration is a sluggish gel. Ther e ar e no primary bonds, as shown by the fact that the gel can be dissolved by adding more solven t. N cvertheless, the tendency of polyvinyl chloride m olecules to associate, segmentwise, with dipole interaction (as shown by the ready formation of crystallinc regions in the solid state [1] 3 and association in dilute solution [2]) , makes plausible the conccpt that there is a network here, also, held together by secondary bonds caused ...

Influence of surgical suture properties on the tribological interactions with artificial skin by a capstan experiment approach

“…In this meanwhile, the visco-elastic property of artificial skin was a significant factor to attribute to the decreasing of coefficient of friction with increasing applied load. Young's modulus E of polymer materials depends upon hydrostatic pressure in the contact zone [24]. With increasing of pressure, the modulus of elasticity for silicon is increased many times [25].…”

Dynamic Mechanical Analysis in the Analysis of Polymers and Rubbers

“…MacKay and Halley (86) recently reviewed chemorheology and the more common kinetic models. A funda-mental method is the Williams-Landel-Ferry model (87), which looks at the variation of T g with degree of cure. This has been used and modified extensively (88).…”

Solutions of the Problems of a Viscoelastic Dynamic Contact between Smooth Curvilinear Surfaces of two Solid Bodies by the Application of the “Method of the Specific Forces”

“…But, the Hertz theory allows only the finding the normal elastic force. The existing methods still cannot give the complete answer, how these nonlinear parameters of viscoelasticity can be found for the practical application by using the dynamic modules of elasticity and viscosity, which usually can be found by using the known methods (Ferry, 1948(Ferry, , 1963Moore, 1975;Van Krevelen 1972;Nilsen, 1978Nilsen, , 1994 For example as we know according the Hertz theory (Landau & Lifshtz, 1944 for the contact of two spherical surfaces . Where E is effective elasticity modulus, R is the effective radius of contact curvature.…”

“…For example, the dynamic elasticity modules are very yieldable to a changing of a velocity and temperature of the matter in the area of deformations (Ferry, 1948(Ferry, , 1963Lee, 1962;Van Krevelen, 1972;Moor 1978;Nilsen, 1978Nilsen, , 1994Lakes, 1998;Meyers, 1994;Menard, 1999;Roylance, 2001;Goloshchapov, 2001Goloshchapov, , 2015Hosford, 2005;Popov, 2010, Popov & Hess, 2015. Also, it is necessary to mention that, the researches in the field of the collision of viscoelastic particles (granules) with identical mechanical properties have been made by Brilliantov, Spahn, Hertzsch and Pöschel (1996).…”

“…It is obvious that, in the case of the contact between a spherical body and a semi-space, the effective radius R and the radius of a body are equal, and if take in account (25) and that M = F τ l x , then if the dynamic viscosities replace by the dynamic viscosity modulus according to the known expressions (Ferry, 1948(Ferry, , 1963Lee, 1962;Van Krevelen, 1972;Moor 1978;Nilsen, 1978Nilsen, , 1994Lakes 1998;Meyers 1994;Menard 1999;Goloshchapov, 2001Goloshchapov, , 2015Hosford 2005;Popov 2010, Popov andHess 2015) and ,…”