High elasticity, normal and shear stresses on shear deformation of low-molecular-weight polyisobutylene

Vinogradov, G. V.; Malkin, A. Ya.; Shumsky, V.F.

doi:10.1007/bf01973473

Cited by 28 publications

(4 citation statements)

References 17 publications

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“…Stretching polymer chains from an equilibrium conformation in flowing polymer melts results in manifestation of the EEF

[ 19 , 22 , 23 ] in proportion to the distance,

between the ends of a macromolecule (see Appendix A ), viz.,

where N is the number of monomeric links in the chain, and l is the length of each unit. The emerging entropic force ( 4 ) reduces activation energy

allowing for the MKU to jump by a distance

proportional to the magnitude of EEF in the direction of flow forces [ 5 , 7 , 14 , 15 , 18 ], viz.,

where B is a pre-exponential factor,

is an activation coefficient having the dimension of energy, a is a coefficient having the dimension of length, and

is a dimensionless size of reversible, rubber-like deformations emerging due to chemical bonding between the monomeric links of a macromolecule [ 21 , 23 , 26 ]. The value

can be assessed by measuring the volume of recoverable deformation in polymer melts after stopping the rotary plane (cone) in a viscometer [ 14 ].…”

Section: Methods: Accounting For Entropic Elastic Forces In Polymer D...mentioning

confidence: 99%

“…Statistical theory of rubber elasticity [ 19 , 20 ] states that stretching would excite the entropic elastic forces (EEF) acting along the stretched macromolecular chains. For example, the rotor of a viscometer immersed into polymer melts rotates backward after the engine shuts down, testifying to highly elastic reversible deformation present in the flow of polymer melts [ 9 , 21 ]. The experimentally observed rubber elasticity increase as the temperature rises also confirms the entropic nature of elasticity [ 19 , 22 , 23 , 24 ], indicating that the kinetic effects of catenation and entanglements of molecular chains should be taken into account while modeling deformation and flowing processes in melted polymers [ 25 , 26 , 27 , 28 , 29 ].…”

Section: Introductionmentioning

confidence: 99%

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Elastic Entropic Forces in Polymer Deformation

Kartsovnik¹,

Volchenkov

2022

Entropy

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The entropic nature of elasticity of long molecular chains and reticulated materials is discussed concerning the analysis of flows of polymer melts and elastomer deformation in the framework of Frenkel–Eyring molecular kinetic theory. Deformation curves are calculated in line with the simple viscoelasticity models where the activation energy of viscous flow depends on the magnitude of elastic entropic forces of the stretched macromolecules. The interconnections between deformation processes and the structure of elastomer networks, as well as their mutual influence on each other, are considered.

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“…Stretching polymer chains from an equilibrium conformation in flowing polymer melts results in manifestation of the EEF

[ 19 , 22 , 23 ] in proportion to the distance,

between the ends of a macromolecule (see Appendix A ), viz.,

where N is the number of monomeric links in the chain, and l is the length of each unit. The emerging entropic force ( 4 ) reduces activation energy

allowing for the MKU to jump by a distance

proportional to the magnitude of EEF in the direction of flow forces [ 5 , 7 , 14 , 15 , 18 ], viz.,

where B is a pre-exponential factor,

is an activation coefficient having the dimension of energy, a is a coefficient having the dimension of length, and

is a dimensionless size of reversible, rubber-like deformations emerging due to chemical bonding between the monomeric links of a macromolecule [ 21 , 23 , 26 ]. The value

can be assessed by measuring the volume of recoverable deformation in polymer melts after stopping the rotary plane (cone) in a viscometer [ 14 ].…”

Section: Methods: Accounting For Entropic Elastic Forces In Polymer D...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Elastic Entropic Forces in Polymer Deformation

Kartsovnik¹,

Volchenkov

2022

Entropy

View full text Add to dashboard Cite

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“…Y. T AKANO and H. ENDO S 0 (t)=L:)"' ("' ("' (hh)(_!_ddrjJ) F(h,N,O)exp [-ftp(e(t')h,N)dt']dh (4) )_ooJ-oo)-oo…”

Section: Theoreticalmentioning

confidence: 99%

Network Theory for Nonlinear Viscoelasticity. Elastic Recoil

Endo

1979

Polym J

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A molecular network theory developed by one of the authors (Y.T.) is applied to an elastic recoil which is one of the nonlinear viscoelastic phenomena of concentrated polymer systems. The integral equation for the constrained recovery on the removal of shear stress following steady shear flow is numerically solved with assuming that the solution for the shear strain is approximately described by a function of timet, as r(t)=r.-rr.-r1) exp (-at), where a is a positive constant, r. an ultimate shear recovery and r1 the instantaneous shear recovery determined by the rate of shear f in the steady shear flow before recovery. The result of this numerical calculation proves that the ultimate recovery increases with f and is larger than the value of s(=tlan1l2a,), where a8 and tlan1 are the shear stress and the first normal stress difference in the steady flow, respectively.

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“…Several experimental studies were performed during the 60's and 70's, analyzing mainly polymers using Weissenberg rheogoniometer or equivalent experimental equipment collecting valuable data, as an example, we could cite the works (60,43,103,35,98,63,94), it is worth to mention the several contributions made by Dr. Alexander Malkin from the Institute of Petrochemical Synthesis at Moscow and co-workers (67,126,73,125,75,124,74). A normal stress correlation with a very good agreement for polyisobutylene fluids based on data available in the literature was proposed by (122).…”

Section: Normal Stressesmentioning

confidence: 99%

An Experimental Study of the Validity of the Von Mises Yielding Criterion for Elasto-Viscoplastic Materials

SICA¹

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in 2010, with a full scholarship (Brazilian Ministry of Education). His final project won the Oscar Niemeyer Award for Scientific and Technological Works, CREA-RJ. Then, he started to work as a research engineer with computational modeling and numerical solution of partial differential equations, focused on thermohydro-mechanical-chemical processes in Geosystems, in the National Laboratory for Scientific Computing (LNCC), where he was already involved in research activities for 2 years and 5 months. After this period he had decided to start his master degree in computational modeling graduating as M.Sc. in Computational Modeling at the National Laboratory for Scientific Computing (LNCC) in February of 2014. In parallel in 2013, he had decided to change his research focus to rheological material characterization and continuum mechanics. Furthermore, he had stayed a year as a research fellow at Texas A&M University under professor Kumbakonam Rajagopal supervision. Bibliographic data Sica, Luiz Umberto RodriguesAn experimental study of the validity of the von Mises yielding criterion for elasto-viscoplastic materials / Luiz Umberto

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High elasticity, normal and shear stresses on shear deformation of low-molecular-weight polyisobutylene

Cited by 28 publications

References 17 publications

Elastic Entropic Forces in Polymer Deformation

Elastic Entropic Forces in Polymer Deformation

Network Theory for Nonlinear Viscoelasticity. Elastic Recoil

An Experimental Study of the Validity of the Von Mises Yielding Criterion for Elasto-Viscoplastic Materials

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