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Published: Kem. Ind. 58 (11) (2009) 515–540
Paper reference number: KUI-15/2009
Paper type: Nomenclature note
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Definition of Terms Relating to Non-Ultimate Mechanical Properties of Polymers (IUPAC Recommendations 1998)

D. Kozak and M. Lucić


The basic definitions of terms related to the elastic and viscoelastic behaviour of different kinds of bulk polymers, which are often in everyday use, have been given clearly in this IUPAC Recommendations. The document gives basic explanations of physical quantities with corresponding mathematical expressions for elastic solids, such as stress tensor, deformation tensor, deformation gradient, deformation ratio, shear of an elastic solid etc., but also for viscoelastic liquids or solids, such as deformation or flow of a viscoelastic liquid or solid, rate-of-strain tensor, vorticity tensor, shear flow, etc. Also given are constitutive equations for an elastic solid and for an incompressible viscoelastic liquid or solid. Important measures connected to stresses with appropriate deformations, such as tensile and shear modulus, compliance and viscosity are also considered in the paper. Special attention has been paid to the viscoelastic behaviour of liquid or solid. The Maxwell and Voigt-Kelvin model have been analyzed in details. Terms relating to viscoelastic behaviour of liquid or solid when constant stress or deformation has been applied, such as relaxation time, retardation time and creep, have been defined. When forced oscillation is present in the viscoelastic material, characteristic parameters, such as loss factor, storage modulus, storage compliance, dynamic viscosity etc., have been discussed. The last chapter deals with stresses and deformations in solids exposed to the free or forced oscillations. The basic terms, such as damping curve, decay constant and frequency, resonance frequency and resonance curve have been explained for the case of torsion pendulum and three-point bending tests.

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deformation of an elastic solid, deformation or flow of a viscoelastic liquid or solid, tensile and compressive stress, tensile and shear compliance, linear viscoelastic behaviour of a liquid or solid, Maxvell model, Voigt-Kelvin model, creep, viscosity, free and forced oscillation, extensional and flexure oscillation, damping, resonance