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Time, temperature, and strain effects on viscoelastic Poisson's ratio of epoxy resins
Author(s) -
Pandini Stefano,
Pegoretti Alessandro
Publication year - 2008
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.21060
Subject(s) - materials science , viscoelasticity , poisson's ratio , epoxy , composite material , poisson distribution , strain rate , glass transition , stress relaxation , deformation (meteorology) , extensometer , relaxation (psychology) , constant (computer programming) , strain (injury) , thermodynamics , polymer , creep , mathematics , physics , medicine , psychology , social psychology , statistics , computer science , programming language
Poisson's ratio of polymeric materials, although generally assumed as a constant, is known to display a viscoelastic dependence on time, temperature, and strain. This article investigates the phenomenology of this dependence on two crosslinked epoxy systems with different glass transition temperatures. Poisson's ratio measurements are performed by contact extensometers simultaneously measuring the axial and transverse deformations under two different tensile testing conditions: (i) constant deformation rate, in which the effects of strain, strain rate, and temperature are highlighted; (ii) stress relaxation (or constant deformation), where the dependence of Poisson's ratio on time is studied at various strain levels. The viscoelastic Poisson's ratio increases as strain, temperature, and time increases, with trends markedly depending on the materials glass transition. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers.