Unusual mechanical response of carbon black-filled thermoplastic elastomers

Published Date
Mechanics of Materials
February 2014, Vol.69(1):116–131, doi:10.1016/j.mechmat.2013.09.019

• Author 

• A.D. Drozdov ^a,,
• N. Dusunceli ^b

• aDepartment of Plastics Technology, Danish Technological Institute, Taastrup 2630, Denmark
• bDepartment of Mechanical Engineering, Aksaray University, Aksaray 68100, Turkey

Received 15 October 2012. Revised 26 September 2013. Available online 8 October 2013. 

Highlights

• •
  Unusual mechanical phenomena are observed in TPEs under cyclic loading.
• •
  Novel constitutive equations are derived in finite viscoplasticity.
• •
  Ability of the model to predict these phenomena is confirmed by simulation.

Abstract

Observations are reported on carbon black-filled thermoplastic elastomer in multi-step uniaxial tensile cyclic tests with various strain rates at room temperature. Experimental data reveal several unusual features of stress–strain diagrams: (i) fading memory of deformation history in cyclic tests with increasing maximum elongation ratios, (ii) transitions from simple to mixed to inverse relaxation and creep in specimens subjected to stretching and subsequent retraction down to various minimum stresses, and (iii) strain rate-induced acceleration of inverse relaxation and creep. A constitutive model is developed for the time- and rate-dependent response of polymer composites under an arbitrary three-dimensional deformation with finite strains. Adjustable parameters in the stress–strain relations are found by fitting the experimental data. Ability of the constitutive equations to describe the mechanical behavior of thermoplastic-elastomer composites under cyclic deformation and to predict the observed phenomena is confirmed by numerical simulation.

Keywords

Polymer composite

Viscoplasticity

Cyclic deformation

Constitutive modeling

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