Long-term viscoelastic properties of an adhesive and molding compound, characterization and modeling

Publication date: 5 May 2017
Source:Polymer, Volume 116
Author(s): Mohammad Rezai Sangtabi, Mehdi Saeed Kiasat
Experimental characterization and theoretical modeling of the viscoelastic behaviors of two epoxy compounds are aimed in the present work. Through bending and torsion dynamic analysis, long-term master curves are obtained for the materials moduli over more than 30 frequency and time decades, and the relevant shift factor over a wide temperature range. The uniqueness of the shift factor for the independent viscoelastic properties is shown. The behavior of the shift factor is categorized in regions below and above the glass transition temperature and expressed by different models. Substantial time dependency of the long-term relaxation bulk modulus and the Poisson's ratio are obtained through incremental relations using the measured relaxation moduli. The characterized viscoelastic behavior of the molding compound is verified by means of a creep test performed at isothermal and non-isothermal conditions. It is further shown that when the adhesive compound is cured between two members as in practice, very low glass transition temperature and mechanical properties are expected due to the more residual diluent.

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