Differential scanning calorimetry – continuum mechanical considerations with focus to the polymerisation of adhesives

Abstract

To study temperature‐induced changes in the specific enthalpy of materials, the differential scanning calorimetry technique (DSC) is a powerful experimental approach. It is well‐established in physical chemistry and materials science but less familiar in continuum mechanics. In this context, the balance equation of energy in conjunction with the theory of internal variables is the fundamental aspect from the point of view of continuum mechanics. This paper presents the theoretical fundamentals of how to take classical and temperature‐modulated DSC tests into account in order to model or identify the thermochemical parts of the specific‐free energy, which is the most commonly used thermodynamic potential in continuum mechanics. The numerical examples treated in this work provide an insight into the possibilities of the DSC technique and into the constitutive representation of exothermal energy changes in curing adhesives.

Experimental investigations and material modelling of curing processes under small deformations

“…In the following, the temperature denoted with T has the unit [T] = • C. The thermodynamic temperature is denoted with the greek symbol θ and has the unit [θ] = K. The meaning of Eq. (1) in the context of continuum mechanics is discussed in [20]. In the first step, we analyse the curing behaviour with the temperature-modulated DSC technique.…”

“…is proposed in [20]. Herein the rate of the internal variable is assumed as a function of the temperature and the internal variable.…”

“…In [20], it is shown that the response of the specimen to the temperature process in Eq. (2) can be splitted into three parts:…”

FE‐simulation of spatially graded gelation during adhesive's curing

“…Toward this end, energy conservation denoted in form of the 1st Law of Thermodynamics in terms of the enthalpy h can be written as (cf. [2]):…”

“…with ̺, C ·· ∆ T , ∇ · q and r beeing the density of the reference configuration, stress power, divergence of the heat flux vector and further heat sources, respectively. After some reformulations shown in [2] and an adaption to the ANSYS R specifications…”