A theoretical model for the prediction of thermal expansion behaviour of particulate composites

Abstract

Abstract:The thermal expansion coefficient of particle-reinforced polymers was evaluated using a theoretical model which takes into account the adhesion efficiency between the inclusions and the matrix -an important factor affecting the thermomechanical properties of a composite. To measure the adhesion efficiency a boundary interphase, i.e. a layer between the matrix and the fillers having a structure and properties different from those of the constituent phases, was considered. This layer is assumed to have varying properties.To obtain information concerning the properties and extent of the interphase, an experimental study of the thermal behaviour of aluminium-epoxy composites was undertaken. Differential Scanning Calorimetry (DSC) measurements were performed to evaluate heat capacity with respect to temperature. In addition, the effects of different factors, such as heating rate and filler concentration on the glass transition temperature of the composite, were examined. The sudden changes in heat capacity values in the glass transition region were used to estimate the extent of the boundary interphase according to an existing theory.Finally, the values of the thermal expansion coefficient, predicted by this model, were compared with theoretical results obtained by other authors and with experimental results.

Effect of an inhomogeneous interphase on the thermal expansion coefficient of a particulate composite

“…Many have modelled the interphase layer as having a certain definite thickness over all possible volume fractions [14][15][16]. It is assumed in much of the literature however, that the thickness of the interphase varies depending on the volume fraction of the inclusions [11,17,18].This important phenomenon is also described in further detail later on in this work.…”

“…Numerous papers [17][18][19][20][21][22] have been written for the prediction of the CTE of particle and fibre reinforced composites incorporating an interphase.…”

Reinforcement of Elastic Polymer Matrix Filled with Ultrafine Particles

“…For instance, the diameter of the filler particles reported for glass-filled epoxy resin was over 10 μm [12]. In our case the diameter of the metal particles is about 1 nm and the diameter of the interphase region is estimated to be of some nanometers.…”

Structural Reliability of Novel 3-D Integrated Thermal Packaging for Power Electronics

“…[44,45] Some of the widely accepted models include Schapery Model for spherical particles, Turner Solution for two-dimensional models and Levin's Model for any isotropic two phase composites.…”