Contribution to the analysis of thermal behaviour of polymer composites: case of polyethylene/titanium diboride composites

To deepen the fundamental knowledge on the effect of titanium diboride (TiB₂) particle interface on thermal conductivity of three different composites with polyethylene matrices (HDPE/TiB₂, MDPE/TiB₂ and LDPE/TiB₂), this paper is devoted to a theoretical approach on the analysis of thermal behaviour of polymer-based composites. This study is based on the Hashin and Shtrikman model, which allows us to determine the thermal conductivity considering an idealized interface between the reinforcing molecules. In addition, the Hasselman and Johnson model is used to evaluate thermal conductivity with an imperfect interface. We mainly discuss the difference between two types of interfaces with the aim of improving the thermal conductivity within the composite material used in this study without altering the mechanical and thermal behaviours. This approach creates new opportunities, especially in manufacturing, to use high-quality composite materials at low-cost and non-destructive. To this end, we have investigated the variations in the effective thermal conductivity of different composites, λ_eff as a function of volume fraction of the reinforcement (TiB₂). In particular, we have emphasized the study on the effective thermal conductivity of the composite, taking into account interactions at the interface between the particles and matrix. Definitely, the random dispersion of spherical particles and cylindrical particles oriented perpendicular to the heat flow is considered. The main conclusion is that the form of particles and the type of interface of the reinforcement drastically affect thermal conductivity of the system under consideration.