Mechanical Behaviour of Multifunctional Epoxy/Hollow Glass Microspheres/Paraffin Microcapsules Syntactic Foams for Thermal Management

Abstract

Epoxy/hollow glass microsphere (HGM) syntactic foams (SFs) are peculiar materials developed to combine low density, low thermal conductivity, and elevated mechanical properties. In this work, multifunctional SFs endowed with both structural and thermal management properties were produced for the first time, by combining an epoxy matrix with HGM and a microencapsulated phase change material (PCM) having a melting temperature of 43 °C. Systems with a total filler content (HGM + PCM) up to 40 vol% were prepared and characterized from the mechanical point of view with a broad experimental campaign comprising quasi-static, impact, and fracture toughness tests. The experimental results were statistically treated and fitted with a linear model, to produce ternary phase diagrams to provide a comprehensive interpretation of the mechanical behaviour of the prepared foams. In quasi-static tests, HGM introduction helps to retain the specific tensile elastic modulus and to increase the specific compressive modulus. The brittle nature of HGMs decreases the Charpy impact properties of the SFs, while the PCM insertion improve their toughness. This result is confirmed in KIC and GIC tests, where the composition with 20 vol% of PCM shows an increase of 80% and 370% in KIC and GIC in to neat epoxy, respectively. The most promising compositions are those combining PCM and HGMs with a total particle volume fraction up to 40 vol%, thanks to their optimal combination of thermal management capability, lightness, thermal insulation, and mechanical properties. The ability to fine-tune the properties of the SFs, together with the acquired thermal energy storage (TES) capability, confirm the great potential of these multifunctional materials in automotive, electronics, and aerospace industries.

Preparation of a low dielectric POSS/epoxy hybrid polymer without sacrificing the mechanical performance

“…The density of the samples was determined experimentally by averaging the mass : volume ratio of five specimens according to the Archimedes principle. 28 Based on the following equation (eqn (2)), the air void porosity trapped in the matrix during the fabrication process was quantified using the ratio of theoretical and experimental densities.…”

Castor-oil biobased foam: the effect of the composition on the physical and mechanical properties via a statistical mixture design

“… 9 Given the substantial number of combinations in the ternary system, it becomes possible to define a specific area for analysis. 10 …”

Development of Novel Polypropylene Syntactic Foams Containing Paraffin Microcapsules for Thermal Energy Storage Applications

“…As reported in our previous articles [ 8 , 42 ], due to the system’s complexity the analysis of the properties could be quite difficult without the application of a rigorous statistical approach. By using RStudio v.1.4.1103 software (RStudio, Inc., Boston, MA, USA) it was possible to fit the experimental results of the samples with different compositions with a quadratic linear model called the “Scheffé quadratic model” by calling “lm” and “ModelPlot” functions in the software (more details can be found in [ 42 ]). Those functions were used mainly to plot the ternary phase diagrams and to report the most important statistical data like the goodness of fit (R 2 adj ) and the residual standard error of the model (S y.x ) defined by Equations (4) and (5).…”

“…The lightening power and the thermal insulation capacity provided by HGMs were highlighted, while the PCM capsules imparted interesting TES properties (about 70 J/g with a paraffin content of 40% by volume). On the other hand, the mechanical performances were slightly reduced by the PCM addition [ 8 , 42 ]. Quite interestingly, no papers can be found in the open literature on the development of multifunctional thermoplastic foams with TES properties.…”