1Tensile tests

The “dogbone” specimens were tested in tension using a universal testing machine Instron model 3367 (Norwood, Massachusetts, USA), which has a maximum load capacity of 30 kN, at RT under a constant crosshead rate of 1 mm/min. An Instron extensometer (50 mm gauge length) was used to record the displacement. At least three specimens were tested to failure for each case.

2. DCB tests

Testing was conducted at RT at a constant displacement rate of 1 mm/min using a MTS 312.31 servo-hydraulic machine (Minneapolis, USA). Four joints were tested to failure for each case. Loads and displacements to failure were recorded. The DCB specimens test set-up is shown in Fig. 8.

3. Thermal analysis

In order to determine the thermal behaviour of the particles while encapsulated in adhesives, the variation of the volume of adhesive samples modified with different wt% TEPs as a function of temperature was recorded. The measurement was made using a dilatometer system DIL801L (Bahr Thermo Analyze DIL801L, Hullhorst, Germany GmbH) allowing the measurement of the specimen volume while enduring a temperature ramp. The temperature was raised from RT to 150 1C at a very slow and controlled rate, of 2 K/min, to allow a homogeneous temperature all over the sample. Three samples were tested for each series (wt% TEPs).

4. SEM analysis

A SEM analysis was performed on the fracture surfaces of the “dogbone” specimens and thermal analysis specimens using a high resolution Scanning Electron Microscope with X-Ray Microanalysis: JEOL JSM 6301F/Oxford INCA Energy 350 (Gatan Alto 2500, Tokyo, Japan). Samples were coated with a gold (Au)/palladium (Pd) thin film (for 120 s. and with a 15 mA current), by sputtering, using the SPI Module Sputter Coater equipment prior to examination. Secondary electron images were collected at different magnifications (200  , 500  , 1000  , 2000  and 5000 ).