*2.3. Morphology and Mechanical Properties of PLLA-SBA2 Fibres*

PLLA-SBA2 electrospun fibres were sputtered with gold by using a Sputter Coater (Q150T, Quorum Technologies, Darmstadt, Germany) and then inspected by SEM and energy dispersive X-ray spectrometry (EDS) (Auriga 0750, ZEISS, Jena, Germany). Average fibre diameters were calculated by analysing a total of at least 100 fibres for each sample, using the software ImageJ [40]. Regarding mechanical properties, as reported by Ricotti et al. [41], mechanical differences in uniaxial aligned arrays are more pronounced. Thus, aligned fibre mats were used in this paper to investigate more specifically the mechanical properties of PLLA-SBA2 composite fibre mats. Mechanical properties of random and aligned composite fibres mats at room temperature were investigated by uniaxial tensile strength tests using a universal testing machine (K. Frank GmbH, Mannheim, Germany). Each sample was cut into a rectangular shape (with cross-section area of 5 × 4 mm2) using a paper square framework and its thickness is measured by using a digital micrometre (0.02–0.06 mm). Then measurements were carried out at a crosshead speed of 10 mm/min using a 50 N load cell, according to a previous

study [42] and the resulted stress-strain curves are used to obtain Young's modulus, elongation at break and tensile strength.
