Characterisation Of The Structure And Mechanical Properties For Electrospinning PCL Fibres

The technology of electrospinning has enabled the engineering of nanostructured materials to meet with the current challenges in tissue repair. Biological fibrous membranes of Polycaprolactone (PCL) and the blends PCL/collagen were generated within this research work. The influence of molecular weight, solution concentration and conductivity on the fibre morphology was studied. With the increase of the polymer concentration, the fibre diameter increases. After reaching a maximum value, the diameter remains constant.Aligned fibrous patches, which were produced by means of a rotating drum, have improved their mechanical properties compared with non-oriented patches. Fibre diameters and crystallinity were determined by SEM and DSC analysis methods. Tensile tests were carried out to compare the different stress-strain behaviours between the nanoscaled and micron scaled fibres. Submicro and nano-sized fibres are more crystalline than micro-sized ones so that the ultimate strength is higher compared with micron sized fibres. However, from the stress-strain curves of the tensile tests, the nanofibres exhibit no elastic deformation during the stress process indicating that they are much stiffer and they break right after the ultimate strength is attained. Compared with nanofibres, micron fibres have larger elongation at break.The elastic properties of the fibres were investigated, using three-point bending tests by AFM. Samples were spun directly on a silicon grating with channels. An increase of elastic modulus was observed when the fibre reached nanoscale dimensions. As for the blends, FTIR measurement suggested that PCL and collagen were compatible. Fibre diameters decreased dramatically, while the proportion of collagen increased, which improved the mechanical properties of the blends.The tensile strength reaches the maximum when the fibre diameter reaches the minimum, however, while the fibre diameter shrinks to a small scale, the elasticity is lowered.Three methods were applied to determine the compatibility of PCL and collagen. The shift of the frequency of the amide bond I and II from the FTIR spectra indicates an interaction between PCL and collagen by creating strong hydrogen bonds. The morphology of the PCL/collagen samples has been observed by transmission electron microscopy (TEM) showing that the blend fibres exhibit a homogenous structure, which means that there is no phase separation presented. Leaching test is another proof that collagen doesn't redissolve from the blends into the water and doesn't produce any structured morphology on the surface.