Page 90 - Tailoring Electrospinning Techniques for Regenerative Medicine - Marc Simonet

CHAPTER 4
Figure 4.7 Averaged (n=5) engineering stress vs. strain curves up to 50 % strain, including standard deviation of the conv. and LTE sca olds of PCL (a) and PLA (b) with 9 μm fibers. Other fiber diameters show a similar mechanical characteristics, so are not shown for the clarity of the graph. All graphs also comprehend the physiological relevant stress-strain range for human saphenous veins (HSV). HSV and LTE curves have their corresponding y axis on the right.
porosity, a ects the mechanical properties of the sca old. This can be deduced from their tensile test behavior displayed in Figure 4.7 on the sca olds with 9 μm fibers. PCL and PLA sca olds with smaller fiber diameters have similar mechanical characteristics as the one with 9 μm fibers. Hence they are not included for clarity of the graph; also note the di erent y-axis for the LTE spun sca old and the human saphenous veins (HSV). The latter data points depict the boarders of the physiological relevant stress-strain range for human saphenous veins (HSV) and are adapted from M. Stekelenburg et al.43
The conventional spun sca olds show typical stress-strain behavior, with a linear and steep increase in stress response far above the physiological range
of HSV. In contrast the mechanical response of PCL and PLA LTE spun sca olds is well in the range of the native tissue. Besides the lower mechanical properties, the LTE spinning also influences the yield point, as can be more clearly seen for the PLA sca olds in Figure 4.7b. Whereas conventional spun PLA sca olds yield and break already a er 3 % elongation, the LTE-spun sca olds have a yield point above 9 %. Of course, as opposite to the native tissue, none of these sca olds show a strain hardening at elevated strain ranges nor should they be considered as fully elastic over the physiological strain range.
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