Elasticity electrospun

Suarez Bagnasco D, Montini BaUarin F, Cymberknop LT, Balay G, Negreira C, Abraham GA, et al. Elasticity assessment of electrospun nanofibrous vascular grafts a comparison with femoral ovine arteries. Mater Sci Eng C 2014 45 446-54. 

Influence of the amount of PEDOT-PSS on mechanical properties was studied using d3mamic mechanical anatysis in tension mode. Uniaxial tensile tests were carried out at 30 1°C with TA Q800 Dynamic Mechanic Analyzer. Elastic modulus and breaking points were measured by increasing ramp force 0.1 N/min to 18.0 N/min. Composite nanofibers were electrospun for three hours to measure mechanical properties. At least four specimens were tested for each measurement and the average values are presented. 

CPs in different forms like nanofibers and thin films for tissue engineering applications were evaluated by Bendrea et Conducting C-PANl was blended with poly[L-lactide-co-e-caprolactone) (PLCL) and then electrospun to prepare a uniform nanofiber scaffold. This scaffold combined the elastic properties (comes from the PLCL domain) with electrical activity (due to conducting C-PANl) at the nanometer-scale features. It was proved that a nanoscale structure with RANI led to a high pore volume, interconnective pores, a uniform mean fiber diameter, and significantly increased conductivity. ... 

The need for mechanical reinforcement has been the driving force for most of the reported work on polymer/CNT composites. In an attempt to investigate the mechanical properties of electrospun PAN/SWNT nanofibers, Ko et al. (75) have used an atomic force microscope (AFM) to measure the elastic modulus of the electrospun composite nanofibers. The obtained fiber modulus was 140 GPa, a value which is much higher than that of conventional PAN fibers (60 GPa) (75). In a somewhat related but independent study, Mathew et al. (92) also used AFM to measure the mechanical properties of electrospun polybutylene/MWNT terephthalate nanofibers. Elastic deformation of MWNTs in electrospun PEO/MWNT and PVA/MWNT nanofibers was studied by Zhou and co-workers (84), and was found to increase with an increase in the modulus of the polymer matrix. In the same study, a simplified model was also proposed to estimate the elastic modulus ratio of MWNT and polymers. To confirm the validity of their model, these authors compared the model predictions with experimental data obtained from AFM measurements. 

By copolymerizing the monomers of two highly crystalline homopolymers it is possible to create a series of less crystalline copolymers with reduced levels of stiffness, elastic modulus and crystallinity depending on the blend level of the two monomers. This has been demonstrated by Soo H5nm Kim and coworkers at KIST, who have been able to synthesize a series of elastomeric (or rubbery) resorbable poly(L-lactide-co-e-caprolactone) copolymers. Because of their superior elastic behavior they have been used to prepare tubular scaffolds for vascular smooth muscle cell (SMC) culture under dynamic pulsatile conditions. We have melt spun and electrospun the 50/50 copolymer to fabricate a two-layer small-caliber vascular prosthesis prototype with radial elongation at break in excess of 300% (Fig. 15.33). " ... 

Kuo YC, Hung SC, Hsu SH. The effect of elastic biodegradable polyurethane electrospun nanoflbers on the differentiation of mesenchymal stem cells. Colloids Surf B Biointerfaces October 1, 2014 122 414-22. 

Punnakitikashem P, Truong D, Menon JU, Nguyen KT, Hong Y. Electrospun biodegradable elastic polyurethane scaffolds with dipyridamole release for small diameter vascular grafts. Acta Biomater 2014 10 4618-28. 

Observation of Figure 8.16 shows that the electrospun fibers are in fact composite fibers with an outer shell that represents 10% to 20% of the total diameter this layer is rigid and should be responsible for the elastic behavior found in the mechanical test. The inner part is soft and fluid and its presence provides one explanation for the existence of the plateau of deformation at constant stress, for higher strain values, after the... 

Another mathematical model that describes the formation of perversions in helices can be found in literature [97-99] and models the transition from a twisted rod to a helix by making some approximations the rod must be elastic, slender and have intrinsic curvature and torsion. The use of this model allowed the calculation [103] of the applied tension on a APC suspended electrospun fiber and the critical tension, below which the fiber starts to twist, by counting the number of turns present in a suspended fiber from pictures obtained by SEM observation. 

Several nanomechanical characterization techniques have been suggested to measure the elastic properties of individual electrospun nanofibers, such as AFM cantilevers, universal tensile tester, and AFM-based nanoindentation system [133, 134]. Among them AFM-based techniques have been widely used to measure the mechanical properties of single electrospun nanofibers. This technique was carried out by attaching nanofiber to two AFM cantilever tips and recording the cantilever resonances for both the free cantilever vibrations and for the case where the microcantilever system has nanofibers attached. The Young s modulus of the nanofiber is then derived from the measured resonant frequency shift resulting from the nanofiber. A similar experiment has been carried out for electros-... 

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