Structural characteristics evaluation of electrospun nonwoven webs

© 2009 Nova Science Publishers, Inc. Fiber diameter is an important structural characteristic for electrospinning process, due to its direct influence on the properties of the produced webs. In this chapter, an image analysis based method called Direct Tracking for measuring electrospun fiber diameter has been developed. Another image analysis method, Distance Transform, was also adapted to that end. In order to evaluate the accuracy of the methods, samples with known characteristics were generated using a simulation scheme known as µ-randomness. Some electrospun webs of PVA were used to verify the capability of the method for the real webs. Due to the necessity of binary input images, micrographs of the real webs obtained from scanning electron microscopy were first segmented using local thresholding. The results obtained from the methods were compared to simulation for simulated images and manual method for the real webs. For instance, in the case of the simulated image with the mean of 15.24 and standard deviation of 5.77 pixels, mean and standard deviation obtained from distance transform were 17.14 and 7.60 pixels and from direct tracking 16.25 and 6.13 pixels respectively. For an electrospun web with the mean of 246.3 nm and standard deviation of 26.0 nm, distance transform and direct tracking resulted in mean of 301.9 and 286.7 nm and standard deviation of 91.6 and 55.1 nm respectively. Results obtained by direct tracking significantly excelled distance transform, indicating that the method could be used for measuring electrospun fiber diameter.