| Summary: | 博士 === 逢甲大學 === 纖維與複合材料學系 === 104 === Vascular grafts are used to replace the impaired native blood vessels, and thus play a significant role in clinical surgery. Making small-diameter vascular grafts that have a match in mechanical properties of blood vessels thus become challenging. Therefore, this study aims to develop composite tubular that possess the comparable mechanical properties to that of blood vessels. The effects of yarn types, tubular knit types, the freeze-thaw cycles of polyvinyl alcohol (PVA), and the drying time of the thawing on the mechanical properties of composite tubular are evaluated in order to assess the implant effectiveness of these composite tubular. Five different wrap yarns are first tested in terms of thermal treatment and twist coefficients, followed by being made into tubular braids, tubular warp knits, and tubular weft knits. Next, PVA hydrogels are combined with the tubular fabrics via casting, after which they are freeze-thawed different cycles with different drying times of thawing. The different composite tubular are evaluated for their mechanical properties. The results indicate that with a thermal treatment temperature of 160 ˚C, the PET/spandex wrap yarn have an elongation that is 86% lower than that of the untreated groups. An increasing thermal treatment temperature results in a decrease in the stress decay and permanent deformation of the PET/spandex wrap yarns. Moreover, an increasing thermal treatment temperature also decreases the shrinkage level of the spandex fibers, and thereby stabilizes the tubular fabrics. The porosity of the tubular fabrics is not dependent on the thermal treatment temperature and yarn types. The tensile strength and elongation of tubular knits are higher than the tensile strength and elongation of the tubular braids. More freeze-thaw cycles lead to a lower compliance, but also a higher bursting strength of vascular grafts, while the combination of spandex fibers improves the compliance of the fabrics and composite tubular. Increasing the drying time for PVA hydrogels is favorable to the compressive strength, bursting strength, and suture retention, while being remarkably adverse to the compliance of the vascular grafts. The warp-knit composite tubular have a higher axial shrinkage when they are circumferentially extended. The weft-knit composite tubular outperform the warp-knit composite tubular in terms of compressive strength, bursting strength and suture retention.
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