Příprava a charakteristika orientovaných vláken metodou drawing
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V dnešní době vznikají neustále nové technologie, či vylepšení pro tvorbu vláken. Tato práce se zabývá metodou pro výrobu vláken, která není moc používaná, a tou je drawing. Technologie je založena na mechanickém vytahování vláken z kapky polymerního roztoku, čímž se vytvoří vlákno o určitých geometrických vlastnostech. Touto metodou lze vyrobit jednotlivá vlákna o přesné délce, či orientované vlákenné struktury.Tato práce byla zaměřena na přípravu a charakteristiku orientovaných polyesterových vláken metodou drawing. Byly použity roztoky polykaprolaktonu (PCL) a kopolymeru polykaprolaktonu a polymléčné kyseliny - poly(lactide-co- -caprolactone) (PLCL). U PCL byly změřeny viskozity a povrchová napětí. Dále byly všechny roztoky, PCL a PLCL, za stejných podmínek zvlákněny a vlákna byla ocharakterizována pomocí elektronové mikroskopie. Na závěr byly otestovány mechanické vlastnosti vláken.Podařilo se zvláknit roztoky PCL a PLCL o koncentracích 6, 8, 12, 16 a 20hm%. Nejtenčí vlákno se vyrobilo z 6hm% PCL a mělo průměr 190nm. U PLCL se nejtenčí vlákno vytvořilo z roztoku 16hm% a jeho průměr byl 490nm. Bylo zjištěno, že průměr vláken je ovlivněn rychlostí a zrychlením. U viskozit byla pozorována exponenciální závislost na koncentraci roztoků. Při mechanickém testování dosahovala PCL vlákna průměrné pevnosti 0,23N a průměrné tažnosti 739%. Průměrná pevnost vláken PLCL byla 0,178N a tažnost 610%.
Currently, new technologies for fiber fabrication constantly emerge, or are improved. This thesis is focused on the method for fiber fabrication called drawing, which is not widely used method for this purpose. The technology is based on the mechanical pulling of fibers from a polymer solution droplet, which creates a fiber of certain geometric properties. With this method we are able to prepare fibers of a given length, or even to create oriented fibrous strucutes.This thesis is focused on the preparation and characterization of oriented polyester fibers prepared by drawing. We used solutions of polycaprolactone and a copolymer of polycaprolactone and lactic acid - poly(lactide-co- -caprolactone). All solutions of PCL and PLCL were drawn into fibers under constant conditions and the fibers were evaluated using electron microscopy. Mechanical properties of the fibers were meassured for both polymers (PCL and PLCL), the viscosity and surface tension was meassured for all PCL solutions. We were able to prepare fibers by drawing from the PCL and PLCL solutions of the concentrations of 6, 8, 12, 16 and 20% (w/w). Thinnest fiber is produced from 6hm% PCL and have a diameter of 190 nm. For PLCL thinnest fiber formed from solution 16hm% and its diameter was 490 nm. It has been found that the diameter of the fibers is affected by velocity and acceleration. The exponential dependence on the concentration of the solutions was observed in the viscosities. In mechanical testing, PCL fibers had an average strength of 0.23 N and an average elongation of 739%. The average fiber strength of the PLCL was 0.178 N and the elongation was 610%.
Currently, new technologies for fiber fabrication constantly emerge, or are improved. This thesis is focused on the method for fiber fabrication called drawing, which is not widely used method for this purpose. The technology is based on the mechanical pulling of fibers from a polymer solution droplet, which creates a fiber of certain geometric properties. With this method we are able to prepare fibers of a given length, or even to create oriented fibrous strucutes.This thesis is focused on the preparation and characterization of oriented polyester fibers prepared by drawing. We used solutions of polycaprolactone and a copolymer of polycaprolactone and lactic acid - poly(lactide-co- -caprolactone). All solutions of PCL and PLCL were drawn into fibers under constant conditions and the fibers were evaluated using electron microscopy. Mechanical properties of the fibers were meassured for both polymers (PCL and PLCL), the viscosity and surface tension was meassured for all PCL solutions. We were able to prepare fibers by drawing from the PCL and PLCL solutions of the concentrations of 6, 8, 12, 16 and 20% (w/w). Thinnest fiber is produced from 6hm% PCL and have a diameter of 190 nm. For PLCL thinnest fiber formed from solution 16hm% and its diameter was 490 nm. It has been found that the diameter of the fibers is affected by velocity and acceleration. The exponential dependence on the concentration of the solutions was observed in the viscosities. In mechanical testing, PCL fibers had an average strength of 0.23 N and an average elongation of 739%. The average fiber strength of the PLCL was 0.178 N and the elongation was 610%.
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Drawing, polykaprolakton, Poly(lactide-co- -caprolactone), tkáňové inženýrství, mechanické vlastnosti vláken, Drawing, polycaprolactone, Poly(lactide-co- -caprolactone), tissue engineering, tensile properties of fibers