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Struktura wewnętrzna pian RVC

Macek W., Gancarczyk A., Iwaniszyn M., Sindera K., Korpyś M., Stępak B., Kołodziej A.

Prace Naukowe Instytutu Inżynierii Chemicznej Polskiej Akademii Nauk

2018

nr 22

69--76

Analiza wewnętrznej struktury szkieletu pian węglowych (Reticulated Vitreous Carbon, RVC), przeprowadzona za pomocą mikrotomografii komputerowej, nie pozwoliła w sposób jednoznaczny określić w jakim stopniu ich struktura jest nieciągła. Dlatego, w celu dokładniejszej obserwacji zastosowano elektronową mikroskopię skaningową oraz optyczną. Wykonano również mikroprzekroje plazmą ksenonu i ablację laserową. Ponadto przeanalizowano topografię powierzchni przełomu szkieletu pian RVC. Na podstawie przeprowadzonych badań stwierdzono, że szkielet pian RVC nie wykazuje wewnętrznej porowatości.

The analysis of the internal structure of RVC foams (Reticulated Vitreous Carbon) skeleton carried out by computed microtomography, did not allow to unambiguously determine to what extent their structure is discontinuous. Therefore, for more accurate observation, scanning electron microscopy and optical microscopy were used. Micro-cuts with Xenon plasma and laser ablation were also done. In addition, the topography of the breakthrough surface of the RVC foam skeleton was analyzed. On the basis of the conducted tests, it was found that the RVC foam skeleton does not show internal porosity.

Fabrication of a polymer-based biodegradable stent using a CO2 laser

Stępak B.

Archives of Civil and Mechanical Engineering

2014

Vol. 14, no. 2

317--326

This paper deals with CO2 laser machining of biodegradable polymers. We investigate the influence of laser parameters on the quality and geometry of cuts made in poly(l-lactide) and poly(l-lactide-co-glycolide). Because of the thermal character of material removal, liquid phase occurs and heat propagates into the material, changing its properties near the cutting zone. For this reason, the mechanical properties of laser cut samples were examined. Oar-shaped samples cut with a CO2 laser were compared with injection moulded samples and also with those manufactured using a KrF excimer laser. Samples with dimensions comparable to those of stent struts were examined in a uniaxial quasi-static tensile test. The influence of laser power and scanning speed on the geometry of cuts was investigated. Narrow cuts (120 µm) were made in 250 µm-thick polymer sheets. A tubular stent based on poly(l-lactide) was designed and then fabricated using a CO2 laser. We noted that this method allows achieving stent struts that are 300 µm wide; however, for such narrow elements the influence of the heat-affected zone can be critical. We believe that this technique has a potential to become an alternative, cost-efficient method of manufacturing biodegradable stents.