Study of Bioresorbable Polymers Thermal Stability for Fiber Production

M. FERRACE; F. MONTINI BALLARIN

Mar del Plata

Congreso; XII Latin-American Congress of Artificial Organs and Biomaterials; 2023

Introduction and objective: Melt Electrospinning Writing (MEW) and Fused Deposition Modelling (FDM) are additive manufacturing techniques that involve the deposition of polymer fibers to create 3D- structures. Both use a heated nozzle to extrude and deposit the molten polymer, but MEW also applies an electric field [1]. Previous studies on traditional electrospinning of poly(ε-caprolactone) (PCL) without heating showed polymer degradation [2]. Understanding the thermal stability of the polymer during its processing is of great importance. The aim of this work is to analyze changes in relative molecular weight distribution and polydispersities of PCL in different heating cycles using gel permeation chromatography (GPC).Methodology: Samples of PCL (Mn ~ 45000 Da, Sigma-Aldrich) were melted at 90°C for 0, 1, 2, 3, 4, 8 and 16 hours. Melt PCL was processed by melt-electrospinning at 140°C with an electric field of 12 kV for 1-3 cycles. Samples from the different heating cycles were analysed by gel permeation chromatography in triplicates. GPC assays were performed at 25°C using a tetrahydrofuran mobile phase. Columns were provided by Shim-Pac (Shimadzu). Results were analyse by Prominence software.Results and discussion: Although, differences in apparent molecular weights and polydispersities were observed at 0, 1, 2, 3, 8 and 16 hours of heating at 90°C, it is believe these correspond to the variability of the characterization technique. No significant difference (p>0.05) were observed when number average molecular weight (Mn) were analyzed for those heating cycles compared with unheated sample. However, a significant difference (p>0.05) at Mn was seen for the simple heated during 4 hours a 90°C. Besides, a decrease in molecular weights of samples processed by MEW at 140°C was observed compared to those only treated by heating at 90°C and the unheated sample (p>0.05). These results, indicate some degree of degradation in PCL chains during successive processing cycles, this behavior was also observed for solution electrospinning processing [2]. A synergistic effect due to melt processing and the high voltage electrical field applied to thepolymer could be the cause of the observed degradation.Conclusions: The variability of the characterization technique was determined by GPC analysis. Thermal degradation is an important aspect to consider when multiple heating cycles are implemented. Additionally, understanding the behavior of the polymer under an applied electric field is crucial. This becomes particularly relevant in the production of fibers using the MEW technique, as there is a dual contribution to degradation. However, due to the difference in processing temperature with respect to heating temperature, the contributions cannot be separated.