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Smart Stimuli-Responsive Polylactic Acid-Hydrogel Fibers Produced via Electrospinning
Danaja Štular,Magnus Kruse,Vera Župunski,Laura Kreinest,Jožef Medved,Thomas Gries,Andreas Blaeser,Ivan Jerman,Barbara Simončič,Brigita Tomšič 한국섬유공학회 2019 Fibers and polymers Vol.20 No.9
In this research we propose a new type of smart microfibers, distinguished by moisture management and proactivetemperature and pH controlled release activity. Hydrogel with submicron-sized particles based on poly(Nisopropylacrylamide)(poly-NiPAAm) and chitosan (PNCS hydrogel) was incorporated into the structure of poly(lactic acid)(PLA) microfibers using the electrospinning technique. Composites with different PLA to PNCS hydrogel ratios wereprepared, and the chemical and morphological properties of the samples were studied using SEM, FT-IR and Ramanmapping. Additionally, the moisture management properties, which were provided by the temperature and pH-related phasechange transition of the incorporated PNCS hydrogel, were studied by determining the temperature-related static contactangle, thin-layer wicking, moisture content and pH-related water uptake. The loading and release abilities of the incorporatedPNCS hydrogel were studied using fluorescent microscopy. The increased concentration of the PNCS hydrogel in spinningsolutions resulted in greater variations in fiber thickness and deterioration of the mechanical properties of the fibers; thus, thehighest concentration of the PNCS hydrogel that could be incorporated within the fibers was found to be 20 % of the spinningmass. The composite sample showed temperature and pH responsiveness, a successful fluorescent-dye loading ability and itscontrolled release at predetermined conditions.
Alisa Šehić,Jelena Vasiljević,Igor Jordanov,Andrej Demšar,Jožef Medved,Ivan Jerman,Marija Čolović,Fiona Hewitt,T. Richard Hull,Barbara Simončič 한국섬유공학회 2018 Fibers and polymers Vol.19 No.6
This research investigated the influence of two flame retardant (FR) mixtures consisting melamine cyanurate (MeCy) and aluminum diethylphosphinate (AlPi), and MeCy and sodium aluminosilicate (SASi) at different weight ratios, on the flammability, thermal behavior and mechanical properties of polyamide 6 (PA6) composite yarns produced by meltspinning. The morphological and chemical properties of PA6/FR filaments were investigated by scanning electron microscopy and Fourier-transform infrared spectroscopy, flame retardancy by vertical burning test UL-94, thermal behavior by thermogravimetric and differential scanning calorimetric analyses, and mechanical properties by tensile tests. The results indicate that within the UL 94 V2 rating, the composite yarns differed significantly from each other in their burning and dripping behavior. The incorporation of both mixtures, MeCy+AlPi and MeCy+SASi, into the PA6/FR yarns significantly decreased the afterflame time relative to pristine PA6, confirming a lower production of flammable volatiles. This phenomenon was attributed mainly to MeCy, which caused an immediate extinguishment of the flame after the withdrawal of the igniting flame. Compared to one component MeCy, the incorporation of the MeCy+SASi mixture enhanced the thermooxidative stability of the PA6/FR yarns because of their additive effect at higher concentrations. In contrast, an antagonistic effect was obtained for the MeCy+AlPi mixture, irrespective of the concentration. Since the incorporation of MeCy+SASi did not drastically reduce the tensile properties of filaments, this mixture enables the production of the PA6/MeCy+SASi composite yarns with the enhanced flame retardancy and thermo-oxidative stability.