ABSTRACT
The development of innovative fibrous materials with valuable multifunctional properties based on biodegradable polymers and modifying additives presents a challenging direction for modern materials science and environmental safety. In this work, high-performance composite fibrous materials based on semicrystalline biodegradable poly-3-hydroxybutyrate (PHB) and natural iron-containing porphyrin, hemin (Hmi) were prepared by electrospinning. The addition of Hmi to the feed PHB mixture (at concentrations above 3 wt.%) is shown to facilitate the electrospinning process and improve the quality of the electrospun PHB/Hmi materials: the fibers become uniform, their average diameter decreases down to 1.77 µm, and porosity increases to 94%. Structural morphology, phase composition, and physicochemical properties of the Hmi/PHB fibrous materials were studied by diverse physicochemical methods, including electronic paramagnetic resonance, optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy, elemental analysis, differential scanning calorimetry, Fourier-transformed infrared spectroscopy, mechanical analysis, etc. The proposed nonwoven Hmi/PHB composites with high porosity, good mechanical properties, and retarded biodegradation due to high antibacterial potential can be used as high-performance and robust materials for biomedical applications, including breathable materials for wound disinfection and accelerated healing, scaffolds for regenerative medicine and tissue engineering.
ABSTRACT
The purpose of this study was to assess the potential for biocomposite films to biodegrade in diverse climatic environments. Biocomposite films based on polyethylene and 30 wt.% of two lignocellulosic fillers (wood flour or flax straw) of different size fractions were prepared and studied. The developed composite films were characterized by satisfactory mechanical properties that allows the use of these materials for various applications. The biodegradability was evaluated in soil across three environments: laboratory conditions, an open field in Russia, and an open field in Costa Rica. All the samples lost weight and tensile strength during biodegradation tests, which was associated with the physicochemical degradation of both the natural filler and the polymer matrix. The spectral density of the band at 1463 cm-1 related to CH2-groups in polyethylene chains decreased in the process of soil burial, which is evidence of polymer chain breakage with formation of CH3 end groups. The degradation rate of most biocomposites after 20 months of the soil assays was greatest in Costa Rica (20.8-30.9%), followed by laboratory conditions (16.0-23.3%), and lowest in Russia (13.2-22.0%). The biocomposites with flax straw were more prone to biodegradation than those with wood flour, which can be explained by the chemical composition of fillers and the shape of filler particles. As the size fraction of filler particles increased, the biodegradation rate increased. Large particles had higher bioavailability than small spherical ones, encapsulated by a polymer. The prepared biocomposites have potential as an ecofriendly replacement for traditional polyolefins, especially in warmer climates.
