1. Decomposition and fragmentation of conventional and biobased plastic wastes in simulated and real aquatic systemsOlivija Plohl, Lidija Fras Zemljič, Alen Erjavec, Noemi Sep, Maja Čolnik, Yee Van Fan, Mojca Škerget, Annamaria Vujanović, Lidija Čuček, Julija Volmajer Valh, 2024, izvirni znanstveni članek Opis: Plastics play a crucial role in our daily lives. The challenge, however, is that they become waste and contribute to a global environmental problem, increasing concerns about pollution and the urgent need to protect the environment. The accumulation and fragmentation of plastic waste, especially micro- and nanoplastics in aquatic systems, poses a significant threat to ecosystems and human health. In this study, the decomposition and fragmentation processes of conventional and biobased plastic waste in simulated water bodies (waters with different pH values) and in real water systems (tap water and seawater) are investigated over a period of one and six months. Three types of plastic were examined: thermoplastic polyethylene terephthalate and thermoset melamine etherified resin in the form of nonwovens and biobased polylactic acid (PLA) in the form of foils. Such a comprehensive study involving these three types of plastics and the methodology for tracking degradation in water bodies has not been conducted before, which underlines the novelty of the present work. After aging of the plastics, both the solid fraction and the leachate in the liquid phase were carefully examined. The parameters studied include mass loss, structural changes and alterations in functional groups observed in the aged plastics. Post-exposure assessment of the fragmented pieces includes quantification of the microplastic, microscopic observations and confirmation of composition by in situ Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy. The leachate analysis includes pH, conductivity, turbidity, total carbon and microplastic size distribution. The results highlight the importance of plastic waste morphology and the minor degradation of biobased PLA and show that microfibers contribute to increased fragmentation in all aquatic systems and leave a significant ecological footprint. This study underlines the crucial importance of post-consumer plastic waste management and provides valuable insights into strategies for environmental protection. It also addresses the pressing issue of plastic pollution and provides evidence-based measures to mitigate its environmental impact.
Ključne besede: polylactic acid, polyethylene terephthalate fabric, melamine etherifed resin fabric, aquatic environment, fragmentation, waste disposal
Objavljeno v DKUM: 09.09.2024; Ogledov: 73; Prenosov: 20
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2. Numerical analysis of a transtibial prosthesis socket using 3D-Printed Bio-Based PLAVasja Plesec, Jani Humar, Polona Dobnik-Dubrovski, Gregor Harih, 2023, izvirni znanstveni članek Opis: Lower-limb prosthesis design and manufacturing still rely mostly on the workshop process of trial-and-error using expensive unrecyclable composite materials, resulting in time-consuming, material-wasting, and, ultimately, expensive prostheses. Therefore, we investigated the possibility of utilizing Fused Deposition Modeling 3D-printing technology with inexpensive bio-based and bio-degradable Polylactic Acid (PLA) material for prosthesis socket development and manufacturing. The safety and stability of the proposed 3D-printed PLA socket were analyzed using a recently developed generic transtibial numeric model, with boundary conditions of donning and newly developed realistic gait cycle phases of a heel strike and forefoot loading according to ISO 10328. The material properties of the 3D-printed PLA were determined using uniaxial tensile and compression tests on transverse and longitudinal samples. Numerical simulations with all boundary conditions were performed for the 3D-printed PLA and traditional polystyrene check and definitive composite socket. The results showed that the 3D-printed PLA socket withstands the occurring von-Mises stresses of 5.4 MPa and 10.8 MPa under heel strike and push-off gait conditions, respectively. Furthermore, the maximum deformations observed in the 3D-printed PLA socket of 0.74 mm and 2.66 mm were similar to the check socket deformations of 0.67 mm and 2.52 mm during heel strike and push-off, respectively, hence providing the same stability for the amputees. We have shown that an inexpensive, bio-based, and bio-degradable PLA material can be considered for manufacturing the lower-limb prosthesis, resulting in an environmentally friendly and inexpensive solution.
Ključne besede: 3D printing, bio-based, polylactic acid, PLA, prosthesis, prosthesis socket, numerical model, finite element method
Objavljeno v DKUM: 14.03.2024; Ogledov: 208; Prenosov: 32
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3. Hybrid polylactic-acid–pectin aerogels : synthesis, structural properties, and drug releaseGabrijela Horvat, Klara Žvab, Željko Knez, Zoran Novak, 2023, izvirni znanstveni članek Opis: Wound-dressing materials often include other materials stimulating wound healing. This research describes the first formulation of biodegradable hybrid aerogels composed of polylactic acid and pectin. The prepared hybrid material showed a highly porous structure with a surface area of 166 +/- 22.6 m(2)center dot g(-1). The addition of polylactic acid may have decreased the surface area of the pure pectin aerogel, but it improved the stability of the material in simulated body fluid (SBF). The pure pectin aerogel showed a high swelling and degradation ratio after 3 h. The addition of the polylactic acid prolonged its stability in the simulated body fluid from 24 h to more than one week, depending on the amount of polylactic acid. Biodegradable aerogels were loaded with indomethacin and diclofenac sodium as model drugs. The entrapment efficiencies were 63.4% and 62.6% for indomethacin and diclofenac sodium, respectively. Dissolution of both drugs was prolonged up to 2 days. Finally, sodium percarbonate and calcium peroxide were incorporated into the bioaerogels as chemical oxygen sources, to evaluate oxygen generation for potential wound healing applications.
Ključne besede: hybrid aerogels, bioaerogel, pectin, polylactic acid, wound healing
Objavljeno v DKUM: 20.02.2024; Ogledov: 357; Prenosov: 24
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