1. Enhanced photothermal based-heat retention in regenerated cellulose fibers via ceramic particles and polyelectrolyte binders-based surface functionalizationÖzkan Yapar, Ajra Hadela, Alenka Ojstršek, Aleksandra Lobnik, 2025, original scientific article Abstract: : There has been growing interest and increasing attention in the field of functional clothing textiles, particularly in product and process development, as well as innovations in heat-generating, retaining, and releasing fibers to maintain a healthy body temperature without relying on unsustainable energy sources. This study, for the first time, reports the various physio-mechanical properties of surface-functionalized regenerated cellulose fibers (RCFs) coated with ceramic particles. The coating imparts photothermal conversion-based heat generation and retention properties with the aid of polyelectrolyte binders. In this design, ZrC enables the conversion of light energy into thermal energy, providing heat for the human body. A feasible coating process was employed, utilizing industrially feasible exhaustion methods to deposit the ZrC particles onto the RCF surface in conjunction with two distinctive polymeric binders, specifically polyethyleneimine (PEI) and polydiallyldimethylammonium chloride (polyDADMAC). The morphological characteristics and tensile properties of the coated RCFs were analyzed via scanning electron microscopy (SEM) and single-fiber tensile testing. Heat retention and release behaviors of a bundle of fiber samples were assessed using infrared (IR) imaging and an IR emission lamp setup. The SEM results confirmed the successful coating of the ZrC particles on the surface of the RCF samples, influencing negligible on their physical–mechanical properties. The heat retention of the coated RCFs with ZrC and both binders was higher than that of reference regenerated cellulose fibers (RCFs), demonstrating their effective heat generation, retention, and heat release properties. Based on the highlighted prominent results for the coated RCFs, these findings highlight the suitability of the developed functional clothing textiles for targeted applications in non-extreme thermal conditions, ensuring thermo-physiological comfort by maintaining body temperature within a tolerable thermal range (36.5–37.5 ◦C), in contrast to studies reporting significantly higher temperatures (50–78 ◦C) for extreme thermal conditions.
Keywords: regenerated cellulose fibers, RCFs, ceramic particles, zirconium carbide, ZrC, surface functionalization, heat generation and retention
Published in DKUM: 01.04.2025; Views: 0; Downloads: 131
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2. A review of electro conductive textiles utilizing the dip-coating technique: Their functionality, durability and sustainabilityAlenka Ojstršek, Laura Jug, Olivija Plohl, 2022, review article Abstract: The presented review summarizes recent studies in the field of electro conductive textiles
as an essential part of lightweight and flexible textile-based electronics (so called e-textiles), with the
main focus on a relatively simple and low-cost dip-coating technique that can easily be integrated
into an existing textile finishing plant. Herein, numerous electro conductive compounds are discussed, including intrinsically conductive polymers, carbon-based materials, metal, and metal-based
nanomaterials, as well as their combinations, with their advantages and drawbacks in contributing
to the sectors of healthcare, military, security, fitness, entertainment, environmental, and fashion,
for applications such as energy harvesting, energy storage, real-time health and human motion
monitoring, personal thermal management, Electromagnetic Interference (EMI) shielding, wireless
communication, light emitting, tracking, etc. The greatest challenge is related to the wash and wear
durability of the conductive compounds and their unreduced performance during the textiles’ lifetimes, which includes the action of water, high temperature, detergents, mechanical forces, repeated
bending, rubbing, sweat, etc. Besides electrical conductivity, the applied compounds also influence
the physical-mechanical, optical, morphological, and comfort properties of textiles, depending on
the type and concentration of the compound, the number of applied layers, the process parameters,
as well as additional protective coatings. Finally, the sustainability and end-of-life of e-textiles are
critically discussed in terms of the circular economy and eco-design, since these aspects are mainly
neglected, although e-textile’ waste could become a huge problem in the future when their mass
production starts.
Keywords: electro conductive textiles, dip-coating, characterization, functional features, durability, sustainability, recyclability
Published in DKUM: 27.03.2025; Views: 0; Downloads: 3
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3. Functional coatings with ethyl cellulose-calcium carbonate alkaline nanoparticles for deacidification and mechanical reinforcement of paper artifactsMatej Bračič, Jasna Malešič, Mihael Brunčko, Doris Bračič, Alenka Ojstršek, Tea Kapun, Sašo Gyergyek, Karin Stana-Kleinschek, Tamilselvan Mohan, 2025, original scientific article Abstract: Paper artifacts susceptible to acid hydrolysis and mechanical stress require effective conservation methods to ensure their longevity. In this study, a novel approach for the deacidification of acidic paper using calcium carbonate (CaCO3) [1,2]-ethylcellulose nanoparticles (CaCO3-EC NPs) dispersed in a non-aqueous ethyl acetate solution is presented. The dispersions were carefully prepared and applied to model acidic paper samples using a dipcoating method and then analyzed for their effectiveness. Transmission electron microscopy showed the formation of agglomerates containing quadrangular alkaline nanoparticles with diameters of 40 to 100 nm and a total agglomerate size of 250 nm. Hydrodynamic analyzes indicate the presence of a swollen ethyl cellulose coating on these agglomerates, which facilitates their dispersion. The results show the effectiveness of the CaCO3-EC NPs system in neutralizing acidic components (change of paper pH from 4.3 to 7) due to the homogeneous distribution within the paper substrates, effectively arresting the degradation processes. Acid-base titration showed a linear correlation between the concentration of alkaline nanoparticles and the alkaline reserve, emphasizing the role of ethylcellulose in facilitating particle transport within the paper matrix. In addition, ethylcellulose was found to improve the mechanical properties of the treated paper, as demonstrated by the standard mechanical tests. Importantly, the optical properties remained unchanged after treatment, as no adverse changes in color were observed. These results underline the effectiveness of the developed deacidification dispersions for the treatment of acidic paper and potentially other cellulose-based cultural heritage documents prone to acidic degradation. This approach offers promising implications for preserving and restoring valuable historical materials.
Keywords: ethylcellulose, calcium carbonate, functional coating, deacidification, strengthening, cultural heritage
Published in DKUM: 20.03.2025; Views: 0; Downloads: 1
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4. Adsorption of pollutants from colored wastewaters after natural wool dyeingAlenka Ojstršek, Primož Vouk, Darinka Fakin, 2022, original scientific article Abstract: The presented study assesses the efficiency of selected adsorbents, zeolite 4A in two
particle sizes and pelletized activated carbon (AC), for the potential removal of color, chemical
oxygen demand (COD), total organic carbon (TOC) and metals from wastewaters after natural wool
dyeing. Firstly, the natural coloring compounds were extracted from dried common walnut (Juglans
regia) leaves and used further for exhaustion dyeing of wool fibers, together with three different
metallic salts in two concentrations (meta-mordanting). Effluents with higher mordant concentration
were additionally treated according to a shake-flask adsorption experiment. The obtained results
revealed efficient removal of exceeded metallic ions by zeolite (up to 94.7%), on account of their
superior ion exchange capability as compared to AC. The zeolites also reduced turbidity and electrical
conductivity significantly. On the other hand, AC was more efficient for the reduction in organic
pollution, COD up to 96% and TOC up to 95%, due to its higher specific surface area and total pore
volume, and, thus, higher potential for adsorption of different compounds in comparison to 4A.
All three proposed adsorbents lowered wastewaters’ coloration remarkably, up to 78% (AC) and up
to 71% (4A), depending on the type of effluent/mordant and inspected wavelength; although, the
spectral absorbance coefficient (SAC) values remained highly above the limit values for discharge of
wastewaters into watercourses.
Keywords: wool dyeing, natural dyes, wastewater treatment, decoloration, heavy metals’ reduction, adsorption
Published in DKUM: 20.03.2025; Views: 0; Downloads: 4
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5. Synergic effect of large MXene nanosheets and protective coatings on improved electroconductivity and wash durability of MXene/polymer-modified cotton fabricLaura Jug, Silvo Hribernik, Alenka Ojstršek, 2025, original scientific article Abstract: E-textiles and their wearable analogues are finding applications in a myriad of sectors, ranging from sensors to health and sports applications. The development of a truly functional and reusable textile substrate presents a challenging task; its design encompasses the fabrication of optimal functional conductive particles, as well as devising strategies for their application that will ensure their functional properties (e.g. conductivity) are retained in an undiminished state for a foreseeable period. In the presented study, we tackled these two aspects in an interdependent way: i) The enhancement of the electrical conductivity of MXene-modified cotton fabric by increasing the lateral size of nanosheets during the Ti3C2TX synthesis, and ii) The improvement of washing durability of MXenes on the fabric surface by selecting suitable protective coatings. The results of Scanning Electron Microscopy (SEM), X-ray powder Diffraction (XRD), Dynamic Light Scattering (DLS) and Atomic Force Microscopy (AFM) revealed the successful synthesis of large and stable MXene nanosheets with ultrathin flakelike nanostructures, high colloidal stability and delamination yields. Using multiple application procedures of dipping and drying, the MXene nanosheets formed extensive adhesion areas on the cotton fabric and overlapped the fibre pores, thus reducing the interfacial resistance between the sheets and improving the coating uniformity and, consequently, increasing electrical conductivity. Weaker adhesion and depletion of large nanosheets were further effectively prevented by protective polymer coatings. The MXene-coated/protected fabrics had sufficient electrical conductivity, even after 20 laundering cycles. Moreover, the surface hydrophobicity was negligibly reduced, preventing water accessibility and, thus, increasing the oxidation stability of the applied MXenes.
Keywords: Ti3C2TX MXene, synthesis parameters, cotton fabric, electrical conductivity, protective coatings, washing durability
Published in DKUM: 10.03.2025; Views: 0; Downloads: 13
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6. Ekologija plemenitilnih procesovAlenka Ojstršek, Darinka Fakin, Selestina Gorgieva, 2024 Abstract: Skripta z naslovom »Ekologija plemenitilnih procesov« je namenjena študentom visokošolskega študijskega programa Tehnologije tekstilnega oblikovanja. Pripravljena je tako, da študente v prvih poglavjih seznani z osnovami tehnoloških procesov plemenitenja tekstilij in njihovo ekološko problematiko. Poseben problem v tekstilni industriji predstavljajo odpadne tehnološke vode, saj so močno obremenjene, vsebujejo različne kemikalije in tekstilna pomožna sredstva, različne tipe organskih barvil, imajo ekstremne pH-vrednosti in visoke vrednosti kemijske potrebe po kisiku (KPK) in biokemijske potrebe po kisiku (BPK), vsebujejo fosfate, sulfate in ostale soli, tenzide, maščobe in olja ter različne tipe težkih kovin. V nadaljevanju so v gradivu predstavljeni alternativni mediji in postopki plemenitenja, ki za dosego izbranega učinka plemenitenja porabijo manj kemikalij in tekstilnih pomožnih sredstev, manj energije in tako vplivajo na manjšo obremenitev okolja. Poseben poudarek je na alternativnih tehnikah obdelave, ki vključujejo avtomatizacijo, ki dodatno vpliva na nižjo porabo vode in energije, manjšo količino odpadkov, odpadnih vod in emisij toplogrednih plinov ter na večjo produktivnost, varnost pri delu in optimalno izrabo delovnega časa. Pridobljeno znanje bo študentom omogočilo, da bodo poleg temeljnih znanj poznali tudi napredne pristope in tehnologije pri razvoju in plemenitenju sodobnih inženirskih materialov.
Keywords: ekologija, plemenitenje, tekstilni materiali, napredni postopki, odpadne vode
Published in DKUM: 16.12.2024; Views: 0; Downloads: 36
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7. Dopamine-assisted modification of polypropylene film to attain hydrophilic mineral-rich surfacesAlenka Ojstršek, Angela Chemelli, Azra Osmić, Selestina Gorgieva, 2023, original scientific article Abstract: The presented study focuses on the modification of polypropylene (PP) film with tetraethyl orthosilicate (TEOS) under heterogeneous conditions via polydopamine/polyethylene imine (PDA/PEI) chemistry using a facile dip-coating procedure to attain hydrophilic mineral-rich surfaces. Thus, the resulting PP-based films were further immersed in ion-rich simulated body fluid (SBF) to deposit Ca-based minerals onto the film’s surfaces efficiently. In addition, the chemical reaction mechanism on PP film was proposed, and mineralisation potential inspected by determination of functional groups of deposits, zeta potential, hydrophilicity and surface morphology/topography using Fourier transform infrared (FTIR) spectroscopy, streaming potential, water contact angle (WCA), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The obtained results show the improved wettability of samples on account of PDA inclusion (WCA was reduced from 103° for pure PP film to 28° for PDA-modified film), as well as the presence of functional groups, due to the PDA/PEI/TEOS surface functionalisation, increased the ability of minerals to nucleate on the PP film’s surface when it was exposed to an SBF medium. Moreover, the higher surface roughness due to the silica coatings influenced the enhanced anchoring and attachment of calcium phosphate (CaP), revealing the potential of such a facile approach to modify the chemically inert PP films, being of particular interest in different fields, including regenerative medicine.
Keywords: polypropylene film, dopamine-assisted modification, hydrophilicity, mineralization
Published in DKUM: 15.03.2024; Views: 300; Downloads: 9
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8. Cellulose nanofibrils-reinforced pectin membranes for the adsorption of cationic dyes from a model solutionAlenka Ojstršek, Selestina Gorgieva, 2024, original scientific article Abstract: In the presented research, a facile, one-step method for the fabrication of cellulose nanofibrils/pectin (CNFs/PC) membranes is described, which were tested further for their ability to remove cationic dyes from the prepared model solutions. For this purpose, ten membranes were prepared with different quantities of CNFs and PC with/without citric acid (CA) or CaCl2 as mediated crosslinking agents, and they were characterised comprehensively in terms of their physical, chemical, and hydrophilic properties. All the prepared CNFs/PC membranes were hydrophilic with a Water Contact Angle (WCA) from 51.23◦ (without crosslinker) up to 78.30◦ (CaCl2 ) and swelling of up to 485% (without crosslinker), up to 437% (CaCl2 ) and up to 270% (CA). The stability of membranes was decreased with the increase in PC; thus, only four membranes (M1, M2, M3 and M5) were stable enough in water after 24 h, and these were additionally applied in the adsorption trials, using two structurally different cationic dyes, i.e., C.I. Basic Yellow 28 (BY28) and C.I. Basic Blue 22 (BB22), in four concentrations. The highest total surface charge of M3 (2.83 mmol/g) as compared to the other membranes influenced the maximal removal efficiency of both dyes, up to 37% (BY28) and up to 71% (BB22), depending on the initial dye concentration. The final characteristics of the membranes and, consequently, the dye’s absorption ability could be tuned easily by changing the ratio between the CNFs and PC, as well as the type and amount of crosslinker.
Keywords: cellulose nanofibrils, pectin, cationic dyes, adsorption, dye removal
Published in DKUM: 12.03.2024; Views: 320; Downloads: 30
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9. Cotton woven fabrics as protective polymer materials against solar radiation in the range of 210–1200 nmPolona Dobnik-Dubrovski, Darinka Fakin, Alenka Ojstršek, 2023, original scientific article Abstract: The proposed paper describes the influence of woven fabric constructional parameters (type of weave, relative fabric density) and colouration (obtained by eco-friendly dyeing) on the solar transmittance of cotton woven fabrics in the range of 210-1200 nm. The cotton woven fabrics in their raw state were prepared according to Kienbaum's setting theory, at three levels of relative fabric density and three levels of the weave factor, and then exposed to the dyeing process with natural dyestuffs (beetroot, walnut leaves). After ultraviolet/visible/near-infrared (UV/VIS/IRA) solar transmittance and reflection in the range of 210-1200 nm were recorded, the influence of the fabric construction and colouration were analysed. The guidelines for fabric constructor were proposed. The results show that the walnut-coloured satin samples at the third level of relative fabric density provide the best solar protection in the whole solar spectrum. All the tested eco-friendly dyed fabrics offer good solar protection, while only raw satin fabric at the third level of relative fabric density can be classified as solar protective material with even better protection in IRA region than some coloured samples.
Keywords: fabric engineering, solar protection, woven fabric structure, natural dyeing of polymer material, testing
Published in DKUM: 15.02.2024; Views: 296; Downloads: 17
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10. Razvoj celulozno-pektinskih membran za adsorpcijo kationskih barvil iz modelnih raztopin : magistrsko deloMaja Mazej, 2023, master's thesis Abstract: Vse večja rast prebivalstva in razvoj industrije sta močno vplivala na povečano porabo vode. Velik problem pri tem pa predstavljajo predvsem obarvane odpadne vode v tekstilni industriji, ki so zelo obremenjene in predstavljajo ob izpustu veliko obremenitev za okolje. Odstranjevanje barvil iz odpadnih vod, zaradi kompleksnih molekulskih struktur predstavlja velike izzive industriji. Tako so želje po ponovni uporabi spodbudile razvoj novih tehnologij, ki bi na učinkovit in cenovno ugoden način te vode pred izpustom v vodotok tudi ustrezno prečistile. Že predhodne raziskave so pokazale, da je ena izmed učinkovitejših fizikalnih metod ločevanja barvil membranska adsorpcija.
Magistrsko delo predstavlja preučitev različnih možnosti in načinov, s katerimi bi uspešno ločili kationska barvila iz modelnih odpadnih vod z uporabo membranskih adsorbentov na osnovi celuloznih nanofibrilov in pektina. Cilj magistrskega dela je bil sinteza cenovno – učinkovitih, okolju prijaznih membran, na osnovi nanofibrilirane celuloze in pektina, na osnovi enostavnih postopkov mešanja, vlivanja in sušenja z dodatkom citronske kisline (CA) in CaCl2 kot zamreževalca. Različne strukturirane membrane smo primarno okarakterizirali glede na njihove morfološke in fizikalno-kemijske lastnosti, ter sekundarno glede na njihove adsorpcijske lastnosti, na podlagi katerih smo preučili mehanizme in učinkovitost adsorpcije. Pri tem smo pridobili membrane, ki bi lahko uspešno vplivale na ločitev kationskih barvil iz vodnih medijev.
Gravimetrična analiza membran nam je podala zaključek, da so vse membrane na osnovi mešanic primarnih surovin brez dodanih zamreževalcev neobstojne v vodi, zato je dodatek zamreževalcev ključnega pomena. Opazili smo, da membrana formirana le iz CNFjev, ne potrebuje zamreževalca, saj je samostojno obstojna v vodi, kar pa gre pripisati intenzivnemu in ireverzibilnemu povezovanju nanofibrilov pri procesu sušenja, v odsotnosti drugih komponent.
Z ATR – FTIR spektroskopijo smo ugotovili, da obe vrsti zamreževalca, tako CA kot CaCl2, naredita spremembo v kemijski strukturi, in prispevata k določeni meri stabilizacije in s tem nakazujeta na uspešno ionsko (CaCl2), ter kovalentno (CA) vezavo. Z rezultati, pridobljenimi pri potenciometrični titraciji, smo ugotovilii, da dosežejo največji skupni naboj tiste membrane, ki vsebujejo zamreževalec CA. K doseganju največjega naboja membrane je prispevala predvsem prisotnost karboksilnih skupin, ki tudi vplivajo na večjo adsorpcijsko sposobnost membran. Izmerjene vrednosti z goniometrijo pri vseh membranah so bile nižje od 90° in kažejo na izrazito hidrofilnost membran, saj osnovne komponente vsebujejo hidrofilne hidroksilne, ter karboksilne skupine. Z optično mikroskopijo smo membrane le makroskopsko opazovali in zaključili, da imajo membrane izotropne strukture, brez preferenčne ureditve. Z rezultati gravimetričnega določanja % nabrekanja smo ugotovili, da zamreževalec pozitivno vpliva na ohranjanje strukture membrane v vodi. Pektin pa očitno vpliva na nestabilnost (karboksilne skupine, ob stiku z vodo dezintegrirajo), če primerjamo membrane z dodanim pektinom in membrano 10, ki ima vključen samo CNF. Z analizo adsorpcije barvil (UV-VIS spektrokoskopija) vidimo uspešno adsorpcijo obeh barvil Basic Yellow 28 kot tudi Basic Blue 22 v različnih koncentracijah na membrane. Najbolj uspešen primer navzemanja barvila je v primeru CNF/PC membran, ker ima pektin naboj, ki omogoča uspešno vezavo barvila. Dokazali smo tudi uspešno navzemanje barvila na membrane, pri obeh vrstah barvila. Odstotek razbarvanja kopeli se razlikuje glede na koncentracije v primeru najnižje koncentracije in najmanjše razbarvanje v primeru najvišje koncentracije, kar velja za vse membrane.
Adsorpcija barvil je pogojena s kemijsko strukturo ter mikrostrukturo membrane, ki se uporabi kot adsorbent.
Keywords: Celulozni nanofibrili, pektin, zamrežanje, membrana, membranska adsorpcija, kationska barvila
Published in DKUM: 09.02.2023; Views: 664; Downloads: 73
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