Šehić Alisa: Priprava funkcionalnih poliamidnih tekstilij s povečano termično stabilnostjo
In the doctoral dissertation, functional polyamide textiles with increased thermal stability were prepared by three processes of chemical modification of polyamide 6
(PA6) fibers, by sol-gel application of combination of flame retardants 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide-modified vinyl trialkoxysilane (DOPO–VTS) and tetraethoxysilane (TEOS) onto flat textiles, with melt spinning process of filament yarn samples with incorporated flame retardant (FR) additives melamine cyanurate (MeCy), aluminium diethylphosphinate (AlPi), sodium aluminosilicate (SASi), carbon nanotubes (CNT) and carbon black (CB), and melt spinning of the newly synthesized PA6 copolymer with a directly included flame retardant group DOPO (PA/DCA) on the polyamide chain. The results indicate that the presence of the sol-gel finishing DOPO-TEOS reduced PA6 decomposition rate and favored char formation, which confirms an increase in thermo-oxidative (TO) stability. The presence of the coating reinforce the fibre structure, stopped melt dripping but did not prevent the burning of PA6. FR additive MeCy had the biggest flame retardant influence on the PA6
filament yarns by decreasing the onset temperature of thermo-oxidative and increasing char stability at 800 °C The presence of MeCy completely stopped the flaming combustion of the filament. While SASi and CB interacted with MeCy, the addition of AlPi and CNT in a mixture with MeCy inhibit flame retardant properties of MeCy and only slightly improve TO stability of composite filament yarn samples. The presence of DOPO in copolymer caused a decrease of the onset temperature of the TO-decomposition of PA/DCA, a decrease of the decomposition temperature of the first step of degradation, and a slight increase of the temperature of the decomposition of the second step compared to PA6 and influence in the reduction of amount of residue. This indicates the operation of DOPO in the gas phase. The burning time of the PA/DCA copolymer yarn sample was significantly reduced compared to the burning of PA6 yarn, but the dripping melt of the copolymer was not self-extinguishing. These results were not as good as on films prepared from PA/DCA, where the dripping melt of the copolymer did not burn. The addition of all FR additives increased the degree of crystallinity of the yarn and slightly reduced its tensile properties.
Vasiljević Jelena: Oblikovanje večfunkcionalnih zaščitnih tekstilij s plazmo in tehnologijo sol-gel
The aim of this doctoral dissertation research was to usethe nanotechnology processes of plasma surfacepre-treatment and sol-gel finishing to impart long-lasting novel multifunctionalities, i.e.,low-adhesion super-hydrophobicity, oleophobicity, self-cleaning properties, flame-retardancy and antibacterial properties,to textiles. The plasma surface activation and etching of cotton and polyester fibres by low-pressure watervapour andoxygen plasmas wereusedas a pre-treatment to improve the water-and oil-repellent performance as well as the durability of the sol-gel coatings. The used sol-gel treatments were (i) the surface depositionof Stöber silica particles followed by thein situgrowthof the TEOS-based particle-containing polysiloxane layer to create the rough,bumpysurface topography of the fibre surface,and (ii) the fabricationofthe organo-functionalized hybrid coatings using fluoroalkyl-functional oligosiloxane (FAS) and 1H,1H,2H,2H-perfluorooctyltriethoxysilane (SiF) for water-and oil-repellency, P,P-diphenyl-N-(3-(trimethoxysilyl)propyl) phosphinic amide (SiP) and 10-(2-trimethoxysilyl-ethyl)-9-hydro-9-oxa-10-phosphaphenanthrene-10-oxide (Si-DOPO) for flame retardancy and 3-(trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride (SiQ) for antibacterial properties. Furthermore, organocyclotetrasiloxane 2,4,6,8-tetrakis(2-(diethoxy(methyl)silyl)ethyl)-2,4,6,8-tetramethyl–cyclotetrasiloxane(T4) was used toincreasethecoating’sorientation and adhesion. The water vapour and oxygen plasma pre-treatmentsimproved the water-and oil-repellencyperformance of the FAS and SiFcoatingsformed on the cotton fibresurface, respectively; however, theydid not markedly influencethe coating’s adhesion ability, thusnot improving thewashing fastness of the coatings. In contrast, in the case of polyester fibres, although the water vapour plasma pre-treatment did not influence the water and oil repellency of the FAScoating, the washing fastness of the coating wasmarkedly improved. Both Si-DOPOandSiPincreased the thermo-oxidative stability of the cotton fibresand retarded glowing combustion. Compared to Si-DOPO, SiP provided an approximately two-fold higher total quantity of dry solid add-on at the same concentration of the applied sols and provided very high hydrophobicity. Therefore, an approximate 2-fold lower concentration of SiP compared to that of the Si-DOPO provided a comparable thermo-oxidative stability. The water-and oil-repellent, antibacterial, and flame-retardant properties of the SiF, SiQ and SiP precursors were successfully associated in the multifunctional two-(SiF-SiP andSiF-SiQ) and three-component (SiF-SiQ-SiP) organofunctionalized polysilsequioxanecoatings formed on the cotton fibre surface. The cooperative action of the SiF, SiQand SiP components in the three-component coating provided the cotton fabric withexceptional and novel multifunctional properties, including simultaneous high hydrophobicity(waterstatic contact angle of 135°), oleophobicity(n-hexadecanestatic contact angle of 117°), antibacterial activity (bacterialreduction of 100 %for bothE. coliandS. aureus), enhanced thermo-oxidative stabilityand “glow” retardancy.Creation of the roughened,bumpysurface topography by the surface depositionof Stöber silica particles followed by thein situgrowthof the TEOS-based particle-containing polysiloxane layerwas ahighly efficientpre-treatment for improving the water-and oil-repellency performance and washing fastness of the FAS coating. This procedure enabled thefabrication of the long-lasting “Lotus effect”accompanied by an exceptionally high oleophobicity.The structure of the multifunctional three-component water-and oil-repellent, antibacterial, and flame-retardant hybrid polysilsesquioxane coatingwas optimisedto increase its washing fastness to cotton fibres.By including T4as the fourth component in the multifunctional SiF-SiQ-SiP coating, the washing fastness of the coating was increased, and thiswas even more pronounced if silica particles followed by the in situgrowthof the TEOS-based particle-containing polysiloxane layer were deposited on the cotton fibre surface in the pre-treatment process. The structural optimisation also led to the improvement of the functional properties of the coating, which exhibited the “Lotus effect” (waterstatic contact angle of161° and water roll-offangle of 4°) and simultaneously demonstrated high antibacterial activity (the Rvalues for E. coliand S. aureuswere 81.6 and 100 %, respectively), enhanced thermo-oxidative stability and “glow” retardancy. The only weakness of the optimised coating is the impairment of its oleophobicity.
Danijela Klemenčič: Protimikrobna zaščita tekstilij z uporabo nanosrebra
Doktorska disertacija sega na področje plemenitenja tekstilij in vključuje nove postopke kemijske modifikacije vlaken z namenom oblikovati funkcionalne tekstilne izdelke z visoko dodano vrednostjo. Raziskava je interdisciplinarna, v njej se prepletajo področja tekstilstva, kemije, materialov in mikrobiologije.
Osrednji del raziskave predstavlja razvoj novega univerzalnega postopka protimikrobne apreture s srebrom (Ag) za pripravo tekstilnih kompozitov s protimikrobnimi zaščitnimi lastnostmi. Kemijska modifikacija bombažne (CO), volnene (WO), svilene (SE), viskozne (CV), poliamidne (PA) in poliestrske (PES) tkanine ter tkanin iz CO/PES in WO/PES je bila izvedena dvostopenjsko, pri čemer je bila z nanosom anorgansko-organskega zamreževala (RB) na površini vlaken oblikovana silicijeva matrica, v katero so bili in situ sintetizirani delci srebrovega klorida (AgCl). Lastnosti apreture so bile določene s SEM-, z EDS- in ICP-MS-analizami ter z mikrobiološkimi testi. Iz rezultatov raziskave je razvidno, da je nov postopek primeren za kemijsko modifikacijo naravnih in sintetičnih vlaken. Prisotnost matrice je povečala adsorpcijsko sposobnost vlaken za AgCl, zmanjšala velikost delcev AgCl in omogočila njihovo fizikalno vezanje, kar ni oviralo njihovega sproščanja z vlaken. Zaradi večje koncentracije AgCl, vezanega v silicijevo matrico, se je povečala protimikrobna aktivnost apreture tudi po večkratnem pranju.
Izvirnost, sodobnost in aktualnost doktorskega dela potrjuje 8 izvirnih znanstvenih člankov, ki jih je doktorandka v soavtorstvu objavila v mednarodno priznanih revijah, od tega 5 člankov v revijah s faktorjem vpliva kategorije 1A1, ki jim stroka priznava znanstveno odličnost.