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Poly(lactic acid) (PLA) stands out as the most promising biodegradable alternative to conventional petrochemical-based polymers for manufacturing of high-performance materials applied in medicine, pharmacy, food, textile, and electronic industry. This review was aimed to present the conventional and up-to-date technologies for PLA processing including melt blending and molding, hot melt extrusion, 3D printing, foaming, impregnation, thermally induced phase separation, nano- and microparticles preparation, wet and dry spinning processes. In addition, the effect of the processing parameters and polymer characteristics on the properties of the final material was elaborated. Diverse possibilities to tailor properties of PLA-based materials by variation in polymer characteristics and concentration, solvent selection, drying method, processing pressure and temperature, incorporation of bioactive components, and so on were highlighted. The examples of the relations between processing methods, parameters, and end-product properties are given for a better understanding of all aspects that need to be perceived for fabrication of PLA-based materials with required performances.

Porous acetate cellulose (CA) beads were tested as carriers for thymol, eugenol and carvacrol, natural compounds well known for their biological activity. For this purpose, selected compounds were impregnated into CA using the environmentally friendly medium, supercritical carbon dioxide (scCO2). Firstly, impregnation of CA with thymol was tested in the pressure range of 10, 15, and 20 MPa for 2 and 24 h at a temperature of 50 °C. The pressure increase resulted in only slight increase in thymol loading. On the other hand, an increase in operating time at 10 MPa resulted in increase in thymol loading from 4.6 to 66.2%. Following the obtained results, subsequent experiments of CA beads impregnation with eugenol and carvacrol were performed at 10 MPa during 2 h, achieving amounts of loaded eugenol and carvacrol of 1.33 and 4.6%, respectively. The presence of thymol, eugenol and carvacrol on/in CA beads as well as its interaction with polymer was confirmed by the FTIR analysis. SEM images revealed that the porous structure of CA beads remained unchanged after its exposure to neat scCO2. However, loading of CA with thymol, eugenol and carvacrol at selected conditions led to the slight change in material texture and morphology. This observation was further examined using mercury intrusion porosimetry. While neat CA had an average pore diameter of 286 nm and porosity of 58%, loaded CA beds expressed an overall reduction in these values. The results were in line with the amounts of loaded active compounds. Namely, for the higher amount of loaded active substance, the higher decrease of specific surface area was observed. These results gave the guidelines for an effective functionalization of neat CA with compounds that have pronounced antimicrobial and antioxidant activity. 7th International Congress of the European Polysaccharide Network of Excellence, Nantes, 11-15.10.2021

U ovoj doktorskoj disertaciji su ispitane mogućnosti natkritične impregnacije (NKI) različitih polimernih nosača (pamučna tkanina, polipropilenski (PP) netkani materijal, poliamidni (PA) tekstilni materijali (tkanina, nanovlakna) i acetat celuloze (AC) u formi granula i filmova) ekstraktom piretrina, kako bi se istražila mogućnost dobijanja funkcionalizovanih materijala sa repelentnim svojstvima. Kao aktivna supstanca u procesima impregnacije je korišćen ekstrakt piretrina iz cveta Chrysanthemum cinerariaefolium zbog svog dokazanog insekticidnog dejstva. Rastvorljivost ekstrakta piretrina u natkritičnom ugljenik(IV)-oksidu (nkCO2) i mogućnost NKI odabranih polimera ekstraktom, ispitane su korišćenjem sledeće opreme: ćelija za rad pod visokim pritiscima (25 cm3) i laboratorijsko postrojenje za rad pod visokim pritiscima (300 cm3), primenom statičke metode. Otpuštanje ekstrakta iz impregniranih supstrata je ispitivano na vazduhu tokom 30 dana u kontrolisanim uslovima temperature (25 °C) u digitalnom inkubatoru. Impregnirani nosači su analizirani sledećim metodama: FT-IR, FE-SEM, DSC, HPLC i metodom živine porozimetrije. Vrednosti rastvorljivosti ekstrakta piretrina u nkCO2 bile su u opsegu od 15,09-48,69 kg/m3. Sadržaji impregniranog ekstrakta na pamučnoj tkanini od 0,5% i 1% obezbedili su repelentnu aktivnost materijala protiv krpelja. Impregnacija PP netkanog materijala je omogućila inkorporaciju velikih količina ekstrakta piretrina u polimer (do 78,01%), dok su prinosi impregnacije polimera na bazi PA bili u opsegu od 4,55-59,59%, a za AC od 0,86-30,43%. Impregnirana PP vlakna su pokazala sposobnost da otpuste velike količine ekstrakta (>70% tokom 30 dana), dok je sadržaj impregniranog ekstrakta u PA polimerima ostao stabilan nakon ispitivanog perioda. This PhD thesis was aimed to investigate the possibility of supercritical solvent impregnation (SSI) of selected polymer materials (cotton fabric, polypropylene (PP) non-woven fabric, polyamide (PA) polymers (fabric, nanofibres) and polymers of cellulose acetate (CA) in the form of granules and films) with pyrethrin extract in order to develop functionalized materials with repellant properties. Pyrethrum extract obtained from Chrysanthemum cinerariaefolium with proven insecticidal properities was selected as an active substance in the impregnation experiments. Determination of the pyrethrum extract solubility in supercritical carbon dioxide (scCO2) and the SSI of selected solids with the same extract were studied in the high pressure view cell (25 cm3) and the high pressure laboratory system (300 cm3) using a static mode. The pyrethrum extract release from the impregnated substrates was evaluated by exposing them to air for 30 days under controlled temperature (25 °C) with an use of digital incubator. Impregnated substrates were analized by FT-IR, FE-SEM, DSC, HPLC and mercury intrusion porosimetry methods. The solubilities of pyrethrum extract in scCO2 were in the range of 15.09-48.69 kg/m3. Impregnated cotton fabrics with pyrethrum contents of 0.5% and 1% exhibited significant repellent activity against ticks. The SSI enabled incorporation of large amounts of the extract into the PP non-woven fabric (up to 78.01%). Impregnation yields of PA and CA polymers were in the range of 4.55-59.59% and 0.86-30.43%, respectively. The impregnated PP non-woven fabrics revieled potential to release large amounts of repellent (>70% for 30 days period), while repellent content in the impregnated PA substrates remined stable after 30 days of exposure to air.

This PhD thesis was aimed to investigate the possibility of supercritical solvent impregnation (SSI) of selected polymer materials (cotton fabric, polypropylene (PP) non-woven fabric, polyamide (PA) polymers (fabric, nanofibres) and polymers of cellulose acetate (CA) in the form of granules and films) with pyrethrin extract in order to develop functionalized materials with repellant properties. Pyrethrum extract obtained from Chrysanthemum cinerariaefolium with proven insecticidal properities was selected as an active substance in the impregnation experiments. Determination of the pyrethrum extract solubility in supercritical carbon dioxide (scCO2) and the SSI of selected solids with the same extract were studied in the high pressure view cell (25 cm3) and the high pressure laboratory system (300 cm3) using a static mode. The pyrethrum extract release from the impregnated substrates was evaluated by exposing them to air for 30 days under controlled temperature (25 °C) with an use of digital incubator. Impregnated substrates were analized by FT-IR, FE-SEM, DSC, HPLC and mercury intrusion porosimetry methods. The solubilities of pyrethrum extract in scCO2 were in the range of 15.09-48.69 kg/m3. Impregnated cotton fabrics with pyrethrum contents of 0.5% and 1% exhibited significant repellent activity against ticks. The SSI enabled incorporation of large amounts of the extract into the PP non-woven fabric (up to 78.01%). Impregnation yields of PA and CA polymers were in the range of 4.55-59.59% and 0.86-30.43%, respectively. The impregnated PP non-woven fabrics revieled potential to release large amounts of repellent ( gt 70% for 30 days period), while repellent content in the impregnated PA substrates remined stable after 30 days of exposure to air. U ovoj doktorskoj disertaciji su ispitane mogućnosti natkritične impregnacije (NKI) različitih polimernih nosača (pamučna tkanina, polipropilenski (PP) netkani materijal, poliamidni (PA) tekstilni materijali (tkanina, nanovlakna) i acetat celuloze (AC) u formi granula i filmova) ekstraktom piretrina, kako bi se istražila mogućnost dobijanja funkcionalizovanih materijala sa repelentnim svojstvima. Kao aktivna supstanca u procesima impregnacije je korišćen ekstrakt piretrina iz cveta Chrysanthemum cinerariaefolium zbog svog dokazanog insekticidnog dejstva. Rastvorljivost ekstrakta piretrina u natkritičnom ugljenik(IV)-oksidu (nkCO2) i mogućnost NKI odabranih polimera ekstraktom, ispitane su korišćenjem sledeće opreme: ćelija za rad pod visokim pritiscima (25 cm3) i laboratorijsko postrojenje za rad pod visokim pritiscima (300 cm3), primenom statičke metode. Otpuštanje ekstrakta iz impregniranih supstrata je ispitivano na vazduhu tokom 30 dana u kontrolisanim uslovima temperature (25 °C) u digitalnom inkubatoru. Impregnirani nosači su analizirani sledećim metodama: FT-IR, FE-SEM, DSC, HPLC i metodom živine porozimetrije. Vrednosti rastvorljivosti ekstrakta piretrina u nkCO2 bile su u opsegu od 15,09-48,69 kg/m3. Sadržaji impregniranog ekstrakta na pamučnoj tkanini od 0,5% i 1% obezbedili su repelentnu aktivnost materijala protiv krpelja. Impregnacija PP netkanog materijala je omogućila inkorporaciju velikih količina ekstrakta piretrina u polimer (do 78,01%), dok su prinosi impregnacije polimera na bazi PA bili u opsegu od 4,55-59,59%, a za AC od 0,86-30,43%. Impregnirana PP vlakna su pokazala sposobnost da otpuste velike količine ekstrakta ( gt 70% tokom 30 dana), dok je sadržaj impregniranog ekstrakta u PA polimerima ostao stabilan nakon ispitivanog perioda.