Application of supercritical carbon dioxide in fabrication of materials with repellent properties based on pyrethrins

Abstract

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.