Uticaj pesticida na strukturu polimera pri ubrzanom starenju poli(etilen tereftalata)

Abstract

Upotreba ambalaže od poli(etilen tereftalata), PET, u industriji pesticida sve je zastupljenija zahvaljujući dobroj dimenzionoj stabilnosti PET, hemijskoj otpornosti, mehaničkim svojstvima i transparentnosti. Imajući u vidu da se u formulaciji pesticida koriste organski rastvarači i jedinjenja petrohemijskog porekla koja mogu biti i toksična, jasno je da je izbor amabalaže za pakovanje pesticida izuzetno važan. U praksi tu odluku donosi proizvođač pesticida bez validne metode koja bi potvrdila opravdanost izbora određenog pakovanja. Takođe, upotreba pesticida upakovanih u plastičnu ambalažu doprinosi porastu ambalažnog otpada od plastičnih materijala. Na osnovu statističkih analiza o kretanju i postupanju sa ambalažnim otpadom u Evropi iz 2019. godine, oko 75 % ambalažnog otpada od plastičnih materijala se reciklira ili koristi kao energent, dok ostatak (oko 25 %) ukupnih količina ambalažnog otpada biva uskladišteno na deponijama, najčešće kao neadekvatno uskladišten ambalažni otpad bez procene rizika na životnu sredinu i uticaja degradacije polimera i ostataka upakovanih proizvoda koji se mogu zadržati u plastičnom materijalu. Cilj ove disertacije bio je ispitivanje mogućnosti i opravdanosti pakovanja organskih rastvarača i pesticida u obliku koncentrata za emluzije (EC) sa aspekta stabilnosti, sigurnosti i reciklabilnosti PET ambalaže uzimajući u obzir promene na PET ambalaži do kojih dolazi pod dejstvom upakovanih pesticida tokom životnog veka proizvoda. Osnova eksperimentalnog rada u disertaciji bila je metoda CIPAC 1.MT.46 koja se koristi za određivanje stabilnosti pesticida u originalnoj ambalaži i podrazumeva skladištenje pesticida na 54 ± 2 °C tokom 14 dana i simulaciju ponašanja proizvoda tokom dve godine roka trajanja („test starenja“). Promene na PET bocama konstatovane tokom „testa starenja“ (promena mase boca, promena stepena kristaliničnosti, promena dimenzija boca izazvane bubrenjem polimernog materijala, kao i sadržaj apsorbovanog rastvarača/pesticida) ukazale su na promene u strukturi PET boca. Udeo kristalne faze je određen metodom analize slike uz primenu softvera Image Pro Plus kao nedestruktivne metode kojom se brzo i efikasno dobijaju informacije o promeni strukture PET ambalaže tokom „veka trajanja" pesticida. Primenom analize slike detektovane su i izdvojene zone na bocama koje su pretrpele promene tokom „testa starenja”, a merenjem transperentnosti i stepena sivoće izdvojenih zona, izvršena je korelacija dobijenih podataka sa sadržajem udela kristalne faze PET-a. Konvencionalna DSC VI metoda za određivanje udela kristalne faze potvrdila je saglasnost sa rezultatima dobijenih određivanjem udela kristalne faze metodom analize slike. Pored promena u strukturi, eksperimentalni rezultati nakon „testa starenja“ ukazali su na različit stepen difuzije i emisije različitih tipova organskih rastvarača i pesticida kroz PET boce, ali i na značajnu količinu organskih rastvarača/pesticida koji su ostali apsorbovani u PET-u čime je potvrđena opravdanost kategorizacije PET ambalaže za pakovanje pesticida kao opasnog otpada koji zahteva poseban tretman. Na osnovu rezultata promena mase boca tokom „testa starenja“ različitih formulacija pesticida sa aktivnom materijom Cipermetrin (CY) u disertaciji je opisan i postupak stvaranja veštačke neuronske mreže sa opštom regresijom (General regression neural network -GRNN) čijom se primenom može predvideti emisija pesticida kroz PET boce. Na osnovu dobijenih eksperimentalnih podataka (promena mase boca sa pesticidima i vremena skladištenja), obučavanja i testiranja neuronske mreže, analizom „osetljivosti" modela veštačke neuronske mreže, dobijeni su pouzdani podaci o proceni emisije pesticida kroz PET ambalažu tokom vremena skladištenja.

The use of poly (ethylene terephthalate), PET packaging in the pesticide industry is a consequence of good dimensional stability of PET, chemical resistance, mechanical properties and transparency. Bearing in mind that organic solvents and compounds of petrochemical origin are used in the formulation of pesticides, which can also be toxic, the choice of packaging for pesticide packaging is extremely important. In practice, this decision is made by the pesticide manufacturer without a valid method that would confirm the justification of the choice of a particular package. Also, the use of pesticides packed in plastic packaging contributes to the increase of packaging waste from plastic materials. Based on statistical analyzes on the movement and treatment of packaging waste in Europe in 2019, about 75% of packaging waste from plastic materials is recycled or used as energy, while the rest (about 25%) of total packaging waste is stored in landfills, most often as inadequately stored packaging waste without an environmental risk assessment and the impact of degradation of polymers and residues of packaged products that can be retained in the plastic material. The aim of this dissertation was to examine the possibility and justification of packaging organic solvents and pesticides in the form of emulsion concentrates (EC) from the aspect of stability, safety and recyclability of PET packaging, taking into account changes in PET packaging that occur under the action of packaged pesticides. The basis of experimental work in the dissertation was the method CIPAC 1.MT.46 which is used to determine the stability of pesticides in the original packaging and involves storing pesticides at 54 ± 2 ° C for 14 days and simulates the behavior of the product during two years ("aging test“). Changes in PET bottles observed during the "aging test" (change in the bottle weight, change in the degree of crystallinity, change in the bottle size caused by swelling of the polymer material, as well as the content of absorbed solvent / pesticide) indicated changes in the structure of PET bottles. The crystalline phase was determined by the image analysis method using Image Pro Plus software as a non-destructive method that quickly and VIII efficiently provides information on changes in the structure of PET packaging during the "shelflife" of pesticides. "Aging test", and by measuring the transparency and degree of grayness of the isolated zones, the obtained data were correlated with the content of the crystalline phase of PET. In addition to the changes in the structure, the experimental results after the "aging test" showed a different degree of diffusion and emission of different types of organic solvents and pesticides through PET bottles, but also a significant amount of organic solvents/pesticides that remained absorbed in PET, confirmed justification of categorization of PET packaging for pesticide packaging as hazardous waste that requires special treatment. Based on the results of the bottle mass change during the "aging test" of different pesticide formulations with the active substance Cypermethrin (CI), the dissertation describes the procedure of creating artificial neural networks with general regression (General regression neural network-GRNN) which can predict pesticide emissions through PET bottles. Based on the obtained experimental data (change in weight of pesticide bottles and storage time), training and testing of neural networks, analysis of "sensitivity" of artificial neural network models, reliable data on pesticide emissions through PET packaging during storage time were obtained.