Vpliv staranja materiala na kakovost dvostranske metalizirane folije : diplomsko delo

Grm, Neža (avtor), Slabe, Damjan (mentor), Tomšič, Brigita (komentor), Bohinc, Klemen (recenzent)

Uvod: Dvostranska metalizirana folija je od leta 2005 v Sloveniji obvezni del kompleta prve pomoči za vsa motorna vozila. Služi kot zaščita pred vremenskimi vplivi, njen osnovni namen pa je pasivna zaščita pred podhladitvijo. Uporabljajo jo gorniki, jamarji, popotniki, taborniki, gasilci, člani ekip prve pomoči, Civilne zaščite in Rdečega križa in drugi. Folija je lahka, tanka, vodoodporna, preprosta za uporabo, izolativna in dobro vidna. Njena negativna lastnost je, da zadržuje kondenz, ob uporabi pa se na ostrih robovih hitro strga in lušči. Osnovni material, ki gradi dvostransko metalizirano folijo, je polietilen tereftalat, ki je spremenjen z ustreznimi dodatki. Namen: Ugotoviti vpliv staranja materiala na kakovost dvostranske metalizirane folije. Metode dela: Pri pisanju sta bili uporabljeni domača in tuja strokovna ter znanstvena literatura, pridobljeni s pomočjo podatkovnih baz COBISS.SI, Web of Science, PubMed, ScienceDirect in Google Učenjak. Iz različnih kompletov prve pomoči je bilo zbranih 34 dvostranskih metaliziranih folij z datumom proizvodnje od leta 2006 do 2022. Za laboratorijske preizkuse je bilo med zbranimi folijami uporabljenih 15 folij, ki so bile označene po abecednem vrstnem redu in z zaporedno številko glede na datum proizvodnje. Sledila je analiza lastnosti dvostranske metalizirane folije, pri čemer so bile določene barvne, morfološke in kemijske lastnosti, natezna trdnost, toplotna ter električna prevodnost. Rezultati: Z barvnometrično analizo je bilo ugotovljeno, da se zlata barva vzorcev dvostranske metalizirane folije razlikuje v barvnih koordinatah CIE L*a*b*, kar je potrdilo vizualna opažanja. Optična in vrstična elektronska mikroskopija nista pokazali večjih razlik na površinah proučevanih vzorcev, zato je bila narejena podrobnejša analiza površine vzorcev z energijsko-disperzijsko spektroskopijo rentgenskih žarkov. Na zlatih in srebrnih površinah vseh proučevanih vzorcev je bilo opaziti prisotnost ogljika in kisika, na nekaterih površinah pa so bili prisotni tudi drugi elementi, med njimi aluminij in silicij. Vpliv staranja materiala na kemijske lastnosti je bil posnet z infrardečo spektroskopijo s Fourierjevo transformacijo vzorcev A1, H3 in N2. Iz spektrov zlate strani je bila razvidna prisotnost absorpcijskih trakov značilnih za polietilen tereftalat, karbonilno skupino estrske vezi in za benzenski obroč. Iz spektrov srebrnih strani vzorcev H3 in N2 je bila ugotovljena prisotnost absorpcijskih trakov poliestra, ki jih pri vzorcu A1 na srebrni strani ni bilo opaziti. Z dinamometrom Instron je bila izmerjena sila pretrga prečne in vzdolžne smeri proučevanih vzorcev, ki je v povprečju znašala 21,7083 N. Z meritvami pretržne sile je bilo ugotovljeno, da vrednosti natezne trdnosti padajo skladno s starostjo materiala. Toplotne lastnosti so bile proučene z meritvami toplotne prevodnosti, ki dokazujejo, da srebrne in zlate strani proučevanih vzorcev delujejo izolativno, saj so bile izmerjene vrednosti izredno nizke, in sicer od 0,0017 ? do 0,0035 ?. S termografsko kamero je bilo izmerjeno prepuščanje toplote skozi folijo, pri čemer je bil za simulacijo človeškega telesa uporabljen termofor. Ugotovljeno je bilo, da pri vseh proučevanih vzorcih, z izjemo najstarejšega vzorca A1, srebrna stran, obrnjena k termoforju (zlata stran obrnjena navzven), zadržuje toploto, saj je bila izmerjena temperatura na zlati strani, obrnjeni navzven, nižja v primerjavi s temperaturo, izmerjeno na srebrni strani, obrnjeni navzven. Povprečna izmerjena temperatura pri vseh vzorcih, razen pri vzorcu A1, je bila na zunanji zlati strani za 11,4 °C nižja v primerjavi s temperaturo, izmerjeno na zunanji srebrni površini folije. Z meritvami električne prevodnosti je bilo ugotovljeno, da vzorca H3 in N2 ne prevajata električnega toka na obeh straneh folije in ravno tako ne skozi folijo. Električni tok prevaja le srebrna stran najstarejšega vzorca A1, kjer je bila izmerjena električna upornost z vrednostjo 5,3 ?. Razprava in zaključek: Staranje folije ni povzročilo večjih morfoloških sprememb, kar nakazuje, da material ostaja funkcionalen tudi po daljšem času. Kljub nekaterim kemijskim razlikam, ki so posledica uporabe različnih organskih barvil, so se natezne trdnosti folije znižale le minimalno, kar je skladno z literaturo o staranju polietilen tereftalatnih materialov. Predlagano je, da bi se doba trajanja folije podaljšala, kar bi ekološko zmanjšalo nepotrebne odpadke.

• Jezik: Slovenski jezik
• Ključne besede: diplomska dela, ortotika in protetika, podhladitev, kemijska sestava, pretržna trdnost, temperatura, prevodnost
• Vrsta gradiva: Diplomsko delo/naloga
• Tipologija: 2.11 - Diplomsko delo
• Organizacija: ZF - Zdravstvena fakulteta
• Kraj izida: Ljubljana
• Založnik: [N. Grm]
• Leto izida: 2024
• Št. strani: 38 str., [4] str. pril.
• PID: 20.500.12556/RUL-163856
• UDK: 617.3
• COBISS.SI-ID: 211392771
• Datum objave v RUL: 13.10.2024

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Effect of material ageing on the quality of rescue blanket : diploma work

Izvleček

Introduction: Double sided metallized sheeting has been a mandatory part of the first-aid kit for all motor vehicles in Slovenia since 2005. Double sided metallized sheeting serves as weather protection while its main purpose is to protect against hypothermia. It is used by mountaineers, cave explorers, travellers, campers, firefighters, members of the civil defence and first aid teams of the Red Cross and others. Double sided metallized sheetings are light, thin, waterproof, easy to use, insulated and highly visible. Its disadvantage is that it retains condensation, and it quickly scratches and flakes off when exposed to sharp edges. The base material from which double sided metallized sheeting is made is polyethylene terephthalate, modified with suitable additives. Purpose: To investigate how material ageing affects the quality of double-sided metallized sheeting. Methods: Domestic and international literature from web databases such as COBISS.SI, Web of Science, PubMed, SicenceDirect and Google Scholar was used. 34 metallized sheetings with a production date between 2006 and 2022 from various first aid kits were collected. 15 metallized sheetings were used for the laboratory tests and labelled both in alphabetical order and with a consecutive number according to the production date. The properties of the metallized sheeting were determined by examining the colour, morphological and chemical properties, tensile strength, thermal and electrical conductivity. Results: Colorimetric analysis revealed that the gold colour of the double-sided metallized foil samples varied in the CIE colour coordinates L*a*b*, which was confirmed by visual observation. Optical and line electron microscopy showed no major differences on the surfaces of the samples examined, so a more detailed analysis of the samples’ surface was carried out using energy dispersive X-ray spectroscopy. The presence of carbon and oxygen was detected on the gold and silver surfaces of all the samples examined, and other elements were also present on some surfaces, including aluminium and silicon. The effects of material aging on the chemical properties were recorded by Fourier transform infrared spectroscopy of samples A1, H3 and N2. The spectra of the gold side showed the presence of absorption bands characteristic of polyethylene terephthalate, the carbonyl group of the ester bond and the benzene ring. The spectra of the silver sides of samples H3 and N2 showed the presence of absorption bands of polyester, which were not observed on the silver side of sample A1. An Instron dynamometer was used to measure the fracture force in the transverse and longitudinal directions of the tested samples, which amounted to 21.7083 N on average. The fracture force measurements showed that the tensile strength values decrease as the material ages. The thermal properties were investigated by thermal conductivity measurements, which proved that the silver and gold sides of the tested samples have an insulating effect, as the measured values were extremely low, from 0.0017 λ to 0.0035 λ. The heat transfer through the film was measured with a thermographic camera, using a thermophore to simulate the human body. It was found that the silver side facing the thermophore (gold side facing outwards) retained heat in all samples tested, except for the oldest sample A1, whereas the temperature measured on the gold side facing outwards was lower than the temperature measured on the silver side facing outwards. The average measured temperature was 11.4 ˚C lower on the gold outward-facing side than on the silver outward-facing side of the film for all samples except for sample A1. When measuring the electrical conductivity, it was found that samples H3 and N2 did not conduct the electrical current on both sides of the foil or through the foil. Only the silver side of the oldest sample A1 conducted electricity, with a measured electrical resistance of 5.3 Ω. Discussion and conclusion: The aging of the film did not lead to any major morphological changes, which indicates that the material is still functional even after a long time. Despite some chemical differences due to the use of different organic colorants, the tensile strength of the film decreased only slightly, which is consistent with the literature on the aging of polyethylene terephthalate materials. It is suggested to extend the shelf life of the film, which could prevent unnecessary waste.

• Ključne besede: diploma theses, orthotics and prosthetics, hypothermia, chemical composition, breaking strength, temperature, conductivity