Vpliv nevodnih postopkov razkislinjenja z nano- ali mikrodelci na stabilnost papirja

Kadivec, Mariša (avtor), Kralj Cigić, Irena (mentor)

Razgradnja papirja je proces, ki se mu ne moremo izogniti, saj je papir izdelan iz organskih sestavin, ki se s časom razgrajujejo. Postopek izdelave papirja se je preko stoletij spreminjal. V obdobju med leti 1850 in 1990 so pri izdelavi papirja uporabljali les ter aluminijev sulfat, kar je povzročilo, da je papir iz tega obdobja kisel, krhek in ima kratko življenjsko dobo. Konzervatorji in znanstveniki skušajo z razvojem in uporabo različnih postopkov stabilizacije upočasniti razgradnjo zgodovinskega papirja in s tem ohraniti kulturno dediščino. Razkislinjenje je pomemben in pogosto uporabljen konzervatorski postopek za upočasnitev razgradnje papirja in posledično podaljšanje njegove življenjske dobe. Cilj raziskave je bil, da na testnih ligninoceluloznih papirjih preverim in ocenim učinkovitost različnih brezvodnih disperzij za razkislinjenje med termično pospešeno razgradnjo. Preverila sem učinkovitost komercialno dostopnih disperzij nanodelcev Ca(OH)2 v etanolu in 2-propanolu (Nanostore paper, CaLoSiL), disperzijo za razkislinjenje Bookkeeper (submikronski delci MgO v organskem topilu perfluoroheptanu) ter laboratorijsko pripravljeno disperzijo nanodelcev CaCO3 v etanolu in 2-propanolu. FE-SEM in SEM-EDS analizo sem uporabila za določitev velikosti delcev CaCO3 v disperziji ter njihovo porazdelitev na površini papirja. Učinkovitost sredstev za razkislinjenje po obdelavi papirja sem preverila z določitvijo pH vrednosti, alkalne zaloge in spektrofotometrično določitvijo barve. Kinetiko razgradnje papirja sem preučevala z velikostno-izključitveno kromatografijo, in sicer z določevanjem stopnje polimerizacije celuloze pred razgradnjo in po 4, 9 in 14 dneh pospešene termične razgradnje. Med pospešeno termično razgradnjo sem spektrofotometrično določila tudi spremembo barve papirja. Vsem obdelanim vzorcem papirja so se glede na neobdelan vzorec papirja konstante hitrosti razgradnje celuloze znižale. Razkislinjenje vzorcev papirja z disperzijo Bookkeeper in z disperzijami kalcijevega hidroksida je vidno vplivalo na barvno stabilnost papirja. Iz tega razloga lahko trdim, da razkislinjenje ligninoceluloznega papirja, pri katerem je pomembna barvna stabilnost (rokopisi, umetniške slike ...), z disperzijo Bookkeeper in disperzijami kalcijevega hidroksida ni priporočljiva. Za ohranitev tovrstnega gradiva je bolje uporabiti šibko alkalno sredstvo za razkislinjenje, in sicer disperzijo kalcijevega karbonata.

• Jezik: Slovenski jezik
• Ključne besede: Razkislinjenje, nanodelci, nano kalcijev karbonat, nano kalcijev hidroksid, sprememba barve
• Vrsta gradiva: Magistrsko delo/naloga
• Tipologija: 2.09 - Magistrsko delo
• Organizacija: FKKT - Fakulteta za kemijo in kemijsko tehnologijo
• Leto izida: 2021
• PID: 20.500.12556/RUL-128187
• COBISS.SI-ID: 73939971
• Datum objave v RUL: 05.07.2021

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: The effect of non-aqueous deacidification processes with nano or micro particles on paper stability

Izvleček

The degradation of paper is an inevitable process, as the paper is composed of organic compounds which decompose due to the processes of natural ageing. The papermaking process has changed through centuries. Between 1850 and 1990, wood and aluminum sulfate were used for the paper production, which caused paper acidity, brittleness and its limited durability. Conservators and conservation scientists are trying to find solutions to slow down the degradation of historical paper to preserve the cultural heritage. Deacidification is an important and widely used conservation treatment to slow down the degradation of paper due to acid hydrolysis and consequently increase its longevity. The aim of this study was to evaluate the effectiveness of various non-aqueous deacidification dispersions during thermally accelerated degradation on model lignocellulose papers. The effectiveness of commercially available nano calcium hydroxide dispersions in ethanol or 2-propanol (Nanostore Paper, CaLoSiL), Bookkeeper deacidification dispersion (containing submicron MgO particles in organic solvent perfluoroheptane) and laboratory prepared nano calcium carbonate dispersions in ethanol or 2-propanol was evaluated. FE-SEM and SEM-EDS analyses were performed to determine the size of CaCO3 particles in the dispersion and distribution of calcium ions on the paper surface. The effectiveness of non-aqueous dispersions after deacidification of paper was evaluated by determinations of pH value, alkaline reserve, and spectrometric determination of the color changes. The kinetics of paper degradation was studied by size-exclusion chromatography. The degree of polymerization of cellulose was determined before and after 4, 9 and 14 days of accelerated thermal degradation. During thermally accelerated degradation, the changes of paper color were followed. For all treated paper samples, the degradation rate constants decreased in comparison to the untreated control paper sample. Deacidification of paper samples with Bookkeeper dispersion and with nano calcium hydroxide dispersion in ethanol or 2-propanol had a noticeable effect on color stability of model paper samples. Therefore, it can be concluded that deacidification for such lignocellulose papers, where color stability is important (manuscripts, paintings, etc.) with Bookkeeper and calcium hydroxide dispersions is not recommended. To preserve such objects, the use of less invasive and milder alkaline deacidification agent, such as dispersion of nano calcium carbonate is recommended.

• Ključne besede: Deacidification, Nanoparticles, Nano calcium hydroxide, Nano calcium carbonate, color changes