Biopolymers-based treatments for the protection of stone in the cultural heritage

Andreotti, Serena (2019) Biopolymers-based treatments for the protection of stone in the cultural heritage, [Dissertation thesis], Alma Mater Studiorum Università di Bologna. Dottorato di ricerca in Ingegneria civile, chimica, ambientale e dei materiali, 31 Ciclo. DOI 10.6092/unibo/amsdottorato/9005.
Documenti full-text disponibili:
[img] Documento PDF (English) - Richiede un lettore di PDF come Xpdf o Adobe Acrobat Reader
Disponibile con Licenza: Salvo eventuali più ampie autorizzazioni dell'autore, la tesi può essere liberamente consultata e può essere effettuato il salvataggio e la stampa di una copia per fini strettamente personali di studio, di ricerca e di insegnamento, con espresso divieto di qualunque utilizzo direttamente o indirettamente commerciale. Ogni altro diritto sul materiale è riservato.
Download (14MB)

Abstract

The guiding thread of the research is testing biopolymers-based treatments for the protection of stone in cultural heritage against water and salt crystallization. The idea developed is that the reversibility requirement can be fulfilled by bio-polymeric treatments, owing to a “reversibility by biodegradation” once their efficacy has finished. The first part aimed at investigating the performance of two poly(hydroxyalkanoate)s-based (PHAs-based) formulations, namely solutions of poly(3-hydroxybutyrate (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-4-hydroxyvalerate) (PHBVV), as hydrophobic coating. These formulations were applied to sandstone, limestone and marble, in order to investigate their behaviour on different substrates. Their effectiveness and compatibility were evaluated and the samples wettability after application of biopolymers and of two commercial products was compared. Promising results in terms of efficacy and compatibility were obtained, although the present PHAs-based formulations still need improvement to increase their durability and on-site applicability. Among the strategies proposed to mitigate the damage caused by salt crystallization, the modification of the surface of the pore wall, by means of a polymer coating able to minimize the repulsive disjoining force normally acting between the stone and the crystallizing salt, is particularly promising. Thus, some polyectrolyte biopolymers (alginic acid sodium salt, chitosan and tannic acid) were selected and compared with a polymer (polyacrylic acid sodium salt) for preliminary screening tests, designed and performed in order to assess whether the selected polymers fulfil some basic requirements such as good adsorption onto the stone substrate, film-forming ability, affinity and interaction with sodium sulfate. Moreover, in order to reduce calcite dissolution in water that may trigger the effect of the polymer coating, a diammonium hydrogen phosphate (DAP) water-based treatment was applied as coupling layer on carbonate substrates. Then, the effectiveness of the coatings was evaluated by two macroscale crystallization tests on limestone with promising results especially for chitosan and alginic acid coupled with DAP.

Abstract
Tipologia del documento
Tesi di dottorato
Autore
Andreotti, Serena
Supervisore
Co-supervisore
Dottorato di ricerca
Ciclo
31
Coordinatore
Settore disciplinare
Settore concorsuale
Parole chiave
biopolymers; protection; conservation; hydrophobic coating; stone; cultural heritage; polymer coatings; PHAs; chitosan; salt damage; sodium sulfate; disjoining pressure; hydroxyapatite; calcite dissolution; salt crystallization test.
URN:NBN
DOI
10.6092/unibo/amsdottorato/9005
Data di discussione
4 Aprile 2019
URI

Altri metadati

Statistica sui download

Gestione del documento: Visualizza la tesi

^