Desarrollo de nuevas estructuras laminares de nanocelulosa con propiedades avanzadas para el packaging
(English) Changes in the use of raw materials and major lifestyle changes in first world societies have driven the massive use of petroleum-based materials in a wide range of applications. Plastic waste has become pervasive in our surroundings, creating serious problems concerning both the environme...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2024 |
| País: | España |
| Institución: | CBUC, CESCA |
| Repositorio: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/693742 |
| Acceso en línea: | http://hdl.handle.net/10803/693742 https://dx.doi.org/10.5821/dissertation-2117-425484 |
| Access Level: | acceso abierto |
| Palabra clave: | Àrees temàtiques de la UPC::Enginyeria dels materials Àrees temàtiques de la UPC::Enginyeria paperera Àrees temàtiques de la UPC::Enginyeria biomèdica Àrees temàtiques de la UPC::Desenvolupament humà i sostenible 502 620 67 |
| Sumario: | (English) Changes in the use of raw materials and major lifestyle changes in first world societies have driven the massive use of petroleum-based materials in a wide range of applications. Plastic waste has become pervasive in our surroundings, creating serious problems concerning both the environment (affecting biodiversity) and human health. For this reason, it is essential to develop alternatives to these materials, which are finite, polluting and non-biodegradable. It is upon this context that the present doctoral thesis is framed, wherein from one of the most abundant natural biopolymers on the planet (cellulose), new laminar and transparent biomaterials with barrier and biodegradable properties were created, suitable for use in food packaging. Specifically, nanocellulose was used, combined with natural additives or, chemically or enzymatically functionalised to obtain the required properties: transparency, physico-mechanical properties, acting as a barrier to water and water vapour, grease and oxygen. In order to achieve the objective of this thesis, three work lines have been followed. In the first line of work, films were prepared using crystalline nanocellulose (CNC) and the effects of different natural additives such as sorbitol, glycerol, maltitol, xylitol, mannitol, gellan gum, and ethylene glycol on the CNC matrix at different doses were evaluated. Transparent films with UV protective properties were obtained. Most of the additives showed good results at low doses, both in terms of elongation and tensile strength, as well as to homogeneity, smoothness, and oxygen and water barrier properties (including at high relative humidity conditions). At all the doses tested, biodegradability of films was improved. With the two additives that provided the best properties (maltitol and xylitol), the possibility of a synergistic effect between them was evaluated an improvement in transparency, tensile strength, elongation, as well as an improvement in water vapour and oxygen barrier properties were observed. The second line of work was also based on CNC, but this time it was mixed with fibrillar nanocellulose (CNF) and/or carboxymethylcellulose (CMC) in varying percentages. The obtained films also demonstrated good barrier and mechanical properties. Both the CNF and the CMC increased tensile strength and elasticity (elongation) in the CNC films, as well as providing increased resistance to airflow and UV light. Moreover, both increased hydrophobic, and barrier properties to water vapour as well as oxygen. These effects were confirmed by a food packaging simulation test, in which the CMC films provided the best food preservation. Finally, it was demonstrated that the created films were biodegradable, and this property was enhanced in the presence of either CMC or CNF. Finally, the final line of work began with CNF films and investigated the effects of selective oxidation with sodium periodate upon the creation of aldehyde groups. These groups formed hemiacetal and hemialdal bonds and consequently the resulting films were highly transparent, elastic, and resistant, even under conditions of humidity saturation. In fact, the oxidation treatment with periodate reduced the polarity of the films, thereby significantly improving their water barrier properties. The presence of aldehyde groups allowed the immobilisation of the enzyme laccase, which efficiently captures oxygen and therefore prevents food decomposition. The laccase-containing films oxidised 80% of the methylene blue dye and maintained their enzymatic activity after a month of storage and twelve cycles of reuse, which opens the door to the possible creation of a reusable packaging that could substitute single-use packaging. |
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