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Nano e Micro Celulose como material de Consolidação e Reforço de Papel
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O património documental é alvo de diversos fenómenos de degradação. Objetivando a sua
salvaguarda e conservação, têm-se desenvolvido e aprimorado diferentes métodos, que
permitem a sua consolidação e reforço. Na última década, um material antigo, mas que tem
vindo a ser revisitado para esta finalidade, devido às suas propriedades à nano escala, é a
nanocelulose (NC). Algumas das propriedades da NC, tais como, a biocompatilidade, os
benefícios a nível ecológico, a elevada resistência e a transparência material, têm vindo cada
vez mais a suscitar forte interesse no seio da comunidade científica.
Tendo por base este enquadramento, a presente dissertação, pretende avaliar os prós e contras
da utilização da NC, no contexto da conservação e restauro de papel, analisando para efeito as
suas principais propriedades e potencial aplicabilidade. Para tal, foram estudados dois tipos de
NC, sendo eles, a Nano Celulose Cristalina (NCC) e a Celulose Microfibrilada (CMF).
As NCCs e CMFs, foram dispersas em água e realizadas suspensões com diversas
composições, que incluíram também a adição de um derivado da celulose -
Carboximetilcelulose (CMC), e posteriormente, por evaporação do solvente, foram obtidos
filmes sólidos. A adição da CMC, além de atribuir um “caráter adesivo” aos filmes, foi efetuada
com o propósito de controlar as propriedades óticas e mecânicas dos filmes sólidos obtidos
inicialmente a partir da NCC. Com o objetivo de comparar as propriedades dos filmes
preparados a partir das NC e CMC, foi igualmente testado o papel japonês (PJ). A escolha do
PJ recaiu exclusivamente no facto de este ser o material tradicionalmente utilizado na
consolidação e reforço de papel.
A fim de identificar as principais vantagens e desvantagens da aplicação da NC em papel, foi
utilizada a seguinte metodologia: criação das amostras e a sua caracterização físico-química
que se traduziu na observação das propriedades visuais das mesmas; realização de análises de
colorimetria, de espetroscopia de infravermelho (FTIR-ATR), na emissão de raio-x induzido
por partículas (µ-PIXE), e na execução de testes de tração uniaxial. De referir que a maioria
das análises foi feita antes e após envelhecimento controlado das amostras.
Os resultados indicam que a NCC, quando comparada com a CMF, é um material que possui
mais limitações de aplicação ao nível das propriedades óticas e mecânicas. No entanto, após
envelhecimento, a CMF inicial apresenta igualmente alterações nas suas propriedades óticas.
Deste modo, foi ainda posteriormente utilizada uma outra CMF, produzida maioritariamente
por processos mecânicos, a qual permitiu produzir filmes sólidos mais promissores, não só a
nível das propriedades óticas (cor e transparência) como também resistência mecânica (módulo
de Young e resistência à fratura).
Documentary heritage can be subjected to several degradation phenomena. To preserve the documentary heritage, different methods have been developed and improved, focusing on its consolidation and reinforcement. In the last decade, an old material, that has been revisited for this purpose due to its nanoscale properties, is nanocellulose (NC). Some of the properties of NC, such as biocompatibility, ecological advantages, high resistance, and material transparency, have been generating strong interest in the scientific community. Based on this framework, this dissertation aims to evaluate the pros and cons of using NC in the context of conservation and restoration of paper, thus studying its main properties and potential applicability. To this end, two types of NC were studied, namely, Nano Crystalline Cellulose (NCC) and Microfibrillated Cellulose (CMF). The NCCs and CMFs were dispersed in water with different compositions, which also included the addition of a cellulose derivative - Carboxymethylcellulose (CMC), and later, solid films were obtained by solvent evaporation. The purpose of adding CMC, besides the benefit of providing an “adhesive function” to the films, was to control the optical and mechanical properties of the solid films obtained initially from the NCC. To compare the properties of films prepared from NC and CMC, Japanese paper (JP) was also tested. The choice of this material was exclusively based on the fact that it is traditionally used in the consolidation and reinforcement of paper. In order to identify the main advantages and disadvantages of applying the NC on paper, the following methodology was used: preparation of the samples and their physical-chemical characterization, which was translated into the observation of their visual properties; with colourimetry analysis, infrared spectroscopy (FTIR-ATR), the emission of x-rays induced by particles (µ-PIXE), and the execution of uniaxial traction tests. It should be noted that most analyses were performed before and after controlled ageing of the samples. The results indicate that NCC, when compared to CMF, is a material that has more limitations in terms of optical and mechanical properties. However, after ageing, the available CMF used also demonstrates changes in its optical properties. Consequently, a new CMF was used, produced mainly by mechanical processes, allowing the production of more promising solid films, not only in terms of optical properties (colour and transparency) but also mechanical resistance (Young's modulus and fracture resistance).
Documentary heritage can be subjected to several degradation phenomena. To preserve the documentary heritage, different methods have been developed and improved, focusing on its consolidation and reinforcement. In the last decade, an old material, that has been revisited for this purpose due to its nanoscale properties, is nanocellulose (NC). Some of the properties of NC, such as biocompatibility, ecological advantages, high resistance, and material transparency, have been generating strong interest in the scientific community. Based on this framework, this dissertation aims to evaluate the pros and cons of using NC in the context of conservation and restoration of paper, thus studying its main properties and potential applicability. To this end, two types of NC were studied, namely, Nano Crystalline Cellulose (NCC) and Microfibrillated Cellulose (CMF). The NCCs and CMFs were dispersed in water with different compositions, which also included the addition of a cellulose derivative - Carboxymethylcellulose (CMC), and later, solid films were obtained by solvent evaporation. The purpose of adding CMC, besides the benefit of providing an “adhesive function” to the films, was to control the optical and mechanical properties of the solid films obtained initially from the NCC. To compare the properties of films prepared from NC and CMC, Japanese paper (JP) was also tested. The choice of this material was exclusively based on the fact that it is traditionally used in the consolidation and reinforcement of paper. In order to identify the main advantages and disadvantages of applying the NC on paper, the following methodology was used: preparation of the samples and their physical-chemical characterization, which was translated into the observation of their visual properties; with colourimetry analysis, infrared spectroscopy (FTIR-ATR), the emission of x-rays induced by particles (µ-PIXE), and the execution of uniaxial traction tests. It should be noted that most analyses were performed before and after controlled ageing of the samples. The results indicate that NCC, when compared to CMF, is a material that has more limitations in terms of optical and mechanical properties. However, after ageing, the available CMF used also demonstrates changes in its optical properties. Consequently, a new CMF was used, produced mainly by mechanical processes, allowing the production of more promising solid films, not only in terms of optical properties (colour and transparency) but also mechanical resistance (Young's modulus and fracture resistance).
Descrição
Palavras-chave
Celulose Nanocelulose Papel Consolidação Reforço