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Resumo(s)
Os resíduos plásticos estão atualmente a ser produzidos a um ritmo preocupante, aproximando-se de 300 milhões de toneladas por ano, das quais apenas 10% são recicladas, o que contribui para a rápida acumulação destes materiais no ambiente. Assim, é prioritário desenvolver métodos de reciclagem de plásticos mais eficientes e acessíveis, garantindo simultaneamente a preservação da qualidade dos polímeros reciclados. Entre os diferentes processos de reciclagem, a dissolução/precipitação – um método de reciclagem física – surge como uma solução promissora, uma vez que permite recuperar o polímero com preservação das suas propriedades. No entanto, a utilização de solventes orgânicos voláteis convencionais tem sido a escolha mais comum, motivando a procura de solventes alternativos mais eficientes e sustentáveis. Neste sentido, o principal objetivo deste trabalho foi analisar a dissolução de poliestireno (PS) em solventes alternativos à base de terpenos e nas suas respetivas misturas eutécticas a temperaturas
moderadas. Numa primeira fase, a capacidade de dissolução de vários solventes foi avaliada através de ferramentas preditivas, nomeadamente o COnductor-like Screening Model for Realistic Solvents (COSMO-RS) e os parâmetros de solubilidade de Hansen. Posteriormente, os melhores solventes foram testados experimentalmente na dissolução de PS. Após as análises, constatou-se que os solventes que apresentaram os melhores resultados de dissolução a 60 ºC foram o p-xileno, α-pineno, β-pineno, fenchona, p-cimeno e as amostras industriais de terebintina pinaster e terebintina elliottii. As propriedades do polímero, avaliadas por
Espectroscopia no Infravermelho com Transformada de Fourier (FTIR) indicaram que não houve alterações estruturais significativas. De uma forma geral, os solventes utilizados neste estudo mostraram-se bastante promissores na dissolução de PS, destacando-se como alternativas mais sustentáveis para a reciclagem de plásticos. Esta abordagem não só promove a circularidade dos polímeros, como também abre caminho
para processos de reciclagem de plásticos industriais mais ecológicos e economicamente viáveis.
Plastic waste is currently being produced at an alarming rate, approaching 300 million tons per year. However, only 10% of this plastic is recycled, which significantly contributes to the rapid accumulation of these materials in the environment. Therefore, it is a priority to develop more efficient and accessible plastic recycling methods while simultaneously ensuring the preservation of the quality of the recycled polymers. Among the different recycling processes, dissolution/precipitation – a physical recycling method – emerges as one of the most promising options since the quality of the polymer is preserved. However, until now, the use of conventional volatile organic solvents has been the most common choice, encouraging the search for more efficient and sustainable alternative solvents. In this context, the main objective of this work is to analyze the dissolution of polystyrene (PS) in alternative solvents based on terpenes and in their respective eutectic mixtures at moderate temperatures. In the first phase, the dissolution ability of several solvents was evaluated using predictive tools, namely the Conductor- like Screening Model for Realistic Solvents (COSMO-RS) and the Hansen solubility parameters. Next, the best solvents were experimentally tested for dissolving PS. The characteristics of the polymer were evaluated before and after dissolution using different analytical techniques. After the analyses, it was found that the solvents showing the best dissolution results at 60°C were p-xileno, α-pineno, β-pineno, fenchone, p-cymene, and the industrial samples of pinaster turpentine and elliottii turpentine. The characteristics of the polymers post-dissolution show that there are not significant structural changes. Overall, the solvents used in this study proved to be quite promising in dissolving PS, standing out as more sustainable alternatives for plastic recycling. This approach not only promotes the circularity of polymers but also points to the possibility of developing more ecological and economically viable recycling processes.
Plastic waste is currently being produced at an alarming rate, approaching 300 million tons per year. However, only 10% of this plastic is recycled, which significantly contributes to the rapid accumulation of these materials in the environment. Therefore, it is a priority to develop more efficient and accessible plastic recycling methods while simultaneously ensuring the preservation of the quality of the recycled polymers. Among the different recycling processes, dissolution/precipitation – a physical recycling method – emerges as one of the most promising options since the quality of the polymer is preserved. However, until now, the use of conventional volatile organic solvents has been the most common choice, encouraging the search for more efficient and sustainable alternative solvents. In this context, the main objective of this work is to analyze the dissolution of polystyrene (PS) in alternative solvents based on terpenes and in their respective eutectic mixtures at moderate temperatures. In the first phase, the dissolution ability of several solvents was evaluated using predictive tools, namely the Conductor- like Screening Model for Realistic Solvents (COSMO-RS) and the Hansen solubility parameters. Next, the best solvents were experimentally tested for dissolving PS. The characteristics of the polymer were evaluated before and after dissolution using different analytical techniques. After the analyses, it was found that the solvents showing the best dissolution results at 60°C were p-xileno, α-pineno, β-pineno, fenchone, p-cymene, and the industrial samples of pinaster turpentine and elliottii turpentine. The characteristics of the polymers post-dissolution show that there are not significant structural changes. Overall, the solvents used in this study proved to be quite promising in dissolving PS, standing out as more sustainable alternatives for plastic recycling. This approach not only promotes the circularity of polymers but also points to the possibility of developing more ecological and economically viable recycling processes.
Descrição
Palavras-chave
Terpenos Misturas eutécticas Dissolução de plásticos Poliestireno Parâmetros de solubilidade de Hansen COSMO-RS