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Determinação de massa molecular média de copolímeros de acrilonitrilo por viscosimetria capilar
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Abstract(s)
No âmbito do tema central deste trabalho, foram realizados ensaios, sob diferentes condições,
para verificar a robustez do método de medição de número de viscosidade NSP (parâmetro
interno da SGL Composites) para os polímeros produzidos pela empresa. O método de
medição de NSP é correntemente usado no laboratório de controlo de Qualidade da empresa
sendo que por vezes os resultados podem influenciar a tomada de decisões na área de
produção. Dos resultados obtidos, constatou-se que o método correntemente utilizado é
robusto, uma vez que não se verificaram desvios significativos dos resultados obtidos em
condições normais, quando as mesmas foram submetidas a perturbações impostas. A massa
molecular média viscosimétrica destes polímeros foi também determinada por viscosimetria
capilar. Os resultados obtidos para a massa molecular média viscosimétrica (𝑀𝑉) são
comparáveis com a massa molecular média (𝑀𝑊) obtida por GPC (Gel Permeation
Chromatography). Deste modo, a viscosimetria capilar é uma boa alternativa aos métodos
absolutos.
Foi também estudada a utilização potencial de microscopia ótica do tipo hot stage com o
objectivo de monitorizar a dissolução dos polímeros produzidos pela empresa. Contudo, não
foi possível implementar o método num contexto prático devido à ineficiência da transferência
uniforme de calor do hot stage para a amostra no equipamento utilizado.
Foi ainda dado suporte analítico a testes industriais na área de polimerização contínua para
otimizar o caudal de água de lavagem na etapa de filtração da suspensão de polímero, tendo se definido o ótimo com sucesso.
Iniciou-se também um segundo conjunto de testes fabris para otimização do caudal de água
de processo injetada na coluna durante a separação dos monómeros não reagidos da mistura
reacional à saída do reator de polimerização por destilação, cujo final irá ocorrer em janeiro
de 2021.
In the context of the main theme of the present work, trials under different conditions were carried out to verify the robustness of the NSP viscosity number (SGL Composites internal parameter) evaluation method for the polymers produced by the company. The NSP measure method is currently used at Quality Control laboratories and often the results may influence the production area. From the obtained results, it was found that the method currently used is robust since there were no significant deviations from the results obtained in normal conditions, when perturbations were imposed. The viscosimetric average molecular weight of these polymers was also obtained by capillary viscosimetry. The average viscosimetric molecular weight (𝑀𝑉) are comparable with the weight average molecular weight (𝑀𝑊) obtained by GPC. Thus, capillary viscosimetry is indeed a good alternative to absolute methods. The potential usage of hot stage microscopy to monitor dissolution of the polymers produced by the company was also studied. However, it was not possible to implement the method in a practical context due to the inefficiency of uniform heat transfer from the hot stage to the sample in the used equipment. Analytical support was also done to industrial trials in the continuous polymerization area to optimize the process washing water flow rate in the polymer slurry filtration. The optimum flowrate was successfully achieved. Analytical support to a second series of industrial trials for the optimization of the process water flow rate injected in the column during the separation of unreacted monomers from the reaction mixture at the outlet of the polymerization reactor by distillation was also started. The end of the trials is expected to occur in January 2021.
In the context of the main theme of the present work, trials under different conditions were carried out to verify the robustness of the NSP viscosity number (SGL Composites internal parameter) evaluation method for the polymers produced by the company. The NSP measure method is currently used at Quality Control laboratories and often the results may influence the production area. From the obtained results, it was found that the method currently used is robust since there were no significant deviations from the results obtained in normal conditions, when perturbations were imposed. The viscosimetric average molecular weight of these polymers was also obtained by capillary viscosimetry. The average viscosimetric molecular weight (𝑀𝑉) are comparable with the weight average molecular weight (𝑀𝑊) obtained by GPC. Thus, capillary viscosimetry is indeed a good alternative to absolute methods. The potential usage of hot stage microscopy to monitor dissolution of the polymers produced by the company was also studied. However, it was not possible to implement the method in a practical context due to the inefficiency of uniform heat transfer from the hot stage to the sample in the used equipment. Analytical support was also done to industrial trials in the continuous polymerization area to optimize the process washing water flow rate in the polymer slurry filtration. The optimum flowrate was successfully achieved. Analytical support to a second series of industrial trials for the optimization of the process water flow rate injected in the column during the separation of unreacted monomers from the reaction mixture at the outlet of the polymerization reactor by distillation was also started. The end of the trials is expected to occur in January 2021.
Description
Keywords
Acrilonitrilo Viscosidade Massa molecular média Hot stage Caudal de água Acrylonitrile Viscosity Average molecular weight Water flow