A influência dos processos de envelhecimento gerados pelo biodiesel, em diferentes condições de tempo e temperatura, nas propriedades mecânicas da poliamida 12
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Dissertação
Data
2015
Autores
Nascimento, R. A.
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Souza, Adriana Martinelli Catelli de
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NASCIMENTO, R. A. A influência dos processos de envelhecimento gerados pelo biodiesel, em diferentes condições de tempo e temperatura, nas propriedades mecânicas da poliamida 12. 2015. 102 f. Dissertação (Mestrado em Engenharia Mecânica) - Centro Universitário da FEI, São Bernardo do Campo, 2015 Disponível em: . Acesso em: 24 set. 2015.
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Biodiesel,Poliamida 12
Resumo
A busca por combustíveis renováveis é uma tendência que terá impacto permanente sobre a evolução dos próximos anos e décadas. Uma das alternativas disponíveis que está se tornando realidade é o biodiesel. Biodiesel é o nome dado ao diesel não derivado do petróleo com importância crescente em todo o mundo, especialmente na mistura com o diesel fóssil. Ele é produzido a partir de óleos vegetais ou gorduras animais, bem como, óleos de cozinha reciclados. Atualmente, o biodiesel puro ou os diferentes percentuais de mistura ao diesel fóssil, só podem ser utilizados se os fabricantes de veículos desenvolverem motores e sistemas de combustível compatíveis com estes combustíveis. A poliamida 12 – PA12 é o material não metálico mais utilizado na fabricação de tubulações de combustível para motores e sistemas de combustível automotivo. Diante deste cenário, este trabalho tem como objetivo avaliar a influência de três diferentes tipos de biodiesel nas propriedades mecânicas da PA12 através do processo de envelhecimento por imersão em biodiesel, em três diferentes períodos de tempo e em duas condições de temperatura. Os biodieseis utilizados foram B5 - diesel padrão de mercado com 5% de biodiesel, B50 – obtido pela mistura de 50% de diesel padrão de mercado com 50% de biodiesel puro e B100 – biodiesel puro. A poliamida 12 utilizada foi o VESTAMID®X7393, os corpos de prova foram moldados por injeção, envelhecidos e posteriormente utilizados nas análises de espectroscopia no infravermelho com transformada de Fourier (FTIR), difração de raios X (DRX) e nas análises das propriedades mecânicas através de ensaios de resistência à tração e de resistência ao impacto. As análises FTIR indicaram que provavelmente a PA12 imersa nos diferentes combustíveis sofreu degradação termo oxidativa que foi acelerada pelo aumento da temperatura de envelhecimento e apresentou-se com maior intensidade nas amostras envelhecidas em B5. As análises de DRX indicaram que a cristalinidade das amostras de PA12 envelhecidas a 23ºC nos diferentes combustíveis não apresentaram alterações significativas. Porém, as amostras envelhecidas a 100ºC nos três combustíveis analisados apresentaram tendência de ligeiro aumento da cristalinidade com o aumento do tempo de envelhecimento. Foi observado decréscimo da resistência à tração das amostras de PA12 envelhecidas em B5, B50 e B100 a 23ºC e das amostras de PA12 envelhecidas em B5 e B50 a 100ºC com o tempo de envelhecimento, e mais efetivamente a 100°C. Este fato pode estar relacionado à degradação da PA12 que foi observada pelas análises de FTIR. Porém, foi observado um aumento da resistência à tração da PA12 envelhecida em B100 com o tempo de envelhecimento a 100ºC podendo estar relacionado com o aumento da porcentagem de cristalinidade da PA12 observada pelas análises de DRX. Observou-se que existem dois comportamentos distintos do módulo de elasticidade nos três combustíveis analisados a partir de 3000 horas de envelhecimento: decréscimo a 23ºC e aumento significativo a 100ºC. Observou-se também o decréscimo do alongamento na ruptura da PA12 com o aumento do tempo de envelhecimento. Nos ensaios de impacto a 23ºC não houve rompimento das amostras de PA12 em nenhuma das condições avaliadas, entretanto a 100ºC, as amostras de PA12 somente apresentaram rompimento a partir de 3000 horas de envelhecimento. Os resultados mostraram que a resistência ao impacto diminuiu com o aumento do tempo de envelhecimento. Nos ensaios de impacto a -40ºC as amostras de PA12 romperam em todas as condições de envelhecimento, porém, apresentaram comportamentos distintos no envelhecimento a 23ºC e a 100ºC.
The search for renewable fuels is a trend that will have permanent impact on the development of the coming years and decades. One of the feasible alternatives is biodiesel. Biodiesel is the name given to a diesel not derived from petroleum with growing importance in the world, especially in mixtures with fossil diesel. It is produced from vegetable oils or animal fats, as well as recycled cooking oils. Currently, pure biodiesel or mixed at different percentages with fossil diesel can only be used if vehicle manufacturers develop engines and fuel systems compatible with these fuels. Polyamide 12 - PA12 is the most used non-metallic material for manufacturing fuel lines for engines and automotive fuel systems. Taking into account this scenario, the aim of this study is to evaluate the influence of three different types of biodiesel, B5 – market standard diesel containing 5% biodiesel, B50 – mixture of 50% market standard diesel and 50% pure biodiesel and B100 – pure biodiesel, on mechanical properties of polyamide 12 through ageing by immersion in biodiesel at three different time periods and two temperatures. The polyamide 12 used was VESTAMID®X7393, the specimens were injection molded, aged and subsequently used in Fourier transform infrared spectroscopy (FTIR) analysis, X-ray diffraction (XRD) analysis and in mechanical properties analysis through tensile and impact strength tests. FTIR analysis indicated that PA12 specimens immersed in different fuels likely underwent thermo oxidative degradation that was accelerated by the increase in ageing temperature and was also noticed with greater intensity in the specimens aged in B5. X-ray diffraction (XRD) analysis revealed no significant changes in the crystallinity of PA12 specimens aged at 23°C in different fuels. However, PA12 specimens aged at 100°C in the three different fuels showed a slight tendency to increase crystallinity proportionally to the increase in ageing time. The tensile strength decrease of PA12 specimens aged in B5, B50 and B100 at 23°C and PA12 specimens aged in B5 and B50 at 100°C with ageing time and more effectively at 100°C may be related to the degradation of PA12 which was observed by FTIR analysis. However, the tensile strength increase of PA12 specimens aged in B100 with ageing time at 100°C may be related to the increase in the percentage of crystallinity of PA12 observed by XRD analysis. The elasticity modulus presented two distinct patterns from 3000 hours of ageing time in the three fuels analyzed: decreased at 23°C and a significant increase at 100°C. A decrease in elongation at break of PA12 specimens with increasing ageing time was also observed. In the impact tests carried out at 23°C, the aged PA12 specimens did not present break in any of the evaluated conditions, but at 100°C, the PA12 specimens presented break from 3000 hours of ageing time. The impact test results showed that the impact strength decreased proportionally to the increase in ageing time. In the impact tests carried out at -40°C, the aged PA12 specimens presented break at all ageing conditions, however, different behavior was seen when aged at 23°C and at 100°C.
The search for renewable fuels is a trend that will have permanent impact on the development of the coming years and decades. One of the feasible alternatives is biodiesel. Biodiesel is the name given to a diesel not derived from petroleum with growing importance in the world, especially in mixtures with fossil diesel. It is produced from vegetable oils or animal fats, as well as recycled cooking oils. Currently, pure biodiesel or mixed at different percentages with fossil diesel can only be used if vehicle manufacturers develop engines and fuel systems compatible with these fuels. Polyamide 12 - PA12 is the most used non-metallic material for manufacturing fuel lines for engines and automotive fuel systems. Taking into account this scenario, the aim of this study is to evaluate the influence of three different types of biodiesel, B5 – market standard diesel containing 5% biodiesel, B50 – mixture of 50% market standard diesel and 50% pure biodiesel and B100 – pure biodiesel, on mechanical properties of polyamide 12 through ageing by immersion in biodiesel at three different time periods and two temperatures. The polyamide 12 used was VESTAMID®X7393, the specimens were injection molded, aged and subsequently used in Fourier transform infrared spectroscopy (FTIR) analysis, X-ray diffraction (XRD) analysis and in mechanical properties analysis through tensile and impact strength tests. FTIR analysis indicated that PA12 specimens immersed in different fuels likely underwent thermo oxidative degradation that was accelerated by the increase in ageing temperature and was also noticed with greater intensity in the specimens aged in B5. X-ray diffraction (XRD) analysis revealed no significant changes in the crystallinity of PA12 specimens aged at 23°C in different fuels. However, PA12 specimens aged at 100°C in the three different fuels showed a slight tendency to increase crystallinity proportionally to the increase in ageing time. The tensile strength decrease of PA12 specimens aged in B5, B50 and B100 at 23°C and PA12 specimens aged in B5 and B50 at 100°C with ageing time and more effectively at 100°C may be related to the degradation of PA12 which was observed by FTIR analysis. However, the tensile strength increase of PA12 specimens aged in B100 with ageing time at 100°C may be related to the increase in the percentage of crystallinity of PA12 observed by XRD analysis. The elasticity modulus presented two distinct patterns from 3000 hours of ageing time in the three fuels analyzed: decreased at 23°C and a significant increase at 100°C. A decrease in elongation at break of PA12 specimens with increasing ageing time was also observed. In the impact tests carried out at 23°C, the aged PA12 specimens did not present break in any of the evaluated conditions, but at 100°C, the PA12 specimens presented break from 3000 hours of ageing time. The impact test results showed that the impact strength decreased proportionally to the increase in ageing time. In the impact tests carried out at -40°C, the aged PA12 specimens presented break at all ageing conditions, however, different behavior was seen when aged at 23°C and at 100°C.