Síntese e caracterização de um pré polímero de uretano fundido confeccionado com poliol de origem vegetal e avaliação das propriedades mecânicas
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Data
2022-09-05
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Universidade Estadual Paulista (Unesp)
Resumo
Os poliuretanos são polímeros termofixos (termorrígidos) empregados em diversos tipos de aplicações, como espumas rígidas, espumas flexíveis, elastômeros e outros, e tendo como matérias-primas isocianato e poliol. Cada tipo de poliuretano possui suas determinadas características, modos de reação e aditivos utilizados em sua formulação. Existem diferentes tipos de isocianatos e de polióis para a confecção do pré polímero de uretano. Neste presente trabalho, o tipo de poliuretano utilizado é o pré polímero de poliuretano fundido, que pertence à classe dos elastômeros, conhecido em inglês por “hot cast”, pois são os polímeros derramados em moldes e que dão origem a peças sólidas, geralmente peças técnicas de engenharia utilizadas no mercado da mineração, petróleo e gás, rodas de empilhadeiras e outros. O trabalho visa avaliar a possibilidade de substituir o poliol de origem sintética, por óleo de mamona, um óleo vegetal e renovável amplamente encontrado em solo brasileiro, na qual é obtido a partir da semente da planta cientificamente denominada Ricinus Communis L. A substituição do poliol sintético pelo óleo vegetal de mamona se deu pelas questões de sustentabilidade e para obter-se de um produto natural para a produção de pré polímeros de uretanos. Foram realizados testes pilotos utilizando o tolueno diisocianato (TDI) e o óleo de mamona, em concentrações e níveis de NCO diferentes, além deste, também foi produzido uma mistura entre o óleo de mamona e o politetrametileno éter glicol (PTMEG 2000 – poliol sintético) com o tolueno diisocianato (TDI), e um padrão de comparação do tolueno diisocianato (TDI) e politetrametileno éter glicol (PTMEG 2000). Após a reação dos pré polímeros de uretanos, foi realizada a quantificação de NCO via titulação, e posteriormente estes materiais foram reagidos com a amina 4,4'-metileno-bis-(orto-cloroanilina) e com o próprio óleo de mamona na devida proporção e cálculo, que são denominados como extensores de cadeia. Após a cura e pós-cura, foi realizada caracterização e a avaliação de propriedades mecânicas com os corpos de prova de poliuretanos, sendo obtido resultados promissores para propriedades mecânicas com a mistura do óleo de mamona e o politetrametileno éter glicol (PTMEG 2000), com 35% de resiliência, 36,22 m³ de resistência a abrasão, 570,12 psi de resistência a tensão, 325,39% de alongamento, 29,53 kJ.m-2 de resistência ao rasgo e 65 Shore A de dureza.
Polyurethanes are thermoset polymers used in various types of applications, such as rigid and flexible foams, elastomers and others, and the raw materials based on isocyanate and polyol. Each type of polyurethane has specific characteristics, reaction modes and additives used in its formulation. There are different types of isocyanates and polyols to produce the urethane. In this work, the type of polyurethane used is the cast polyurethane prepolymer, which belongs to the elastomer types, known as hot cast, as they are the polymers poured into molds and which give rise to solid parts, usually parts engineering tools used in mining, oil and gas, forklift wheels and others. The work has focus on replacing the synthetic polyols with castor oil, a vegetable oil and renewable widely found in Brazilian and obtained from the seed Ricinus Communis L plant. The synthetic polyol replacement for vegetable castor oil was decided due sustainability issues and to obtain a natural product to produce urethane prepolymers. Pilot tests were performed using toluene diisocyanate (TDI) and castor oil, in different concentrations and levels of NCO. Besides of this, other sample was designed with a mixture between castor oil and polytetramethylene ether glycol (PTMEG 2000 – synthetic polyol) with toluene diisocyanate (TDI), and a compared with standard systems containing toluene diisocyanate (TDI) and polytetramethylene ether glycol (PTMEG 2000). After the reaction of the urethane prepolymers, the quantification of NCO was performed via titration, and then these materials were reacted with the amine 4,4'-methylene-bis-(ortho-chloroaniline) and with the castor oil itself in the appropriate proportion, which are named as chain extender. After curing and post curing, the characterization and the evaluation of mechanical properties tests of the polyurethane specimens were conducted. Promising results for mechanical properties with castor oil and polytetramethylene ether glycol (PTMEG 2000) mixture, with 35% of rebound resilience, 36,22 m³ of abrasion resistance, 570,12 psi of tensile strength, 325,39% of elongation, 29,53 kJ.m-2 of tear resistance and 65 Shore A as hardness.
Polyurethanes are thermoset polymers used in various types of applications, such as rigid and flexible foams, elastomers and others, and the raw materials based on isocyanate and polyol. Each type of polyurethane has specific characteristics, reaction modes and additives used in its formulation. There are different types of isocyanates and polyols to produce the urethane. In this work, the type of polyurethane used is the cast polyurethane prepolymer, which belongs to the elastomer types, known as hot cast, as they are the polymers poured into molds and which give rise to solid parts, usually parts engineering tools used in mining, oil and gas, forklift wheels and others. The work has focus on replacing the synthetic polyols with castor oil, a vegetable oil and renewable widely found in Brazilian and obtained from the seed Ricinus Communis L plant. The synthetic polyol replacement for vegetable castor oil was decided due sustainability issues and to obtain a natural product to produce urethane prepolymers. Pilot tests were performed using toluene diisocyanate (TDI) and castor oil, in different concentrations and levels of NCO. Besides of this, other sample was designed with a mixture between castor oil and polytetramethylene ether glycol (PTMEG 2000 – synthetic polyol) with toluene diisocyanate (TDI), and a compared with standard systems containing toluene diisocyanate (TDI) and polytetramethylene ether glycol (PTMEG 2000). After the reaction of the urethane prepolymers, the quantification of NCO was performed via titration, and then these materials were reacted with the amine 4,4'-methylene-bis-(ortho-chloroaniline) and with the castor oil itself in the appropriate proportion, which are named as chain extender. After curing and post curing, the characterization and the evaluation of mechanical properties tests of the polyurethane specimens were conducted. Promising results for mechanical properties with castor oil and polytetramethylene ether glycol (PTMEG 2000) mixture, with 35% of rebound resilience, 36,22 m³ of abrasion resistance, 570,12 psi of tensile strength, 325,39% of elongation, 29,53 kJ.m-2 of tear resistance and 65 Shore A as hardness.
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Palavras-chave
Poliuretanos, Pré polímero de uretano, Polímeros vegetais, Óleo de mamona, Propriedades mecânicas, Polyurethanes, Urethane prepolymer, Vegetable polymers, Castor oil, Mechanical properties