A influência de óleos vegetais sobre a degradação e propriedades do polipropileno reciclado

• Autor(a) principal: Esteves, Leonardo Luis
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/7973
• topic: Polypropylene; Vegetable oil; Thermal analysis; Recycling; Degradation; Crystallization; Antioxidants; Plasticizing agent; Polipropileno; Reaproveitamento; Óleos vegetais; Polimeros; Biodegradação; Análise térmica; Reciclagem; Degradação; Cristalização; Antioxidantes; Agente plastificante; CNPQ::ENGENHARIAS::ENGENHARIA DE MATERIAIS E METALURGICA::MATERIAIS NAO METALICOS

Polypropylene is one of the most widely used commodity polymers in the world due to its properties of interest such as ease of processing, flexibility, hardness, barrier property and good chemical resistance. Being an olefinic polymer, it presents a great tendency to degradation when exposed to oxidizing atmospheres, ultraviolet light (UV) and by thermal effects, for example, due to successive processing in a recycling application. During its processing it is common to use antioxidants to ensure the quality and applicability of the material throughout its life cycle. Synthetic substances are commonly used to promote the antioxidant effect in polymers, which can have a very high toxicity level and bring environmental impact, and in some cases the use of these additives by legislation is not advisable. From this scenario, we sought to study the effects of vegetable oils of grape seed, Brazil nuts and castor bean oil added to a recycled polypropylene, having as main focus their antioxidant properties. In addition, other properties of interest were analyzed for example, flow index, viscosity, tensile strength, young modulus and its properties as plasticizing agent. In order to investigate the thermal stability of polypropylene containing vegetable oils, thermal analysis techniques such as differential scanning calorimetric (DSC), thermo gravimetric analysis (TGA) and attenuated total reflectance (ATR) technique were used, where the polymer was mixed with and processed consecutively in an extruder eight (8) times to simulate a condition of thermo-oxidative degradation. To verify thermal stability, kinetic models of degradation and crystallization described in the literature and different heating rates were applied in order to determine and compare the activation energies involved in the processes. The results of the thermal analysis and the activation energies obtained for the thermo-oxidative degradation process allow us to conclude that grape oils, Brazil nuts and to a lesser degree castor bean oil, have played a role of potential antioxidant agents for polypropylene. It can be inferred that the vegetable oils used in this dissertation present favorable characteristics for the substitution of synthetic commercial phenolic or amine antioxidants used in industry.