Propriedades físico-químicas, térmicas e mecânicas de materiais compósitos constituídos de óleo vegetal epoxidado e reforçados com partículas de capim elefante (Pennisetum Purpureum Schum) e celulose micro-cristalina

Abstract

In this study, epoxidized soybean oil and lignocellulosic materials derived from elephant grass and microcrystalline cellulose are evaluated to produce composite materials from renewable sources. One of the main difficulties in the production of epoxidized soybean oil is the reaction time, which can reach several hours depending on the catalyst used; in this sense, epoxidation in a microwave reactor was developed as an alternative to reduce reaction time and energy consumption by up to 94%. The epoxidation method with citric acid was also developed and applied to replace acetic acid, which is a viable alternative and brings greater security to the epoxidation process, reducing thermal risks. Soybean oil epoxidized with citric acid and acetic acid as oxygen carriers were evaluated for thermal and mechanical properties, in which it was found that the application of citric acid does not significantly affect the mechanical performance, in addition to bringing materials after curing with greater hydrophobicity compared to that produced with acetic acid. However, epoxidized soybean oil, due to its flexible nature, has limited application in composite materials, especially for structural applications. Two alternatives have been proposed to face these difficulties: one of association with the commercial epoxy of bisphenol A diglycidyl ether and the other production of composite materials based on derivatives of elephant grass and microcrystalline cellulose, with similar mechanical performances in tensile tests. In the crosslinking process for composite materials based on a blend of epoxidized soybean oil and commercial epoxy, the curing time was reduced with the application of microwave curing, in which it was found that the degree of curing was not significantly affected. There was a significant reduction in energy consumption and curing time, making the process practical and reducing equipment costs.