Cure and thermal decomposition kinetics of a DGEBA/amine system modified with epoxidized soybean oil
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Cure and thermal decomposition kinetics of a DGEBA/amine system modified with epoxidized soybean oil Y. J. Woo1 · D. S. Kim1 Received: 11 February 2019 / Accepted: 4 August 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract In this study, epoxidized soybean oil (ESO) was added to a typical diglycidyl ether of bisphenol A (DGEBA) epoxy resin system with an amine curing agent, and the cure and thermal decomposition kinetics of the epoxy resin system were investigated by thermal analyses. ESO content in the epoxy resin system was changed up to 30%, and the stoichiometric amount of ethylene diamine was used. DSC was used for cure kinetics analysis, and TGA was used for thermal decomposition kinetics analysis. FTIR was used to check the completeness of the polymerization reaction of the cured epoxy resin samples for TGA. With increasing ESO content, cure rate decreased and the beginning temperature of thermal decomposition lowered. The cure and thermal decomposition kinetics of the epoxy resin system could be successfully analyzed by the autocatalytic reaction mechanism and the Ozawa method respectively. Keywords Epoxidized soybean oil · Diglycidyl ether of bisphenol A · Ethylene diamine · Cure kinetics · Thermal decomposition kinetics
Introduction Epoxy resins have excellent mechanical properties of high strength and modulus and excellent thermal properties of high glass transition temperature and service temperature. Also, they have high corrosion resistance, excellent adhesion strength and low shrinkage during polymerization. So, epoxy resins are very widely used in a variety of applications including adhesives, coatings and composite matrices for automotive and aerospace components. However, epoxy resins have a disadvantage of low impact strength due to its high cross-linking density, and thus, there is a restriction in its use as materials requiring high impact strength [1–3]. To improve toughness, studies on incorporating rubbers, thermosets, thermoplastics, reinforcements and fillers to neat epoxy resin systems have been widely conducted [4–7]. In general, epoxy resins are based on non-renewable petroleum resources. Recently, as interest in eco-friendly renewable materials has increased, researches on vegetable * D. S. Kim [email protected] 1
Department of Chemical Engineering, Chungbuk National University, 1 Chungdaero, Seowongu, Cheongju, Chungbuk 28644, Korea
oil such as soybean oil [8–11] and linseed oil [12] to obtain bio-based epoxy resins has been carried out. Among many vegetable oils, soybean oil is attracting lots of attention because it has low price, low toxicity and abundant supply. However, soybean oil does not have epoxide groups and needs epoxidation [8–11]. Epoxidized soybean oil (ESO) can play an important role as a toughener, a plasticizer and a diluent for typical epoxy resin systems. ESO has been widely used as a reactive modifier of typical epoxy resin systems because it reduces cross-linking density and the internal stress of the systems [13–17]. Several researchers have studi
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