The effects of residual organic solvent on epoxy: modeling of kinetic parameters by DSC and Borchardt-Daniels method

Abstract

The curing reactions of epoxy resins are a complex process that defines thermosets final properties and are affected by any additive present on its formulation. Considering this, the aim of this study was to analyze the influence of the solvent addition on the curing kinetics of an epoxy system. The epoxy samples were prepared using different percentages by weight of acetone: 0, 2, 5 and 10 wt.%. From DSC and DMA tests, followed by the Borchardt-Daniels kinetic analysis it was reported that the addition of acetone can decrease the reactions rate, activation energy, T g and elastic modulus. The presence of solvent, even in small amounts, can affect the curing mechanisms of epoxy resins. The changes on the curing behavior and the low quality of the final properties for the sample with 10 wt.% of solvent indicates that this may be a limit for acetone addition on the epoxy formulations.

Evaluation of Oxidative Stability and Kinetic Parameters of the Cottonseed and Soybean Biodiesels by Rancimat and Differential Scanning Calorimetry Techniques

“…The method of Borchardt and Daniels was chosen for the kinetic parameters determination of exothermic reaction because of its simplicity and ease of use, which allows the determination of the reaction order, the frequency factor, and the activation energy in a single rapid measurement [15,17,18]. The results obtained by Borchardt and Daniels's method have been compatible with data obtained by conventional methods [29,30].…”

“…However, most of these methodologies require many hours of experimentation and multiple tests, which makes their reproduction more complex and laborious. Thus, DSC appears as an alternative method to determine the thermal behavior of organic molecules and the kinetic parameters of exothermic reactions using a single scan at low heating rates and small specimen sizes, such as the method of Borchardt and Daniels, which is based on the relation between the degree of conversion (α) and enthalpy changes obtained by dynamic DSC analysis and is one of the simplest for modeling exothermic reactions [14][15][16][17][18]. The great advantage of this method is the rapidity of performing the analysis [15].…”

“…With Borchardt and Daniels' method, some parameters such as activation energy (Ea), reaction order (n), and degree of conversion (α) can be evaluated, providing an overview of the kinetics behavior, which can be recommended when a quick assessment of the biodiesel oxidation kinetic parameters is needed since it requires only one DSC scan [15,17,18].…”