Métodos de estudo da cinética de cura de resinas epóxi

Abstract

Nas últimas décadas tem-se estudado a cinética da reação de cura de resinas epóxi por meio de técnicas analíticas como por exemplo a calorimetria exploratória diferencial. O uso desta técnica permite utilizar vários métodos de estudo da cinética de cura, divididos em: métodos dinâmicos e isotérmicos, e cada pesquisador escolhe o que melhor se adapta às suas necessidades. O presente trabalho tem como objetivo orientar na escolha de qual método deve ser utilizado, em função dos sistemas poliméricos em estudo, bem como sumarizar os principais métodos utilizados, auxiliando, dessa forma, no estudo da cinética de cura de resinas epóxi.

Development of a Simple Dielectric Analysis Module for Online Cure Monitoring of a Commercial Epoxy Resin Formulation

“…This method selection was made based on the methodology presented by Costa et al 9 and the kinetic parameters of activation energy (E a ), pre-exponential factor (A) and reaction order (n) were calculated as described by ASTM E2041…”

Hybrid Nanocomposites Based on Epoxy/silsesquioxanes Matrices Reinforced with Multi-walled Carbon Nanotubes

“…Furthermore, the secondary amine may react with another epoxy ring producing a tertiary amine (Scheme 1). This is an autocatalytic process once hydroxyls formed can also open epoxy rings 4,21 . However, the concentration of amine groups present in the copolysilsesquioxane is unable to promote the total cure process and, thus, the hybrids were further cured with a polyamine-based hardener.…”

“…On the other hand, the APTES/PTES copolysilsesquioxane present Si-C bonds in your structure. Furthermore, hydroxyls from silanol groups can also open epoxy rings during the cure reaction 4,21 , forming new Si-C bonds between the APTES/PTES copolysilsesquioxane and the LY matrix. For these reasons, the hybrid matrixes presented Si-C absorption bands and the hybrid matrices cured after 7 days of chemical modification presented slightly higher intensity for the Si-C bonds, comparing with the respective hybrid matrices cured immediately after chemical modification.…”

“…An usual method to enhance epoxy properties is the chemical modification by inorganic structures. Silsesquioxanes are typical organic-inorganic materials and can be incorporated into almost any kind of thermoplastic or thermosetting polymer to improve their properties 4 . Epoxy/silsesquioxane hybrids present improvements in thermal stability 5 , dielectric properties 6 , corrosion resistance 7 , and mechanical properties 8 , as well as reduced flammability 9 , in comparison with neat epoxy resin.…”

Differential Scanning Calorimetry study on curing kinetics of diglycidyl ether of bisphenol A with amine curing agents for self-healing systems

“…For that, mathematical modelling was used to compute the Arrhenius parameters activation energy, pre-exponential factor as well as the minimum temperature to trigger the polymerization process by the Boerchardt and Daniels model [6,7]. The Boerchardt and Daniels approach allows one to calculate the Arrhenius parameters from only a single DSC scan [6]. However, the values of the pre-exponential factor (A) have shown to vary according to the heating rate of the scan [7].…”