Origin of epoxies embrittlement during oxidative ageing

Abstract

is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. b s t r a c tThermal oxidation of three epoxy resins prepared from flexible or rigid prepolymers and hardeners was studied by monitoring epoxy mechanical and physical changes. The physical changes were followed by mass measurements, glass transition temperature using DSC and sub-glass b transition using DMA. It was put in evidence that embrittlement is not directly associated to T g or mass loss changes since epoxy network based on isophorone diamine (IPDA) hardeners were shown to undergo mainly a chain scission at the beginning of exposure process whereas epoxy network based on trioxatridecane diamine (TTDA) hardeners exhibits a crosslinking process with a significant mass loss. The only common feature for both epoxy systems to understand embrittlement is the drop of amplitude of b transition with oxidation.

Effect of Thermal Ageing on the Impact and Flexural Damage Behaviour of Carbon Fibre-Reinforced Epoxy Laminates

“…Fibres are relatively stable but the matrix and the interface can degrade with temperature. Thermal ageing of reinforced thermoset matrix composites is frequently associated with a physicochemical degradation of the resin that involves several changes on the thermomechanical properties of composites [8]. Glass transition temperature ( T g ) of a thermoset polymer defines the region where the material present high stability in mechanical and thermal properties.…”

“…Failure properties are governed by the capacity to promote plastic deformation. Although plastic deformation in glassy state have been studied for various decades, the molecular origin for plastic deformation mechanisms in epoxy resin is not completely understood [8]. The effect of thermal ageing on the elastic modulus is not clear, some researches have not observe any effect while others have noticed modest variations of the elastic modulus with ageing [28,29,30].…”

Effect of Exposure Temperature on the Crashworthiness of Carbon/Epoxy Composite Rectangular Tubes Under Quasi-Static Compression

“…For the 180 °C, the peak and average crushing force reduced as a result of matrix oxidation. The oxidation of epoxy matrix is extensively studied in the literature [ 27 , 38 , 39 ] and it is associated to the chain scission that is induced by decomposition of hydroperoxides. In addition, it occurs quasi instantaneously, since hydroperoxides formed in epoxy amine networks are unstable due to the vicinity of heteroatoms, which induces the short kinetic chains being an intrinsic characteristic of epoxy.…”

“…During its service life, CFRP composites can withstand to temperatures up to 300 °C [ 27 , 28 ]. This high temperature for a certain exposure time affects the properties and structure of the material (both physically and chemically), which results in a degradation in the mechanical properties.…”

“…The effect of temperature exposure on crushing behaviors and failure modes of composite tubes is studied using an insulated temperature-controlled air oven to provide high-temperature environments. In real structure applications, composite tubes can be exposed to air at −73 to 80 °C in aerospace, whereas it is exposed to −140 to 120 °C in space applications [ 27 ]. In automotive, the temperature around the engine and exhaust can exceed the 200 °C [ 28 ].…”