Oxidation induced changes in viscoelastic properties of a thermostable epoxy matrix

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. AbstractThe thermal ageing of a neat epoxy matrix has been studied at 200°C in air by three complementary analytical techniques: optical microscopy, mechanical spectrometry and nanoindentation. Thermal oxidation is restricted in a superficial layer of about 195 µm of maximal thickness. It consists in a predominant chain scission process involving, in particular, chemical groups whose β motions have the highest degree of cooperativity and thus, are responsible for the high temperature side of β dissipation band. As a result, chain scissions decrease catastrophically the glass transition temperature, but also increase significantly the storage modulus at glassy plateau between T β and T α . This phenomenon is called "internal antiplasticization". Starting from these observations, the Di Marzio and Gilbert's theories have been used in order to establish relationships between the glass transition temperature and number of chain scissions, and between the storage modulus and β transition activity respectively. The challenge is now to establish a relationship between the transition activity and the concentration of the corresponding chemical groups.

Thermal oxidation of aromatic epoxy-diamine networks

“…Thermal oxidation of epoxies is documented to induce chain scissions [1,2] and later volatile compounds [3,4]. The subsequent mass loss results in the appearance of cracks favoring the access of oxygen to deeper layers [5].…”

Thermal-oxidation of epoxy/amine followed by glass transition temperature changes

“…They show the depletion of glass transition i.e. that rigid networks (with T g higher than 150 C) undergo chain scissions [1,11,13,17].…”

Nouvelles avancées en modélisation cinétique de la thermo-oxydation des matrices époxy-diamine

“…La détermination de ces relations structure/propriétés a récemment fait l'objet d'une publication [10]. …”