Influence of the silica fillers on the ageing of epoxy resins under irradiations
Description
Various studies were carried out on the ageing of epoxy resins under irradiations. In all cases, pure polymers were studied. The aim of our work managed by the CEA and the CNRS consists on studying the part of fillers and particularly the part of silica on ageing process under electron beam irradiations. Because of their wide use in industrial applications and especially in nuclear environment, the DGEBA-TETA resins (Diglycidylether of Bisphenol A - Triethylenetetramine) were chosen. Those epoxy resins are difficult to analyse because of their insolubility. Some pure and nano-metric silica filled chemical models which chemical structure very close to the one the DGEBA/TETA resin were synthesized and analysed with classical methods in organic chemistry. A major phenomenon of rupture of the C-O and C-N chemical bonds with creation of phenolic extremities, methylketone extremities, of primary and tertiary amines and notably enamine functions were revealed by the analyses. The quantitative 1H and 13C NMR analyses revealed the screen effect due to the silica and the reactions between the chemical species created by the irradiations and the silica surface. Thermic and thermodynamic analyses of the different epoxy resins in function of the irradiation dose and of the kind of silica showed the decrease of the glass transition temperature, of the relaxation temperature and of the crosslink density confirming the major phenomenon of bond ruptures during irradiations. With silica, the decrease of the crosslink density is slowed. This phenomenon can be explained with interactions between the nano-metric silica surface and the epoxy resin offsetting the effect of the chain rupture on the resin mechanical properties. The 13C solid state NMR analyses confirmed the choice of the chemical models and permitted to detect the chemical species created by the irradiations. The analyse of the polarization transfers with 13C CP-MAS NMR spectroscopy revealed the stiffening of the nano-metric silica filled resin and the reactions between the resin and the silica surface during irradiations. This study permits to assert that the silica fillers in the epoxy resins protect the network from the irradiations. (author)
Abstract (French)
L'objectif de ces travaux etait d'etudier l'influence de la silice sur le vieillissement des resines epoxyde sous irradiation. Les resines epoxyde obtenues par la reaction d'une polyamine aliphatique (la Triethyltetraamine) avec le prepolymere DGEBA sont difficilement analysables du fait de leur caractere insoluble et infusible. Des modeles chimiques de structures tres voisines de celle de la resine DGEBA/TETA synthetises purs et en presence de silice nanometrique sont analyses par les methodes classiques de chimie organique (RMN du liquide, SEC, Spectrometrie de masse Maldi-tof). Des differences de reactivite des amines primaires et secondaires en presence de silice nanometrique sont mises en evidence. Les analyses des modeles irradies montrent un phenomene majoritaire de coupures de liaisons C-O et C-N accompagnees par la formation d'extremites phenoliques, de terminaisons methylcetone, de fonctions amines primaires et secondaires et notamment d'une double liaison C=C en alpha d'un azote. La RMN 1H et la RMN 13C quantitative revelent un effet d'ecran du a la silice et mettent en evidence des reactions entre les especes chimiques reactives creees par les irradiations et la surface de la silice. Les analyses thermiques, thermomecaniques des differentes resines epoxyde en fonction de la dose d'irradiation et du type de silice montrent la diminution de la temperature de transition vitreuse, des temperatures des relaxations et de la densite de reticulation confirmant des phenomenes majoritaires de coupures de liaisons au cours des irradiations. En presence de silice nanometrique, la diminution de la densite de reticulation est ralentie. Ce phenomene peut s'expliquer par des interactions entre la surface de la silice nanometrique et la resine epoxyde compensant l'effet des coupures de chaines sur les proprietes mecaniques du materiau. Les analyses des resines epoxyde par RMN 13C CP/MAS du solide confirment la pertinence des modeles et ont permis de detecter les especes chimiques formees au cours des irradiations. L'analyse des transferts d'aimantation par RMN 13C a temps de contact variable met en evidence une rigidification de la resine chargee de silice nanometrique et des reactions entre la resine et la surface de la silice au cours des irradiations. On peut donc dire, a la suite de ce travail, que les charges de silice dans des resines epoxyde sont susceptibles d'avoir un role de protection du reseau polymere vis a vis des irradiationsFiles
43040692.pdf
Files
(11.4 MB)
| Name | Size | Download all |
|---|---|---|
|
md5:6ee3e00f1a7f5a9fcbf270e2e2fa2b36
|
11.4 MB | Preview Download |
Additional details
Additional titles
- Original title (French)
- Etude de l'influence des charges de silice sur le vieillissement des resines epoxyde sous irradiation
Identifiers
Publishing Information
- Imprint Pagination
- 233 p.
- Report number
- FRCEA-TH--3314
INIS
- Country of Publication
- France
- Country of Input or Organization
- France
- INIS RN
- 43040692
- Subject category
- S36: MATERIALS SCIENCE;
- Resource subtype / Literary indicator
- Thesis
- Descriptors DEI
- AGING; EPOXIDES; IRRADIATION; NUCLEAR MAGNETIC RESONANCE; RESINS; SILICA; TRANSITION TEMPERATURE
- Descriptors DEC
- MAGNETIC RESONANCE; MINERALS; ORGANIC COMPOUNDS; ORGANIC OXYGEN COMPOUNDS; ORGANIC POLYMERS; OXIDE MINERALS; PETROCHEMICALS; PETROLEUM PRODUCTS; PHYSICAL PROPERTIES; POLYMERS; RESONANCE; THERMODYNAMIC PROPERTIES
Optional Information
- Notes
- 108 refs.; Available from the INIS Liaison Officer for France, see the 'INIS contacts' section of the INIS website for current contact and E-mail addresses: http://www.iaea.org/inis/Contacts/