Corona discharges aging of recycled PET filled with inorganic reinforcements
Notice bibliographique
Résumé
Polyethylene Terephthalate (PET) is one of the most promising candidate thermoplastics that can replace epoxy resin as insulating material for electric and electronic applications, thanks to its good processability and excellent properties which remain relatively stable in a large range of temperatures. In this paper, two different micrometric fillers, short glass fibers as well as small and large mica platelets have been used to form composites. One of the possible applications is the mechanical support for the HV terminal system of internal combustion engines. In order to evaluate the dielectric endurance of these materials, corona resistance tests were performed in an oven using a point-to-plane configuration in air at several constant temperatures between the room temperature and 170°C. Tests were carried out at 7 kV rms and at a frequency of 300 Hz to accelerate the degradation process. In order to check the effect of time, experiments were also conducted at different times between 24 and 96 hours. The dielectric strength has been evaluated at room temperature before and after erosion according to the ASTM-D149 standard. The dielectric response was evaluated using a broadband dielectric spectroscopy (BDS) at room temperature before and after erosion. Dielectric breakdown strength data obtained before exposure to corona discharges shows that there is a slight difference between the composites filled with large mica platelets and those reinforced with small mica platelets. However, the data obtained after erosion revealed that recycled PET filled with large mica platelets perform better than those filled with small mica platelets. In addition, it was found that an increase of temperature induces a decrease of the residual breakdown voltage. Results demonstrated that the recycled PET based composites reinforced with large mica platelets has good resistance to corona discharges at elevated temperature as compared to small mica platelets filled recycled PET. Data obtained by BDS show a slight increase in relative permittivity for recycled PET filled with large mica platelets as compared to the recycled PET reinforced with large mica platelets. It was also found that an increase of temperature or time results in an increase of dielectric losses mainly at low frequencies. It can be concluded that BDS and dielectric breakdown strength after erosion process were useful to distinct the performance of composites filled with small and large mica platelets, which was not possible with only short term dielectric breakdown measurements.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».