Academic Journal
Improving the photo-stability of polymers using graphene
| العنوان: | Improving the photo-stability of polymers using graphene |
|---|---|
| المؤلفون: | Karimi, Samira |
| بيانات النشر: | École de technologie supérieure |
| سنة النشر: | 2024 |
| المجموعة: | École de technologie supérieure, Montréal: Espace ÉTS |
| مصطلحات موضوعية: | photo-dégradation, graphène, photo-stabilisant, barrière physique, piégeur de radicaux, absorption/réflexion des UV, fragilisation, ductilité, chimie-cristallisation, profondeur de la photo-dégradation |
| الوصف: | This thesis aimed at achieving UV-stabilized polymers, using the incorporation of few-layer graphene (FLG), and to evaluate the dominant action mechanisms of FLG, and optimize its role, as a photo-stabilizer. The FLG performance as a photo-stabilizer and its effect on both macro and microstructural changes of High-Density Polyethylene (HDPE) composites, occurring during photo-degradation, were investigated. HDPE composites containing different FLG concentrations (0, 0.1, 0.25, and 0.5 wt%) were prepared through melt mixing using a twin-screw extruder, followed by exposure to UV-A irradiation for several durations. Rheological and mechanical properties were evaluated as a function of UV exposure time. To determine FLG's photo-stabilizing mechanisms, a specific controlled test, involving the UV exposure process of the mixture of hydrogen peroxide (H2O2) and the FLG aqueous suspensions, was conducted. Then, the amount of created free radicals was measured using an Electron Paramagnetic Resonance (EPR) test. Finally, the effect of the FLG addition on the penetration of photo-degradation within HDPE, and the correlation between photo-degradation depth at which chemi-crystallization occurs, and elongation at break, were investigated using Raman microscopy. It was found that the addition of only 0.25 wt% FLG into HDPE showed a notable UV resistance for an exposure time of 672 hours, evident from sustained retention of rheological and mechanical properties. Additionally, it was shown that 57% of the observed reduction in EPR signals, indicating the reduction in the amount of created free radicals, is due to UV absorption/reflection and 43% due to the free radical scavenging abilities of FLG. It is demonstrated that UV absorption/reflection and free radical scavenging mechanisms are the dominant ones among the three FLG photo-stabilizing mechanisms (UV absorption/reflection, free radical scavenging, and physical barrier to oxygen). Finally, it was found that embrittlement occurred in neat HDPE when photo-degradation ... |
| نوع الوثيقة: | article in journal/newspaper thesis |
| وصف الملف: | application/pdf |
| اللغة: | English |
| Relation: | https://espace.etsmtl.ca/id/eprint/3451/1/KARIMI_Samira.pdf; Karimi, Samira (2024). Improving the photo-stability of polymers using graphene. Thèse de doctorat électronique, Montréal, École de technologie supérieure. |
| الاتاحة: | https://espace.etsmtl.ca/id/eprint/3451/ https://espace.etsmtl.ca/id/eprint/3451/1/KARIMI_Samira.pdf |
| رقم الانضمام: | edsbas.F48BE88E |
| قاعدة البيانات: | BASE |
| الوصف غير متاح. |