Natural Climatic Aging Behavior of Halogen-Free Flame-Retardant PE/EVA Cable Insulation: A Multi-Analytical Study
IEEE Access, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Basım Tarihi: 2026
- Doi Numarası: 10.1109/access.2026.3707306
- Dergi Adı: IEEE Access
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Compendex, INSPEC, Directory of Open Access Journals
- Anahtar Kelimeler: Cable sheathing, dielectric properties, electrical insulation, flame retardants, HFFR, mechanical properties, natural weathering, outdoor exposure, PE/EVA, polyolefin
- İstanbul Üniversitesi-Cerrahpaşa Adresli: Evet
Özet
This work investigates the long-term climatic aging behavior of halogen-free flame-retardant (HFFR) materials based on a polyethylene/ethylene–vinyl acetate (PE/EVA) compound used in electrical cable insulation. Samples were subjected to natural outdoor exposure for a year, and their structural and physical properties were systematically monitored using a variety of analytical techniques: FTIR, SEM-EDS, TGA, DSC, dielectric measurements, mechanical test, and physico-chemical evaluations. Dielectric characterization revealed a progressive decrease in transverse resistivity and dielectric breakdown strength, accompanied by a slight increase in dielectric constant and loss factor, particularly at low frequencies. These trends indicate enhanced charge transport and interfacial polarization induced by moisture uptake and oxidative degradation. Mechanical testing showed a two-stage behavior, with an initial improvement in mechanical properties attributed to post-curing and crosslinking induced by external environmental effects, followed by a decrease in tensile strength, elongation at break, and stiffness due to chain scission and embrittlement mechanisms. FTIR spectroscopy evidenced the formation of carbonyl and hydroxyl groups, while SEM/EDS observations revealed surface roughening, microcrack formation, and changes in chemical composition at the surface. Thermal analyses indicated only minor shifts in degradation temperatures, demonstrating that the aged material exhibited good thermal stability. X-ray diffraction analysis showed a slight reduction in the degree of crystallinity, while the diffraction peak positions remained essentially unchanged, indicating that the crystalline structure of the material was preserved. Overall, the results demonstrated that climatic aging induced moderate but Consistent degradation of HFFR materials, primarily governed by oxidation and moisture diffusion, with a small degree of molecular deterioration. The identified degradation indicators provide a reliable basis for long-term performance assessment of polyolefin-based electrical insulation materials under real environmental conditions.