Improvement of thermo-oxidative stability of electrically insulating polymeric materials by organic–inorganic hybrid coating

• Published in: Polymer degradation and stability Vol. 93; no. 6; pp. 1170 - 1175
• Main Authors: Marini, M., Pilati, F., Saccani, A., Toselli, M.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.06.2008; Elsevier
• Subjects: Applied sciences; Coating, metallization, dyeing; Composites; Degradation; Dielectric properties; Exact sciences and technology; Forms of application and semi-finished materials; Machinery and processing; Organic–inorganic hybrids; Plastics; Polymer industry, paints, wood; Technology of polymers; Thermo-oxidative stability; Degradation; Organic–inorganic hybrids; Thermo-oxidative stability; Dielectric properties; Ethylene terephthalate polymer; Electrical conductivity; Hybrid material; Thermooxidative degradation; Property processing relationship; Silica; Thermal stability; Ethylene oxide polymer; Low density ethylene polymer; Cyclic ether copolymer; Olefin polymer; Electrical properties; Ester polymer; Crystallinity; Ethylene oxide copolymer; Experimental study; Coated material; Surface treatment; Thermal properties; Polyvinylalcohol; Cyclic ether polymer; Electric insulating material; Sol gel process; Artificial ageing; Degradation;Thermo-oxidative stability;Organic-inorganic hybrids;Dielectric properties
• ISSN: 0141-3910; 1873-2321
• DOI: 10.1016/j.polymdegradstab.2008.03.002

The thermo-oxidative stability of poly(ethylene terephthalate) (PET) and low-density polyethylene (LDPE) films, coated with organic–inorganic hybrid coatings of various compositions, has been investigated after accelerated ageing tests, in order to ascertain a possible beneficial effect of these coatings on the electrical performances of these insulating materials. The results have shown that the coating affects degradation mechanisms for both LDPE and PET. Thermo-oxidation is slow in LDPE, leading to significantly better insulating characteristics after ageing: a strong reduction of the embrittlement time was also observed. The strong increase of crystallinity upon ageing, observed for both coated and uncoated PET samples, probably dominates the effect of ageing on the electrical properties. As a consequence, only slight beneficial effects on PET electrical performances have been observed (both on conductivity and electrical strength). On the other hand, the coating has a strong effect on molecular weight changes leading to a significant increase of molecular weight for coated PET, while uncoated PET undergoes a significant decrease. This suggests that coated PET should present significantly better properties upon very long times of ageing.