Accelerated weathering performance of polylactide and its montmorillonite nanocomposite: Fid-Bau Portal

Accelerated weathering performance of polylactide and its montmorillonite nanocomposite

Kaynak, Cevdet / Sarı, Burcu

Abstract The goal of this study was to compare accelerated weathering performance of neat polylactide (PLA) and its 1 mass% organically modified montmorillonite (Mt) nanocomposite; compounded and shaped by twin-screw extrusion melt mixing and injection molding, respectively. Accelerated weathering test system applied consecutive steps of UV irradiation and humidity in accordance with ISO 4892-3 standards for 200h. Chain scission reactions such as photolysis, photooxidation and hydrolysis resulted in significant decrease in the molecular weight of PLA; consequently reductions in the mechanical properties of modulus, strength, ductility and toughness of the specimens occurred. However, after comparing mechanical properties of PLA and Mt–PLA before and after 200h accelerated weathering, use of PLA with only 1 mass% Mt was extremely beneficial not only for “indoor applications” but also for “outdoor applications”. This was due to the effective nanoscale reinforcing and barrier actions of intercalated/exfoliated Mt layers. For example, flexural strength was 6% beneficial before weathering, but after weathering the benefit was 88%.

Highlights • Weathering degradation decreased molecular weight and mechanical properties of PLA. • Use of PLA with only 1 mass% Mt was extremely beneficial before and after weathering. • e.g. benefit in flexural strength before weathering was 6%, but after weathering 88% • Benefits were due to effective nanoscale reinforcing and barrier actions of Mt layers.