A “core-shell” structure imparting both gas barrier and UV shielding properties for a PLA/ PGA/ PBS ternary blend film

Abstract

The core-shell structure enhances polymer blend systems by orderly assembly and leveraging complementary properties. This study aims to enhance the flexibility and barrier properties of polylactic acid (PLA, L) by blending it with polyglycolic acid (PGA, G) for gas barrier and polybutylene succinate (PBS, B) for flexibility. Encapsulating PGA in a core-shell structure using PBS resolves PGA's rapid hydrolysis issue. The theoretical models predicting dispersion patterns based on spreading coefficients and interfacial tensions were validated through SEM observations, confirming the formation of a core-shell structure in the 5L1G4B ternary blend. Compared to the PLA/PBS binary blend film, samples with PGA (5L1G4B and 4L1G5B) exhibit higher elongation at break and tearing strength. For instance, the elongation at break of the 5L1G4B sample increases from 272.3 % of 6L4B to 470.85 %. The 5L1G4B showed comparable oxygen and carbon dioxide barrier properties to the 6L4B sample. The 5L1G4B and 4L1G5B samples show <2 % UV transmittance in the UVA region, indicating excellent UV shielding. The 5L1G4B blend film, with its mechanical properties, oxygen barrier, UV resistance, and biodegradability, is ideal for outer layer packaging film and has the potential to replace LDPE in packaging juice and dairy product bottles.