Plasticization of polylactic acid reinforced multi-walled carbon nanotube utilizing polyethene glycol via solvent casting: Rheological, viscoelastic, and thermal properties

Abstract

This study aims to explore the impact of polyethylene glycol (PEG) composition and its molecular weight (Mw) on the polylactic acid (PLA) properties that are reinforced with multi-walled carbon nanotubes (CNT). Chloroform was utilized in a solvent casting method to produce PLA nanocomposites. The weight of CNT in the PLA composite varied at 0wt%, 4wt%, 8wt%, and 12wt%. Additionally, at 8wt% CNT, PEG (Mw: 1,000 Da and 10,000 Da) was added with various compositions of 0wt%, 6wt%, 10wt%, and 14wt% to examine the effect of plasticization on the properties of PLA nanocomposites. The FTIR test revealed a significant change in the carbonyl group peak at 1749 cm⁻¹. The carbonyl group spectra peaks increased with an increase in concentration and molecular weight of PEG. The frequency sweep of the melt rheological test showed that the storage modulus (G'), loss modulus (G”), and complex viscosity |η^*| increased with rising CNT loading and tended to decrease with the presence of PEG in the PLA nanocomposites. The same trend was observed in the analysis of the temperature sweep of the solid samples with respect to the storage modulus (G'). The addition of CNT and PEG resulted in a shift of the glass transition and melting temperature of PLA within the range of 0–5°C, while the crystallinity encountered a change of approximately 4.9%. The Coats-Redfern equation was employed to determine the degradation kinetics of the PLA and PLA nanocomposites over mass-loss regions from 315 to 411°C. The findings indicate that the presence of CNT improves thermal stability, whereas the incorporation of PEG appears to produce a contrary effect.