Tailoring the mechanical and thermal properties of polylactic acid-based bionanocomposite films using halloysite nanotubes and polyethylene glycol by solvent casting process

Abstract

The inherent brittleness of PLA is a major challenge for its use in various applications. In this study, the effect of incorporation of halloysite nanotube (HNT) and polyethylene glycol (PEG) on mechanical and thermal properties of polylactic acid (PLA) was investigated. Various concentrations of PEG-600 and HNT were used with PLA, and films were prepared by solvent casting method. Mechanical, morphological, and thermal properties of these composite films were investigated to study the effect of PEG and HNT on the properties of PLA. Addition of PEG increased elongation at break, but reduced the tensile strength. However, addition of HNT in PLA/PEG compensated the fall in tensile strength. Addition of 3 wt% HNT into PLA blend involving 5 wt% PEG increased its elongation at break by 640% and tensile strength by 22%, while no significant change in Young’s modulus was observed. Dynamic mechanical thermal analysis (DMTA) showed significant improvement in storage modulus of PLA/PEG/HNT films in the rubbery region. Glass transition temperature decreased for the PEG-plasticized films, while the crystallinity improved as compared to neat PLA. Thermal stability of PLA/PEG/HNT films was higher than those of PLA, PLA/PEG, and PLA/HNT films. The degree of crystallinity obtained using X-ray diffraction analysis showed good agreement with that determined from differential scanning calorimetry (DSC).