Polylactic acid nanocomposites containing functionalized multiwalled carbon nanotubes as antimicrobial packaging materials

Abstract

Intended for food packaging, nanocomposites films based on poly (lactic acid) reinforced by polydopamine-wrapped carbon nanotubes (PLA/PDA-MWCNTs) or TiO2 modified PDA-MWCNTs (PLA/TiO2-PDA-MWCNTs) as nanofillers were elaborated via melt-blending and characterized by several techniques. The success of the synthesis of the modified MWCNTs was confirmed by transmission electron microscopy, Raman and Fourier transform infrared spectroscopies and thermogravimetric analysis. Properties such as slow crystallization rate, barrier, mechanical, antibacterial and antifungal properties, required for food packaging, have been investigated. As compared to a PLA pristine film, the PLA based modified MWCNTs at 3 wt% loading exhibited better properties, particularly the PLA/TiO2-PDA-MWCNTs nanocomposite film. Indeed, the crystallization rate increased about 10% for PLA/TiO2-PDA-MWCNTs and 7% for PLA/PDA-MWCNTs compared to the neat PLA. Besides, these improved results have positively impacted on the nanomechanical and barrier properties of PLA nanocomposites films. The Young modulus was increased by 161% for PLA/TiO2-PDA-MWCNTs and 113% for PLA/PDA-MWCNTs and the hardness was improved by 815% for PLA/TiO2-PDA-MWCNTs and 79% for PLA/PDA-MWCNTs, respectively, as compared to the pristine PLA. Furthermore, PLA based modified MWCNTs nanocomposite films displayed a strong antimicrobial and antifungal activity compared to pure PLA.