Antimicrobial low-density polyethylene/low-density polyethylene-grafted acrylic acid biocomposites based on rice bran with tea tree oil for food packaging applications

Natural volatile antibacterial and anti-mycotoxin tea tree oil (TTO) with rice bran (RB) were used as a solid carrier for achieving a sustained release profile with high antimicrobial efficiency in polyethylene films. Acrylic acid (AAc) monomer was grafted onto a low-density polyethylene (LDPE) through melt blending using a Brabender Plasti-Corder. The low-density polyethylene-grafted acrylic acid (LDPE-g-AAc) was thoroughly characterized by attenuated total reflectance-Fourier transform infrared spectroscopy. LDPE and LDPE-g-AAc (80/20) were mixed with different contents of untreated RB and treated TTO/RB using melt blending to obtain sustainable composites, namely LDPE/LDPE-g-AAc/RB and LDPE/LDPE-g-AAc/TTO-RB, respectively. The effect of the addition of untreated and treated RB on the properties of biocomposites was assessed by using mechanical, barrier, and thermal properties. A prominent decrease in water vapor transmission rate occurred when adding 30 wt% of TTO/RB to LDPE/LDPE-g-AAc blend compared to virgin polymer. This decrease was due to the barrier effect of lignocellulosic material, particularly at high bio-filler content. The prepared biocomposites revealed good thermal stability when compared to virgin LDPE. Moreover, the biodegradability and antimicrobial properties of LDPE/LDPE-g-AAc/TTO-RB biofilms were enhanced with increasing TTO/RB contents from 10 phr to 30 phr due to the combination between LDPE-g-AAc and TTO. The obtained data revealed excellent possibility for using biopolymer grafted with antimicrobial TTO by adding RB for food packaging and biomedical purposes.

Automated summary

This study investigated the usage of tea tree oil and rice bran as solid carriers for achieving sustained release and high antimicrobial efficiency in polyethylene films. The addition of treated rice bran and tea tree oil significantly improved the barrier properties and thermal stability of the composite materials, as well as enhanced their biodegradability and antimicrobial properties.