Enhancing gas and moisture barrier properties in castor oil-derived poly (urethane urea) with graphene for sustainable packaging

Abstract

This study investigates the potential roles of graphene in enhancing gas barrier properties and moisture resistance in poly (urethane-urea) (PUU) and poly (dimethyl siloxane) (PDMS) composite films for sustainable packaging applications. Castor oil (CO) was selected as a cost-effective, eco-friendly alternative to petroleum-based polymers. However, CO-based PUU polymers have mechanical strength limitations. To address this, graphene flakes (GF) were incorporated at various concentrations to improve mechanical properties and gas barrier performance. The synthesized CO-PUU-PDMS/GF composite films demonstrated significant increases in tensile strength and stiffness with increasing GF concentrations. Notably, the O2 and CO2 permeability of the GF 0.5 film decreased by approximately two orders of magnitude, from 241.94 to 1.71 barrer and 1111.50 to 15.25 barrer, respectively, compared to the GF 0 film. Additionally, gas selectivity for CO2/N2 and O2/N2 pairs increased by approximately 3.5 times and 2 times, respectively. The water vapor transmission rate decreased to 7.0 × 10-12 g‧cm/cm2‧s‧Pa due to the tortuous pathways created within the composite matrix, which effectively enhanced moisture resistance. The carrot storage test further confirmed the excellent packaging performance. Therefore, the CO-PUU-PDMS/GF composite films hold promise as eco-friendly packaging materials, potentially extending food shelf life and offering a sustainable alternative in packaging.