Improved mechanical and barrier properties of low-density polyethylene nanocomposite films by incorporating hydrophobic graphene oxide nanosheets

The high hydrophilicity of graphene oxide nanosheets (GONSs), arising from their abundant oxygen-containing functional groups, gravely restricts their application in non-polar polymer nanocomposites. In the present study, alkylated GONSs were fabricated by facile refluxing of GONSs and octadecylamine (ODA), thus giving rise to the selective dispersion of ODA-GONSs in non-polar xylene rather than in polar water. Fourier-transform infrared spectroscopy, atomic force microscopy, and X-ray diffraction results demonstrated the occurrence of the nucleophilic substitution reaction between the primary amine groups of ODA and the epoxide groups of GONSs during the refluxing. In the low density polyethylene (LDPE) nanocomposites, ODA-GONSs were uniformly and randomly dispersed, exhibiting excellent compatibility with the LDPE matrix. As a result, when adding 4.0 wt% ODA-GONSs, the Young's modulus was improved by 58.9%; O-2 permeability was reduced by 37.0%; and initial decomposition temperature was elevated by 15.9 degrees C. Besides, the inclusion of ODA-GONSs could effectively block the transmission of UV light in the nanocomposite films and serve as heterogeneous nucleating agents for LDPE crystallization. These results confirm that such long alkane chain modification holds great value or potential to design and prepare LDPE nanocomposite films for packaging applications with excellent integrated performance.