Improved rheological, barrier, antibacterial, and electromagnetic interference shielding properties of graphene and graphene derivatives based linear low density polyethylene nanocomposites

Abstract

Multifunctional polymer/graphene based lightweight and flexible nanocomposite films are increasingly being utilized in the packaging, electronics, and pharmaceutical industries together. Herein, two graphene derivatives: silver nanoparticle decorated reduced graphene oxide (G‐Ag) and chemically reduced graphene oxide (rGO) prepared by wet chemical method and graphene nanoplatelets (GNP) have been incorporated into linear low density polyethylene (LLDPE) thermoplastic matrix via melt compounding method. The incorporation of graphene derivatives affected the physico‐mechanical, electrical and thermal conductivity, and barrier properties (both oxygen and water vapor permeability) of the nanocomposite films. With 5 wt% of G‐Ag, rGO, and GNP loading, the thermal conductivity of these three nanocomposite films was enhanced by an average of 136.7%, 123%, and 143.3%, respectively. Graphene having high specific surface area and aspect ratio allow for a tortuous passage of oxygen and water molecules through the nanocomposite film, ultimately improving both oxygen and water vapor impermeability qualities for all LG‐Ag, LrGO, and LGNP nanocomposites. Moreover, the films have been tested against both gram‐positive and gram‐negative bacteria to ensure their bactericidal activity. The prepared composite films also showed Electromagnetic Interference (EMI) shielding effectiveness (−21, −17, and −19 dB) higher than the commercial cut‐offs. The thermoplastic nanocomposite films with promising thermal conductivity might be an excellent choice for bacteria‐resistant and barrier‐capable packaging and efficient thermal management EMI shields in electronics.

Recent Advances in Nanoclay‐ and Graphene‐Based Thermoplastic Nanocomposites for Packaging Applications

“…An elevated concentration of GNP augments the likelihood of agglomeration formation, which hinders the molecular chains from organizing into crystal lattices, ultimately diminishing the level of crystallinity. Such reduction in percentage crystallinity of rGO-and G-Ag-loaded LLDPE nanocomposites was also reported by Das et al [62]. It is noteworthy that the incorporation of a minute quantity of graphene has been observed to enhance the water resistance characteristics of PVA [98].…”

“…The improved antibacterial characteristics of graphene and graphene derivatives containing PLC, PEG and PVDF composite films that can be utilized for food packaging are also reported in the literature. Ghosh et al investigated the antibacterial effectiveness of rGO-Ag-loaded LLDPE thermoplastic nanocomposite films against both gram-positive and gram-negative bacteria by disk diffusion method [62]. The results indicated that graphene-contained thermoplastic films exhibited very effective antibacterial activity in terms of reduction in CFU (colony-forming units) against both bacterial strains [9].…”

“…(A) Permeation of oxygen and vapour molecules through neat thermoplastic and (B) and (C) tortuous path formed by clay and graphene nanoparticles for oxygen and water vapour molecules through nanocomposite film thickness (reproduced from Ref. [62] with permission from Wiley), respectively.…”

“…Ghosh et al. investigated the antibacterial effectiveness of rGO‐Ag–loaded LLDPE thermoplastic nanocomposite films against both gram‐positive and gram‐negative bacteria by disk diffusion method [62]. The results indicated that graphene‐contained thermoplastic films exhibited very effective antibacterial activity in terms of reduction in CFU (colony‐forming units) against both bacterial strains [9].…”

“…However, the improvement in thermal stability was higher for silane‐modified nanoclay‐filled samples owing to the more uniform distribution of functionalized nanofillers in the LLDPE matrix [28]. In their other work, they also studied the thermal properties of graphene‐ and graphene derivative–based LLDPE nanocomposite films and observed promising improvement in maximum decomposition temperatures and heat resistance index due to the high degree of dispersion of these large aspect ratio carbonaceous inclusions [62]. Few authors studied the thermal properties of sepiolite reinforced PP nanocomposites under different conditions such as surface treatment, particle size, shape and concentration of sepiolite.…”