Mechanical Properties and Tribological Behavior of MoS2-Enhanced Cellulose-Based Biocomposites for Food Packaging

Abstract

Synthetic polymers are the most commonly used polymers in daily life. Therefore, it is necessary to develop environmentally friendly polymers. Hydroxypropyl methylcellulose (HPMC) is a potential candidate for a biopolymer, owing to its unique properties. However, HPMC biopolymers have some disadvantages compared to synthetic polymers. In this study, the mechanical properties and tribological performance of MoS2 additive-enhanced cellulose matrix biocomposites were investigated in order to improve the properties of HPMC. MoS2 was incorporated into the HPMC matrix as a strengthening additive. The mechanical properties, bonding, and water vapor permeability of the composites were analyzed. The mechanical and vapor barrier properties of the HPMC films were significantly enhanced. The ultimate tensile strength and Young’s modulus of the composite films increased with the addition of up to 1 wt% MoS2. The water vapor permeability of HPMC films reduced when additives were incorporated. The wear test proves that the MoS2 additives can improve the tribological performance of the HPMC composite while reducing the friction coefficient. The main reason for enhanced tribological performance is the improvement in load capacity of the composite coating by the MoS2 additive. This MoS2/HPMC biocomposite can be used in food packaging.

Polyethylene with MoS2 nanoparticles toward antibacterial active packaging

“…74 This phenomenon is not observed in oxygen permeability (Figure 6b) as the presence of MoS 2 filler decreased this value around 25% as compared with the pure matrix, except for composite with 1.0 wt%. Similar results have been reported for waterborne polyurethane and 26,27 To understand the different tendency in the effect of MoS 2 on the oxygen and water permeations, we focus on the interactions between these molecules and the polymer matrix knowing that the permeation coefficient is the product of the solubility and diffusion coefficients. 75 In amorphous polyethylene, the solubility coefficient of oxygen is much higher (by several orders of magnitude) than of water although both presented similar diffusion coefficients.…”

“…3 In this context, MoS 2 is a promising candidate for high barrier polymer film materials, as shown in polyurethane and hydroxypropyl methylcellulose matrices reducing the water vapor permeability associated with the hydrophobic nature of the filler and the intermolecular bonding between the additive and matrix. 26,27 A drastic reduction in the permeability of helium (95%) and hydrogen (94%) of PVA was further observed by embedding either pure MoS 2 or modified MoS 2 with hydroxy functional groups, respectively, due to the impermeable characteristics of these nanosheets increasing the diffusion path tortuosity. 18,19 Alongside these changes in the barrier properties, polymer/MoS 2 composites can present antibacterial behavior arising from the capacity of this layered nanoparticle to generate ROS.…”

“…11,[23][24][25] Alongside the high effect of the filler concentration, the matrix characteristics are relevant as an increased toughness without relevant changes in stiffness was observed in PVA/MoS 2 composites, 19 while in hydroxypropyl methylcellulose, the tensile strength improved but the elongation at break decreased drastically. 26 Despite the fact that layered nanoparticles are wellknown fillers for improving the behavior of polymer in packaging applications, few studies have been carried out focusing on MoS 2 . Noteworthy, in two reviews of polymer/MoS 2 composites, this application is not mentioned.…”

Advances in two‐dimensional engineered nanomaterials applications for the agro‑ and food‐industries

“…81 Another example shows the benefits of incorporating layered nanostructures (MoS 2 in this case) within natural biopolymers such as cellulose, which produces enhancements in its mechanical, tribological, and gas-barrier characteristics. 82 Interestingly, as can also be observed for the other reviewed studies, the amount of 2D nanomaterials used as additives for these types of applications is relatively small (around 1 wt%), revealing an economic potential for improvement of food and other agricultural-related products.…”

“…Other types of 2D materials are also starting to appear as advanced alternatives for food and agricultural products’ smart packaging; lamellar structures of h‑BN were used in composites with polyurethane to improve not only their barrier properties against water and oxygen but also their adhesion and mechanical stability for usage in impermeable and flexible packaging films 81 . Another example shows the benefits of incorporating layered nanostructures (MoS 2 in this case) within natural biopolymers such as cellulose, which produces enhancements in its mechanical, tribological, and gas‐barrier characteristics 82 . Interestingly, as can also be observed for the other reviewed studies, the amount of 2D nanomaterials used as additives for these types of applications is relatively small (around 1 wt%), revealing an economic potential for improvement of food and other agricultural‐related products.…”