Novel Structure to Improve Mechanical Properties of Polymer Blends: Multilayered Ribbons

Improvement of Natural Polymeric Films Properties by Blend Formulation for Sustainable Active Food Packaging

Active packaging manufactured with biopolymers extracted from agri-food waste is one of the most innovative and eco-sustainable strategies for maintaining food quality. However, biopolymers often present poor performances, which hinders their competitiveness compared with plastics. This work focused on developing and optimizing a natural polymeric blend produced by solvent casting based on zein and chitosan to improve the pure biopolymers' properties. The best results were obtained by blending zein and chitosan in a 1:2 weight ratio. The films were characterized in terms of morphology, mechanical and oxygen barrier properties, thermal stability, transparency and wettability. The blend production allowed us to obtain lower brittleness and lower stiffness materials compared with pure polymer films, with oxygen permeability values two orders of magnitude lower than pure zein, better optical properties with respect to pure chitosan and good thermal stability. The wettability properties of the blend did not result in being altered with respect to the single polymer, which was found to have hydrophilic behavior, highlighting the strong influence of glycerol used as a plasticizer. The results suggested that the polymer blending strategy is a viable and cost-effective method for producing packaging materials as alternatives to plastics.

Recent Development of Polyhydroxyalkanoates (PHA)-Based Materials for Antibacterial Applications: A Review

The diseases caused by microorganisms are innumerable existing on this planet. Nevertheless, increasing antimicrobial resistance has become an urgent global challenge. Thus, in recent decades, bactericidal materials have been considered promising candidates to combat bacterial pathogens. Recently, polyhydroxyalkanoates (PHAs) have been used as green and biodegradable materials in various promising alternative applications, especially in healthcare for antiviral or antiviral purposes. However, it lacks a systematic review of the recent application of this emerging material for antibacterial applications. Therefore, the ultimate goal of this review is to provide a critical review of the state of the art recent development of PHA biopolymers in terms of cutting-edge production technologies as well as promising application fields. In addition, special attention was given to collecting scientific information on antibacterial agents that can potentially be incorporated into PHA materials for biological and durable antimicrobial protection. Furthermore, the current research gaps are declared, and future research perspectives are proposed to better understand the properties of these biopolymers as well as their possible applications.

In-situ constructing highly oriented ductile poly(3-hydroxybutyrate-co-3-hydroxyvalerate) nanoribbons: Towards strong, ductile, and good heat-resistant polylactic-based composites

It remains a great challenge to manufacture polylactic (PLA) with high strength, ductility, and heat resistance simultaneously. Herein, PLA/poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanoribboned composites, the highly oriented PHBV nanoribbons decorated by the PLA lamella, are successfully achieved through the multistage stretching extrusion (MSE) system. SEM confirms that in-situ highly oriented PHBV nanoribbons are achieved by biaxial-stretching field during the MSE process. Through investigating crystalline architecture of PLA/PHBV nanoribboned composites, it is found that the stiff shish and sparse lamellae of PLA are obtained under the coupling effect of PHBV nanoribbons and biaxial-stretching field. DMA reveals partial compatibility between PLA and PHBV. Interestingly, during tensile test, PHBV nanoribbons show high flexibility and synergistically facilitate the stretch of semi-rigid chains of PLA by an effective interfacial interaction. Consequently, even they both are extremely brittle, PLA/PHBV nanoribboned composites exhibit excellent strength (82.9 MPa) and ductility (186.7 %), compared with pure PLA (71.4 MPa and 12.3 %). Additionally, due to the promotion of the crystallization of PLA, PLA/PHBV nanoribboned composites show excellent heat resistance (E'_140°C > 350 MPa). The nanoribboned composites are of immense significance, which provide significant guidance for the simultaneous enhancement of ductility and strength of polymer materials.

A Journey from Processing to Recycling of Multilayer Waste Films: A Review of Main Challenges and Prospects

In a circular economy context with the dual problems of depletion of natural resources and the environmental impact of a growing volume of wastes, it is of great importance to focus on the recycling process of multilayered plastic films. This review is dedicated first to the general concepts and summary of plastic waste management in general, making emphasis on the multilayer films recycling process. Then, in the second part, the focus is dealing with multilayer films manufacturing process, including the most common materials used for agricultural applications, their processing, and the challenges of their recycling, recyclability, and reuse. Hitherto, some prospects are discussed from eco-design to mechanical or chemical recycling approaches.