During the last decade, the consumption of plastics has increased highly in parallel with plastic waste. The transition towards a circular economy is the only way to prevent the environment from landfilling and incineration. This review details the recycling techniques with a focus on mechanical recycling of polymers, which is the most known and developed technique in industries. The different steps of mechanical recycling have been highlighted, starting from sorting technologies to the different decontamination processes. This paper covers degradation mechanisms and ways to improve commodity polymers (Polyolefins), engineering polymers (PET, PA6), and bio-sourced polymers (PLA and PHB).

Lignocellulosic fillers have attracted considerable attention over the years as a promising alternative to conventional petroleum-based fillers (carbon black) in rubber composites due to their renewability, biodegradability, availability, high mechanical properties, low density and low cost. Based on the literature available, a comprehensive review is presented here of rubber biocomposites reinforced with plant-based fillers. The study is divided into different sections depending on the matrix (natural or synthetic rubber) and the type of lignocellulosic fillers (natural fiber, microcrystalline cellulose, lignin and nanocellulose). This review focuses on the curing characteristics, mechanical properties and dynamic mechanical properties of the resulting rubber biocomposites. In addition, the effect of hybrid filler systems, lignocellulosic filler surface modification and modification of the rubber matrix on the properties of these rubber biocomposites are presented and compared. A conclusion is finally presented with some openings for future works.

New materials and the interactions between them are the basis of novel energy storage devices such as supercapacitors and batteries. In recent years, because of the increasing demand for electricity as an energy source, the development of new energy storage materials is among the most actively studied topics. Conductive polymers (CPs), because of their intrinsic electrochemical activity and electrical conductivity, have also been intensively explored. While most of the high capacitance reported in the literature comes from hybrid materials, for example, conductive polymers composed of metal oxides and carbon materials, such as graphene and carbon nanotubes, new chemistry and the 3D structure of conductive polymers remain critical. This comprehensive review focuses on the basic properties of three popular conductive polymers and their composites with carbon materials and metal oxides that have been actively explored as energy storage materials, i.e., polypyrrole (PPy), polyaniline (PANi), and polythiophene (PTh), and various types of electrolytes, including aqueous, organic, quasi-solid, and self-healing electrolytes. Important experimental parameters affecting material property and morphology are also discussed. Electrochemical and analytical techniques frequently employed in material and supercapacitor research are presented. In particular, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) are discussed in detail, including how to extract data from spectra to calculate key parameters. Pros and cons of CP-based supercapacitors are discussed together with their potential applications.

Fuel cells are gaining increasing importance as a promising alternative to traditional energy sources, primarily due to their exceptional efficiency and environmental advantages. The electrical performance of proton exchange membrane fuel cells (PEMFCs) largely depends on the effectiveness of proton and electron transport within the cell components. A critical factor impacting this efficiency is the electrical conductivity of polymer‐based bipolar plates (BPPs), which play a fundamental role as current collectors. BPPs in PEMFCs can be made from various materials including coated metallic materials, graphitic materials, and polymer composites. This review exclusively concentrates on polymer composite BPPs. Enhancing the overall cell performance is achievable through the integration of electrically conductive additives into the polymer matrix of these plates. Graphite (GR), carbon black (CB), carbon fibers (CF), carbon nanotubes (CNT), and graphene (Gr) all emerge as highly promising functional materials capable of substantially elevating BPPs performance. This study, among its various objectives, delves into the synergistic effects of these electrically conductive additives and their capacity to enhance the electrical conductivity within polymeric matrices. Furthermore, this review article thoroughly explores the influence of the polymeric matrix, encompassing co‐continuous morphology and processing conditions. In essence, it focuses on the improvement of BPPs electrical conductivity through innovative designs of their polymer‐based composites and nanocomposites and the particular selection of the electrically conductive fillers. The insights derived from this study significantly contribute to a more profound understanding of how to effectively harness the potential of this vital PEMFC component.