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Fiber-reinforced polymers (FRPs) are low-density, high-performance composite materials, which find important applications in the automotive, aerospace, and energy industry, to only cite a few. With the increasing concerns about sustainability and environment risks, the problem of the recycling of such complex composite systems has been emerging in politics, industry, and academia. The issue is exacerbated by the increased use of FRPs in the automotive industry and by the expected decommissioning of airplanes and wind turbines amounting to thousands of metric tons of composite materials. Currently, the recycling of FRPs downcycles the entire composite to some form of reinforcement material (typically for cements) or degrades the polymer matrix to recover the fibers. Following the principles of sustainability, the reuse and recycling of the whole composite—fiber and polymer—should be promoted. In this review paper, we report on recent research works that achieve the recycling of both the fiber and matrix phase of FRP composites, with the polymer being either directly recovered or converted to value-added monomers and oligomers.

The European Union is working towards the 2050 net-zero emissions goal and tackling the ever-growing environmental and sustainability crisis by implementing the European Green Deal. The shift towards a more sustainable society is intertwined with the production, use, and disposal of plastic in the European economy. Emissions generated by plastic production, plastic waste, littering and leakage in nature, insufficient recycling, are some of the issues addressed by the European Commission. Adoption of bioplastics–plastics that are biodegradable, bio-based, or both–is under assessment as one way to decouple society from the use of fossil resources, and to mitigate specific environmental risks related to plastic waste. In this work, we aim at reviewing the field of bioplastics, including standards and life cycle assessment studies, and discuss some of the challenges that can be currently identified with the adoption of these materials.

Polyethylene-based organic inorganic hybrids were prepared by one-step reactive melt mixing using a mono-functionalized nanofiller, i.e., allyl-heptaisobutyl-substituted polyhedral oligomeric silsesquioxane (1POSS) and a multi-functionalized octavinyl polyhedral oligomeric silsesquioxane (8POSS). The hybrids were also prepared in dicumyl peroxide (DCP) presence and morphological, spectroscopical and calorimetric analysis were carried out. Moreover, rheological measurement and Sohxlet extraction were performed on investigated samples. It was inferred that double bonds of POSS functional groups were triggered by radicals coming from the peroxide decomposition or from the degradation reactions occurring during preparation. The type of the functional groups (mono- or multi-reactive) of the POSS is a leading factor, along with radicals content in the systems, in the formation of a polymeric network. In particular, the presence of multi-reactive groups in 8POSS molecules results in a successful POSS grafting/crosslinking in the polymeric backbone: the covalent bonds formation between nanofillers and matrix during processing improves POSS dispersion within the polyolefin matrix and leads to a network structure formation.

This study reports the one-step reactive melt mixing preparation of organic–inorganic hybrid based on maleic anhydride-grafted polyethylene and 3-(2-aminoethyl)aminopropyl-heptaisobutyl substituted polyhedral oligomeric silsesquioxane, (NPOSS), as well as on low-density polyethylene and allyl-heptaisobutyl-POSS (1POSS) in dicumyl peroxide presence, which is believed to activate the unsaturation of the reactive functional group of POSS itself. The successful grafting of POSS molecules onto polymeric backbones was probed through rheological and spectroscopic analysis. Grafting of POSS molecules enhances their dispersion in the polymeric matrix as shown by morphological analysis. Moreover, the rheological analysis of the organic–inorganic hybrids reveals a solid-like behavior, due to the formation of a network related to the interactions between grafted POSS molecules. The homogeneous dispersion of POSS molecules along with the strong interaction between polymeric segments and the nanoparticles influences the calorimetric and mechanical properties of the obtained hybrids.