Agri-food wastes (such as brewer’s spent grain, olive pomace, residual pulp from fruit juice production, etc.) are produced annually in very high quantities posing a serious problem, both environmentally and economically. These wastes can be used as secondary starting materials to produce value-added goods within the principles of the circular economy. In this context, this review focuses on the use of agri-food wastes either to produce building blocks for bioplastics manufacturing or biofillers to be mixed with other bioplastics. The pros and cons of the literature analysis have been highlighted, together with the main aspects related to the production of bioplastics, their use and recycling. The high number of European Union (EU)-funded projects for the valorisation of agri-food waste with the best European practices for this industrial sector confirm a growing interest in safeguarding our planet from environmental pollution. However, problems such as the correct labelling and separation of bioplastics from fossil ones remain open and to be optimised, with the possibility of reuse before final composting and selective recovery of biomass.

In the last decades, new synthetic hybrid materials, with an inorganic and organic nature, have been developed to promote their application as protective coatings and/or structural consolidants for several substrates in the construction industry and cultural heritage field. In this context, the scientific community paid attention to geopolymers and their new hybrid functional derivatives to design and develop innovative and sustainable composites with better chemical resistance, durability and mechanical characteristics. This review offers an overview of the latest progress in geopolymer-based hybrid nanofunctional materials and their use to treat and restore cultural heritage, as well as their employment in the building and architectural engineering field. In addition, it discusses the influence of some parameters, such as the chemical and physical characteristics of the substrates, the dosage of the alkaline activator, and the curing treatment, which affect their synthesis and performance.

In this work, the wear behavior of the mechanical coupling between the biomedical polymer ultrahigh molecular weight polyethylene (UHMWPE) and the titanium-aluminum-vanadium alloy pin (Ti4Al6V) manufactured by electron beam melting (EBM) is investigated. Pure and oxidized graphite fillers is added to the UHMWPE matrix to boost the wear resistance. The tribological test is performed in dry and under the action of various lubricating media (distilled water [DW], simulated synovial fluid [SSF], and natural bovine serum [NBS]) in order to investigate their effects on wearing. The physical-mechanical characterization results show a progressive increase in wear resistance of more than 60% in the nanocomposite (UHMWPE/GO) with the addition of paraffin oil (PO) compared to the UHMWPE and higher under NBS lubricant (more than 80%). The observed wear action is reduced in the order Dry > DW > SSF ≥ NBS, thereby lowering the debris production.

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