Material Library System for Circular Economy: Tangible-Intangible Interaction for Recycled Composite Materials

Currently the development of new circular materials has brought up the necessity to transfer their knowledge amongst the interested stakeholders for their real exploitation. This chapter aims to illustrate the design of a physical and virtual library system of the FiberEUse project. In particular, this library system wants to foster the development of new applications and value chains through the showcase of the new recycled composite materials and archetypal remanufactured products developed during the project. After the definition of the system concept, specific taxonomies were designed for the physical and virtual parts considering the technical properties and the expressive-sensorial qualities of the new recycled materials and products. A hierarchical organization was then designed to allow both tangible and intangible interactions with the samples, resulting in a coherent experience to explore these new recycled materials. Meanwhile, the physical exhibitors and the library website were developed to collect the physical and virtual samples. At the end, the whole system will be freely accessible through the library website and by booking a visit to the physical part. Thanks to its transdisciplinary nature, this system can stimulate the real exploitation of new value chains and applications

Recycling Glass and Carbon Fibers for Reusable Components in the Automotive Sector through Additive Manufacturing

This work explores the use of additive manufacturing (AM) to reprocess recycled glass and carbon fibers in the automotive sector. It aims to foster exploitation of recycled Glass Fiber Reinforced Polymers (rGFRPs) and recycled Carbon Fiber Reinforced Polymers (rCFRPs) through two manufacturing workflows: indirect Fused Filament Fabrication (FFF) and UV-assisted Direct Ink Writing (UV-DIW). An industrial case study on vehicle components has been considered by prototyping one real component. After the tensile tests, some molds were fabricated with a FFF 3D printer for the indirect 3D printing process to cast an epoxy-based thermosetting resin with rGFs and rCFs. The second technology consisted in fabricating the parts by hardening in-situ a photo- and thermal-curable thermosetting acrylic liquid resin with rGFs. These results validate the use of AM and recycled composites for applications in the automotive sector. These approaches may be implemented for customizable components for batches below 100 vehicles as the first step for their exploitation

Metallization of Recycled Glass Fiber-Reinforced Polymers Processed by UV-Assisted 3D Printing

An ever-growing amount of composite waste will be generated in the upcoming years. New circular strategies based on 3D printing technologies are emerging as potential solutions although 3D-printed products made of recycled composites may require post-processing. Metallization represents a viable way to foster their exploitation for new applications. This paper shows the use of physical vapor deposition sputtering for the metallization of recycled glass fiber-reinforced polymers processed by UV-assisted 3D printing. Different batches of 3D-printed samples were produced, post-processed, and coated with a chromium metallization layer to compare the results before and after the metallization process and to evaluate the quality of the finishing from a qualitative and quantitative point of view. The analysis was conducted by measuring the surface gloss and roughness, analyzing the coating morphology and thickness through the Scanning Electron Microscopy (SEM) micrographs of the cross-sections, and assessing its adhesion with cross-cut tests. The metallization was successfully performed on the different 3D-printed samples, achieving a good homogeneity of the coating surface. Despite the influence of the staircase effect, these results may foster the investigation of new fields of application, as well as the use of different polymer-based composites from end-of-life products, i.e., carbon fiber-reinforced polymers

Additive Manufacturing of Recycled Composites

An additive remanufacturing process for mechanically recycled glass fibers and thermally recycled carbon fibers was developed. The main purpose was to demonstrate the feasibility of an additive remanufacturing process starting from recycled glass and carbon fibers to obtain a new photo- and thermally-curable composite. 3D printable and UV-curable inks were developed and characterized for new ad-hoc UV-assisted 3D printing apparatus. Rheological behavior was investigated and optimized considering the 3D printing process, the recyclate content, and the level of dispersion in the matrix. Some requirements for the new formulations were defined. Moreover, new printing apparatuses were designed and modified to improve the remanufacturing process. Different models and geometries were defined with different printable ink formulations to test material mechanical properties and overall process quality on the final pieces. To sum up, 3D printable inks with different percentages of recycled glass fiber and carbon fiber reinforced polymers were successfully 3D printed

Composite Finishing for Reuse

Coating processes are emerging for new applications related to remanufactured products from End-of-Life materials. In this perspective, their employment can generate interesting scenarios for the design of products and solutions in circular economy frameworks, especially for composite materials. This chapter would give an overview of coating design and application for recycled glass fiber reinforced polymers on the base of the experimentation made within the FiberEUse project. New cosmetic and functional coatings were developed and tested on different polymer composite substrates filled with mechanically recycled End-of-Life glass fibers. Afterwards, recycled glass fiber reinforced polymer samples from water-solvable 3D printed molds were successfully coated. Finally, new industrial applications for the developed coatings and general guidelines for the coating of recycled glass fiber reinforced polymers were proposed by using the FiberEUse Demo Cases as a theoretical proof-of-concept

Italian Offshore Platform and Depleted Reservoir Conversion in the Energy Transition Perspective

New hypotheses for reusing platforms reaching their end-of-life have been investigated in several works, discussing the potential conversions of these infrastructures from recreational tourism to fish farming. In this perspective paper, we discuss the conversion options that could be of interest in the context of the current energy transition, with reference to the off-shore Italian scenario. The study was developed in support of the development of a national strategy aimed at favoring a circular economy and the reuse of existing infrastructure for the implementation of the energy transition. Thus, the investigated options include the onboard production of renewable energy, hydrogen production from seawater through electrolyzers, CO2 capture and valorization, and platform reuse for underground fluid storage in depleted reservoirs once produced through platforms. Case histories are developed with reference to a typical, fictitious platform in the Adriatic Sea, Italy, to provide an engineering-based approach to these different conversion options. The coupling of the platform with the underground storage to set the optimal operational conditions is managed through the forecast of the reservoir performance, with advanced numerical models able to simulate the complexity of the phenomena occurring in the presence of coupled hydrodynamic, geomechanical, geochemical, thermal, and biological processes. The results of our study are very encouraging, because they reveal that no technical, environmental, or safety issues prevent the conversion of offshore platforms into valuable infrastructure, contributing to achieving the energy transition targets, as long as the selection of the conversion option to deploy is designed taking into account the system specificity and including the depleted reservoir to which it is connected when relevant. Socio-economic issues were not investigated, as they were out of the scope of the project

Thermoresponsive polymer micropatterns fabricated by dip-pen nanolithography for a highly controllable substrate with potential cellular applications

We report a novel approach for patterning thermoresponsive hydrogels based on N,N-diethylacrylamide (DEAAm) and bifunctional Jeffamine ED-600 by dip-pen nanolithography (DPN). The direct writing of micron-sized thermoresponsive polymer spots was achieved with efficient control over feature size. A Jeffamine-based ink prepared through the combination of organic polymers, such as DEAAm, in an inorganic silica network was used to print thermosensitive arrays on a thiol-silanised silicon oxide substrate. The use of a Jeffamine hydrogel, acting as a carrier matrix, allowed a reduction in the evaporation of ink molecules with high volatility, such as DEAAm, and facilitated the transfer of ink from tip to substrate. The thermoresponsive behaviour of polymer arrays which swell/de-swell in aqueous solution in response to a change in temperature was successfully characterised by atomic force microscopy (AFM) and Raman spectroscopy: a thermally-induced change in height and hydration state was observed, respectively. Finally, we demonstrate that cells can adhere to and interact with these dynamic features and exhibit a change in behaviour when cultured on the substrates above and below the transition temperature of the Jeffamine/DEAAm thermoresponsive hydrogels. This demonstrates the potential of these micropatterned hydrogels to act as a controllable surface for cell growth

The role of sol–gel chemistry in the low-temperature formation of ZnO buffer layers for polymer solar cells with improved performance

A new approach is proposed in this work to chemically control the low-temperature sol-gel formation of ZnO thin films used as efficient electron transporting layers (ETLs) in inverted polymer solar cells (PSCs). The chemical composition of the ZnO sol-gel precursor was modified by systematically employing different [H2O]/[Zn2+] molar ratios in the starting sol formulation and evaluating their influence on film properties and PSC device performance. A thorough characterization of the obtained ZnO ETLs evidenced the key importance of the [H2O]/[Zn2+] molar ratio to achieve effective control on the sol-gel hydrolysis and condensation processes. Based on these evidences, a mechanism for the formation of the ZnO films at the low processing temperatures used in this work was proposed. PSC devices were fabricated incorporating ZnO ETLs obtained from ZnO sol precursor formulations with increasing [H2O]/[Zn2+] ratios and their photovoltaic characterization revealed the presence of a maximum device efficiency for intermediate [H2O]/[Zn2+] values. Finally, the effect of water in the ZnO sol precursor on the long-term (>1000 h) shelf-life of PSCs fabricated onto flexible PET substrates was investigated and a correlation was found between chemical composition of the ZnO sol precursor and device shelf-life. The results of this study give a clear demonstration of a viable strategy to achieve improved PSC device performance by chemically controlling the formation of the sol-gel based ZnO ETL at processing temperatures compatible with flexible plastic substrates and provide useful guidelines for the development of efficient sol-gel derived metal-oxide buffer layers for highly performing flexible photovoltaics

Biomass waste materials through extrusion-based additive manufacturing: A systematic literature review

Circular economy and bioeconomy models have increasingly spread the principles of sustainable development through different strategies such as reuse and recycling. Biomass waste and by-products are often considered valuable resources. Digital technologies, i.e., extrusion-based additive manufacturing, may potentially foster their exploitation as new materials, although the current framework has not been clearly defined yet. This work wants to systematically review the publications focused on new materials from biomass waste or by-products for extrusion-based additive manufacturing processes. The current situation was analyzed on 69 selected works from 2016 searched on Scopus and WoS, focusing on the different raw materials, new 3D printable materials, 3D printing processes, and potential applications. Afterward, the emerging trends were highlighted through selected best practices from the design practice and industrial sectors. Despite the significant development of thermoplastic reinforced materials, i.e., PLA-filled composites, a wide range of biomass waste and by-products have been studied, especially for small format low-cost Fused Filament Fabrication. Although the academic field may be less focused on exploiting these new circular materials, the interest in new applications is increasing within the design practice and industrial sectors, fostering new synergies within bioeconomy and circular economy contexts