Full Recyclability Research Articles

Gold nanoparticles stabilized by modified halloysite nanotubes for catalytic applications

A highly sustainable prototype of a flow system based on gold nanoparticles (4.2 nm) supported on thiol‐functionalized halloysite nanotubes (HNTs) was developed for catalytic applications. The catalytic performances were evaluated using the reduction of 4‐nitrophenol to 4‐aminophenol as a model system. Under the best experimental conditions (0.0001 mol%, 1.97 × 10−8 mg of Au nanoparticles), an impressive apparent turnover frequency value up to 2 204 530 h−1 was achieved and the halloysite‐based catalyst showed full recyclability even after ten cycles. The high catalytic activity confirms the importance of the use of HNTs as support for Au nanoparticles that can exert a synergistic effect both as medium for transfer of electrons from borohydride ions to 4‐nitrophenol and by modulating interfacial electron transfer dynamics. With the application of flow technology, the obtained heterogeneous HNT@Au catalyst was fully recovered and reused for at least one month.

Reprocessable and robust crosslinked elastomers via interfacial C[sbnd]N transalkylation of pyridinium

Covalently cross-linked elastomers with high elasticity are widely found in daily life and high-tech areas. However, the irreversibility of the crosslinked networks hinders the rubber products from reprocessing or recycling, causing a major environmental problem. Recently developed vitrimer chemistry provides fantastic avenues for cross-linked elastomers to achieve full reprocessability and recyclability. Herein, we disclose a novel CN transalkylation of pyridinium by model studies and implant this chemistry into the interfaces of an elastomeric composite. As a proof of concept, (3-bromopropyl)trimethoxysilane modified silica was used to crosslink butadiene-styrene-vinylpyridine rubber, forming pyridiniums in the interfaces. The composites were prepared by straightforward mechanical compounding and subsequent hot-pressing. Because of the covalent interfacial bridges and excellent dispersion of silica, the composites possess robust mechanical properties. Furthermore, the CN transalkylation reactions of pyridiniums at elevated temperature endows the composites with vitrimer properties, such as malleability and reprocessability. As the pyridine moieties can be easily introduced into a great variety of commercial polymers, we envision this newly demonstrated CN transalkylation of pyridinium possesses significant potential in broadening the gallery of vitrimer materials.

Needs, restrictions and priorities for the development and installation of a multifunctional C-ITS solution on existing road pavement

Abstract The scope of this paper is to recognize the needs, restrictions and priorities in developing effort of a breaking through technology that will achieve to enable Cooperative Intelligent Transportation System (C-ITS) applications in existing road infrastructure, to make roads self-explanatory and forgiving for all road users and all vehicle generations with reduced maintenance cost, full recyclability and added value services, as well as supporting real-time predictive road maintenance functions. The enhanced broad functionality of the system on multiple levels imposes emerging needs and demands that will constitute the groundwork of the Use Cases for the implementation of the project, which are extracted through an iterative user-centered methodology approach and correspond to the target applications of the system. More particularly, the needs, views and priorities of all the relevant stakeholders have been captured through the outputs of 431 respondents participated from 10 countries in on-line and in-depth surveys. From the infrastructure point of view, the complementary investigation of relevant accident/incident and gaps/priorities was based on literature while the legal/operational limitations have been based on the study of relevant Directives and the view of experts. These sources provided important qualitative as well as quantitative outcomes, the aggregation of which led to the prioritisation of the target applications, two of which (last in ranking) are considered to be secondary in the sense that can be implemented with some flexibility.

Ionic Liquid Approach Toward Manufacture and Full Recycling of All‐Cellulose Composites

AbstractAll‐cellulose composites (ACCs) are prepared from high‐strength rayon fibers and cellulose pulp. The procedure comprises the use of a pulp cellulose solution in the ionic liquid (IL) 1‐ethyl‐3‐methyl imidazolium acetate ([EMIM][OAc]) as a precursor for the matrix component. High‐strength rayon fibers/fabrics are embedded in this solution of cellulose in the IL followed by removal of the IL. Different concentrations of cellulose in the IL are investigated and the mechanical properties of the final ACCs are determined via tensile, bending, and impact testing. ACCs prepared in this study show mechanical properties comparable to thermoplastic glass fiber‐reinforced plastics. Apart from being bio‐based, they possess several advantages such as biodegradability and full recyclability. The recycling of ACCs is successfully demonstrated in several cycles by using the recycled cellulose for subsequent matrix preparation.

Rehealable imide–imine hybrid polymers with full recyclability

Mechanically strong yet rehealable and recyclable thermosets were achieved through hybridization of rigid imide moieties and dynamic imine linkages.

Repairable Woven Carbon Fiber Composites with Full Recyclability Enabled by Malleable Polyimine Networks

Carbon-fiber reinforced composites are prepared using catalyst-free malleable polyimine networks as binders. An energy neutral closed-loop recycling process has been developed, enabling recovery of 100% of the imine components and carbon fibers in their original form. Polyimine films made using >21% recycled content exhibit no loss of mechanical performance, therefore indicating all of the thermoset composite material can be recycled and reused for the same purpose.

Experimental evaluation of a fully recyclable thermoplastic composite

For several years the application of composite materials with continuous fiber were limited to those with thermosetting matrix. Indeed, in recent years, there is a growing interest in composites with thermoplastic matrix thanks to the considerable advantages in terms of recyclability, and the reduction in weight and in production costs. In the automotive sector, increasingly stringent requirements for reduced emissions of CO2, the maximum return on capital investment and the increase in plastic recycling and reuse, are some of the most important problems that directly influence the development of new materials. The thermoplastic composites appear to be the right alternative to the materials currently used for vehicles. They can replace not only the not structural parts (such as the interiors), but also the structural components located in areas potentially subject to impacts.This paper presents the results of an experimental campaign made on a full thermoplastic composite, where both the reinforcement and the matrix are made in thermoplastic. The target is to know the mechanical properties in order to design an energy absorber with this new material. Initially, tensile, compression, bending and shear tests were made according to standards to obtain the mechanical characteristics. Subsequently, static and dynamic tests on thin-walled cylindrical tubes subjected to axial load were made in order to assess the energy absorption capacity varying the project parameters. The data were recorded and analyzed in terms of load–displacement curves, specific energy absorption (SEA), crush force efficiency (CFE), stroke efficiency (SE) and crushing stress. Comparing the new material to a common thermosets composite, different values of SEA are evident; fully thermoplastic composites are 3/4 times lower in energy absorption capacity. Nevertheless, taking into account the other favorable characteristic (such as full recyclability and shorter processing times) this fully thermoplastic material continues to be interesting for lightweight design. From the point of view of the energy absorption its spring back behavior offers some advantages respect to thermoset and conventional materials that tend to shatter and to buckle in the event of impact, respectively.

Recyclable Ligands for the Non-Enzymatic Dynamic Kinetic Resolution of Challenging α-Amino Acids.

Structurally simple and inexpensive chiral tridentate ligands were employed for substantially advancing the purely chemical dynamic kinetic resolution (DKR) of unprotected racemic tailor-made α-amino acids (TM-α-AAs), enabling the first DKR of TM-α-AAs bearing tertiary alkyl chains as well as multiple unprotected functional groups. Owing to the operationally convenient conditions, virtually complete stereoselectivity, and full recyclability of the source of chirality, this method should find wide applications for the preparation of TM-α-AAs, especially on large scale.

Compression properties of novel thermoplastic carbon fibre and poly-ethylene terephthalate fibre composite lattice structures

A novel manufacturing route to efficiently produce fibre composite lattice structures has been developed. By using thermoplastic composite materials, flat sheets have been continuously folded, cut into a lattice shape and joined into a sandwich structure. Carbon fibre reinforced poly-ethylene terephthalate (CPET) and poly-ethylene terephthalate fibre reinforced poly-ethylene terephthalate (SrPET) materials have been used to explore two different core options; a carbon fibre option which gives high performance but low recyclability and a single polymer PET option which gives lower performance but full recyclability. Parametric numerical simulations have been used to investigate how the various manufacturing parameters affect the mechanical performance of the core. The carbon fibre composite cores have mechanical performance on-par or better than existing metallic and composite lattice cores presented in literature. Single polymer PET cores show better performance compared to high-end foam cores but have considerable lower performance than carbon fibre lattice cores.

Highly Enantioselective Michael Additions in Water Catalyzed by a PS-Supported Pyrrolidine

The development of a highly efficient, polymer-supported organocatalyst for the Michael addition of ketones to nitroolefins is described. A 1,2,3-triazole ring, constructed through a click 1,3-cycloaddition, plays the double role of grafting the chiral pyrrolidine monomer onto the polystyrene backbone and of providing a structural element, complementary to pyrrolidine, key to high catalytic activity and enantioselectivity. Optimal operation in water and full recyclability make the triazole linker attractive for the immobilization of organocatalysts.

Forty years of industrial developments in the field of isotactic polyolefins

AbstractThe interest for the stereospecific polymerization of olefins discovered by prof. Natta in 1954 was so high that only a few years elapsed between the discovery and the commercialization of polypropylene. The polypropylene discovery generated a tremendous scientific and technological effort for the development of the catalyst, the process, the products. The fundamental achievements in the polypropylene technology had a significant impact over the polyolefin technology in general. Thanks to it, polyolefinic polymers, copolymers and rubbers, polyefinic based materials and alloys via heterogeneous Ziegler‐Natta catalyst polymerization are today largerly the most important family of plastic materials.The ability to vary melt flow and the broad properties range of these materials, the excellent thermal and physical‐mechanical properties of isotactic polyolefins together with the favorable economics and their full and easy recyclability widen the concept of monomaterial application fuelling their dynamic expansion since the early sixties.