For industrial-scale additive manufacturing (AM) to be successful, the adoption and innovation of sustainable materials made from biobased and renewable resources is vital. Herein, we explore the potential of using waste cork particles as a high-volume filler in nylon-12-based thermoplastic composites, with processing and performance characteristics optimized for fused filament fabrication (FFF) to create customized, lightweight engineered products. To generate engineering thermoplastic composites for FFF, we modified the cork with a silane coupling agent and melt-mixed it with nylon-12. A thorough evaluation was conducted on the impact of the volume fraction of the surface-modified cork filler on the viscoelastic and processing characteristics of the polymer melt. Using the optimized composition, filaments for 3D printing by FFF were produced, and their properties including thermal stability, crystallization behavior, filament extrusion morphology, and mechanical properties were evaluated. Scanning electron microscopy (SEM) was used on the tensile-fractured surface of the failure specimens to understand the mode of failure and correlate it with strength. Micro-CT was used as a nondestructive test to study the distribution of cork in the filament and the 3D-printed products. The surface roughness of the 3D-printed product was evaluated through digital microscopy. It was observed that (3-aminopropyl)triethoxysilane is an effective interaction promoter for nylon-12/cork composites. The melt rheology of nylon-12 and its composites exhibits non-Newtonian shear-thinning behavior and thermorheological complexity, with higher cork content further enhancing such shear-thinning characteristics. Considering processability, 3D printing capabilities, and final properties, a similar to 15 vol % cork content was observed to be optimal. It has been confirmed that 3D-printed nylon-12/cork composite products can offer superior mechanical properties, flexibility, and elongation at failure compared to compression-molded samples. This study provides valuable insights into the composite's feasibility for 3D printing and its potential applications.

Amongst various strategies to mitigate the environmental impact of non-degradable polymers, the integration of Cork with fossil fuel-derived Nylon is considered an attractive option to develop a lightweight, strong composite. To optimize the integration of these materials for processing as 3D printed structures requires the exploration of functional compatibilizers to enhance the homogeneity and 3D printability of the Nylon-Cork composite. In this paper, Nylon-12 (PA-12) was mixed with cork in varying melted compositions using one coupling agent/stabilizer/compatibilizer, namely: 3-aminopropyl triethoxysilane (APTS), to improve the interfacial bond between the components and amenability for 3D printed composite structures. This paper examines the characteristics of this composite using scanning electron microscope (SEM), rheology experiments and differential scanning calorimetry (DSC). These findings are used to understand and explain the ensuing 3D printed characteristics using the APTS compatibilizer and Nylon-Cork ratios. This work is expected to be critical for developing low-density engineering products using PA-12-Cork composites and for sustainable processing, using 3D printing technologies.

Herein, we demonstrate how compatibilizers affect the thermorheological properties and morphology of engineering thermoplastic composites based on nylon and cork. Nylon12 was melt-mixed with cork treated with four distinct compatibilizers with radically different chemical structures and compositions, respectively: (i) Octadecanamide (ODA), (ii) polyethylene-graft-maleic anhydride (PE-g-MA), (iii) polypropylene-graft-maleic anhydride (PP-g-MA), and (iv) (3-aminopropyl)triethoxysilane (APTS). The rheological behavior was assessed using an oscillatory rheometer and the morphology was visualized using a scanning electron microscope. The rheological data were thoroughly analyzed using different formalisms based on empirical, phenomenological, and molecular origin, including the Carreau-model, time-temperature superposition (TTS), Han plot, and van Gurp-Palmen (vGP) plot. It is observed that rheological data of neat nylon can be treated as themorheologically simple. However, the inclusion of cork makes the composite thermorheologically complex and increases the relaxation time (tau) by >50-fold when compared to the neat polymer. As compatibilizers, ODA and PP-g-MA significantly lower tau, improve internal flow behavior, and demonstrate good cork distribution and dispersion. However, PE-g-MA does not affect the tau of composites significantly. The application of APTS as a compatibilizer enhances the interfacial interaction between Nylon12 and cork most significantly, which leads to a notable rise in tau, and the composite's elastic modulus surges by two orders in magnitude compared to neat Nylon. Additionally, the polymer melt flow becomes elastically dominant. Finally, it is observed that the Han plot offers a better insight into the correlation between changes in the thermorheological behavior and the microstructural modifications to the composites.

Mycelium composites have gained attention in recent years for its environmental credentials and low-cost manufacturing. This emerging material has shown comparable strength to polystyrene foams and particle boards, resulting in its consideration as a sustainable alternative for many applications. Researchers have worked to improve many of mycelium composites properties; however, its strength has seen particular focus. The subject of this review is the methods of hybridization and reinforcement explored to strengthen mycelium composite boards and foams. The result of these methods is highly varied, with most having little effect on improving mycelium composites beyond control samples. Methods which did improve strength were often impractical and/or weaker than samples in which no hybridization or reinforcement was used. While mycelium composites remain an interesting solution for more sustainable materials, methods of hybridization and reinforcement do not appear to be contributing to viable improvements which could be applied to new applications.

The nature and the quality of the interfacial interaction and adhesion play a critical role in determining the physical characteristics and mechanical properties of all blends, composites, and nanocomposites. Herein, we examined the roles of functional compatibilizers of different natures and compositions that influenced the processing, interfacial interaction, bulk morphology, and final properties of Nylon-12/cork composites. In this study, Nylon-12 was melt-mixed with cork at 190 & DEG;C in an internal laboratory mixer in various compositions using four different compatibilizers namely, (i) octadecanamide (O), (ii) polyethylene-graft-maleic anhydride (PE-g-MAH), (iii) polypropylene-graft-maleic anhydride (PP-g-MAH), and (iv) 3-aminopropyl triethoxysilane (APTS), to improve the interfacial interaction and thereby their adhesion. To understand the impact of compatibilizers on the mechanical properties, morphological characteristics, and degradation properties, the developed composites were investigated using universal tensile testing (UTS), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscope (SEM), and X-ray diffraction (XRD) analysis. In addition, a high-resolution synchrotron macro-attenuated total reflection Fourier transform infrared (macro-ATR-FTIR) microspectroscopy was employed to explore the interfacial characteristics of the composites at the molecular level. The results indicated that cork was more evenly distributed in the Nylon-12 matrix when a small amount of compatibilizer was added to Nylon-12/cork composites. In particular, the mechanical properties of the Nylon-12 composites with APTS were substantially improved when compared with the composites without compatibilizers or with other types of compatibilizers used in this study. Furthermore, the study demonstrated the power of the high-resolution chemical mapping capability offered by the synchrotron macro-ATR-FTIR technique to acquire the spatial distribution and molecular-level information on the interfacial interactions of different components in composites. This fundamental information is pivotal for developing lightweight engineering products using Nylon-12/cork composites.

Supercapacitors have surfaced as a promising technology to store electrical energy and bridge the gap between a conventional capacitor and a battery. This chapter reviews various fabrication practices deployed in the development of supercapacitor electrodes and devices. A broader insight is given on the numerous electrode fabrication techniques that include a detailed introduction, principles, pros and cons, and their specific applications to provide a holistic view. Key performance parameters of an energy storage device are explained in detail. A further discussion comprises several electrochemical measurement procedures that are used for the supercapacitor performance evaluation. The performance characterization section helps to determine the correct approach that should be utilized for supercapacitor device performance measurement and assessment.

Surgical site infections (SSI) are amongst the most common medical infections, occurring in 2 to 4% of patients undergoing a surgical procedure. Smart surgical sutures can play an important role in preventing infection. For example, antimicrobial sutures detectable via clinical imaging modalities can support monitoring wounds post-surgery and enhance patient recovery. However, no commercial suture products possess these properties. Herein, contrasting iodine carbon nanoparticles (ICPs) are synthesized using a solvothermal approach. These ICPs were incorporated into polycaprolactone (PCL) via a coaxial extrusion technique inspired by the "core-shell" multilayered suture structure, which integrates multiple clinically favourable functions into one suture device. This system exhibits high imaging contrast capabilities for real-time imaging even after 22 days in-vitro, with strong antimicrobial properties and a reduction in biofilm formation. The multifunctional and biocompatible suture composite developed in this study shows strong antimicrobial properties and can act as an immobilized marker to monitor the surgical site during and after surgical procedures. Identifying suture integrity and location within the body through minimally invasive methods can alleviate patient discomfort and minimize the risk of infection.

Gallium and its alloys, such as eutectic gallium indium alloy (EGaIn), a form of liquid metal, have recently attracted the attention of researchers due to their low toxicity and electrical and thermal conductivity for biomedical application. However, further research is required to harness EGaIn-composites advantages and address their application as a biomedical scaffold. In this research, EGaIn-polylactic acid/polycaprolactone composites with and without a second conductive filler, MXene, were prepared and characterized. The addition of MXene, into the EGaIn-composite, can improve the composite's electrochemical properties by connecting the liquid metal droplets resulting in electrically conductive continuous pathways within the polymeric matrix. The results showed that the composite with 50% EGaIn and 4% MXene, displayed optimal electrochemical properties and enhanced mechanical and radiopacity properties. Furthermore, the composite showed good biocompatibility, examined through interactions with fibroblast cells, and antibacterial properties against methicillin-resistant Staphylococcus aureus. Therefore, the liquid metal (EGaIn) polymer composite with MXene provides a first proof-of-concept engineering scaffold strategy with low toxicity, functional electrochemical properties, and promising antimicrobial properties.

The transmission of seat structural vibration to the human body contributes to vibration discomfort particularly near the resonant frequencies (> 10 Hz). The conventional methods of controlling vehicle seat vibration may no longer be used on lightweight seat structures efficiently. Here, a new control method derived from multi-mode shunt damping using piezoelectric patches is proposed and is implemented on a vehicle seat to suppress the transmission of seat vibration to the occupant's body by controlling the seat foam vibration. The results indicate that the proposed method is effective for controlling seat vibration at the resonant frequencies of the seat. The application of the piezoelectric shunt damping system holds some promise for the future development of lightweight vehicle seats with enhanced ride comfort.

The use of additive manufacturing (AM) has moved well beyond prototyping and has been established as a highly versatile manufacturing method with demonstrated potential to completely transform traditional manufacturing in the future. In this paper, a comprehensive review and critical analyses of the recent advances and achievements in the field of different AM processes for polymers, their composites and nanocomposites, elastomers and multi materials, shape memory polymers and thermo-responsive materials are presented. Moreover, their applications in different fields such as bio-medical, electronics, textiles, and aerospace industries are also discussed. We conclude the article with an account of further research needs and future perspectives of AM process with polymeric materials.

Chitin and its derivative chitosan are popular constituents in wound-treatment technologies due to their nanoscale fibrous morphology and attractive biomedical properties that accelerate healing and reduce scarring. These abundant natural polymers found in arthropod exoskeletons and fungal cell walls affect almost every phase of the healing process, acting as hemostatic and antibacterial agents that also support cell proliferation and attachment. However, key differences exist in the structure, properties, processing, and associated polymers of fungal and arthropod chitin, affecting their respective application to wound treatment. High purity crustacean-derived chitin and chitosan have been widely investigated for wound-treatment applications, with research incorporating chemically modified chitosan derivatives and advanced nanocomposite dressings utilizing biocompatible additives, such as natural polysaccharides, mineral clays, and metal nanoparticles used to achieve excellent mechanical and biomedical properties. Conversely, fungi-derived chitin is covalently decorated with -glucan and has received less research interest despite its mass production potential, simple extraction process, variations in chitin and associated polymer content, and the established healing properties of fungal exopolysaccharides. This review investigates the proven biomedical properties of both fungal- and crustacean-derived chitin and chitosan, their healing mechanisms, and their potential to advance modern wound-treatment methods through further research and practical application.

Mycelium composites are an emerging class of cheap and environmentally sustainable materials experiencing increasing research interest and commercialisation in the EU and USA for construction applications. These materials utilise natural fungal growth as a low energy bio-fabrication method to upcycle abundant agricultural by-products and wastes into more sustainable alternatives to energy intensive synthetic construction materials. Mycelium composites have customisable material properties based on their composition and manufacturing process and can replace foams, timber and plastics for applications, such as insulation, door cores, panelling, flooring, cabinetry and other furnishings. Due to their low thermal conductivity, high acoustic absorption and fire safety properties outperforming traditional construction materials, such as synthetic foams and engineered woods, they show particular promise as thermal and acoustic insulation foams. However, limitations stemming from their typically foam-like mechanical properties, high water absorption and many gaps in material property documentation necessitate the use of mycelium composites as non- or semi-structural supplements to traditional construction materials for specific, suitable applications, including insulation, panelling and furnishings. Nonetheless, useful material properties in addition to the low costs, simplicity of manufacture and environmental sustainability of these materials suggest that they will play a significant role in the future of green construction.

Fungi-derived leather substitutes are an emerging class of ethically and environmentally responsible fabrics that are increasingly meeting consumer aesthetic and functional expectations and winning favour as an alternative to bovine and synthetic leathers. While traditional leather and its alternatives are sourced from animals and synthetic polymers, these renewable sustainable leather substitutes are obtained through the upcycling of low-cost agricultural and forestry by-products into chitinous polymers and other polysaccharides using a natural and carbon-neutral biological fungal growth process. Following physical and chemical treatment, these sheets of fungal biomass visually resemble leather and exhibit comparable material and tactile properties. Fungi-derived material can substitute for leather. This Review synthesizes information on this process and its environmental and ethical benefits.

Mycelium, the vegetative growth of filamentous fungi, has attracted increasing commercial and academic interest in recent years because of its ability to upcycle agricultural and industrial wastes into low-cost, sustainable composite materials. However, mycelium composites typically exhibit foam-like mechanical properties, primarily originating from their weak organic filler constituents. Fungal growth can be alternatively utilized as a low-cost method for on-demand generation of natural nanofibrils, such as chitin and chitosan, which can be grown and isolated from liquid wastes and byproducts in the form of fungal microfilaments. This study characterized polymer extracts and nanopapers produced from a common mushroom reference and various species of fungal mycelium grown on sugarcane byproduct molasses. Polymer yields of ∼10-26% were achieved, which are comparable to those of crustacean-derived chitin, and the nanopapers produced exhibited much higher tensile strengths than the existing mycelium materials, with values of up to ∼25 MPa (mycelium) and ∼98 MPa (mushroom), in addition to useful hydrophobic surface properties resulting from the presence of organic lipid residues in the nanopapers. HCl or H2O2 treatments were used to remove these impurities facilitating tuning of mechanical, thermal, and surface properties of the nanopapers produced. This potentially enables their use in a wide range of applications including coatings, membranes, packaging, and paper.

Agricultural by-products can be upcycled into environmentally-sustainable, inexpensive chitinous materials and nanofibers derived from fungal mycelium for composites, cosmetics, pharmaceuticals and water treatment applications. This study determined the suitability of common agricultural by-products as medium for fungal growth. Growth was measured by quantifying ergosterol, a unique fungal product, in solid and liquid media. The results reveal that fungi grew less on rice hull, sugarcane bagasse and wheat straw agricultural by-products than on commercial wheat grains. However, the liquid agricultural by-product blackstrap molasses facilitated very high biomass production, outperforming the commonly used laboratory nutrient malt extract. Hyphal fusion, sheet formation and hyphal diameter metrics of fungi growing on each substrate were evaluated by SEM to assess suitability for chitin nanofiber production. Utilising these materials offers a cheap, renewable, easily-isolated, and abundant alternative to problematic crustacean chitin that when implemented on a large scale could rapidly upcycle low-value agricultural by-products into high-value chitinous materials.

SummaryMycelial growth attracts academic and commercial interest because of its ability to upcycle agricultural and industrial wastes into economical and environmentally sustainable composite materials using a natural, low‐energy manufacturing process able to sequester carbon. This study aims to characterise the effect of varying ratios of high silica agricultural and industrial wastes on the flammability of mycelium composites, relative to typical synthetic construction materials. The results reveal that mycelium composites are safer than the traditional construction materials considered, producing much lower average and peak heat release rates and longer time to flashover. They also release significantly less smoke and CO2, although CO production fluctuated. Rice hulls yielded significant char and silica ash which improved fire performance, but composites containing glass fines exhibited the best fire performance because of their significantly higher silica concentrations and low combustible material content. Higher concentrations of glass fines increased volume‐specific cost but reduced mass‐specific and density‐specific costs. The findings of this study show that mycelium composites are a very economical alternative to highly flammable petroleum‐derived and natural gas‐derived synthetic polymers and engineered woods for applications including insulation, furniture, and panelling.

Composite materials produced using mycelial growth attract commercial and academic interest due to their economic, environmentally sustainable and green manufacturing process. However, their manufacture via slow biological growth affects the larger scale production viability of these materials, which must compete with rapidly producible synthetic materials. Hyphal characteristics vary significantly by species, which is the most influential growth performance factor in conjunction with environmental conditions and chemical nutrition. This study assessed the effect of potential growth predictors such as hyphal type, pathogenicity, taxonomic and association based classification systems on hyphal extension rate and growth density for commonly used and non-traditional species. It provides a simple, low-cost process for screening species by growth performance prior to more application-dependent mechanical evaluation. This facilitates more efficient and accurate species selection for composite manufacturing applications. Trimitic and dimitic species containing skeletal hyphae exhibited higher hyphal extension rates than species containing generative-binding or purely generative hyphae but no other parameters investigated in this study were good predictors for growth performance with significant species-specific variation present instead. However, the methodology used to test growth performance did prove effective and could be used on a case by case basis for growth screening in mycelium composite applications.

This paper studies a two degree of freedom electromagnetic vibration energy harvesting system with a magnet arrangement of the Halbach array. A theoretical analysis and computational simulation of the system were established through frequency response analysis and time domain integration of the system motion equations using the Matlab Simulink software. The results of the theoretical analysis and simulation models were compared with the results of a series of experiments, verifying the analysis approach.

Bulk metallic glass matrix composites are advocated to be material of future owing to their superior strength, hardness and elastic strain limit. However, they possess poor toughness which makes them unusable in any structural engineering application. Inoculation has been used as an effective means to overcome this problem. Zr47.5Cu45.5Al5Co2 bulk metallic glass matrix composites (BMGMC) inoculated with ZrC have shown considerable refinement in microstructure owing to heterogeneous nucleation. Efforts have also been made to exploit modern laser-based metal additive manufacturing to fabricate BMGMC parts in one step. However, the effect of laser treatment on inoculated material is unknown. In this study, an effort has been made to apply laser based additive manufacturing on untreated and inoculated BMGMC samples. It is observed that laser treatment not only refined the microstructure but resulted in change of size, morphology and dispersion of CuZr B2 phase in base metal, heat affected zone and fusion zone. This effect is documented with back scattered electron imaging. This provides a basis for further research to quantify this phenomenon and full-scale part development.